[notchabovechevy]

I bought a set of gt-40p heads today. New valves, springs, locks, and retainers. Surface is cleaned and has been crack tested. I want to run maybe a x303 cam. I was told the single pattern cams work well with these heads. If I mill them .030 I should have 10to1 compression correct?I know I will have to purchase headers. I'm thinking bbk long tubes. What roller rockers do you guys reccomend? Also what springs and retainers will work well with this cam I know it's to big for stock springs. Should I have valve clearance problems? any help is always appreciated. I paid $350 complete good deal?

[Rustbelt]

harland and sharp rockers.

i see that tmoss is on the site now check out his site for porting info. porting your heads might make sense with your cam choice and other mods. he would be a great person to ask.

[CAMN89GT]

Originally Posted by Rustbelt harland and sharp rockers. i see that tmoss is on the site now check out his site for porting info. porting your heads might make sense with your cam choice and other mods. he would be a great person to ask.

I secondly recommend this shop because I have *WITNESSED* real life what this man can do. My buddy Rich Groh(Lives in IL) is sponsored by Harland and Sharp, some of you may know Rich, also sponsors JPC(Justin Burcham) ... Let me know if I can do anything, I am only 10 minutes from their shop. Harland Sharp

[notchabovechevy]

I was told that w/ stock heads the most you could go with stoch eyebrow pistons is about .535 I'm seriously considering stroking it. Is it true that a 331 has a better rod to stroke ratio than the 347? or is it really not enough diff. to worry about?

[notchabovechevy]

What about jegs #942-1-94160be?

[built351w]

for rockers I'd go with comp pro-magnums, just personally......

I run manley valves and my engine builder actually put chevy springs on my head. I'm pretty sure they were comp.

[Iownastang]

Originally Posted by notchabovechevy I was told that w/ stock heads the most you could go with stoch eyebrow pistons is about .535 I'm seriously considering stroking it. Is it true that a 331 has a better rod to stroke ratio than the 347? or is it really not enough diff. to worry about?

another one with the rod to stroke ratio!!hold on man.

[Iownastang]

darrel wrote this


The ring stack of a 1.090 piston doesn't make it any more likely to burn oil. The pin intersecting the oil ring doesn't make it more likely to burn oil. There are engines that come from the factory like this. Stroker pistons for various brands have been this way for years. The oil ring scrapes the cylinders. It doesn't car where the wrist pin is located. I've owned/built several 347s and not one of them has had an issue. Rod ratio means nothing. The best rod to stroke ratio is 8-rods to one crank. The common 347 uses a 1.58 rod to stroke ratio, why is that bad. The 454 and 502 Chevy has a 1.53 rod to stroke ratio. The Chevy 400 has a 1.48 rod to stroke ratio. The Ford 5.4 has a 1.59 as does the 6.8 V10. These engines are some of the most common and reliable engines ever made.

Somewhere along the way about 10 years ago someone started the rumor that 347s burn oil due to wrist pin location. That rumor was proven wrong. Then the rumor was started that a 347 is very unreliable because the rod to stroke ratio is so horrible. Nothing could be further from the truth. There are no reliability issues, no piston rock issues and no oil burning issues with a 347. The only time you will have an issue with a 347 (or any other engine for that matter) is poor machine work, poor assembly or part failure.

This misinformation snowballs on the internet. One guy can post some bullshit and thousands read it and tell their friends. Those friends tell other friends and so on.

[notchabovechevy]

Well I appreciate you clearing that up for me well it's 347 now bigger is better. The good info like this is why I joined this site. I paint on do body work on cars if I can ever help any of you send me a e-mail. If I don't know I won't bs you I'll find out. Still naad to know if I should mill those gt-40p heads .030 or not. will the nitrous react better to 9:5 to1 or 10:5? Thanks for the info so far.

[Iownastang]

I would do 10.5.1 c/r b/c compressio n ratio does not affect nitrous and i wouldnt use those gt40 heads buy a set of aftermarket ones

[notchabovechevy]

Even ported? I'm not trying to have a drag car just a stout street car w a small shot to play around with. 400 to 500 with the gas and I will be extreamly happy. Is that asking to much out of these heads? Also 10 to 1 what gas do you reccomend?

[Iownastang]

i would still go with aftermarket heads trick flow tw;s b/c you will have almost as much in the gt40's when you get done

[Iownastang]

Originally Posted by notchabovechevy Even ported? I'm not trying to have a drag car just a stout street car w a small shot to play around with. 400 to 500 with the gas and I will be extreamly happy. Is that asking to much out of these heads? Also 10 to 1 what gas do you reccomend?

never run anything under 93

[40thmustanggt]

now you gotta sell those gt-40p's and get something better.. are you buying all this cause of me?? don't lie cousin

[notchabovechevy]

you dont't thint they can support 400 to 500 hp with a 150 shot.

[notchabovechevy]

no just want to be taken serious around town.

[Iownastang]

you want do real good w/o the nitrous,im not saying they cant support 400-450 just saying it would be money better spent on aftermarket heads b/c they will give you room to grow

[notchabovechevy]

but when I do get it done hope you do more to yours

[40thmustanggt]

Originally Posted by notchabovechevy no just want to be taken serious around town.

you better step it up past 400-500rwhp then theres a 98 single turbo ls1 running around lexington and west columbia pushing 650rwhp

[notchabovechevy]

stock block don't need to go to big I'm building a racecar for that. currently on hold though.. What school r u going to? I went to nadc for a short while.