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Holley adjust

1079 Views 8 Replies 4 Participants Last post by  zipchip
Hi, need some help with a diagnosis....just recently completed 70 454 (full Ls6 specs) full restoration with aftermarket Holley 850 dbl pumper, elec chock disabled, choke wide open. Carb rebuilt about 24 mos ago, ran in cam/engine, then carb sat for 12 mos before final re-install. Car has only 15 miles on it....plugs look fine, timing at usual 4 btdc.

Cold start is just fine, idle is good at around 750, no hesitation, float levels good...when engine is hot having two issues

1- Engine diesels loudly at shut down (rpm at 750)
2- Hot restart is a problem, engine cranks and acts and smells like it is flooded, will start with pedal to the floor.

Any suggestions? Also need a book or website on tuning and adjustments for a 850 dbl pump.

1 - 2 of 9 Posts
Crank the timing up on that thing. Try setting the initial at about 16* and see how it runs then. You also want to know where your total is, so you know what your advance is.

The search function here on TC is probably better than any book for Holley's and timing. There is a good Holley book out there, though. I got it at Barnes & Noble, it's called Tuning Holley Carburetors, or something similar to that.
I'm also not sure on your timing remarks, Tom. Post how you set the timing for us. What kind of distributor do you have anyway (HEI, points, stock, aftermarket)?

Hopefully it sounds something like this. With the vacuum advance disconnected and plugged/blocked, get the idle low around 600 or so, then set the initial timing to 16* BTDC. Then check your total timing and hopefully it ends up at 36* BTDC all in by 3000 rpm.

Don't even be concerned with the vacuum while setting the timing. When all is said and done, you will probably have like 54* of total timing with the vacuum advance included.

Get the timing squared away first before you start on the carb.
1 - 2 of 9 Posts
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