SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: TAPPED OUT on May 19, 2012, 12:29:35 AM
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Is anyone familiar with a 9381 Holey carb, I have a modded out 471 olds that likes gas!!!, the stock holley carb has 78 jets all four corners with 6.5 power valves installed on both ends. any advice on jet size or power valves? I think I need to block off the secondary power valve with a 84/94 jetting for more power, anyone got any ideas? Also where is a performance shop, or the best place to buy a holley jet kit in Las Vegas?
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It's set correct with a jet size 78 primary, 78 secondary, & two 6.5 power valves. Blast it & go up one size at a time from there if it runs too lean. By the way nice carburator.
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It's set correct with a jet size 78 primary, 78 secondary, & two 6.5 power valves. Then go up one size at a time from there if it runs too lean. By the way nice carburator.
I would actually stay with the 78/78 jets but I would drop the PV rating from 6.5 to 4.5 if this thing is as radical as you insinuate....
Take a manifold vacuum reading with it idling in the water and find out where you are, I bet in the low 6's, so you PV's are always "in"...Makes them difficult to get a good dial in.
Your guess on the jet sizes with a lugged PV is pretty close, but it will probably lose some driveability (stumble)...
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Thanks for the replies, I was really lean with the 78's, spark plugs were cleaner than new, I bumped all the way to 84's in all four corners, I am getting a little bit of color now on the spark plugs and the engine seems to run better. This is the first time using this type of carb, it reminds me of a mechanical fuel injection. I agree it is a nice carb so far.