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Header for 50's GMC inline 6

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Header for 50's GMC inline 6

Postby Ron Golden » Tue Feb 27, 2007 12:36 am

I'm building a 1950's style dragster with a 321cid, 1950's GMC inline 6 cylinder. I have to use the stock head which has 3 simease intake ports (1&2), (3&4) and (5&6) and 4 exhaust ports with the center cylinders (2&3) and (4&5) simease. The end cylinders (1&6) have individual exhaust's.

Now that everyone is finished laughing here's my problem:

Does anyone have any knowledge about how to build a good header for this engine? I plan to dyno the engine and tune the exhaust but I'd like to have a good starting place to work from. My dyno time is unlimited and free so dyno cost's aren't a problem. I'd just like to keep my learning curve as short a possible.

Does anyone know if Pipemax addresses the problem of simease ports? Does anyone have a link to Pipemax?

Thanks for any and all help,

Ron
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50's 6 headers

Postby Adger Smith » Tue Feb 27, 2007 1:08 am

Ron,
Take a look at the Pontiac 3 tube header design. (big single center tube)That might get you some sizes to start thinking about.
Larry, maxracesoftware@yahoo.com
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Postby Brad » Tue Feb 27, 2007 8:50 am

You might talk to Ed at headersbyed.com In conversations with him it was mentioned he had done things like this back in the day.
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Postby jacksoni » Tue Feb 27, 2007 2:54 pm

You might go look at www.landracing.com and ask there. A number of these run at Bonneville from time to time and someone might have some leads for you.

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Postby Stan Weiss » Tue Feb 27, 2007 3:32 pm

Is it possible to add a divider in the two Siamese port to make individual runner?
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Postby mactheknife » Tue Feb 27, 2007 5:28 pm

We race a stock head at Bonneville and had to make improvements to the head to work . You can split the ports, but its not for the week at heart as it requires lots of welding. You can also clean the flow by adding some lumps to the intake side runners. I would talk to Mike Kirby at www.sissellsautomotive.com , he race a twin 6 cylinder rail or Joe Fontana at www.fontana-automotive.com , he races one at Bonneville and makes lots of parts for this engine. Send me an email and I will send you pics of what we did to the head. Are you running gas or going to put some pop into it?
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GMC head

Postby Ron Golden » Tue Feb 27, 2007 11:21 pm

Thanks guys for the response.

I'll talk to ED @ headersbyed and see if he has any experience with this head. The Pontiac center port suggestion makes a lot of sense.

I've thought about welding the head to divide the port but not sure I want to tackle that if I can get the flow to an acceptable level. My luck the head would crack in two and I'd be back to ground level again.

Mactheknife, I talked to Mike Kirby and tried his suggestion (build up the short turn on the intake) and just clean up the exhaust but I must have misunderstood his instructions because it didn't help. I know he has something he calls a "lump port" but not sure exactly what it is.

The pictures would help a bunch. "A picture/ thousand words" etc.

I have to run gasoline

Bob Johansen (Howard's Rods) called me today and is sending me a set of aluminum rods tomorrow. Then I can figure my compression distance,
make a mold of the combustion chamber, and get that sent off to JE so I can get a set of pistons made. I'll say one thing; SB Chevy's are a piece of cake compared to this antique monster.

Thanks guys for the help, Ron (Goldenri@aol.com)
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Re: Header for 50's GMC inline 6

Postby hsh » Sun Jan 02, 2011 2:52 pm

Ron Golden wrote:I'm building a 1950's style dragster with a 321cid, 1950's GMC inline 6 cylinder. I have to use the stock head which has 3 simease intake ports (1&2), (3&4) and (5&6) and 4 exhaust ports with the center cylinders (2&3) and (4&5) simease. The end cylinders (1&6) have individual exhaust's.

Now that everyone is finished laughing here's my problem:

Does anyone have any knowledge about how to build a good header for this engine? I plan to dyno the engine and tune the exhaust but I'd like to have a good starting place to work from. My dyno time is unlimited and free so dyno cost's aren't a problem. I'd just like to keep my learning curve as short a possible.

Does anyone know if Pipemax addresses the problem of simease ports? Does anyone have a link to Pipemax?

Thanks for any and all help,

Ron


Hi, Ron,

I have a 240cid engine in a car in France with the same porting, which i would like to pep up a bit:
did you get yours set up?
I would really be grateful for any suggestions and experience : have you some pictures of the result?
hsh6@orange.fr

henry
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Re: Header for 50's GMC inline 6

Postby PackardV8 » Sun Jan 02, 2011 4:06 pm

This is a really old thread, but since it was reopened, thought I'd throw in something no one mentioned above.

For an exhaust divider in an exhaust port to be effective, it doesn't have to be welded to the head or even hermetically sealed. All it has to do is survive the heat. Since the late '40s-early '50s Gen I Kettering V8s - Cadillac, Olds, Studebaker and Packard, we've made headers with a divider attached to the header flange. Smooth the top and bottom of the exhaust port parallel and square up the back wall. Fab a stainless steel plate to divide the port and fit as closely as possible, bolt up the header flange so it pushes the divider tight against the head and weld the divider to the header flange. For practical purposes, 1/8" is minimum and 1/4" stock is better.

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Re: Header for 50's GMC inline 6

Postby Keith Morganstein » Sun Jan 02, 2011 5:10 pm

This has been discussed in few threads.

Some things that have come up.

Variations of branch header designs http://victorylibrary.com/mopar/lcb-c.htm.

Long tube designs such as those made by Burns Headers.

Log manifolds.

Stubs or zoomies.

For a pulling tractor we ended up using parts from weld up header kit and called it good enough.
"Nil Satis Nisi Optimum"
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Re: Header for 50's GMC inline 6

Postby Ron Golden » Sun Jan 02, 2011 6:16 pm

After all the head scratching the engine was dynoed and tuned with a set of 24" zoomies. We put these on to get the car running for a nostalgia drag race. On the dyno it made 347 Hp @ 5700 and 346 TQ @ 4600. Below 3500 the engine was a dog. Later I built a set of 4x1, 40 x 1 3/4 with a 2 1/2 x 24 collector. The TQ increase was a BUNCH and the HP stayed about the same. At least the car ran the same MPH with both headers.

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Re: Header for 50's GMC inline 6

Postby Ron Golden » Sun Jan 02, 2011 6:18 pm

Henry,

Did you get my email with pictures?

Ron
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Re: Header for 50's GMC inline 6

Postby pdq67 » Sun Jan 02, 2011 8:09 pm

I gotta ask so please bear with me!

What's the bore spacing because just maybe a pieced together furnace brazed V-8 engine head to fit the 6-banger block may be way better in the end!!

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Re: Header for 50's GMC inline 6

Postby ZIGGY » Sun Jan 02, 2011 8:45 pm

pdq67 wrote:What's the bore spacing because just maybe a pieced together furnace brazed V-8 engine head to fit the 6-banger block may be way better in the end!!


Been done, hasn't it? Kay Sissell and others?
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Re: Header for 50's GMC inline 6

Postby panic » Sun Jan 02, 2011 11:25 pm

Bore pitch doesn't match anything else, the average is about 4.45"
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