Quote:
Originally Posted by big matt
I have a 1972 yb code 455ho. Its the original engine to a 72 gto coupled to a th400. I want it to retain the factory heads, and appear from the outside to be stock, even valve covers, except for the fact it will have black long tube headers. It will have a full 3", rear exit exhaust.
My gut says put a modern rotating assembly instead of reconditioning the rods, and using a oem crank. Stroker kits worth it? I would like to hear whats good in 2021. Eagle, Butler?? I need to Pick out roller cam that will work with the iron heads and oem aluminum intake. Head wise, i am looking to leave them mostly alone except a clean up cut, valve job, and recommended springs retainers. Perhaps some crower enduro rockers. Would prefer to keep it on premium pump gas if i can.
Also an opinion on the converter. Rear gear will be a 12 bolt, somewhere around a 3.42 gear. 27" tall tire. This car will be used as an aggressive weekend cruiser. Maybe 2000 miles per season. I want it to straight up snap your neck. Chime in if you have any opinions. This kinda is a blank canvas. I am willing to spend some coin. This is a one time deal. I want it to run. Thanks
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I was trying to do exactly what you are years ago. Here is the problem and people can say what they want, but since my 455 HO is quicker than any pump gas 455 HO I know of I think you should at least listen. If someone has been quicker with a pump gas HO feel free to chime in.
The cam required to get 550-600 HP out of HO heads even at 9-1 CR is not streetable. You have zero chance without real port work.
I have HO 197s done by one of the best, Dan Whitmore. Bunch of money in them. The cam is a nasty solid roller close to .700 lift. Open exhaust with a ported Warrior and my GTO runs 10.80s. the heads were milled something like .060 to get the CR up to just over 9-1. I would not do that to yours in this day of age when you can just buy aluminum which was not available when I started.
You have zero chance of getting a HO head 455 to pull to 6500 RPM because you simply can not get enough air in the cylinder to push the piston with that long of stroke at that RPM. But there is noting wrong with making your bottom end stay alive up there as mine has been there many times, when I make a mistake shifting after 5500 RPM.
If you really want 550-600 HP get some aluminum heads and you will get it done without cutting up your HOs and spending almost what it would take to buy some E heads. Even your E heads might need port work as the more they flow the less cam you need to make the power you are after which = more streetable.
If you are dead set on your HO heads go for 500 streetable HP and be done with it.
The worse heads flow and all Pontiac iron heads flow like crap , the more nasty the cam you need to make power. There are very few real H0 head 455s that make a true 600 HP. I do not know of any unless big bucks are spent and its not worth is because the chambers are so deep.
There are no Pontiac HO heads that flow 300cfm unless they are full of brass/weld/epoxy. There are RAIV that flow than much but they have a smaller chamber, that is the reason.
These day I would not mess with a hyd roller, too many problems. Spend the bucks on bushed solid rollers and do not worry about little needle bearings flying around.
If you are dead set on using your HO heads Paul Carter is a good one to send them to.