# 1971 400 with 1968 #16 Heads CAM Selection



## khackney (May 8, 2017)

Hi,

I'm a new member to the forum. I have a 1969 GTO, 400, 4 speed muncie, matador red, with a black vinyl top and black interior. My mom bought this car new in 1969, the year she and my dad got married. Sometime while I was in elementary school they sold the car. Around 30 years later my dad and uncle came across it and my dad was able to purchase it back. The car was not in the best shape and no longer had the original motor. Since then, I bought the car from my parents and my dad and I are in the process of doing a frame off restoration.

Right now, we're working on the motor. We have a 1971 Pontiac 400. Since, this motor only had somewhere around 8:1 compression, I purchased a set of 1968 Pontiac #16 heads with 72cc chambers. From what I've read, these heads along with flat top pistons will get the motor back to the 10.75:1 compression of the original motor. My question is, what cam should I get? I've looked at the Edelbrock performer plus and RPM cams and intakes. I'm not going to race the car but want it to be driveable with as much or more torque and horsepower as the original motor. Not looking for the motor to lope but a nice sounding idle, good throttle response that will make a good driver.

Thanks


----------



## bigD (Jul 21, 2016)

(1) 068 clone, such as a Melling SPC-7

http://www.ebay.com/itm/Engine-Cams...ash=item3cecc103df:g:inIAAOSwNnRYlsIl&vxp=mtr

(2) Summit 2801, which is a high lift version of an 068

https://www.summitracing.com/parts/sum-2801

(3) Lunati 10510312

http://www.lunatipower.com/Product.aspx?id=1759&gid=278

(4) 744 clone, such as a Melling SPC-3

http://www.ebay.com/itm/Engine-Cams...ash=item19fe4bee4b:g:cCMAAOSwTglYmKMN&vxp=mtr

(5) Summit 2802, which is a high lift version of a 744 

https://www.summitracing.com/parts/sum-2802

The next size up is probably a Crower 60243. But, they cost a lot more, and I think are probably a little more cam than a mild street 400 needs.

https://www.summitracing.com/parts/...aLe7dTVH3BilkWdJKJZSapjUZ3RUrr6w8EaAkmd8P8HAQ


"...get the motor back to the 10.75:1 compression..."

If you build with that much compression, you'll need to add a good octane booster, like Torco Accelerator, or mix in some race gas, or switch to E-85. Otherwise you could have detonation problems. Most Pontiac engine builders today, recommend no more than 9.5:1 CR, with closer to 9:1 being safer, with today's pump gas.

If you are rebuilding the short block, you can go with dish pistons, to reduce your CR, using the 72cc heads. The cheapest would probably to buy the Speed Pro forged L2262F pistons & have a competent machine shop cut a dish in the top. This is a common practice. 

Icon makes a 400 piston with a 14cc dish. They are about $500 + shipping. 

http://www.cnc-motorsports.com/icon-ic891-030-forged-dish-pistons-4150-bore.html

If you're gonna buy forged rods, you might be able to use some SP WL2323F 455 Olds pistons, with some H-beam rods. These pistons are around $320 shipped. They have an 18cc dish and a slightly higher pin height, which should put the piston top near zero deck, without cutting the decks down any. The SP cast 455 Olds pistons are cheaper & should be plenty good for a decent street 400 build.

We've been discussing this on the PY site. Not positive it'll work. But looks like it might. I offered to buy one of the pistons, so an engine builder could try one & see if it will work. So far, no takers. I'll make you the same offer. If it won't work, you can just throw the piston away. If it does work, all you have to do is buy 7 more pistons. 

https://www.summitracing.com/parts/slp-w369p/overview/

https://www.summitracing.com/parts/slp-wl2323f

The RPM Pontiac H-beams are $400 shipped.

http://www.racingpartsmaximum.com/sae4340steelhbeam-2.html


----------



## khackney (May 8, 2017)

Thanks for the info on the cams and especially the compression and detonation issue. I had wondered if that would be an issue. I'm having a hard time deciding which way to go. Friends and family think I should just go with the 10.75:1 and use octane booster. I guess that would be alright if it works. 

I wonder how much torque and hp I would end up with using 9.14:1 with dished pistons? Seems like that might be the best solution if it isn't a significant drop.

The E85 sounds pretty interesting but about only 1 gas station per town where we live has it and from what I've read it requires a different carb and fuel pump. Just not sure what the other impacts are from running E85.

I really appreciate the advice. I'm just learning about a lot of this stuff. So, you're experience and opinion means a lot.


----------



## bigD (Jul 21, 2016)

"...Friends and family think I should just go with the 10.75:1 and use octane booster. I guess that would be alright if it works..."

Torco Accelerator - It's not just an octane booster

TORCO UL ACCELERATOR - CASE OF (6) 32oz CANS | eBay

"...The E85 sounds pretty interesting but about only 1 gas station per town where we live has it and from what I've read it requires a different carb and fuel pump. Just not sure what the other impacts are from running E85..."

https://www.google.com/search?q=e-8...6j69i59j0l3.5405j0j4&sourceid=chrome&ie=UTF-8

My engine guy built a 400 block stroker that made 755hp @ 5900rpm on the dyno, running E-85. He put it in a modified dirt track car, where it ran very strong, and stayed very cool. 

There are plenty of E-85 carbs & pumps readily available. I personally would just run premium pump gas with the Torco booster, IF the car will not be driven very much. BUT, if it will be driven a lot, I'd build for about 9:1 CR, or slightly over. If no more CR than that, I'd run a Voodoo cam--probably a 262. 

Voodoo Hydraulic Flat Tappet Cam - Pontiac V8 262/268 - Lunati Power

If you use the #16 heads, many think it is a good idea to have hardened valve seat inserts installed, for use with unleaded fuel. The 6X & 5C heads have factory hardened seats. Others say hardened seats are not necessary for normal street driving. 

I'd run a GOOD 800cfm Q-jet. 

SMI Carburetor Street Performance Rochester Quadrajet 800CFM Buick, Oldsmobile and Pontiac Quadrajet 4BBL SMI- Sean Murphy Induction

But, a member here did some testing & decided to go with a Quick Fuel SS-680-VS, for his 400. 

http://www.gtoforum.com/f178/opinion-carberater-400-motor-86857/index2.html#post624025

http://www.gtoforum.com/f178/opinion-carberater-400-motor-86857/index3.html#post624121

https://www.amazon.com/Quick-Fuel-Technology-SS-680-VS-Carburetor/dp/B003M8YV4I


"...I wonder how much torque and hp I would end up with using 9.14:1 with dished pistons? Seems like that might be the best solution if it isn't a significant drop..."

No reason why a 9:1 400 can't make an easy 350hp. Here's the recipe for a 9.25:1 400 that is advertised to make aprox 385hp. 

400 Long Block


----------



## Charles Rummel (Apr 30, 2017)

I have a 70 GTO with the stock 400 V8 still under the hood. It is the standard 350 HP YS code motor. I looked up the 72cc to check and it seems both ram air and plain GTO heads like mine pre 71 all had 72cc. OK so IF that means you have the same set up I do here's what I learned from research. I sent to Pontiac years ago for an info packet on my car ( you could do that back then) they sent a copy of my window sticker (for real but with some info inked out for some reason) a pic of a 70 GTO in B/W and a whole bunch of photo copied pages of Pontiac history and performance articles. 
There was a gentleman named Nunzi Romano in NY who was touted as THE Pontiac performance guy on the east coast in one article. ( I bet I have your full attention now haha) I called him at Nunzi's Automotive in Brooklyn, got him on the phone and asked him what the most powerful, streetable cam I could use in my 70 YS 400 was. (this was like 15 years ago) After telling me I should really build a 455 for calm power he said "if you want to go all out use a Comp cams 501 lift 292 duration" BUT, it would lope and winter starting would require a manual choke and powerful battery as I recall. If the car was going to be a daily driver or needed less lope for whatever reasons (pwr accessories, frequent traffic driving) whatever that the stock Ram Air cam was among the first computer designed cams from GM and would give a good power increase with mild manners. I was younger at the time and chose the 501 Comp cam. You can hear and feel the lope and car guys always can tell I'm running a hot cam. The car is easy enough for me to drive anywhere even daily if I wanted to, but I have to be careful not to blip the throttle in drive then get off it like if a red light turned green but then I saw someone running the light just after touching the gas and let it pedal snap back to hit the brake. That will stall the car and it will take a few seconds to start it again just enough to get the people behind you to beep their horns. In addition the articles mostly all said the stock manifolds were very hard to improve on, unless you wanted to go full out and build or find a tunnel ram (they were rare in the aftermarket at that time) you would be best to spend performance dollars elsewhere on the motor.


----------



## Charles Rummel (Apr 30, 2017)

I agree w/your friends but only if you want the power to keep up newer sports cars and can afford to run 93 0r 91 gas with booster. If something requires you to use the car daily; if I back off my timing I can run on 89 provided I don't get on it or climb any super steep hills without downshifting.


----------



## bigD (Jul 21, 2016)

That CC 292 Magnum cam is WAY to big for a street 400. I have one in a 455 bracket engine. I would not even consider running it on the street, in a 455, much less a 400. It has a nasty idle, even with Rhoads lifters. It has 244 degrees of duration @ .050 lift. That's 13 degrees bigger than a Ram Air 4 cam.

Even a Ram Air 4 Cam is too big for a mild street 400. If I HAD to run one, I'd definitely use Rhoads lifters, to calm down the idle, and give more vac & low rpm torque. The biggest cam I'd run with a high compression 400 would be a Summit 2802, or Crower 60243.

A Summit 2801 would probably provide better low rpm operation and have a smoother idle. 

Between the 2801 & 2802 would be the Lunati 10510312 & the Crower 60916.


----------



## Charles Rummel (Apr 30, 2017)

I never knew about E-85 until you mentioned it. Other than being bad for rubber hoses is there anything else we should know about running it in older V8s I guess a lead substitute for lube or something?


----------



## bigD (Jul 21, 2016)

Charles Rummel said:


> I never knew about E-85 until you mentioned it. Other than being bad for rubber hoses is there anything else we should know about running it in older V8s I guess a lead substitute for lube or something?


No need for lead sub if you have hardened seats. Unleaded gas has the same amount of lead in it that E-85 has--none. Pontiac began hardening the seats, back in the early '70's, '73 I believe, when they began reducing the amount of lead in pump gas.

On the Google search I linked, you'll probably find all the E-85 info you need.


----------



## khackney (May 8, 2017)

Wow, thanks for the great info! I would be pretty happy with 385hp using 9.25:1 compression on pump gas. I like the idea of the quadrajet too. Sounds like it's a good performer, plus the original factor. I'd like to know what cam they're using in that 400 long block and if they're using dished pistons to get the compression down to 9.25:1. 

I may give those guys a call and see if they would mind sharing any more info. I'm thinking that's the way to go if I can get that kind of performance on pump gas.


----------



## BearGFR (Aug 25, 2008)

You need to make a decision: Do you want a car that you can drive and enjoy, or do you want a car that is as close to 100% original as you can get it. Make no mistake, this is an either/or proposition, not a both. 

Realize that no 400 actually left the factory with 10.75:1 compression. That was a factory rating for racing purposes for a "blueprinted" engine - only - with heads milled down so that the chambers were significantly smaller than the nominal 72cc's that were usual for #16 D-port heads - like around 68 cc's - and had been zero-decked. An assembly line 400 with "everything nominal" was actually around 9.8:1 Don't take my word for it, take all the dimensions (4.120 bore, 3.750 stroke, usual 0.020 deck clearance, .045 compressed head gasket thickness, 6 cc's in the piston valve reliefs, 72cc's in the chambers) and calculate it out for yourself. It's all just basic math. The ratio of the largest volume (piston at bottom dead center) to the smallest volume (piston at top dead center).

If you want to be able to drive the car and enjoy it, then you should build it for a target compression ratio of around 9.3:1 or less. Yeah, some folks can and do successfully "push it" some beyond that but honestly, in a 400 with all else being equal the difference between 9.0:1 and 10.0:1 is going to amount to about 5-8 hp or less. But it's also going to make the difference between an engine you don't have to worry about and one that you have to constantly stay on top of the tune, the cooling system, the fuel, and watch like a hawk for the slightest evidences of detonation - and may have to pull timing out of it (which is going to kill performance) just to keep it alive. Worth it? Not for me.

Bear


----------



## bigD (Jul 21, 2016)

khackney said:


> ... I'd like to know what cam they're using in that 400 long block and if they're using dished pistons to get the compression down to 9.25:1.


The description says it has Rhoads lifters. Therefore, I'd guess that the cam is an 041 clone, or something similar.

No, it doesn't use dish pistons. Actually they use flat top SP L2262F forged pistons, and have to cut some off the 6X heads to get the compression UP from just over 8:1, to 9.25:1.

http://www.ebay.com/itm/Speed-Pro-T...ash=item2c6fd95bc6:g:ZnwAAOSwDuJWvhoN&vxp=mtr

6x-8 head 400's were rated at only 7.6:1 CR. The 6x-4 head 400's were rated around 8:1 CR. So, I assume that Len cuts the blocks down to near zero deck height, then cuts the 6x-4 heads down to achieve the advertised CR, of 9.25:1. 

If you build for between 9:1 & 9.25:1 CR, a Voodoo 262 cam should make over 350hp. 

Voodoo Hydraulic Flat Tappet Cam - Pontiac V8 262/268 - Lunati 
Power

Here's a CR calculator you can use to figure CR, if you know all the numbers to plug into it. 

http://www.wallaceracing.com/cr_test2.php

I got 9.23:1 CR by plugging in these numbers: 400 + .030, 85cc heads, 6.7cc valve reliefs, .039 x 4.3 head gaskets, .000 deck height. So, the heads would need to be cut down from just under 94cc, to 85cc. If the block is bored more than .030 over, then the head chambers could be slightly larger. 

For a .030 over bore, I plugged in 88cc heads & got 8.99 CR. I figure this CR, with the Voodoo cam should make a good strong, pump gas friendly 400 engine, especially if you add some H-beam rods.


----------

