scootchu

I have a set of GT40 heads with the casting number F3ZE-AA on each. From what I have read they are the same heads from a '93 Cobra, but these do not have 7/16" bolts, but have 1/2" holes. Would these be off a 351 and if so would the chamber volume same if they in fact were?? How can I tell the difference since the stock springs on these heads changed depending on what they were installed in.

I will post some pics, but so far I cleaned them up (media blasted them), lapped the valves, repaired one broken intake bolt (Helicoil), Media blasted the rockers, springs and such, replaced the valve seals, did some mild porting to the exhaust, chased all threads, primered and painted.

The stamped rockers have a #5 on them and the spring retainers are different with one being a two piece that comes apart and the other a two piece that is assembled as one.

I didn't want to spend a lot on these so I have reassembled with the stock rockers and springs hoping that these would be adequate for a mild cam.

There are so many variables with these heads that I get impression that there are no set rules when looking at casting numbers. Also there are other numbers cast into the head. Do they mean anything?

Also when assembling the rockers, are the grooves in the rocker and the fulcrum supposed to match? I am assuming they are.

And one more the accessory holes are 3/8 all around and i am assuming that these already have the inserts in them, but want to be sure. I guess I would find out when I fired them up, correct?

I have new FEL-8548PT-2 gaskets on the way as well as a new ARP bolt set and the reducing bushings. I don't think I have ever spent more time preparing for something and yet I still have questions.

kalli

from a bit of googling it seems they are 60-63 cc
but you can always check with play-doh
Fill one of the chambers with playdo just to whyere the head is milled, peel it back out, make a ball out of it (is easier) and measure how much that is.
If you have something for measuring liquids volume, then you can always fill up a mug with a spout to the brim and measure how much water you spill when you put the play-doh ball in there ... my description is hopeless but you might understand it ;-)

scootchu

No, I follow. LOL
If I had a graduated beaker or something I could just measure the liquid either placed or removed from the chamber and come up with the volume, but I will have to see what I have laying around.

kalli

just googled for graduated beaker ... that's exactly it. break into a science lab close to you ...

urban_cowboy

I know Comp Cams has a kit for measuring volume. It is probably more expensive than getting a plan pipet, but they have it at least if you cannot find one somewhere.

scootchu

A couple of towns over I may be able to find a Meth lab or two... or three. Not too far from Atlantic City either. I also think I have a marinade injector somewhere. That might have measurements on it. Now to find it.

scootchu

Well I found a children's liquid tylenol cup with ml marked on it, but only in 2.5ml increments. With that being said I leveled the head and poured in approx 65ml which is equal to 65cc's. Not exact, but good enough to administer pain medication to children.

kalli

isn't the metric system a wonderful thing? 65ml of water = 65cc ;-)