Should I go with gt-40 heads?? Help!!

[ddtforu]

Hi all,

My engine is being rebuilt right now and I've been thinking about possibly adding different cylinder heads to the mix but need more opinions first. Here's the setup as it is, .40 over, fs 260h-10 high energy cam(although this can be replaced), edelbrock rpm manifold, holley 600cfm, and with stock 54cc heads now, and we're planning on roller rockers. But I can pick up a set of gt40 heads from a 93 svt lighting f150(same as cobra) with 50k miles for $300.

If I do do the swap, what else will need to be changed as far as springs, pushrods etc etc?? I know I will lose compression with the bigger chambers, so would it be more advantageous to rework the original heads with bigger valves/porting to keep the higher compression, or go with the gt40's? Also if it means anything we're also swapping out the toploader for a t-5. Thanks for all your input, I need as much information as I can get as soon as possible.

 

[steel1212]

I have a set of those 54cc heads like you have that have been reworked before I got them. If I have some spare change this winter I'll probably step up from the 1.84 and 1.5 valves that are in them to 1.9s and 1.6s. But other than that they have been ported and polished with screw in studs and gide plates as well as comp cams magnum roller tip rockers. I don't know what the machine shops charge around where you live to rework you heads but I know I like mine.

Are the gt-40s aluminum? If they aren't I don't see why you don't work your heads unless it will end up being a lot more than the gt-40s. Just my .02

 

[ddtforu]

They are irons....not sure what it would run, car is actually in the phoenix area at my dad's where the rebuild is happening, I'm in northern Cali where I'm sure it would be expensive here like everything else. I'm sure there's probably some reasonable people that he knows, any ideas on ballpark figures?? I know he was planning on putting hardened seats in himself and new valves, would there be much more work putting in the larger valves etc? Also what about porting them ourselves, know of any good online guides etc? thanks a bunch.

 

[steel1212]

I don't know much about porting or polishing so I bought a set that came with flow numbers. The "good" local shops around here wanted to charge me about 700 or so just to put in hardened seats, new valves and screw in studs. That was during the racing season though and they charge more during that time. I would say you could probably have your heads worked for about 500 or so. I think I looked at gt-40 heads versus my flow numbers and mine are a little bit above those. If the gt-40 heads don't require a rebuild and have screw in rockers they might be worth it but you'll lose compression by going to them. Its kind of a toss up in my opinion after I get to thinking about it. On one hand you already have some high compression heads that need to be worked on the other hand you can get some decent heads for a good price if they don't need to be worked.

 

[ddtforu]

guess I'll stick with the original heads, didnt get enough feedback about what else will need to be changed/bought etc, and I needed good numbers on what it would cost me to go with the new heads. Sounds like the guy doing my block will also do heads, but he's very slow(but can't complain for the price, he gives a good friend discount to my dad).

 

[steel1212]

If you don't mind me asking what is he charging you and what all will he be doing? Does he have a flow bench?

 

[ddtforu]

Haven't heard a final number from my dad yet, but probably in the $200 area. I don't think he has a flow bench but I don't know for sure, but my dad says he does a lot of race motorcycle engines(he's boring the block for a couple hundred, but like I said before he takes his time doing it). Now that I've thought about it more, I don't plan on racing, so I'm not too concerned with getting the "max" potential out of the engine, it ran really good before without the porting so the way I look at it even an extra 10-20 hp is just bonus hp. But overall we're just putting in hardened seats and new valves on the heads.

 

[steel1212]

If he is doing harden seats, new valves, might as well have him at least smooth everything. I don't think that would be much. Also is he pulling the studs and installing screw in studs? I'm probably going to have my heads matched to my intake this winter...outta be good for a couple of hp.