Gary Berg

Hi i plan on swapping my Pontiac 455 engine and th400 tranny into a third gen. Just wondering the hp and torque rating for a Pontiac 455? Im running a mild cam. Cam lift Intake .295, Exaust .310, Valve lift Intake .443, Exaust .465 Dur .050. Stock pistons, Stock valves, Stock Heads CR 8.5/1. The engine has been completely rebuilt top to bottom. Im using a performer intake and carb. Also plan on running with headers. And The stock th400. Not sure or the gear ratio yet?
Any Ideas?

Thanks, Gary

84firebird383

I'm looking at a copy of Musclecar Review that has an artical of a 73 superduty 455 trans am. It came with a factory ramair lll cam and a cylinder head that was a variation of the ram air lV and 455 H.O. head. With emissions equipment it was rated at 290hp and 395 lb ft torque.The artical goes on to say that pontiac claims replacing the exhaust manifolds with tube headers would be the single biggest improvement.While the heads you have are not as good as the SD heads you have a slightly better cam and headers with no emissions. so I'd say you will be just over 300 HP and around 425 lbft of torque.

Gary Berg

thank you just was wondering. now in the future i plan on getting alu. heads would that change the hp and torque?

84firebird383

Yes. The aluminum heads will flow better and make more power than the SD heads.If the chambers are smaller you would also pick up compression,which would mean more HP and torque.I think the combo you have right now will be a great set up for the street. It will have tons of off the line torque.I would guess with a mild gear,like 3.08 or 3.23, a 2.5" dual exhaust and a stock converter with traction you could hit mid 13's in the 1/4 mile.Traction would be the key tho.

avro206

455s varied wildly in power out put. You have to find out the year. However since you have an aftermarket cam we can't give an exact number anyhow.

84firebird383

here is a link to a carcraft write up on a 501 hp 455 pontiac




http://www.carcraft.com/techarticles...iac/index.html

Gary Berg

Its a 73.

Dens71TA

iTrader: (5)

'73 D-port 455 4-bbl was rated at 250HP/380 ft lbs net. Its a regular fuel engine and has a low 8.1:1 compression. Basically a cookie cutter engine that was used in Bonnevilles, Catalinas, Grand Villes, and Firebirds.

With those mods it will probably put it near 300 HP.

PROSTOCK5031

iTrader: (1)

like this?

Gary Berg

no lol more on the stock side. I wish i had the money to do that. maybe someday down the road.

PROSTOCK5031

iTrader: (1)

Where in PA? I have a race at the Maple Grove this yr....Ed Quay in Pottstown built my car. My new motor is a 535 CID with Wensler 2 heads, 380 cfm, and 15.8 to 1 compression. My friend had a stock rebuilt 455 with 6x heads and a RA4 cam in a 3rd gen it ran mid 12's, then quicker later...here is the new motor

Gary Berg

Chalfont, pa its in bucks county. hey did your friend put headers on that 455 if he did wat kind?

PROSTOCK5031

iTrader: (1)

Actully 2 of my friends had 455's in 3rd gens both used 69 GTO with one tube moved. I think 3 tube are a bolt on. best bet are having them made. or look on performance years BBS and ask if anyone is selling any used.

Gary Berg

used like custom or manufactured?

Gary Berg

I just looked on performance years and the headers they have are expensive and they look like they would have clearance issues.

PROSTOCK5031

iTrader: (1)

I ment to look on the tech BBS, under race ask there...someone may did up a 69 gto set then is selling them to have a custom set done.

Gary Berg

could you maybe give me a link to point me in the right direction? i understand what ur saying but it seems i cant find anything to do with headers.

PROSTOCK5031

iTrader: (1)

http://performanceyears.com/newsite/index.html then go to the tech then to race, and ask there...