I have a SBC that has a spread bore Rochester Qjet pattern that I’m swapping out for a Holley 4160 Squarebore. I have a Mr. Gasket 1932 adaptor that’s going on my Weiand 8004 intake to make everything fix. I can seem to find any info or pics on how this adaptor goes on my intake, does the spread bore design go face down and the Sqaure design go up to mate with the Holley or is it vice versa. Any info would be great appreciated, pics would be good to if anyone has some.
I’d assume one side matches to the carb, other to the intake, right? If so that’s how I would put in on
I won't start an argument about the relative performance of the Q-Jet versus the Holley. But, unless you want to go significantly SLOWER and also own stock in Shell Oil, you won't be happy with the performance using the adapter. If you want to use a square-bore carburetor, best to use a square-bore intake manifold. And if you are using the adapter to its best use (as a paperweight), it really doesn't matter which side is up or down! Jon.
Turn it upside down and run it until you get the right manifold. Engines are air pumps and don’t care as long as there are no vacuum leaks. It just won’t be as efficient as it could be with a good dual plane for the street.
Adapter suck. Get the right manifold. Doing this a long time. Or Get a Jegs Q-jet for Your manifold. They WORK. Bolt on,adjust air and idle speed and go.
the pictures of that manifold i see online show its drilled for bolth patterns. have you set a holley on it to see if it will seal up
Having had to use the adapter on many dirt track cars because of the rules. Spending some time with some cartridge rolls port matching an Edelbrock adapter works best and makes the most power. Cutting the center of the plenum helps top end power . they changed the rules on me after I dominated the pure stock class with a Caddy Qjet on a stock cast iron intake. If it were my car I would run a Qjet and leave that Holley on the shelf.
If you're using a dual plane manifold. The adapter defeats the purpose. There is no center to separate the 2 planes on the adapter. It wouldn't matter if it is a single plane manifold.
One can easily do the math. The common Q-Jet is 750 CFM (read as 150 CFM primary, and a variable 600 CFM secondary). So for an example, replacing the Q-Jet with a 750 CFM Holley square-bore (read 375 CFM on both primary and secondary) The Q-Jet manifold will allow 150 CFM on the primary side (the rest of the 375 from the Holley is wasted). The secondary of the Holley is 375 FM. Adding 150 + 375 + 525 CFM. Some of this can be regained by long hours on a milling machine, port matching and smoothing the adapter AND manifold surfaces. And best to remove the manifold before machining. Personally, I am lazy. Much easier to either leave what one has, or change the manifold to use what one desires. Southcross - local racing authorities are good at changing the rules. We had the same thing happen to an outlaw midget we sponsored three consecutive years! Each time the legal carburetor was made not legal. They finally went to one Holley list number being the only carb allowed. Jon.
I ran that adapter for awhile when I switched from a Holley spread bore to a Holley square bore double pumper dumper, then eventually switched to a dual quad Carter setup. You won't have a problem running the adapter, the car will do all its supposed to do with it on there. I will say that the car had the best "seat of the pants" acceleration with those big spread bore barrels but was really about equal after the novelty of the kick in the pants was over.
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