# Installing a 4.3l vortec in a 68 Lemans



## scottiesautomotive (Dec 31, 2021)

Probably frowned upon to the “keep it a classic” guys on here but I want to try something new and I can’t find information on this anywhere on google and I m semi new to engine/trans swaps. I have an 05 Silverado 1500 with a 4.3l 4l60e combo that I’d like to put in my 68 tempest lemans that originally had a Pontiac 350/350 auto trans. What all would need to be done in order to make this happen? I’m not concerned with the power downgrade as I won’t be racing it or anything like that. Just a playtoy i saved from the crusher. Any and all information is helpful


----------



## PontiacJim (Dec 29, 2012)

scottiesautomotive said:


> Probably frowned upon to the “keep it a classic” guys on here but I want to try something new and I can’t find information on this anywhere on google and I m semi new to engine/trans swaps. I have an 05 Silverado 1500 with a 4.3l 4l60e combo that I’d like to put in my 68 tempest lemans that originally had a Pontiac 350/350 auto trans. What all would need to be done in order to make this happen? I’m not concerned with the power downgrade as I won’t be racing it or anything like that. Just a playtoy i saved from the crusher. Any and all information is helpful


OMG! A Chevy in a Pontiac and a V6 at that! Holy Moley.

Should be different as the 4.3 V6 is a good engine, have one in my 1992 S10 with a 5-speed and it's my little hot rod when I want to race around down and try and chirp gears. LOL

There won't be any easy/simple bolt it. My guess is that this is going to be a custom fabrication deal. You are most likely going to have to fit the engine/trans to the car/frame. Then adapt your shift linkage, custom made driveshaft, upgrade the fuel system for use with the engine, and sort out all your wiring if you go electronic.

I would pull the nose off the car leaving just the open engine bay/frame and then set the engine/trans in place and go from there. I don't know if you could use late model LS frame/engine mounts? They do offer these for conversions, but I have no idea what the V6 uses. Same goes for the trans. The V6 is much smaller, so I don't think you will find any issues with the exhaust manifolds.

Throw a supercharger/turbo on that V6 and no one will even know due to the extra power that it isn't a Pontiac.

My guess is that it will require a lot of fabrication and fit. May almost cost more to do the conversion than to drop another Pontiac engine in it. So I would write up a plan/list of all the items needed for the swap and see what cost you come up with.


----------



## scottiesautomotive (Dec 31, 2021)

Thanks for the information pontiacjim! I need to replace the entire fuel and exhaust system anyhow since I’m short a tank, pump, sending unit, etc and exhaust piping in general so I’m literally starting with a clean slate. Also no floor pans though I have them otw. I was wondering since the body is shot in my truck anyway, couldn’t I just use the fuel system and tank from that? Though the filler neck location wouldnt be the same. Also, any idea about electronics and computer? I’m sure I could use the one from the truck but as far as linking everything to the simple harness this 68 has or could I just run everything new using the truck harness?


----------



## Lemans guy (Oct 14, 2014)

Have you considered selling the 4.3 and trans from the truck and sourcing a used Pontiac engine? It would just bolt in with a lot less fabrication…..and the difference may not be too big…lot’s of 400’s 350’s out there.


----------



## scottiesautomotive (Dec 31, 2021)

I could do that but what’s the fun in that? Plus, I want a newer engine and trans in it, not the old 350 or even the 400. Shouldn’t be too much fabrication far as the engine/trans placement aside from mount location right? I could use the mounts out of the 1500 pickup possibly or just have one made for me. I understand fuel lines were on the opposite side though between Pontiac and Chevy which is fine since again all needs to be replaced anyhow. Exhaust shouldn’t get in the way of anything since it’s a smaller engine than the Pontiac 350 is. I’ll get to the driveshaft, fuel tank, etc once the engine/trans are in. Also, I like the idea of fuel injection as well, another reason for the 4.3 idea aside from the major reason I have one available to me that I know runs and drives. It’s a complete truck.


----------



## scottiesautomotive (Dec 31, 2021)

PontiacJim said:


> OMG! A Chevy in a Pontiac and a V6 at that! Holy Moley.
> 
> Should be different as the 4.3 V6 is a good engine, have one in my 1992 S10 with a 5-speed and it's my little hot rod when I want to race around down and try and chirp gears. LOL
> 
> ...


Thanks for the information pontiacjim! I need to replace the entire fuel and exhaust system anyhow since I’m short a tank, pump, sending unit, etc and exhaust piping in general so I’m literally starting with a clean slate. Also no floor pans though I have them otw. I was wondering since the body is shot in my truck anyway, couldn’t I just use the fuel system and tank from that? Though the filler neck location wouldnt be the same. Also, any idea about electronics and computer? I’m sure I could use the one from the truck but as far as linking everything to the simple harness this 68 has or could I just run everything new using the truck harness?


----------



## An0maly_76 (Dec 25, 2021)

Salvage yards list your donor application as a 180-hp X-code 4.3 Vortec. Not the 190-hp HO, but not a huge difference. PCM programming and camshaft profile, that's about it.

If you're serious about this project, a head start for the tank / pump. G-body Regals used injected turbo 3.8s, and that tank and pump assembly may fit the 68 A-body with some modification. The tricky part is getting the correct fuel pressure in its stock form, these engines are very fussy about fuel pressure - 60/62 psi to start, 55-60 to run, and it doesn't take much of a variance to cause problems. Walbro makes an excellent pump upgrade that fits that tank, you may want to see if it fits those start / run specifications. However...

I forget if GM makes the actual intakes, but Mercruiser used a marine version of the 4.3 with an aluminum intake and rail-style injection, much better than the PlastiCrap intake and fuel injection 'spider' in the van / truck engines. I would highly recommend this, these injection spiders are a HUGE PITA. Ask me how I know. Also, these intakes have no provisions for EGR, which is another consideration, as your donor's factory setup does, which would probably mean adapting the donor's catalytic converter(s) and related wiring.

1996+ have two sensors per cat, one before the converter, one after, which would require four for true dual exhaust -- issues in this area could mean constant P0420 codes and rich exhaust. A marine setup with a marine EPROM / flash tune would probably be best, I believe the '68 should be smog exempt, though I have heard that some states require emissions-engine swaps to retain the powertrain's emissions standards, not those of the vehicle it is in. AFAIK, the marine intake's injection system doesn't require a great deal of work to swap other than adapting the factory PCM's injector harness connections.

Edelbrock has options to carburete these engines, remember that the Vortec's intake-to-head bolts are straight-up-and-down, not splayed as the previous generation's were, and Edelbrock makes an intake for those also. Interestingly, these blocks CAN interchange the two different designs of heads, but the intake and both heads must be swapped together. Another hurdle is the Vortec distributor, it likely will not work without the PCM. However, I believe an earlier HEI 4.3 dizzy will work in this engine with the Edelbrock intake, as I am sure they thought of this. If converted to carb and HEI dizzy, a TH350 or 700-R4 shouldn't be a problem at this point unless GM used its 'corporate' bellhousing pattern on these Vortecs (possible, but could be adapted I think).

Engine mounts are likely easier than you think. The earlier 4.3 was the base engine in Caprice and Monte Carlo, as well as an option in the first-gen S10, so frame pads and mounts probably won't be that hard to find.

CC or HRM magazine did a 200-4R swap into one of these cars, replacing an ST-300 2-speed. The article stated that they only had to either flip the crossmember upside down or turn it around 180 degrees for the mount to line up, I believe this will probably accommodate the 700-R4 or 4L60(E) also.

The only possible roadblocks I see are the following:

1) PCM anti-theft locking out fuel / ignition delivery

2) Accessory drive belt if not retaining A/C (accessory drive may not allow for removing compressor)

3) Adapting the 4.3's P/S pump to your existing steering box (this engine used hydroboost in some applications such as the Astro / Safari if swapping to hydroboost is desirable, but still requires an engine-driven pump).

4) It is possible the lack of ABS and/or traction control in the LeMans could cause issues with trans control and driveability. (Possible easy fix by swapping ABS controller / wiring / sensors / differentials / spindles, as wheel speed sensors are in the wheel hubs)

One thing to remember. GM factory turbocharged the 4.3 in the Syclone and Typhoon in the '90s. Though I think the base was the 190 hp HO, and I don't think it was a stock crankshaft either -- not to mention a standard 4L60E probably wouldn't like that very much. Still a thought.

Sounds like an interesting project if there aren't too many hurdles. I wonder what the wheelbase difference is between the two vehicles and if it might not be easier to lengthen / shorten the pickup frame as necessary and swap the LeMans body -- If so, I'm sure someone here would be interested in the LeMans frame and running gear if it is solid and rust-free. Could prevent a lot of headaches of the nature of "Hey! Where's this sensor? I won't run right without it!"

If I can think of anything else helpful, I'll add it.


----------



## scottiesautomotive (Dec 31, 2021)

An0maly_76 said:


> Salvage yards list your donor application as a 180-hp X-code 4.3 Vortec. Not the 190-hp HO, but not a huge difference. PCM programming and camshaft profile, that's about it.
> 
> If you're serious about this project, a head start for the tank / pump. G-body Regals used injected turbo 3.8s, and that tank and pump assembly may fit the 68 A-body with some modification. The tricky part is getting the correct fuel pressure in its stock form, these engines are very fussy about fuel pressure - 60/62 psi to start, 55-60 to run, and it doesn't take much of a variance to correct problems. Walbro makes an excellent pump upgrade that fits that tank, you may want to see if it fits those start / run specifications. However...
> 
> ...


Very helpful insight and much appreciated. Worth looking into with the whole body swap instead of frame swap cause I’m willing to bet the truck frame is in better shape than the lemans frame. Wheel base probably isn’t far off from each other. If I didn’t do that I planned to just swap damn near everything from the truck, fuel delivery system, ECM, all the modules, exhaust, spindles, gearbox(68 lemans didn’t have p/s, barely had A/C lol) and thinking of how much work that’d end up being it’d probably be easier just to swap the body that way I wouldn’t have to completely redo everything. Wondering if I could make that Silverado dash fit in the lemans too🤔


----------



## An0maly_76 (Dec 25, 2021)

scottiesautomotive said:


> Very helpful insight and much appreciated. Worth looking into with the whole body swap instead of frame swap cause I’m willing to bet the truck frame is in better shape than the lemans frame. Wheel base probably isn’t far off from each other. If I didn’t do that I planned to just swap damn near everything from the truck, fuel delivery system, ECM, all the modules, exhaust, spindles, gearbox(68 lemans didn’t have p/s, barely had A/C lol) and thinking of how much work that’d end up being it’d probably be easier just to swap the body that way I wouldn’t have to completely redo everything. Wondering if I could make that Silverado dash fit in the lemans too🤔


I'm sure it's doable. I can appreciate most anything when it comes to swaps, and I remember well an '03 Cobra Terminator that was grafted into the upper / outer body of a 65 fastback, complete with its blown 4.6 4V / 5-speed and IRS rear, the whole nine yards. And yes, the full interior and dash from the '03 was retained. Was very well done too, it looked pretty much like a 65 with a wheel swap from the outside, but inside, it was clear this was not the case. I believe they retained the antitheft, airbags, the whole nine yards. Here's a link to an article about it.

If THAT can be done, this should be a piece of cake. You might even consider some cut-and-paste with the respective firewall areas in regard to A/C and heat, as I've seen several GM applications that weren't designed with A/C delete in mind. Just be sure to record the donor truck's original VIN for future parts needs. And it's possible that 4.3 might even be able to stand a little light boost or nitrous (I wouldn't try both without a SyTy crankshaft and rod swap).


----------



## PontiacJim (Dec 29, 2012)

scottiesautomotive said:


> Thanks for the information pontiacjim! I need to replace the entire fuel and exhaust system anyhow since I’m short a tank, pump, sending unit, etc and exhaust piping in general so I’m literally starting with a clean slate. Also no floor pans though I have them otw. I was wondering since the body is shot in my truck anyway, couldn’t I just use the fuel system and tank from that? Though the filler neck location wouldnt be the same. Also, any idea about electronics and computer? I’m sure I could use the one from the truck but as far as linking everything to the simple harness this 68 has or could I just run everything new using the truck harness?


Not sure on the tank/fuel system because it is not a factory drop-in. Again, you won't know until you try.

I can't say I know much about electronic controls, sensors, and all that crap. But, I just see it as more work, frustration, and problems when things go sour. So.....

If me, I would make things simple. I might consider an aftermarket Edlebrock 4 bbl intake and then because you want EFI, add something like the Holley Sniper EFI kit which is self learning. And, the Holley matching distributor.

Just throwing this out there as an example that may make things easier? Personally, I would go old school carb and an HEI distributor and bypass all the electronics.

Can't help with the trans either, I posted a website from a trans builder that has a ton of info you may want to read.









2005 CHEVROLET 4.3L/262 Intake Manifolds, Carbureted - 4-barrel square bore Carburetor Mounting - V6 Engine Type - Free Shipping on Orders Over $99 at Summit Racing


Find 2005 CHEVROLET 4.3L/262 Intake Manifolds, Carbureted 4-barrel square bore Carburetor Mounting, V6 Engine Type and get Free Shipping on Orders Over $99 at Summit Racing!




www.summitracing.com










Holley Sniper EFI 550-849 Holley Sniper EFI 2300 Self-Tuning Kit - Shiny Finish


Holley just brought EFI within range! Introducing Sniper EFI 2300! It's perfect for any vehicle that came standard with a 2300 Holley Flange like some Fairlanes, Galaxies, Falcons, Comets, F100s, Javelins, Rebels, Mustangs, Thunderbirds, Cougars and more. It's economically priced so you can...




www.holley.com










Holley Sniper EFI 565-317 HyperSpark Distributor - GM V6


HyperSpark distributors are plug and play with all Holley Sniper EFI systems, featuring a high-quality billet distributor housing, hall effect crank trigger sensor, and they come included with the foolproof patented clear installation cap. Hyperspark CD Ignition Box (556-152) and Ignition Coil...




www.holley.com













700R4 Tip Sheet, 700R4 Information, 700R4 Swap, 700R4 Problems, 700R4 Specs


This information is for the non-transmission mechanic to help identify problem, know how much the job should cost and how to have the problem corrected.




transmissioncenter.net


----------



## An0maly_76 (Dec 25, 2021)

PontiacJim said:


> Not sure on the tank/fuel system because it is not a factory drop-in. Again, you won't know until you try.
> 
> I can't say I know much about electronic controls, sensors, and all that crap. But, I just see it as more work, frustration, and problems when things go sour. So.....


#1 - The 80s G-body turbo Buick fuel tank application I mentioned is a rear-fill, under-trunk mount design with an in-tank pump for factory fuel injection, and with boost in mind, pump pressure range may be compatible or at least attainable with minimal upgrade. It is the closest thing I can think of to a bolt-in, apart from lines and pump wiring.

#2 - Great minds think alike! This is exactly why I suggested the body swap. Probably a lot less work. +1 on your thoughts.


----------



## armyadarkness (Dec 7, 2020)

Oddly enough and coincidentally, I've posted about this exact swap, before. Back in 1995 I had to weld up a frame on a 66 front end, and the guy had a brand new crate 4.3 in it. He used a carb, though. Those engines had the same "side to side" dimensions and layout as a 350, so it was a direct drop in for him. Like putting a SBC in a Chevelle.


----------



## scottiesautomotive (Dec 31, 2021)

Sounds like there’s some hope after all. If I can’t go the body swap route, I may just do the engine/trans swap route, either way I’m sure I have my work cut out for me. Thanks everyone for all the info. I’ll do more research and keep everyone posted.


----------



## armyadarkness (Dec 7, 2020)

It's as simple as finding out if and when the motor mounts changed location on the 4.3 block. As I said, it's just a Chevy 350 without the front two cylinders. Everything else is the same.


----------



## scottiesautomotive (Dec 31, 2021)

An0maly_76 said:


> #2 - Great minds think alike! This is exactly why I suggested the body swap. Probably a lot less work. +1 on your thoughts.


Probably be the better option as far as length is concerned there’s only about 22in difference between the Silverado long bed(what I have) and the lemans. Wheelbase is about the same difference as well. Width would be the issue possibly. About 4inches of difference.


----------



## scottiesautomotive (Dec 31, 2021)

armyadarkness said:


> Oddly enough and coincidentally, I've posted about this exact swap, before. Back in 1995 I had to weld up a frame on a 66 front end, and the guy had a brand new crate 4.3 in it. He used a carb, though. Those engines had the same "side to side" dimensions and layout as a 350, so it was a direct drop in for him. Like putting a SBC in a Chevelle.


Do you have the thread link for this? The 66 was the longer body style but shouldn’t be much different in the engine bay


----------



## An0maly_76 (Dec 25, 2021)

armyadarkness said:


> It's as simple as finding out if and when the motor mounts changed location on the 4.3 block. As I said, it's just a Chevy 350 without the front two cylinders. Everything else is the same.


Mounts varied with the 1/2 ton pickup's various chassis changes from when GM began offering the 4.3, but here's your answer. One GM vehicle offered the 4.3 throughout its various incarnations and remained otherwise unchanged throughout its year-model production -- the Astro and Safari van. Auto Zone shows that Astro 4.3s used the same mounts from 1985-2005, regardless of transmission or fuel system. And any given year, the Astro / Safari used the same X-code 4.3 that OP's donor has, right alongside its H.O. Z-code brother.



scottiesautomotive said:


> Probably be the better option as far as length is concerned there’s only about 22in difference between the Silverado long bed(what I have) and the lemans. Wheelbase is about the same difference as well. Width would be the issue possibly. About 4inches of difference.


Width probably isn't as much of an issue as you think -- in the aforementioned '65 Mustang / '03 Cobra mashup, the '65 body was 5 inches narrower than the Cobra interior that was stuffed into it, but they made it work without any sign, maintaining full functionality of the '03's creature comforts and nuances. The wheelbase issue was actually solved in the front strut towers, believe it or not. The photos in the linked article show the end result of a factory-looking car that never came that way.

That being said, V-6 power is hardly new or recent. GM has an interesting history with it over the years, with several incarnations, displacement, fuel system, you name it. In 1962, Buick shortened their “Wildcat” 310 V-8 (300 CID) to a 225 “Fireball” V-6 (so named for Fireball Roberts of 1950s Buick racing fame). Ahead of its time, interest was snuffed by cheap fuel, so Buick sold the tooling to Willys/Jeep, who marketed it as the Dauntless V6.

The fuel economy of such engines pushed them into the limelight during the 1973 oil crisis, so Buick bought back the tooling, reworking it on the 300's replacement, the Buick 350, creating the 231 (3.8), 198 (3.2), and 252 (4.1). I can attest to the fuel economy, I dragged a $200 Park Avenue out of the bushes with 180k on it. The first-gen 3800 got 37+ mpg highway with the A/C pumping hard.

Unfortunately, Chevy was late to this new party. Their 250 and 292 stove-bolt sixes were capable, but thirstier than Buick's V-6s. Downsizing and weight reduction were the first steps to improving fuel economy, but more compact engines were needed for the smaller engine bays in smaller cars. Chevy's first, the 200 CID, was a "me-too" offering to improve economy over the stove-bolt engines, but it did well.

The 200 gave way to the 229. Most six-cylinders rotate an even 180 degrees between power strokes. The 229 does not -- 108 degrees _bang_ 72 degrees _bang_ I believe. This increased the engine's torque, making it popular with dirt track racers, but created a harsh idle the odd-fire 231 Buick shared, and was soon replaced by the 262, aka the 4.3L. Note: The 200, 229, and 262 share bore and stroke with the 267, 305, and 350, respectively. But on to the fuel systems.

The 200, 229 and early 262 were carbureted, giving way to throttle-body injection around 1987. Essentially a carburetor, but with injectors instead of jets. GM began phasing out TBI for Central Port Injection in 1991 or 1992. Essentially a poorly executed attempt at electronically controlling mechanical fuel injection, it didn't age well. Central Sequential Fuel Injection replaced it in 1996, and was even worse. The 350 / 5.7 and possibly the 454 / 7.4 was also saddled with this abomination, having six or eight injector tubes (hence the nickname “spider”) depending on the engine. Sequential electronic injectors in each head port's intake runner are fed with plastic tubes from a plastic central metering block, but engine heat makes everything get brittle and leak.

Simply put, despite the success of rail-style multiport and tuned port on GM's other offerings, someone tried and failed to reinvent the wheel, not once, but twice. Hence my suggestion to swap your donor 2005's CSFI for the better rail-style marine engine injection. Swapping over to the earlier TBI / HEI ala S-truck, Monte Carlo or Caprice, with a TH350 or 700-R4 could simplify things further. You may also want to investigate curb weight difference between the two vehicles, allowing for the weight savings in the V-6 – you may find an axle gear change may be necessary to promote fuel economy.

I kind of like this idea, take it all around, especially with rising fuel prices lately. I knew a guy once that was swapping an early CPI 4.3 into a 1950s Chevy 3100, but died of cancer before he could finish it. While I'm not a fan of diesel power, being an asthmatic, a YouTuber known as The Car Wizard, has been repowering a 70s land yacht with an Oldsmodiesel. While I don't know the end result, I know the guy's abilities, and I'm sure it turned out well. The 5.7 Oldsmodiesel's little brother, also a 4.3 V6, acheived mid-40s MPG in the likes of G-bodies and early front-drive A-bodies.

But I digress. The point is, if you're simply looking for a cool everyday cruiser and not interested in racing, GM's cheapskate approach of largely avoiding "clean-sheet-of-paper" designs and building on existing ones unwittingly gave us interchangeability that allows more options to deviate from the as-delivered package in the name of reliability and simplicity than you might think. Why else do you think they're called “General” Motors? LOL


----------



## scottiesautomotive (Dec 31, 2021)

Thanks for all the knowledge! I’ve been considering what engine to put in it for awhile now and then going from there cause I’d like to do something that’ll last awhile but at the same time I kinda just wanna use what’s available to me and being I have this truck already and being the body is shot but it runs and drives good, it’d be a waste not to use it. After more than 20 years I’m surprised they haven’t come out with a problem solver part for the plastic spider injectors that lasts longer… my particular truck is a 2005 classic but I know they’ve pretty much stayed the same since the mid 90’s atleast. I had a square body s10 with a 4.3 but it had the carb conversion. That thing would do a burnout 3-4 car lengths it was pretty insane. Wish I still had it, would’ve dropped that in there but had a little too much fun with it in a small town and every cop had a itchy butt to pull me over so I had to sell it. I think the better option would be to do a body swap, less work that way.


----------



## An0maly_76 (Dec 25, 2021)

scottiesautomotive said:


> Thanks for all the knowledge! I’ve been considering what engine to put in it for awhile now and then going from there cause I’d like to do something that’ll last awhile but at the same time I kinda just wanna use what’s available to me and being I have this truck already and being the body is shot but it runs and drives good, it’d be a waste not to use it. After more than 20 years I’m surprised they haven’t come out with a problem solver part for the plastic spider injectors that lasts longer… my particular truck is a 2005 classic but I know they’ve pretty much stayed the same since the mid 90’s atleast. I had a square body s10 with a 4.3 but it had the carb conversion. That thing would do a burnout 3-4 car lengths it was pretty insane. Wish I still had it, would’ve dropped that in there but had a little too much fun with it in a small town and every cop had a itchy butt to pull me over so I had to sell it. I think the better option would be to do a body swap, less work that way.


There is a solution to the spider -- marine multiport or carb conversion. LOL. The former being more desirable if you'd rather body swap and don't want to change transmissions. But it will require a PCM reflash, as it does not allow for EGR. I've added a bit more info to my last post, may want to re-read it.

For those poo-poo'ing this idea...

1) OP is saving the body from the crusher.

2) This V6 swap can eventually pave the way for a modern V8 swap, even if it isn't true Pontiac power.

3) This V6 can be modded with Syclone / Typhoon internals and boost or nitrous to thrash with even the fastest street-legal cars. In the early 1990s, Motor Trend got a wild hair and tested a Syclone against a Ferrarri 348ts. Ferrarri's loss to Ford at the '66 LeMans pales in comparison to how an iron-block, iron-headed Chevy V6 hurt old Enzo's feelings that day. I quote: "In a blink, the Ferrari is looking at tailgate. And the tailgate is getting smaller. Half a car-length, one, two car-lengths of daylight between them before the Ferrari tops out of first gear. The race has just begun and already it looks like a massacre."

OP, if you decide to use the bottle or boost, do yourself a favor. Use the appropriate forged pistons, and file the rings accordingly -- nitrous requires modifications and tuning that lack thereof causes rings to pinch themselves and the pistons to grenade if everything isn't perfect. For an intuitive seat-of-the-pants tutorial on what to do and not to do with nitrous and boost, check out this video. But keep in mind, increased power requires gearbox and driveline fortification for reliability. Think of nitrous as an on-demand super-cold-air-induction. Colder, denser air requires more fuel, however -- and running lean is another factor when a nitrous-fed engine blows up. But the video explains all this.

One other thing, the 4.3 was built by two plants, Tonawanda and Romulus. Beyond the heads and intake, not a great deal of interchangeability between the two, they are internally different. Also have learned the marine crankshaft appears stronger and beefier than the stock cast crank in most of these truck engines. Not sure whether the turbocharged SyTy versions were Romulus or Tonawanda blocks, or if they had special crankshafts, but according to this link, they did use a special piston.


----------



## An0maly_76 (Dec 25, 2021)

So, the purists here can shoot me if they like for even suggesting this, but thinking about this has got me thinking about the fact that Pontiac got a huge range of displacement from more or less the same engine block -- but never got the chance to show what they could do in the V8-shortened-to-V6 game. No way to know for sure, of course, but I wonder if there was a reason for this beyond pure bean-counting and lunkheaded management at GM corporate.

So I created some hypotheticals, feeding Butler Performance's bore and stroke data for 326 - 455 Pontiac engines into a Spicer engine displacement calculator to see what V-6 versions would displace, then feeding the V-6 displacements into a Wallace Racing calculator for estimated horsepower. Finally, I fed those horsepower ratings into a Spicer Horsepower Torque calculator to estimate torque in correlation to those horsepower figures. They are indeed, purely hypothetical and do not account for compression ratio and camshaft profile changes, but an interesting glimpse nonetheless.

The numbers are quite impressive really, and show that had Pontiac been given a chance to play this game, they would have wiped up the floor with similar offerings from GM's other divisions. Quite frankly, with Buick's turbo 3.8 showing such an impressive power-to-weight ratio and jet-like acceleration, but seeing how the horsepower / torque numbers of Buick's naturally aspirated V6 pale in comparison to these Pontiac hypotheticals, one might wonder if this is why Pontiac's engines were put out of production.

The 326 V8 would make a 244 V6, with a projected 243 - 406 hp and 240 - 402 ft-lb
(by way of comparison, Buick's 252 was rated at 125 hp and 205 ft-lb in base form)

The 350 V8 would make a 265 V6, with a projected 260 - 434 hp and 258 - 430 ft-lb
(by way of comparison, Chevy's 262 was rated at 155 hp and 230 ft-lb in base form)

The 389 V8 would make a 291 V6, with a projected 281 - 469 hp and 278 - 465 ft-lb

The 400 V8 would make a 299 V6, with a projected 288 - 480 hp and 286 - 476 ft-lb
(by way of comparison, GMCs 305 was rated at 142 hp and 260 ft-lb in base form)

The 421 V8 would make a 315 V6, with a projected 295 - 491 hp and 292 - 487 ft-lb

The 428 V8 would make a 319 V6, with a projected 298 - 496 hp and 295 - 491 ft-lb

The 455 V8 would make a 341 V6, with a projected 309 - 515 hp and 306 - 510 ft-lb
(by way of comparison, GMC's 351 was rated at 155-190 hp and 288-304 ft-lb in base form)

It's an interesting thought, to say the least... Just sayin'... Maybe someone should send some cracked Pontiac V-8 blocks and engine parts to the Garage 54 guys and see what they come up with... LOL


----------



## armyadarkness (Dec 7, 2020)

Big Pontiac V8's disappeared in 1979, and if you're correct that the 4.3 came out in 85, that explains why they never got to "make a 6 out of an 8"


----------



## armyadarkness (Dec 7, 2020)

I support anyones idea. One mans ceiling is another mans floor. If he has the time and resources, then go for it. My only advice is to not overthink it and not over complicate it. 

Any scrap yard, parts house, or Google, should know if the 4.3 shares the SBC engine mounts, which I suspect it does. If so, then this is a drop in job. Just need a drive shaft.


----------



## Duff (Jan 12, 2020)

I once bought a 1 owner 65 lemans that at one time had a 1970's? Olds diesel in it, when I finally bought the car, it had a 350 Olds gas. A large chunk had been torched out of the crossmember, guessing to clear the Olds diesel starter?


----------



## An0maly_76 (Dec 25, 2021)

Duff said:


> I once bought a 1 owner 65 lemans that at one time had a 1970's? Olds diesel in it, when I finally bought the car, it had a 350 Olds gas. A large chunk had been torched out of the crossmember, guessing to clear the Olds diesel starter?


Quite possible, but it's also possible the Oldsmodiesel had a larger sump (common for diesels) that required notching to clear also. However, lots of people hated the Oldsmodiesel even when they were new, and someone I know claims a Cadillac Eldorado he owned (factory Oldsmodiesel) was put back on gasoline power. So the engine you speak of was possibly a factory diesel that was so modified.

It holds water, an overlap between 12:1 and 13:1 allows either fuel to ignite, and I can imagine if enough timing were pulled, it could run on pump gas with a head / intake / distributor swap. Even running on pump gas, though, it certainly would have had to retain the beefier starter for the higher-compression pistons. So chances are good that car never saw a drop of diesel spilled on its bumper.



armyadarkness said:


> I support anyones idea. One mans ceiling is another mans floor. If he has the time and resources, then go for it. My only advice is to not overthink it and not over complicate it.
> 
> Any scrap yard, parts house, or Google, should know if the 4.3 shares the SBC engine mounts, which I suspect it does. If so, then this is a drop in job. Just need a drive shaft.


 It appears that in the 262 / 4.3's case, the engine mounts themselves are the same throughout its production, it's the frame pads that will vary from chassis to chassis.



armyadarkness said:


> Big Pontiac V8's disappeared in 1979, and if you're correct that the 4.3 came out in 85, that explains why they never got to "make a 6 out of an 8"


Yes, but to clarify, the first bowtie 90-degree V6 was actually the 200 CID, debuting in 1977, with the 229 debuting for 1980, before the 262 was released for 1985. However, you have to also account for at least a year for R&D and tooling for this, meaning someone got the ball rolling for the 200 in 1975 or 1976, not long after Buick had repurchased the rights and tooling to its original 225 in 1974. My guess is that by the time Buick's "shortened V8" caught on, Pontiac's larger V-8s were already in the guillotine on paper, even if they hadn't been told.

Now, this could have been shortsightedness of Pontiac division management in failing to recognize an opportunity to salvage Pontiac's market share in a changing market, GM brass saying no, or maybe it simply would have cost too much to retool the 400 and 455 that were still in production. As any enthusiast knows, after 1979, only the 265 and 301 remained, which are largely known as lackluster and unresponsive to modification as delivered.

Maybe I'm way off base, but I think Pontiac either missed an opportunity that could have saved them long-term, or was denied it. Maybe they just decided they weren't going out like that. Even the 265 or 301 could have made a decent V-6 with a little more imagination. Interestingly enough, I've found information indicating Pontiac built V-8s I've never heard of, the first-ever a 287 in 1955, followed by the 317 in 1956, the 347 in 1957, and the 370 in 1958, before the 389 debuted in 1959.

For anyone interested, these are the hypotheticals for those scenarios (same methodology as previous post)

The 265 V8 would make a 198 V6, with a projected 221 hp and 219 ft-lb
(by way of comparison, Buick's 196 was rated at 105 hp and 160 ft-lb in base form)
(by way of comparison, Chevy's 200 was rated at 95 hp and 160 ft-lb in base form)

The 287 V8 would make a 215 V6, with a projected 230 hp and 228 ft-lb

The 301 V8 would make a 226 V6, with a projected 245 hp and 243 ft-lb
(by way of comparison, Buick's 225 was rated at 160 hp and 225 ft-lb in base form)
(by way of comparison, Chevy's 229 was rated at 110 hp and 170 ft-lb in base form)

The 317 V8 would make a 237 V6, with a projected 249 hp and 247 ft-lb
The 347 V8 would make a 260 V6, with a projected 260 hp and 258 ft-lb
The 370 V8 would make a 277 V6, with a projected 275 hp and 273 ft-lb

I won't go into mixing and matching bores and strokes from different engines, but you can see there were some options here. I seem to remember something about the lunkheaded brass of the 70's at GM may have enacted some obscure rule that either each division would only be allowed one V8, or only certain divisions would be allowed a V-8 beyond a certain displacement or something. Possibly V6 power was similarly regulated. Does this ring any bells with anyone?


----------



## armyadarkness (Dec 7, 2020)

An0maly_76 said:


> Yes, but to clarify, the first bowtie 90-degree V6 was actually the 200 CID, debuting in 1977, with the 229 debuting for 1980, before the 262 was released for 1985. However, you have to also account for at least a year for R&D and tooling for this, meaning someone got the ball rolling for the 200 in 1975 or 1976, not long after Buick had repurchased the rights and tooling to its original 225 in 1974. My guess is that by the time Buick's "shortened V8" caught on, Pontiac's larger V-8s were already in the guillotine on paper, even if they hadn't been told.
> 
> Now, this could have been shortsightedness of Pontiac division management in failing to recognize an opportunity to salvage Pontiac's market share in a changing market, GM brass saying no, or maybe it simply would have cost too much to retool the 400 and 455 that were still in production. As any enthusiast knows, after 1979, only the 265 and 301 remained, which are largely known as lackluster and unresponsive to modification as delivered.


Wouldve been cool to see, but the 4.3's claim to fame was that it had the same bore and stroke as the SBC 350. Using that math, a Pontiac 400 would've become a 5.0 liter engine, which GM already had several of. 

By that time, GM and Pontiac had long abandoned doing things that customers wanted. Pontiac's supercharged Sunfire and Bonneville were a blast to drive. Wouldve been cool to see them with supercharged 6's. But it also wouldve been cool to see Pontiac bring back the 69 Judge in 2005, instead of glorified Grand Am, which became the new GTO. No offense to the new gen guys.

Last night we drove home behind a new Buick Suv. I'm surprised that anyone can even find a dealership still. The invention of the GTO was political. The ending of the tri power was political, and the ending of Pontiac was political. Therefore, there's no "sense" to be made of it.


----------



## An0maly_76 (Dec 25, 2021)

armyadarkness said:


> Wouldve been cool to see, but the 4.3's claim to fame was that it had the same bore and stroke as the SBC 350. Using that math, a Pontiac 400 would've become a 5.0 liter engine, which GM already had several of.
> 
> By that time, GM and Pontiac had long abandoned doing things that customers wanted. Pontiac's supercharged Sunfire and Bonneville were a blast to drive. Wouldve been cool to see them with supercharged 6's. But it also wouldve been cool to see Pontiac bring back the 69 Judge in 2005, instead of glorified Grand Am, which became the new GTO. No offense to the new gen guys.
> 
> Last night we drove home behind a new Buick Suv. I'm surprised that anyone can even find a dealership still. The invention of the GTO was political. The ending of the tri power was political, and the ending of Pontiac was political. Therefore, there's no "sense" to be made of it.


Oh, boy.... All good points, but where do I start with these?

I don't remember seeing a supercharged Sunfire, unless it was based on the Cobalt SS. AFAIK, the Bonneville SSEi did offer the SC3800, however, it was not a Pontiac engine, obviously. The 05 GTO I guess could sort of be likened to Grand Am styling, but it is, after all, essentially a Holden Monaro, and my thoughts on the styling are more with a 95-03 GP with a nose bearing a striking resemblance to a 00-05 Impala. Still a good-looking car, but (and no offense to owners of these, as I'd love to have one), but I just don't feel these cars captured the spirit of the original, especially without true Pontiac power.

They're nice cars and all, but I feel GM sort of did Pontiac an injustice with these, sort of a final middle finger before they were pushed out the door. Let's face it, Pontiac hasn't REALLY been Pontiac since the '70s, when the first front-drive Phoenix rolled off the line with a 2.8 V6. That was the start of GM being more interested in cheapening their product line and building cookie-cutter cars across multiple divisions, thinking consumers wouldn't notice.

And you're right, politics played heavily into the mismanagement of Pontiac's marketing, etc., just as they played into cancelling the turbo Buick V6s. Once word got out they could run with or smoke the mighty Corvette, it was "no turbo for YOU!" Which Buick, of course, gave their own final middle finger by literally increasing production ten-fold the final model year, and sending 547 "special" cars to McLaren to build the Grand National that no Corvette owner would EVER want any part of. In true Tony Montana style... "You wanna PLEH? O-KEH! Say 'ELLO to my LIL' FREN'!"

As for a Buick dealership, from what I see, GM has more or less made everything a GM dealership, I haven't seen a dealership that only sells one division for some time. Every one I see is Chevrolet / Cadillac / Buick dealer. Which is a lot of GM's problem. It's all cookie-cutter vehicles with no individualism to any one of them. There's no brand identity anymore, just badge-engineering. Hummer?... Hummer, you say? Let's not go there, the name alone is a bad joke, and the vehicles nothing more than higher markup on gussied-up light-duty GM trucks and SUVs that were already overpriced for the quality.

I think that with some mixing and matching of bore / stroke, some still-competitive V6s could have been built from these engines, but as you say, politics won out over common sense. And that is why GM has struggled with their bottom line ever since. Forest for the trees.


----------



## armyadarkness (Dec 7, 2020)

My bad, it was a Sunbird. Super fun to drive, fast as Hell, but front wheel drive so it couldnt ever get traction. Well... the original version was a Chevy Vega and you could get it with a 305 Chevy, but that's another story. 

There are a few for sale online. It's basically a Cavalier but I dont think Chevy ever had a turbo cavalier. It actually had a few decent performance attempts made on it.


----------



## An0maly_76 (Dec 25, 2021)

armyadarkness said:


> My bad, it was a Sunbird. Super fun to drive, fast as Hell, but front wheel drive so it couldnt ever get traction. Well... the original version was a Chevy Vega and you could get it with a 305 Chevy, but that's another story.
> 
> There are a few for sale online. It's basically a Cavalier but I dont think Chevy ever had a turbo cavalier. It actually had a few decent performance attempts made on it.


The car pictured was a little cooler me-too version of the J-body Z24 / Type-10 hatchback -- one of the better-looking GM front-drivers of the 80s. And you're correct, no turbo Cavalier. To my knowledge, Pontiac's turbo 3.1L Grand Prix GTPs were the only other factory turbo GM front-drivers. The early turbo Sunbirds displaced 1.8 if memory serves, later replaced with a 2.0 -- perhaps both were Daewoo engines, the 2.0 for sure, also offered in the pathetic (and thankfully short-lived) LeMans reboot circa 1988.

Turbo Sunbirds would move for what they were, but they didn't last, fraught with problems. If memory serves, head cracks and gasket failures were common -- by contrast, the 60-degree V6 offered in the Cavalier and, later, the Sunbird, had similar performance and fared much better long-term. Side note here, I had a stock 92 manual-trans 2.2L Cavalier with some minor tuning upgrades. After awhile of running 89 octane, most of those kids pimping out their Civics wanted nothing to do with me LOL. Ah, my misspent youth.

Now that I know there were earlier, smaller, more obscure versions of the Pontiac V-8s, makes me want to stuff one into a RWD H-body with a Muncie. Talk about a sleeper. Better yet, do the same with its replacement, the Phoenix. I've seen Chevettes with V-8s stuffed into them, I know it could be done. I would say go for the gusto with a 400 or better, but you'd never get it to hook with street tires. Ah, yes, the RWD H-body Sunbird, Monza, SkyHawk, Starfire(?) cars. Those were phased out for FWD way too soon.


----------



## armyadarkness (Dec 7, 2020)

I had two Vegas with small blocks. Fun, but lot's O repairs. Everything broke... burnouts broke the rears, traction meant wheelies on the street, which broke everything from the front bumper to the back bumper.


----------

