Reply With QuoteI've always changed 2 sizes at a time, 1 size will hardly make any noticeable differences.
Get the non stick buna-n gaskets so you can reuse them in case you have to get in there a few times
I've got a 468, intercooled, B&M 420, two 650 Holleys, 8 pounds of boost...last season ran great with the current jets/carb settings...minimal transon soot. Over the winter I freshened it up, installed one size smaller cam shaft and dropped the boost to 5psi...now the whole back of the boat is always covered with soot. I know it's not just from a rich idle, because it's from top to bottom like when your up and running. The carbs aren't boost referenced and the power valves are not blown....
Anyway my question is...is dropping just one jet size going to make that big of a difference...or should I drop it 2-3 sizes??? Currently I've got 84s on the secondarys and 78s on the primarys?? I just don't want to tare it apart three or four times to get it right...maybe just once or twice..
Thanks in advance. Gary
I've always changed 2 sizes at a time, 1 size will hardly make any noticeable differences.
Get the non stick buna-n gaskets so you can reuse them in case you have to get in there a few times
maybe you should drop the size of the rear jets only two sizes at a time this way you wont affect slow speed operation
I ended up dropping 2 sizes all the way around...cleaned up most of the mess on the transom and still runs great. I figure that's close enough without putting it on a dyno...definitely don't want to go on the lean side....
Want to solve all your problems, put a hat on it!...I know I know, I'm a fkn smartass!..
I have a similar set-up. I have 75 Prim. with 90 Sec. 6.5 power valves. I have not run this set-up yet. Im sure im way to rich.
dan keep it rich with the blower if it want puffing black on the trailer its lean on the high end
I'd re-check everything...
fuel pressure, timing, and basic carburetor adjustments.
Going down a couple jet sizes wouldn't hurt, but your settings are fairly cookie cutter for blower set-ups. Now going to a smaller cam will warrant a leaner mix but not as much as you think.
Check your floats again. Sometimes they go bad, specially being removed from the boat during a cam swap. Just some food for thought.
~Ty
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