holley help


Active Member
when i turn the air/idle mixture screws in all the way
the idle increases, i thought that ment it was too rich.
i have jetted down 6 sizes in my new 1000 cfm 4150 hp carb
the throttle response is way better with this carb than with my
850 but the best idle is when the screws are bottomed out
any ideas
WOW! That's a lot of carburetor! What else is done to the engine?

There are holley's with reverse idle screws, although I would be surprised if you had one.

When running correctly, the car should stall when you trun the idle misture screws in. The reason it doesn't is because it is drawing from the main metering system. This is because your idle speed screw is holding your primary butterflys too far open. They must sit closer to the closed position. To run properly, this problem must be solved.

While I probably can't help you much farther than that, you should post a good description of your motor and the old carb numbers, and the new carb numbers. Contributing factors could be in your timing curve. What is it at idle, how fast does it come in?


Active Member

the timing is all in at 32 @ 3000 i have never checked to see what it is at idle, 455, stg1 heads p&p stainless valves big springs, 11-1 compression
gs110 cam 542int/542exh, head studs, main studs, hv oil pump, headers,
ta sp1 intake match ported to heads, th350 trans with the hd stuff, 4000 stall converter, 410 posi rearend, boxed upper and center correcting lowers the carb last year was an 850 with downleg boosters, this one the 1000 has the annular boosters, this carb is much more responsive than the other though with the weather at the track it was hard to tell the diff,
though the new flowmaster single chamber race mufflers did cost me .50
when i uncapped it was faster. i will try adjust the carb more tomorrow.
does it make sense that with the new carb flowing more air it would be more responsive or not
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I hope someone with more experience than me jump in here...

I would look at initial timeing. Hopefully it is at 8 or something mild. I would add 2 degrees, back of the idle screw to bring down the rpm and see if I got adjustment out of the air screws. If not, I would add a couple of more degrees and try again. I would feel comfortable doing this to 12 degrees, and under certain circumstances, maybe farther. It is a good idea to hook up a vacuum gauge when adjusting idle. Basically the instructions with a vacuum guage are something like increase timing till it is at it's highest, them back it off one pound.

Something to play with anyway:thumbsup:

Good luck!