# Best options for street performance with '71 455?



## slingshot (Aug 22, 2021)

I know this has been discussed in various threads over the years but wanted to hear from the learned on here people's thoughts on best options for a mild performance upgrade to a non-HO '71 455. Motor was professionally rebuilt about 15 years ago and has maybe 8000 miles on it since. Starts and runs smooth and runs decent--just want more. 
Has Eagle H-beam rods, J&E flat top forged pistons, RA IV cam, stock intake, stock Q-Jet carb, stock D-port heads, stock log-style exhaust manifolds with 2 1/4" muffler shop crimped exhaust. Rest of the combo is a Turbo 400 trans with 3.55 posi rear and Ram Air hood and air cleaner set up added at some point in the past. 
Thinking of starting with Ram Air Resto 2.45" ceramic coated cast iron exhaust manifolds with 2 1/2" mandrel bent downpipes and 2 1/2" mandrel bent exhaust. Questions are many... what is the potential of the stock intake/carb/heads? Worth it to change to an aluminum HO intake? Thoughts on changing to Rhodes lifters? Harland Sharp roller rockers to extend the rpm range a little? Other suggestions?
Not looking for supercar performance, just wanting a smooth running occasional driver that can still run 12's when I get the urge to put the hammer down...


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## PontiacJim (Dec 29, 2012)

slingshot said:


> I know this has been discussed in various threads over the years but wanted to hear from the learned on here people's thoughts on best options for a mild performance upgrade to a non-HO '71 455. Motor was professionally rebuilt about 15 years ago and has maybe 8000 miles on it since. Starts and runs smooth and runs decent--just want more.
> Has Eagle H-beam rods, J&E flat top forged pistons, RA IV cam, stock intake, stock Q-Jet carb, stock D-port heads, stock log-style exhaust manifolds with 2 1/4" muffler shop crimped exhaust. Rest of the combo is a Turbo 400 trans with 3.55 posi rear and Ram Air hood and air cleaner set up added at some point in the past.
> Thinking of starting with Ram Air Resto 2.45" ceramic coated cast iron exhaust manifolds with 2 1/2" mandrel bent downpipes and 2 1/2" mandrel bent exhaust. Questions are many... what is the potential of the stock intake/carb/heads? Worth it to change to an aluminum HO intake? Thoughts on changing to Rhodes lifters? Harland Sharp roller rockers to extend the rpm range a little? Other suggestions?
> Not looking for supercar performance, just wanting a smooth running occasional driver that can still run 12's when I get the urge to put the hammer down...


RA IV/HO aluminum intake really won't be needed as the ports are larger than your stock heads.

You have flat top pistons like all Pontiacs, but what heads and what is your compression? Stock 1971 455 heads were #66 or #98 and are low compression. The #98's have smaller valves and press-in studs which makes the big chamber heads even worse.

Too late to add Rhodes lifters. You don't want to chance new lifters on an already broke in cam with the lifters it now has.

RA exhaust manifolds & mandrel bent pipes and good flowing mufflers will be a plus.

Dialing in the timing and timing curve can be a plus if that has not already been done. Lots of info on how to do this on the forum.

Stock stall converter? Shift kit in the TH-400?

Aluminum heads? That would add some HP/TQ, but you want to factor your compression to be nearer 10.0-10.25 with them. They will have RA IV intake ports and that is where the RA IV/HO intake could be used. You will need new head bolts.


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## slingshot (Aug 22, 2021)

Update. I do have the #66 heads and the converter is a TCI 2200 stall. May be going down a different path though. Ran into a well known Pontiac guy locally that I had not previously met. He recommended the following: ported 455HO heads, ported Performance Products repop 455HO intake, custom grind cam with 1.65 roller rockers and Rhodes Lifters, performance build on the Q-Jet, Doug's headers, full mandrel bent 2 1/2" exhaust and dynotune. Put everything together with ARP hardware. Should make adequate power for what I want to do and still look stockish with the hood open except for the headers of course. Going to get together with him for more advanced planning before I do anything. Will just keep all the stock parts for prosperity and drive the car like I stole it.


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