Gt40 Irons?!?!

[ninety15.0]

Well i got a sweet deal on some Original Iron Gt40's. They were taken off a lightning and they only had 12k miles on them. I have been trying to get some important info on them to see exactly what i need/want to do to them before i bolt them on. I found this link online but the info does not seem all that accurate?! http://www.themustang-net.com/tech_articles/gt40p.shtml
What size are the Combustion Chambers for real...66.5cc doesnt seem right? I would like to keep my 10:1 compression and i know stock heads are something like 58-59 cc. How much would i need to shave off the gt40's to keep my 10:1? Or can that even be done? Also I already have real nice comp cams springs, new retainers, guideplates, pushrods and CC pro magnum 1.6 rockers. These are all on my current stock heads...will I be able to reuse everything on the gt40s? I will be taking the gt40's to the shop for a 3 angle valve job and to check the straightness and valve guide condition. Is there anything else i need to do or buy ahead of time? How much power should i expect from the upgrade? Mods are in sig..thanks!

 

[ninety15.0]

ttt

 

[R2D2]

ya they are 65, you will also need head bolt spacers since they were off a 351 and the 302 uses a 7/16th head bolt and the 351 uses a 1/2 inch

 

[mob]

Taking them to a machine shop to get the 3 angle valve job is a good idea, and having them checked out is also good, You probably wont be that far from stock compression even with the cc size on those, having them worked on will just cost more money. Its always a great idea to get new springs and retainers, you probably wont need new pushrods, but ALWAYS measure, the only reason youll need new pushrods is if your stock ones arent the right size, with new rr's youll have to measure. You probably wont notice more then a 40hp increase. For a budget build gt40 heads are the way to go, I went with p heads and am expecting to run 12's or close to it with mods in sig.

 

[ninety15.0]

Taking them to a machine shop to get the 3 angle valve job is a good idea, and having them checked out is also good, You probably wont be that far from stock compression even with the cc size on those, having them worked on will just cost more money. Its always a great idea to get new springs and retainers, you probably wont need new pushrods, but ALWAYS measure, the only reason youll need new pushrods is if your stock ones arent the right size, with new rr's youll have to measure. You probably wont notice more then a 40hp increase. For a budget build gt40 heads are the way to go, I went with p heads and am expecting to run 12's or close to it with mods in sig.

Thats sort of what i was thinking. My Pushrods are not stock and my roller rockers are not brand new they are on my current stock head combo. I was thinking i could mill the heads a little bit to get back some of that compression. I will also be grinding out hose thermactor bumps and getting a three angle valve job...so 300rwhp is a pretty attainable goal in my opinion. thanks..anyone else?!

 

[blkcobra50]

If you are running a 10:1 CR now and you go to the GT40 heads you will lose close to .6 points in CR. Just something to think about. I understand you got a sweet deal on these heads but...If you are in the market from some budget heads why not go for the GT40P's. They are 59cc chambers so CR will remain close to if not the same...and they flow better than the GT40's.

 

[ninety15.0]

If you are running a 10:1 CR now and you go to the GT40 heads you will lose close to .6 points in CR. Just something to think about. I understand you got a sweet deal on these heads but...If you are in the market from some budget heads why not go for the GT40P's. They are 59cc chambers so CR will remain close to if not the same...and they flow better than the GT40's.

I Dont want to buy new headers...and i got a sweet deal. By the time you buy the P heads and a set of headers...theres not point to buying them. You could easily get a set of aluminum heads that flow better for the same price. There will most definately be a vortech on the car next spring with 6-9 psi so I am not concerned with getting the most NA power. I want to stop at 425rwhp and focus more on suspension and looks. Perhaps dropping the CR to 9.5:1 would be more blower friendly...but i just love the way a high compression car drives and 10:1 is still plenty safe for 6-9psi
So no-one knows how much can be milled off the heads to gain back that 0.6 CR or at least a good part of it.