Thread: Intake swap

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Originally Posted by TomJ

NTFDay, I think the rare fuelie heads are the 997 heads. The charts I see show them as heads for F.I. and 4 barrel and hp from 220-270. The chart shows the 283 hp heads to be the 539 casting. This could be wrong maybe.

Don't know about casting numbers, but from what I remember about the 57 fuelie heads is that they had two rectangles on top of the pad, one short, one long. I do remember that 283 hp was first offered in 57 with FI and GM made a big deal of it, 1 hp per cubic inch.

This is the cam card for the Isky 30/30 I have in the garage

Tom how did you cut the nice radius in the sheet metal? If it doesn't require special tools I'd be interested in doing it myself.

Steve, tinsnips, I have a little 3 foot sheet metal bender I bent the sheet with. you could probably rig something with angle irons to to that.

NTF, I think the reason those fuelie heads are so expensive is that they are rare. I doubt they are any different thant the 283 hp heads. I have like an 097 cam in it now that is like the original Duntov cam. That 30/30 cam is little to hairy for me.

Offenhauser 360 SBC Intake | eBay

This would work fine for your application and IMHO it's hard to beat an Offy 360º. I'm convinced it's the manifold Chevy copied and used on the 67 Z28.

Thanks Tom!

NTF, do you know what the port size is on the offy 360? I bid on one on ebay then got to thinking the ports may be too big for my heads same as the typhoon.

I sure do like that gauge set up, wish you luck on your man/carb change.

Originally Posted by TomJ

NTF, do you know what the port size is on the offy 360? I bid on one on ebay then got to thinking the ports may be too big for my heads same as the typhoon.

I'm not sure and I can't get to the one I have in the garage, but suffice it to say that the only thing that will fit your heads exactly are heads from the era. I doubt that the exhaust ports line up exactly with your headers either. I wouldn't worry too much about the ports lining up since it won't make that much difference with what you expect of the engine. There is only so much that can be designed into a mass produced intake manifold and IMHO Offenhauser came upon the optimum design in the 360º years ago and everyone else has been copying since. I wouldn't think twice about dropping one on your heads with no more than a Holley 600 with no more than 62 jets in the primary, probably smaller, and no more than 64's in the secondary.

Originally Posted by NTFDAY

I'm convinced it's the manifold Chevy copied and used on the 67 Z28.

I don't think so Ken. The Offenhauser 360, single-plane design allows all 8 cylinders to see each other, plus all the manifold volume and all venturis of the carburetor.
The Z-28 manifold was a 180, dual-plane design that allows only 4 cylinders to see each other, plus only half the intake manifold volume and only the left or right side venturis of the carburetor.

You'll notice that all OEM carbureted motors have used the 180 design from the factory. That's because that particular design works best from idle to 4500/5000 rpm's, generally the limit for a factory stock cam. A larger runner 180 intake, such as the Weiand 8016 Stealth, 300-36 Holley or Edelbrock Performer RPM will make more power under curve from idle to 6000 than any other manifold design, including 360 single-plane designs in my experience.

Urban legend says that Edelbrock copied the Chevrolet Z-28 design to make the RPM and that Weiand and Holley followed suit with their copies of the 180-degree, dual-plane design .

It is of no consequence here, but one of the prettiest motors I ever saw was a 460 Ford with a Weiand Stealth intake and a large X huge Holley double pumper (the original Stealth, not one of the current Stealths which are a watered-down design).

Of course, I could be wrong.


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Every single plane manifold I've seen has an open plenum and the Offy 360º I have in the garage and the Offy 360º dual quad I have are both split plenum.

Does anyone here have access to an early 55/56 sbc head so they can measure the distance from the center of the manifold bolt hole to the bottm of the casting that would be in the lifter galley?

As a follow up on previously mentioned work, all up grades are complete and truck starts and runs great. I upgraded the heads to '57 283 heads which are 9 1/2 to 1 compression and had them ported to match the Typhoon manifold. I used the demon carb as it was out of the box only had to adjust idle air. I also installed a mini starter aluminum oil pan and front cover, mechanical fuel pump, fuel pressure regulator and reworked the steering and exhaust.

that looks real purdy!
i see you have a fuel pressure gauge on the regulator whats the other gauge you can see?
thanks for the follow up report
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