Reply With Quoterun it and check the plugs
Installing a stock double pumper on my small block chevy. Do I need to do any rejetting?
run it and check the plugs
Run it as is to start with then go from there!. If the carb is close to what the motor requires, you may not need to do anything to it!....
If you go with a Holley 3310 or 4160 you should be good with the stock jetting. Of course it depends on how built this 350 is. Just put it on and check the plugs and go from there, jets are cheap.
I put a 0-80559 4150 DP 600cfm mec secondary marine carb on mine. Little cam, thats all (xe274h). Large logs/w short O/T trumpets.
Lean, lean, lean. Came with 67 and 74 jets. Put the new ones in, 70 and 80 but havent tried it yet.
Plugs came out clean, clean, clean, with a little (detonation) spotting on them. This was after some WOT and idle and everything.
1st run was with r43t plugs. Second was with r34ts, ran worse.
Idle, start real good. A little hesitation on acceleration thru midrange, but steady. A little ragged on WOT. We shall see.
Now i made me some baffles (actually modified x mufflers). Wonder how the baffles affect jetting?
mikeT
Run the carb right out of the box , check plug's , if their real black and sooty jet down. If the boat pulsates or hesitate's on the top end jet up. I try to jump up only a couple of jet's at a time ,so as not to over compensate all at once.You might try Holley vent baffle's while you have it apart, they really control fuel slosh.The carb is definately going to use more fuel than a vacuam secondary though . I have a 600 vac sec. with jet's on both side's on my 327 and it run's great. At partial throttle all four barrel's are going to be starting to dump fuel.Unlike a vacuam which will be running on only two barrel's.
Properly done, i should have checked the mainfold vacuum and sized the power valves accordingly. I did get a set of even numbered jets. Consensus of the experienced say FAT IS BETTER and safer. Not much time to test.
Maybe one day i will be among them.
I knew there were extensions, but did not know about the baffles. I did get sightglasses.
mikeT
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