# 455 Build question



## Vapor Locker USA (Feb 5, 2014)

Hey guys, my mild 389 build is just a little too mild for my liking and I was able to find an untouched 455 short block. I need to do this on a budget, so I want to use as much of it as possible, but willing to upgrade a few parts for better performance and reliability. My question is what parts made a strong pulling, 455 cruiser that can still PASS a gas station? Looking for known combos that like 90 octane.

Thanks in advance!!

My setup is:
73 455 from a big car
6X-4 heads 93.5cc already redone
Performer RPM intake
FiTech EFI
RAM AIR exhaust manifolds


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## PontiacJim (Dec 29, 2012)

Vapor Locker USA said:


> Hey guys, my mild 389 build is just a little too mild for my liking and I was able to find an untouched 455 short block. I need to do this on a budget, so I want to use as much of it as possible, but willing to upgrade a few parts for better performance and reliability. My question is what parts made a strong pulling, 455 cruiser that can still PASS a gas station? Looking for known combos that like 90 octane.
> 
> Thanks in advance!!
> 
> ...



If you already have all that on your 455, what else do you need or are looking for? Need to be specific. High performance & gas mileage don't mix - either one or the other. :thumbsup:


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## 60sPontiacs (Jul 14, 2016)

Assuming you'll be 30 over/all else standard with new pistons, your static CR with 93.5cc heads will be about 9.64:1 (9.59:1 with stock bore), which is said to require higher than 90 octane for best timing. Cam choice can drop Dynamic CR which is what matters. I'm at this learning point with a 9.56:1 400 but don't have time to mess with it now (but am reading...).

What kind of car is this going in [ah, i see a 67 GTO/3400lbs]? Rear axle ratio? transmission?

These are interesting articles, and people on this forum know their stuff/can point you to other info.
http://www.crankshaftcoalition.com/wiki/Cam_and_compression_ratio_compatibility
http://www.crankshaftcoalition.com/wiki/Hot_rodding_the_HEI_distributor

Also read what Jim Hand did. He ran 87cc heads (10.2:1) with his 455 on 92 octane.. well under 12 second 1/4 miles in a 4000 lb station wagon.
Jim Hand's 455 Pontiac Power

----just noticed the EFI on your list... now I understand what PontiacJim means...
Also just noticed you're in my town... when I'm there. Am in CA now - we both had high of 63F today, but tonight goes down to 49F here while LSL nosedived to 14F (the old STL 50 degree drop...). You can get 93 octane at U-Gas just off 70 on Hwy-Z so your engine will be okay.


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## Vapor Locker USA (Feb 5, 2014)

Thanks for the responses. I think I worded the question wrong. My goal is to run on 90 octane because I can get that at any gas station. The main thing I am looking for is a known cam / piston setup for a nice running motor. It’s not going to be raced but I do want enough power to have some fun.

The other variables with the car not stated above.
373 rear end
200r4

These are the cams that I am looking at and looking for piston recommendations.

255DEH
51-206-4 - DUAL Energy? Hydraulic Flat Tappet Camshafts

XE250H
51-220-4 - Xtreme Energy? Hydraulic Flat Tappet Camshafts

XE256H
51-221-4 - Xtreme Energy? Hydraulic Flat Tappet Camshafts


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## PontiacJim (Dec 29, 2012)

It is kinda hard to suggest a piston for any combo without knowing some exact numbers. Most piston choices will be forged, and you can get differing out-of-the-catalog over sized pistons depending on how much the block may need to be bored to clean it up - typically .030" over, then .040", then .060".

Your best bet to run on the 90 octane gas would be to shoot for 9.0 compression. You can go higher, but you may be taking a chance with engine detonation, but some feel comfortable going higher and you will read about guys running 10.0 on pump gas which to me is skeptical, but doable if timing is adjusted and everything is in perfect tune.

Things you need to know are specific values that will determine the compression ratio. You will need to know exactly what your head chamber cc's are, not the numbers they are supposed to be or what the internet says they are. Actual head chamber volume can vary from advertised numbers. Head chamber volumes can change by grinding in the chambers to clean-up/improve flow, head milling, the height of the valve as it sits on the valve seat, or even the design of the valve head. That said, you have your heads cc'd @ 93.5.

You will need to know what the deck height is, ie the top of the cylinder measured to the top of the piston. This is the space above the piston and has volume in cc's. Typically a Pontiac piston will sit .015-.020" down in the bore. A block can be milled down to bring the top of the piston flush - called zero deck height. I don't recommend it, but others will. I'll throw off head/intake angle geometry and the intake side surfaces have to be milled accordingly to match any angle changes. I'd rather see a custom piston with the wrist pin relocated, if anything., but have not heard of this being done, so who knows. The 455, .030" over @ .020" down in the bore will calculate to 4.5 cc's as the cylinder volume above the piston (some pistons are made with a piston edge that is beveled which will add additional cc's in an effort to further reduce compression).

Your head gasket, that hole in the center, has a volume in cc's. The thickness of the gasket used can be used as an adjustment to raise/lower compression slightly. The Felpro gasket, as most will list, is supposedly .039" when compressed. For example, 455 .030" over (4.180") with .039" compressed head gasket is 8.7 cc's. Using a thinner .027" compressed gasket is 6 cc's.

So now with these numbers above, you can calculate for your piston and determine the amount of cc's that has to be built into the piston by either the valve relief notches or a dished area cast/milled into the tops of the pistons. So let's use 93.5 + 4.5 + 8.7 = 106.7 as your total number of cc's above the piston. 

Using the Wallace Compression Calculator, Compression Ratio Calculator - Wallace Racing , you can plug in the numbers. I used the 455 .030" bore, 4.180", as the Gasket Bore Diameter which will be fairly close. Used .020" for Deck Height. I also used the 6.6 Valve Relief/Dome cc's as a baseline for the compression ratio - which is what you adjust to change your compression.

So, plugging in the numbers, I get a compression ratio of 9.37. Not bad. 

You can use a number of different pistons, but in my 455 build I used the Keith Black ICONN pistons which come in 3 different valve relief configurations, 5.5, 11, & 17 cc's. Plugging in the 5.5 cc's in place of the 6.6 cc's and the compression is now 9.44. Getting up into the compression where 90 octane might not be too comfortable.

Plugging in the 11 cc's (which I went with) and the compression is 9.04. Right were you want it.

Pluggin in the 17 cc's and the compression drops to 8.65. Not necessarily where you might want to be BUT, there are options with this ratio.

There is this thing called "Quench Area," the area between the piston and the head when the piston is at top dead center. Many builders like to see this area have a distance of .040 - .045" (depending on piston material used) to maximize the cylinder burning. The tighter measurement can aide in preventing detonation and can sometimes allow for a higher compression. With a deck height of .020" plus a gasket of .039", the Quench is .059". Not really ideal. What I did in my build was go with a Cometic .027" head gasket. .020" + .027" = .047" Quench area. Changing the formula and using the .027" head gasket yields an increased compression ratio of 8.82.

The larger Quench will obviously work because that's factory - .059" - .060", but remember leaded gas was used and leaded gas suppressed detonation. Still, it works with most builds, so not a big problem. So the 9.04 compression will work, but so will the 8.82 compression with the tighter Quench which will reduce the chances of detonation.

Using the 8.65 or the 8.82 compression, you can select a cam with the narrow Lobe Separation Angle (LSA) such as the Competition Cams series with its 110 LSA. These cams have real power in a lower compression engine because they build additional cylinder pressure - essentially acting as higher compression. They are very strong cams, but will peak out in the RPM range early which may not be too much of a problem at all reading into what you want out of your engine and the lower RPM characteristics of the 455. Wider LSA cams (114-116) will provide a broader power range but not have the lower RPM punch of the tighter LSA. The wider LSA cams typically bleed off some of the compression at the lower RPM's and is why they were selected when using higher compression engines. You will pick up the lost compression as the RPM's increase.

So selecting a cam to match your compression is just as important as the compression itself. This is where the difference between Static Compression (your actual number) versus Dynamic Compression (cylinder pressure derived by the camshaft specs, namely the Intake Valve closing degrees After Bottom Dead Center (ABDC) ). This number is found on most cam manufacturers Cam Card. That said, you can use the 9.04 compression ratio or the 8.82 compression ratio to determine your Dynamic Compression by obtaining the cam manufacturers cam spec for the Intake Valve closing point at ABDC. From what I have read, and what I shot for in my 455CI build, it to keep the Dynamic Compression below 8.0. Use this calculator to get your Dynamic Compression ratio Wallace Racing: Dynamic Compression Ratio Calculator

AND, as a DISCLAIMER, because I am not an expert on this, just advising, you want to talk with your engine builder and also get cam manufacturers recommendations to zero in what you want the engine to do as the final voice in your engine build. Keep in mind that a cam that may be strong in a 400, will be milder in a 455 due to the bigger cubes. The Comp Cams XE cams, 262, 268, or 274 would be a good choice with the lower, under 9.0 compression. https://butlerperformance.com/c-123...ams-comp-cams-hydraulic-flat-tappet-cams.html


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## Vapor Locker USA (Feb 5, 2014)

Thanks for the info. I am just worried about buying the wrong stuff and spending good money to build a bad engine. You have made some good points and it looks like I need to wait till the block gets done so I can get the exact numbers to punch into the calculator to help figure out what is needed. 

Thanks again!

Mike


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## Vapor Locker USA (Feb 5, 2014)

I was tearing down the 455 and saw that it had these rods. I cant find any info on these. Does anyone know what these are and are they any good?


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## PontiacJim (Dec 29, 2012)

Vapor Locker USA said:


> I was tearing down the 455 and saw that it had these rods. I cant find any info on these. Does anyone know what these are and are they any good?


Reading the obvious, a reconditioned(rebuilt) rod for TRW. Standard Pontiac cast rod - has a narrow pencil line thin casting flash on the side of the rod beam as opposed to a wider 1/16-1/8" wider casting line ID'ing the rod as a forged rod. Here is one on Ebay: https://www.ebay.com/p/TRW-CR1459-Connecting-Rod-Reconditioned/581138341?_trksid=p2047675.l2644

Would not use a cast rod in any performance build, get a forged rod.


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## Vapor Locker USA (Feb 5, 2014)

So that is what that first word is.... damn, i was hoping to save a couple bucks.

Question on the quench. is it really a big deal, or is it just to squeeze a little extra power out of the motor?


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## PontiacJim (Dec 29, 2012)

Vapor Locker USA said:


> So that is what that first word is.... damn, i was hoping to save a couple bucks.
> 
> Question on the quench. is it really a big deal, or is it just to squeeze a little extra power out of the motor?


Not a real big deal, but it is not so much about extra power as it is about detonation.


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## bigD (Jul 21, 2016)

Vapor Locker USA said:


> Thanks for the responses. I think I worded the question wrong. My goal is to run on 90 octane because I can get that at any gas station. The main thing I am looking for is a known cam / piston setup for a nice running motor. It’s not going to be raced but I do want enough power to have some fun.
> 
> The other variables with the car not stated above.
> 373 rear end
> ...



This is my own personal opinion.

These cams are much too small for 455+Pontiac engines. And, they are steep ramp cams, with a 110° LSA. The XE cams are said to make noise because of slapping the valves shut so hard. These are not popular with most Pontiac guys. 

With 9.5:1 or more CR, it might be a good idea to go with more duration, to bleed off some compression. The Summit 2802 is probably the cheapest decent 455+ cam. 

A Crower 60243 is also a good cam.

The Pontiac 068 cam was used in the 455HO engines, but is considered much too small by most Pontiac guys, today.


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## Vapor Locker USA (Feb 5, 2014)

Well the game plan changed.... Still working with the 455, but just ordered the 495 SCAT stroker kit. Low end torque shouldn’t be an issue now. I should have about 9.3 compression so crap gas shouldn’t be a problem. For a cam, I kept searching and more researching and found Jones Cam Designs. A few emails back and forth and he recommended the cam listed below.

Cam# Pont455, H72334-112
232/232 @.050"
.334"/.334" Lobe Lift
.551"/.551" Valve Lift w/1.65 rockers
110 LSA

One question I have for you guys. PRW or Comp Cams roller tip lifters? I keep reading the comp cams are made overseas and the quality has gone downhill. Not much out there on the PRW, but the specs show it can handle 3X the spring pressure of the 155lbs that the cam needs, so it should be more than tough enough. Just looking for someone who has used them and liked the or had issues.


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## bigD (Jul 21, 2016)

Opinions vary WIDELY on cam choice. The cam you showed is similar to the old, but still popular Pontiac 041 cam, but is a single pattern. Most Pontiac guys prefer a little more duration on the exhaust lobe, than on the intake lobe. I'd prefer an 041 clone, like a Melling SPC-8, CC 51-116-3, Crower 60919, Lunati 10511003, and a few others. I think all these are exactly the same cam, made by the same cam company, probably CMC. I bought the Melling SPC-8 because they were cheaper. Some brands show slightly different specs. But, I'm almost certain that all these cams are exactly the same. 

Anyhow, I always ran these cams with Rhoads lifters, to provide a smoother idle, more vac, & more low end torque. But, some don't like Rhoads lifters. And, since you'll have about 40 more cubes, the cam will "act" smaller. So, good quality reg type lifters are fine. In fact, with that many cubes, a slightly larger cam will probably work just fine. Probably somewhere in the 234-236° @ .050 lift range, on the intake lobe will still be plenty streetable. Obviously, bigger cams will make more hp at a higher rpm. 

Here are 3 cams in that range. You can have a custom ground any way you want it. 

https://www.summitracing.com/parts/crn-284281

COMP Cams 51-318-4: Specialty Hydraulic Flat Tappet Camshaft Lift .489"/.500" Duration 286/292 Lobe Angle 110° | JEGS

Erson-PBM-World-B2C | E310031 - Erson Cams - PONTIAC V8 M/P 3

I don't think most street engines NEED 1.65 rockers. Just adds extra lift and stress on the valve train that is unnecessary, IMO. I've heard several say that they have had good service from the CC roller tip rockers. I think I remember reading at least one post saying they knew of a failure. If you plan to run over 300lbs of open spring pressure, it might be a good idea to go with a decent quality full roller rocker. I think Crower stainless are considered among the best, but also among the highest priced. Some like Scorpion or Harland Sharp.

https://www.summitracing.com/parts/cro-73627-16/overview/make/pontiac

https://www.summitracing.com/parts/csp-s6001/overview/make/pontiac

https://www.summitracing.com/parts/scc-scp3052/overview/make/pontiac

Butler even sells some Lunati Voodoo rockers.

https://butlerperformance.com/i-244...o-7-16-lun-15415-16.html?ref=category:1234784

There are cheaper Chinese rockers, including PRW, which many have had problems with. Don't have any 1st hand experience with PRW. 

https://butlerperformance.com/i-244...ker-set-prw-0245501.html?ref=category:1234784


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## 60sPontiacs (Jul 14, 2016)

"...the 495 SCAT stroker kit... I should have about 9.3 compression"

Cool. 
Curious how you figured 9.3:1.. are you getting dished pistons with the kit?

Maybe this with 16.8 cc dish (looks nice)... 
http://vi.vipr.ebaydesc.com/ws/eBay...descgauge=1&cspheader=1&oneClk=1&secureDesc=0
with 30 over and 0.10 piston to deck clearance I came up with 9.3:1


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## Vapor Locker USA (Feb 5, 2014)

Yup.. Icon 16cc


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## BearGFR (Aug 25, 2008)

A good set of forged rods can be bought for very close to the same money as it would cost you to recondition a set of factory cast rods, so don't fret about that. Considering the factory rods are the 'weak link' in these engines, please don't even consider using them for anything other than a 100% stock (and baby'ed) build.

Quench will be important to you if you want to get by on lower octane fuel. Quench helps promote turbulence in the chamber, and turbulence helps prevent hot spots that can promote detonation. You said your heads are 93.5 cc's --- were they actually measured at that or are you using the factory specs? (Hopefully the former).
It's easy to obsess over compression and get lost in the whole "static vs. dynamic" debate - I know I did at first - but consider this: with everything else held constant, the difference between say 9.2:1 and 10.0:1 is a 455 like you're building is only going to make a difference of a whopping 7-8 horsepower. You'll never be able to feel it in the seat of your pants, and it'll only barely show up on an E.T. slip. So is it worth it to you to "walk the edge" on compression? That's your choice. I've got my own CR calculator I built using Excel - a + 0.030 455 with 93.5 cc chambers and all other measurements "factory nominal", running flat top pistons (usually have about 6 cc's in the valve pockets) is going to come in at about 9.4:1 compression. You'd likely be opk on 93 octane, I'd hesitate to try it on 90. Run a different set of pistons with 11 cc's volume (D-shaped dishes to get the volume and keep the quench pad) and you'll be right at 9:1 (9.036) - should be happy on 90 octane. Are there people who get by with more? Yes - but you have to really stay on top of fuel mixture, cooling system, and other things --- worth the trouble? Again, up to you to decide. Considering that even a mild 455 is going to be serious fun in that car...

Cam -- I'm a big fan of rollers. Even though they're significantly more expensive, my opinion is that the peace of mind is worth the cost. No production engines have used flat tappets for a loooong time now, so the oil additives that flat tappet systems need has all but disappeared so you have to be really careful with oil and additives, plus the quality of parts has declined unless you spring for the expensive stuff like Crower. It doesn't take many wiped cam lobes to make up the cost of a roller system. Again, your choice there. Lately I really like Bullet cams. The principal designer there has been around a long time with different companies and really knows his stuff when it comes to Pontiacs. It'd be worth your time to give them a call (make sure you talk to Tim Goolsby) and get their recommendations based on what you want to do.

Good luck! Keep us up to date on how it's going.

Bear


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## PontiacJim (Dec 29, 2012)

BearGFR: "A good set of forged rods can be bought for very close to the same money as it would cost you to recondition a set of factory cast rods, so don't fret about that. Considering the factory rods are the 'weak link' in these engines, please don't even consider using them for anything other than a 100% stock (and baby'ed) build.

Vapor Locker USA: "but just ordered the 495 SCAT stroker kit."

BearGFR: "Run a different set of pistons with 11 cc's volume (D-shaped dishes to get the volume and keep the quench pad) and you'll be right at 9:1 (9.036)"

Vapor Locker USA:"Yup.. Icon 16cc"

Vapor Locker USA has already stated in his earlier posting that he has purchased the SCAT 495 stroker kit which comes with forged rods and has already chosen the Icon forged pistons with 16cc valve reliefs (listed as 16.8 cc's). :thumbsup:

My suggestions would be to use the ARP main studs, but with a long stroke engine, I would add the 4-bolt main caps to the center 3 mains. Many 455 blocks are already drilled for the 4-bolt mains so it would be a matter of installing and align boring/honing the mains after installation. Check for interference between the crank weight and the oil pan rail as it seems you may have to do some grinding to get the needed clearance - assume you are having a machine shop do the fitting/assembly?

On the 6X heads which you said are already done. Make sure that the valve spring pressures are spec'd for a .551" lift cam and that on full lift you have the needed clearance between the spring coils and the valve retainer-to-valve guide. If this lift is with a 1.65 rocker arm, you will need to clearance the pushrod holes by elongating them ala RA IV or they will bind and you will bend pushrods and/or break things. You also will need the ARP big block 7/16" rocker arm studs and poly locks if this has not already been done on those heads. My guess is that you may be doing some additional work on the heads.

I would also opt for a top quality oil pump and oil pump shaft. I like the Butler Pro Series which are blueprinted https://butlerperformance.com/c-1234738-engine-components-internal-oil-pumps-accessories.html and the oil pump shaft BearGFR got for his engine at Nightmare Performance Standard sleeved & hardened oil pump driveshaft But there are others as well, so your choice.

Should be a stump puller. :yesnod:


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## BearGFR (Aug 25, 2008)

That's what I get for being in a hurry and not reading closely enough....


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## PontiacJim (Dec 29, 2012)

BearGFR said:


> That's what I get for being in a hurry and not reading closely enough....


LOL, all is forgiven and your input is usually pretty spot on - as this was. I am anxious to see that video when you get your engine/car back on the road - should be awesome! :cheers


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## BearGFR (Aug 25, 2008)

I started putting my heads together today. PAC springs, 245 lbs seat pressure at an installed height of 1.910. I got two of the valves done, then my ancient "C-clamp" valve compressor gave up and let one fly. Fortunately, I was being careful to keep my body out of the line of fire and didn't get hurt. However, I'm definitely stopping at this point and will be heading in to Summit in Arlington tomorrow to purchase a better spring compressor tool that will be up to the task.

Bear


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