How do you feel about GT40 iron heads on a 347???

[N8Miller]

my cousin has a set of gt40 iron heads that he is having ported pretty nicely. right now they are going on a 303 with an e-cam, but over the winter he is building a 347. He says that those heads are going to be sufficent enough and i say that they are going to choke it.
what doyou think? they are heads of a 93 cobra.

 

[ss93cobra]

A little small if you ask me. Actually, MM&FF did a write up not that long ago on SEVERAL different heads on a 306 and 347 and showed all sorts of data regarding flow rate, horsepower, torque, etc on head vs head and how much horsepower per dollar each head cost. Memory serves me correctly that Trick Flow and AFR came out on top, but don't quote me on it. Find the write up in the back issues and show him.

 

[mike93lx]

i'll doubt anyone would argue that there are better heads out there, but it (for most of us) always come down to money. it wouldn't hurt for him to try it, worst case he just pulls the heads and gets new ones later on.

it would be interesting to see what kind of power it could make with those heads. i'll bet it would do decent if the intake and cam are picked to match the flow of the heads.

 

[5.0_Gil_89]

Noooooooooo! If you want irons go with some Roush's. I'd go AFR or the new PTL's.

 

[N8Miller]

thanks for the input guys. the intake is a fully ported gt40 and the cam is not determined yet, but will be mild atleast.

 

[TIMMY2734]

He'll be fine. The torque will be unbelievable. Later on down the road, he can swap the heads. Not really that big of a deal. Like the others have said, they arent exactly the first head that comes to mind when buiilding a stroker, but theyll be fine.

 

[RydeOn]

It should run decent. I knew a guy that ran high 12's on stock E7 head 347. For the guys telling you to go with a high dollar aluminum head, maybe set up a paypal donation account so they can contribute.

 

[maverick0716]

Well he spent all that money building a 347......so why the hell would he cheap out on the heads?! Doesn't make any sense to me.....finish the motor right!

 

[hllon4whls]

Ported 40' and an ecam sound decent on a 347. It may not be a low 10 second car, but it might just surprise everyone. As long as he doesnt try to zing it, I'll bet it will make good power.

 

[Mizark347]

I have ported E7's that probably flow around GT-40 specs on my 347 and the low end torque is unbelievable (Need Drag Radials). I do kinda wish i had a little more top end though. Im gonna be goin with the AFR 185s in the future, along with a custom cam. I dont believe MMFF did the head test on a 347. It was a 306 and 331.

 

[jasonlee0704]

EDIT:

I'm an idiot, he's already having them ported.

Done right, they'll make some nice power on a 347.

 

[bmo37]

I think they will be fine, If you look at flow numbers from a gt40p heads versus a 351w stock heads you will see that the stock gt40's beat the 351w head. Now if there ported thats even a greater gain. The smaller valves on those heads will also equate to better throttle response and more lowend on a n/a engine.

http://www.angelfire.com/ex/bmo37/Cylinder_heads_flow_sheet.htm

 

[N8Miller]

wow. i didnt know that the gt40 heads would do that well on a 347.

now, what if he wants to add some boost.... upto a modest 10psi?

 

[N8Miller]

wow. i didnt know that the gt40 heads would do that well on a 347.

now, what if he wants to add some boost.... upto a modest 10psi?

 

[houstonstangguy]

yeah they will make pretty decent power down low and torque too, but up high is where they will fall off to good alu. headed motors on the street. like was mentioned above though, if he isnt happy, then down the road he can sell em and swap. I was in a similar position when i built my 331, but like was also mentioned above, i figured anything less than alum. heads would be half a$$ing it. I built the motor right (except that I reused my ported cobra and the 65mm tb because i ran out of cash........and it is seriously robbing my power) so why cheese out in the head department. thats just me though.