If you know Y blocks you most likely know the Offy 3 x 2 intake is the worst performer. well I picked up one cheap and now I must make the best of it, what can be done to improve it's performance? What I'm thinking is to just clean up the mould flashing (there is a lot) under the area where the carbs mount and round off the 90* turns in the same area. What about carb spacers? If spacers would help about what size, how tall 1/2"? more? less? This intake came with 94 carbs and they look nice but will have to be gone through, I have not taken them apart and don't know what jets are in them. Motor is a 292 with mild cam and lake pipes, 3 speed trans all in a '30 tudor.
Go to www.eatonbalancing.com , In the July 2018 archives is an article Y-block 3x2 testing by Joe Craine where he tests that manifold and its problems. its Good Y-block Reading
Look in the carb ports. It’s because all three feed to the same plane and go to the front, do a 180*, and go to the intake ports as I remember. Not saying to do this but when I had one I thought very seriously of using a hole saw in the out carb ports on each end so the 2 outer carb would go straight into the head ports. I thought of l would leave the center carb ports as they were. I never used it and went to dual quads instead. Any other manufacturers 3-2’s for a y block was better and the Edelbrock the best. Funny but a lot of Offys were made and sold…
This link is to the article by Joe Craine on testing anD flowing the Offy manifold. As you’re aware, it’s not the best starting point. He makes some improvement, but not great. If Joe can’t get the flow up, probably nobody can. But it’s good info. https://www.eatonbalancing.com/wp-content/uploads/2020/10/YBlock-146-Craine-3X2-Test.pdf
I’ve read Joe’s and Ted’s many dyno tests on y blocks in the Y- Block magazine out bi-monthly and have been in Ted’s shop on a visit to Texas with Karol Miller. A surprising few lines written about the tests of a 2 Summit 4 barrels on a Blue Thunder Manifold on the 314” test mule engine prior to the 3-2 tests were enlightening to me. The 500 cfm was only 8 hp behind the 750 cfm both clearing the 1 hp per cubic inch of which none of the 3-2’s could do which is not surprising. I have a BT manifold and new 500 Summit waiting if I ever take off my dual Carter WCFB’s. I’m sure a 500 would be very drivable and friendly.
Thanks for the info on the Joe Craine article, I had read that the other day. Jimmy Six, I'm not sure what you mean, it looks like my intake is just open under the carbs and the ports just tap out of that area. I'll have to look again. I plan on porting what I can, as far down as I can I'm sure I will not end up with as good of an end product as Joe Craine did. In that article they used carb spacers to keep the heat out of the carbs what are the thoughts on that?
Again, we're faced with a form-over-function issue. It sounds like people are telling the OP to go with a single 4-bbl. I agree. Options include the 57 manifold/w plenum opened up to two ovals, Blue Thunder (most expensive, but has heat crossover for choke, unlike Mummert's, and looks stock when painted), and Mummert's (two versions, one taller than the other, but shorter Tbird version still a bit taller than stock).
The Offy I had did not go down to the ports at all. All 3 went into a chamber below the six holes and it went to the front and if I looked into the ports at the intake side I could see a chamber but not the carb one. I gave it away years ago and got it for free. I always thought it was weird…
That is what I have on the car now. I knew this Offy intake was the poor performing one when I bought it and would have liked to get a better one but this was at a swap meet and was good price. And you are right, this is a form over function thing , not really looking more performance just don't want to give up any. Thanks for the tip on the phenolic spacers.
I'm not sure I have the same manifold that you had, mine seems to have a chamber on the drivers side of the plenum that is the heat chamber connected to the exhaust crossover, other than that, it is open from the six holes to the intake runners. Anyway my manifold has terrible casting flashing inside and a bunch of ugly 90* turns that I can clean up.
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