SpeedTalk Store - Opinion Columns

GMC Inline 302 Head Modifications

General engine tech -- Drag Racing to Circle Track

Moderator: Team

GMC Inline 302 Head Modifications

Postby mactheknife » Thu Jul 06, 2006 9:51 pm

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.
mactheknife
Member
Member
 
Posts: 53
Joined: Thu May 04, 2006 10:54 pm

Re: GMC Inline 302 Head Modifications

Postby automotive breath » Thu Jul 06, 2006 10:00 pm

mactheknife wrote: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.
automotive breath
Guru
Guru
 
Posts: 1606
Joined: Sun Aug 28, 2005 10:54 pm

Postby mtkawboy » Sat Jul 08, 2006 11:27 am

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
Pro
Pro
 
Posts: 262
Joined: Sat Jul 17, 2004 12:04 pm
Location: Billings Mt

Postby mtkawboy » Sat Jul 08, 2006 12:01 pm

mtkawboy
Pro
Pro
 
Posts: 262
Joined: Sat Jul 17, 2004 12:04 pm
Location: Billings Mt

Postby mactheknife » Sat Jul 08, 2006 6:49 pm

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
Member
Member
 
Posts: 53
Joined: Thu May 04, 2006 10:54 pm

Postby mactheknife » Sat Jul 08, 2006 6:50 pm

Meant to say un finished projects and have started projects.
mactheknife
Member
Member
 
Posts: 53
Joined: Thu May 04, 2006 10:54 pm

Postby Unkl Ian » Sat Jul 08, 2006 11:24 pm

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 ?
Just because you never studied the Laws of Physics,
doesn't mean they won't try to kick your ass.
Unkl Ian
Guru
Guru
 
Posts: 2849
Joined: Thu Oct 06, 2005 8:23 pm
Location: Just outside Toronto

Postby ClassKing » Sun Jul 09, 2006 12:51 am

Type Glen Self Racing into Google.
Function - the hidden math.
http://www.pontiacengines.com
ClassKing
Expert
Expert
 
Posts: 745
Joined: Sun Jul 11, 2004 12:23 am
Location: So.Cal.

Postby mactheknife » Sun Jul 09, 2006 2:29 am

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.
mactheknife
Member
Member
 
Posts: 53
Joined: Thu May 04, 2006 10:54 pm

Postby Keith Morganstein » Sun Jul 09, 2006 8:47 am

mactheknife wrote: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



Image

Image

Image

Image

Image
"Nil Satis Nisi Optimum"
User avatar
Keith Morganstein
Guru
Guru
 
Posts: 4472
Joined: Sun Feb 19, 2006 10:19 am
Location: MA

Postby mactheknife » Sun Jul 09, 2006 12:43 pm

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.
mactheknife
Member
Member
 
Posts: 53
Joined: Thu May 04, 2006 10:54 pm

Postby Keith Morganstein » Wed Jul 12, 2006 9:44 am

mactheknife wrote: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.
"Nil Satis Nisi Optimum"
User avatar
Keith Morganstein
Guru
Guru
 
Posts: 4472
Joined: Sun Feb 19, 2006 10:19 am
Location: MA

Postby SStrokerAce » Wed Jul 12, 2006 11:32 am

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
Image
Those of you who think you know it all are particularly annoying to those of us who do- Penske garage sign @ Indy circa '71
SStrokerAce
Guru
Guru
 
Posts: 1350
Joined: Sun Jan 16, 2005 12:04 am
Location: Upstate, NY

Postby mtkawboy » Wed Jul 12, 2006 1:23 pm

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
mtkawboy
Pro
Pro
 
Posts: 262
Joined: Sat Jul 17, 2004 12:04 pm
Location: Billings Mt

Postby jacksoni » Wed Jul 12, 2006 2:59 pm

mtkawboy wrote: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. :lol:
jacksoni
Expert
Expert
 
Posts: 761
Joined: Sat Dec 18, 2004 2:54 pm
Location: Maryland

Next

Return to Engine Tech

Who is online

Users browsing this forum: Google [Bot], hammerdamage, leahymtsps and 15 guests