GMC Inline 302 Head Modifications

[mactheknife]

Does anybody have any experience on the early (pre 1962) GMC heads? I want to take the early 302 GMC head and take about 2 inch off the side of the head and add it back in with a 2 inch plate to make it a 12 port head. This way I will be able to raise the runners and seal up the water jackets I would need to cut into.

The stock port configuration all but the outside ports are siamese. My rules require to run a stock head.

[automotive breath]

Does anybody have any experience on the early (pre 1962) GMC heads? I want to take the early 302 GMC head and take about 2 inch off the side of the head and add it back in with a 2 inch plate to make it a 12 port head. This way I will be able to raise the runners and seal up the water jackets I would need to cut into.

The stock port configuration all but the outside ports are siamese. My rules require to run a stock head.

Larry at http://www.t6racing.org/ may be able to help. He is involved with something they call lump porting, a method of raising the floor on old straight six heads.

[mtkawboy]

Theres a guy named Jack Robinson that runs a 7000 RPM 200 mph+ mph GMC powered vintage radically chopped top 32 ford competition coupe that runs over 200 at Bonneville . Id try looking at www,scta.org or landracing.coms message board and ask your question there. Ive also seen some pretty catostrophic blowups on it too, like one that had a hole in the side of the block your head would fit in. There are also a number of other GMC's that run there too but Jack is the man along with a guy named Ferguson who runs a modified roadster

[mtkawboy]

http://www.landracing.net/picturepost/d ... a40778f6fc Picture of Robinsons XO/VGC 32

[mactheknife]

I talked to both Ronbinson and Furgason. They have both been very helpful. In fact thanks to them we have shortened our R&D time. But want to try some new ideas.

In theory it should work. found several people that have finished projects of my idea. But so far its only an idea. I guess is what I need is somebody that is good with welding cast iron. rules require us to use the stock head.

I have herd of guy that did this and he got it to flow better than a 12 port. But still haven’t been able to hook up with him.

[mactheknife]

Meant to say un finished projects and have started projects.

[Unkl Ian]

I'm guessing you've heard of the '70s AMC Pro Stock heads,
where they sectioned the stock cast iron heads horizontally
to make the ports taller.They cut one head above center,
another below center,then reassembled to two larger pieces.
Lots of problems with water leaks,but they worked a lot better,
until they were banned.

The SBF guys used to have trouble with small exhaust ports,
in the factory cast iron heads.Iit was common to mill away
the top of the ports and bolt on a block of aluminum to raise
the top of the port.

Are you sure your radical surgery will still be considered a "stock" head ?
Do the rules allow welding ?

[ClassKing]

Type Glen Self Racing into Google.

[mactheknife]

Like the AMC pro stock heads, I wanted to do the modifications. By taking the section out I would be also to straighten the ports out.

Does anybody know someone that can weld cast iron? The trick would be in welding it. I need to weld up the areas for the water jackets, then pressure test, then weld and so on. But they would definitely need to understand heads. There aren’t any guys that can do that or have the patients t do it where I am. Prefer someone in California. But will look at all.

[Keith Morganstein]

Like the AMC pro stock heads, I wanted to do the modifications. By taking the section out I would be also to straighten the ports out.

Does anybody know someone that can weld cast iron? The trick would be in welding it. I need to weld up the areas for the water jackets, then pressure test, then weld and so on. But they would definitely need to understand heads. There aren’t any guys that can do that or have the patients t do it where I am. Prefer someone in California. But will look at all.

If you search google you will find various companies that have specialized procceses for cast iron.

Cylinder Head Centre in Canada uses a proccess were the head is heated red hot, then torch welded and very slowly cooled in an insulated blanket.

JBV heads on this forum uses spray welding.

I use a technician that is a master of cold stitch repair. Many castings can be repaired and modified this way. See the photo sequence below

[mactheknife]

Keith,

Thanks for the info. This is what I was looking for. I have the pieces to be welded in, just didn’t know the process and if it could be done. Your pictures helped.

[Keith Morganstein]

Keith,

Thanks for the info. This is what I was looking for. I have the pieces to be welded in, just didn’t know the process and if it could be done. Your pictures helped.

I just want to clarify that the process in the photo's is not welding, but a mechanical procedure of locks and threaded pins. This Technician makes all his own locks and pins and is able to do things that might be difficult with commercial systems. Such as locks that follow curves etc...

The block in the photo was pressure tested to 40psi. That is a fair amount of force when you consider the suface area of the piece installed.

[SStrokerAce]

I would imagine with some CNC work to make your new billet piece fit the head csting much better and one of these "welding" techniques for cast iron you could figure out a way to do all of this. I'll wish you luck because it looks like a big undertaking just to get banned later on!

Bret

[mtkawboy]

That generally what happens when you go too fast in a vintage class. At Bonneville theres a vintage head inline class and called X0 {roughly vintage overhead, 59 or earlier, 325 cubes max}. After a certain amount of mods or an aftermarket head you get moved to XXO which is what Ferguson and Robinson run. Nobody cares if its a turd but if it flies everyone starts screaming. Years back Ron Main showed up with a funny car style mega buck blown flathead with computerised fuel injection. After he reset all the records they outlawed it because it failed to meet the sprit of the vintage rules even though at the time it wasnt strictly prohibited. The car was a work of art, reverse flow flathead. It was the worlds most expensive flathead ever built. Do a search under "Flatfire"to see it, it now has a GM project Ecotec 4 cyl in it. Still would be a neat project, keep us posted

[jacksoni]

That generally what happens when you go too fast in a vintage class. At Bonneville theres a vintage head inline class and called X0 {roughly vintage overhead, 59 or earlier, 325 cubes max}. After a certain amount of mods or an aftermarket head you get moved to XXO which is what Ferguson and Robinson run. Nobody cares if its a turd but if it flies everyone starts screaming. Years back Ron Main showed up with a funny car style mega buck blown flathead with computerised fuel injection. After he reset all the records they outlawed it because it failed to meet the sprit of the vintage rules even though at the time it wasnt strictly prohibited. The car was a work of art, reverse flow flathead. It was the worlds most expensive flathead ever built. Do a search under "Flatfire"to see it, it now has a GM project Ecotec 4 cyl in it. Still would be a neat project, keep us posted

Yes, Ron went over 300 with both of those engines. Finally broke my 17year old blown gas record with the Ecotec. 37 mph on the record, about 18 better than my best run. Amazing what megabucks will do.