[StrokedFox]

So I got a 91' Fox with a 347/GT40 Heads (alum.)/X-Cam/GT40 "Cobra" upper/lower. I'm about to start upgrading top half of the motor to let the cubes breathe more. I was thinking over-sized valves, dual coil springs, stainless roller rockers (already have roller lifters), and port-match/polish the intake man. and heads.

My question is this, what size/kind of valves should i get?
You think porting the GT40 intake is worth it? It only holds up to 350 horsepower on it's own...

I need ideas and a little direction from people that know what they're talking about.

[Brian@PAR]

Whatever you do to the heads your choke point it still going to be the intake. There is little that can be done in porting that intake other then a port matching and that can do more harm than good.

If you do anything upgrade the intake to a Track Heat or Systemax and run a 70 mm TB. If you still want to do the heads then they should be ported by a reputable porter. Just having larger valves installed can hurt flow if the work is not done right. Use 2.02 SS valves Manely, COMP or Ferria all make good valves.

I would however look hard at how much money you put into those heads. If you can't get 285 or so CFM then you are better off saving and getting a better suited head.

Lastly you talked about upgrading springs. Springs are determined by the cam so hopefully you had springs installed that were correct and there will be no need to change them. If not they need to be changed regradless of what you do.

[StrokedFox]

Thanx for the advice man. I'll check out the systemax most likely, you're the man

[93mustank]

302 parts make 302 power

[TKOTLARZ]

Originally Posted by StrokedFox Thanx for the advice man. I'll check out the systemax most likely, you're the man

yea its a really good intake..i have one and love it..and theres no port wotk done to it yet

[JBIGBOOTSY]

Originally Posted by StrokedFox So I got a 91' Fox with a 347/GT40 Heads (alum.)/X-Cam/GT40 "Cobra" upper/lower. I'm about to start upgrading top half of the motor to let the cubes breathe more. I was thinking over-sized valves, dual coil springs, stainless roller rockers (already have roller lifters), and port-match/polish the intake man. and heads. My question is this, what size/kind of valves should i get? You think porting the GT40 intake is worth it? It only holds up to 350 horsepower on it's own... I need ideas and a little direction from people that know what they're talking about.

You can get stainless valves, with undercut stems. you can also have the heads milled, or the block decked, or both, but that comes with PTV clearance issues, and with a 347, it would send your compression to the extreme end.

For a real good porting job, new valves, pushrods, exct.. You would be able to get a set of better flowing heads for about the same price.

As for intakes, look into the victor EFI, or RPMII. Maybe the carb based EFI intakes.