Offenhauser intake install

[Goldie80]

Hello, I have a couple of questinos about a dual offenhauser intake and cast iron headers I purchased from Tom Langdon. I was expecting them to be a bolt on installation, but I am seeing quite a bit of overlap when laying them on. Has anyone used this type of setup before? I have a chevy 230 in a 63 C10.

[Heater63]

This is not a big item. Just trim down the aluminum Offy intake bolt flanges to clear the exhaust manifold, and don't make the fit too tight, leave room for thermal expansion between the exhaust and the intake.

Some guys use the stock clamps/bolts, some use some studs, I use both. I have studs on the center port, and bolts everywhere else. Some guys use Bellviele washers (see spring disc washers at McMaster-Carr) for a locking system. You can also use self aligning spherical washers if the two surfaces are not even.

there is some info at inliners.org on this, search their bulletin board. And just a lot of info on the 230/250 and mods there. Make sure you run HEI too.

[Goldie80]

Dude, you are too cool! Thanks for the information, that's going to help a lot.

['68OrangeSunshine]

Also, if you haven't found out yet, the "guide pins" forward of Cyl 1 and aft of Cyl 6 come out with a Vice-grips and are threaded 3/8-16 UNC. So you can put studs or bolts in those positions for superior sealing.
In a couple of places I used the half-balls from rocker arms as manifold washers, but I'm running an Offy 4Bbl intake and Clifford headers on a 292.

[Goldie80]

That's also a great idea. I would not have thought of that. Thanks for the heads up.

[Fred T]

I always wondered why Offy and Fenton didn't work together and solve that problem. It's easiest to fit them with the head on the workbench, makes marking and grinding easier. They didn't fit on the older series sixes either.

Don't be afraid to ask Tom if you have questions. He's been rodding stovebolts since I was in diapers.

[Goldie80]

Thanks for the info guys, I really appreciate it. I did shoot Tom an email and got a pretty timely response too. I figured I would share the info from Tom. There was a handy document that came with the parts I must have forgotten about or perhaps my lovely wife reorganized it for me, who knows. Either way, here it is for those of you who may be curious. Thanks again for the responses everyone was right on the money!!

"HEADER INSTALLATION TIPS• Do a trial fit with the inlet manifold before painting or thermal coating. Minor adjustments to the inlet and/or exhaust header flange area and clamps will be required. On inlet manifold stud locating holes (2), saw "half" of the hole off to provide clearance to the header flange. It is important that the clamps be parallel to the head surface to achieve equal loading on the inlet/exhaust gasket. Depending on your inlet manifold flange thickness, grinding or metal addition to the clamps may be required to get them parallel to the head surface.

• Painting should be done after cleaning and warming to remove surface moisture. After the paint air dries, bake on an outdoor gas grill for one hour to cure the paint.

• The front header requires a tight bend as it exits the flange. The pipe MUST be bent first and then flared second to avoid interference with the clutch linkage.

• These headers do not provide inlet manifold heat. Water heating will be required for good carburetion and driveability. This is a "must".

• To achieve the classic six cylinder sound, we recommend perforated core construction mufflers like the most popular "Smithys" were made back in the '50's. Current "Smithys" are NOT made with a perforated core. Look for the little round holes inside the muffler before you buy. A 2 1/4" front pipe is recommended with full length 2" tailpipes extending to the rear bumper. Locate the mufflers as far forward as possible. Chose 24"-36" muffler length depending on the sound level you desire. Due to the pulse flow present in this type system, joint leaks can be more of a problem than most muffler shops might expect. Do not combine muffler hangers with joint clamps or the resulting distortion will likely cause annoying joint leaks."

[Fred T]

The water heat works, but it's not that great. Many in warmer areas do not install it since it is another place to leak coolant. The last one I worked on we used grey rtv. It's the right color, too.

[Goldie80]

You know, my Dad and I were thinking the same thing. I am in the S.F. bay area and the coldest we get around here is around 30 F and that's in the middle of the night. I figure we can give it a try without, but I have the plate that goes onto the bottom of the intake just incase I decide to run the water.

['68OrangeSunshine]

I got the guide pins tip from Leo Santucci's book, "Chevrolet InLine Six Cylinder Power Manual."
I live in Tucson, Arizona. I don't run carb heat.