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| | | | Joined: Oct 2014 Posts: 11 New Guy | | New Guy Joined: Oct 2014 Posts: 11 | Im going to rebuild a mid 70s 2 jet and adapt it to my 230 (2 into 1 adapter). The carb has #54 Jets in it. If anyone has done this swap can you recommend a good starting size for the Jets | | | | | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | I havn't done a swap like that but I've worked with a lot of those carbs. They usually have 055 jets in them. I would start with what is there & taylor it from there. Sounds like an interesting swap. Let us know how it turns out.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | | | | Joined: Nov 2002 Posts: 2,767 Carburetion specialist | | Carburetion specialist Joined: Nov 2002 Posts: 2,767 | Usually a good idea to jet it stock and then tune from there. Since you are planning on using a 2 -> 1 adapter rather than using a two-barrel intake, I would highly suggest initial plugging of the power system to dial in the main metering jets. The two into one really messes with the vacuum signal.
Just guessing, I would say that with no modifications, it will be pig rich at cruise and very lean at WOT due to the two into one, plus the idle will be exceptionally lean. Believe you will need to eventually use a different power valve actuating valve spring to keep the power valve from being open all of the time, richen the jets 3~4 sizes (again, screwy vacuum signal), and richen the idle jets 0.003~0.006 inch (vacuum). But don't do any of this unless you need to. Just believe this is where you will end up.
Oh, and the vacuum signal to which I refer is the negative pressure in the fuel wells of the carb, not the engine vacuum. The fuel well negative pressure is controlled by air velocity, which is effectively killed by the 2 into 1.
A much better situation would be to modify the original manifold with a two-barrel plenum and NOT use the adapter. Results will be MUCH better.....driveability, power, and fuel economy.
If you watch NASCAR, think "restricter plate"!
Did a LOT of testing one to two and two to one years ago; NEVER with positive results. Average was the two-barrel would produce about 75 percent as much power as the single barrel it replaced.
Jon.
Good carburetion is fuelish hot airThe most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes!The Carburetor Shop | | | | | Joined: Oct 2014 Posts: 11 New Guy | | New Guy Joined: Oct 2014 Posts: 11 | Thanks Jon, I think a 2 barrel manifold would be the way to go. I enjoy all your advice, here and theHAMB. | | |
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