I purchased a Rochester 2G tri power set up on an Edelbrock intake with progressive linkage. I'm running this set up on a stock 350 SBC. I'm looking for some advice on what size jets I should be using in these carbs? Thanks in advance for any help.
No that's my problem. The main carb has 74's in it and I have 2 feet of flames coming out of my headers. I'm thinking they should be some where around 50 ???????
they originally were a "10" difference main to sec. Carbking on here has the books and posted the OEM jets for all the GM trips 57-61...I think he was saying 50 and 60 as a general spec, but don't bank on my memory. I have no clue what jets on secondary's if they are not genuine tripowers, and still have power pistons?
My crate 350s Rochesters run 57s in center carb and 56s in the ends. I'm totally pleased with this setup. I highly recommend heat spacers under carb bases (eliminates gas percolation)
Remember after your happy with them to open it up every so often. Normal single carb use will cause the outers to sometime flood by the vibration against their needles and seats. Back when 3-2's were stock and some were sold to unsuspecting customers servicemen had a hard time explaining that needed to "cleaned" out every so often to maintain proper tune.. Good luck.
Olds 57/58 Cad Eldorado started in 58? Pont had to be 57 or 58 start. Chev 58 first year-to 61? I do have a 57 and a 58 olds parts books I can try to look up carb parts, I just doubt it will give jet sizes though. But I will try tonight .
I just looked in 57 OLDS factory parts book. This will be 371 cubic inch. Olds calls trips a "power package" in the carb section. Direct Quotes:when looking at jets only. - fits 56 w/4barrel, and 57 "power package center carb": "(STD) (stamped 55) (primary) ok, that above reference to "primary" just denotes the primary side of a 4gc, and I assume (std) means the normal jet size, rather than a high altitude optional size? Edit: it can't mean standard shift, as there is no other number for "A/T" cars, so it is a normal altitude jet size. -57 w/power package (for front and rear carb) Ok, there is no note on what size for outboards, just the following part number which does not match any other jets in this book that covers 49-57 carbs 7002650 hope that helps a bit. get some advice on the cubic inch difference on that 55 center jets size? . .
Thanks for all the info. I ordered .056 for the primary and .055 for my secondary's. I think this will get me in the ball park now. I just can't believe that I spent near $2000.00 at Summit Racing for this tri power set up and they sent me this set up with .074 jets in the main carb. Freakin crazy.....
I'm putting a similar tri power setup on my sbc in my '55' Chevy. I also have a tri power setup on another sbc in my '40' Ford. The '40' has a few thousand miles on it and runs great, so I wanted close to the same jets in my new tri power setup. I pulled a plug from the '40' Ford today and it looked great (not too rich or lean). The '40' Ford is running 55's in center carb and 57's on the ends. My new setup came with 56's and 57' so I think I will use them and see how they work. What you ordered should work for you. Have fun with tri power carbs. Dirtcop
Just a quick reminder that the Rochester 2G carbs don't like more than 4 pounds pressure. Be sure to put a regulator and gauge on to confirm pressure. I run right around 3 1/2 pounds and everything seems to work fine. Dirtcop
Really impossible to suggest a beginning main jet size without knowing what carburetors you have. Two carbs, one with .055 jets, and another with 0.065 jets MIGHT have the same A/F ratio depending on the pressed-in air jets. Remember......a carburetor is a device for METERING and mixing BOTH fuel and AIR. With no other knowledge of what you have, would suggest block-off plates under the front and rear, and maybe try some 0.071 (if 0.074 came in the set-up). If that is too rich, drop another 0.003 until you go slightly lean, and then do an intermediate size. Dropping 0.020 at one time without knowing where you are is asking for burned pistons. Do the change safely. Once you get the center dialed in, remove the block-off plates one at a time. If the end carb has no issues, there should be no change in A/F ratio with the end carbs added, but not in use. Of course, under WOT, the end carbs should add both air and fuel. Something else: since you have been into the center carb, is the power valve functional? Some tuners remove the power valve, which requires a large increase in the main metering jets. Not personally a fan of this, but some do it. Jon.
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