Offenhauser dual plane intake and Weber 32/36 DGV on an L16

[laotsu]

So I got this killer Offy intake manifold yesterday, thanks Laecaon, and it has a 1/4 inch riser plate. In my research I have read that this intake is best run with no adapter or riser to get the best low end torque out of it. the best guess on why the riser is here is to keep the long intake studs from interfering with the Weber. is there any reason I can't run it without the riser and just trim the studs?

 

[RedBanner]

The studs come out, I wouldnt trim them.

[Laecaon]

Also, there was never a gasket between my carb and the riser...

[datzenmike]

What do the ports look like? Is there an upper and lower level?

[laotsu]

Yes, split ports.

[datzenmike]

I remember these 'back in the day' In theory the smaller primary has higher flow speed so better cylinder filling at low mid and when the secondary open it's all good. The problem is this only applies to the intake and once the air enters the head is slowed down by the much larger port diameter. It was never clear if it really worked or not.

[Farmer Joe]

Lorri's kingcab has an L20 with one of those intakes. Its okay to putt around on the low end but there a big dead spot when you get the secondary goin. Kinda weird.

[datzenmike]

Maybe that sudden wall just below the secondary throttle plate? The air has to turn a sharp 90 right there.

[Laecaon]

It was on my car, I had no dead spots on my L19, except the idle to primary changeover.

 

It definitely sounded nice, louder than my SUs...

[hobbes_the_cat]

I ran my offy duel plane or duel port, whatever its called on a L18 and had no dead spots once I jetted the weber. It's a nice mani that helps with low end IMO. Noticeably better than a stock mani.

[RBs30]

just double nut those studs and pull em off. 

no need for a riser, offenhauser woulda made the mounting surface taller if they felt it needed to be.

[Z-train]

What's the port diameter on the offy?Is it the size of an L-20B intake?If so,it will HURT low end performance.Removing the spacer will hurt low end performance.Anything that will adversly effect low speed cyinder filling is not good for low down gains.Having said this everything is a trade off.

[Just Joel]

I recently picked up a edlebrock (sp?) Intake and with out a riser, the carb linkage hits the body of the intake at wot. You may or may not have this problem with yours.

 

Joel

[Jesse C.]

Run it if you have a truck as it creates better low end grunt. I had one and it did nothing for me. I had better performance with my stock manifold as it worked better in the higher RPM range. This was in my 69 510 with an L-18