Still running rich

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You have to have the timing where it needs to be FIRST or your wasting your time going
any further.If it was mine i would set the initial timing around 18 -20 at 1000 rpm.Total
timing 34-36 at 3000 rpm.Try another carb if you have a 750 with vac secondaries or 650 dp and see what it does.A 850 dp is a big carb i believe thats what you said was on it.Get the timing right
 
If i remember corectly when i broke it in it was at 19 initial and 36 advanced, ill get a light and check it tho
 
If its got a vac advance canister on it plug it off when you set or check the timing
 
I agree that the ignition/timing needs to be ironed out before you'll ever get the carb right. Even as little as 3-4 degrees of timing advance at idle can affect idle mixture quite a bit. I'd bump initial up to as much as it'll take without bucking on the starter. Of course when you do that you need to watch total timing so it doesn't get too much.
 
Check vacuum at idle in gear. If it's 8 like you say then you need a 4.0 power valve. The 6.5 is way too big. Always run half the number power valve of your vacuum.
 
Take that Carb apart and give every passage a good blast of compressed air. Several timess over. Do this over an old t shirt and see what might come out. Look very closely at the passages for crap stuck in them. I once found a piece of Teflon tape blocking a transfer slot. Be careful and it will only cost you your time.
 
Check your fuel pressure guage against another gauge. Especially those little bargain gauges. I had one recently that was 3lbs off. Wouldn't hold a fuel level for long. Not surprising when the needles were seeing 9lbs instead of the 6 the gauge was reading.
 
Many times a backfire will blow out a Holley power valve. If you have a spare, run it and see if it changes anything. With the PV blown you will be dumping fuel all the time.
 
Captainkirk said:
Many times a backfire will blow out a Holley power valve. If you have a spare, run it and see if it changes anything. With the PV blown you will be dumping fuel all the time.
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That'd possible but that Holley would have to be about 21-22 yrs. old or older for that to happen. In the early 90's Holley incorporated a one way "anti-backfire" valve in the baseplate of their carbs that prevents a backfire from blowing the power valve.
 
fishy68 said:
That'd possible but that Holley would have to be about 21-22 yrs. old or older for that to happen. In the early 90's Holley incorporated a one way "anti-backfire" valve in the baseplate of their carbs that prevents a backfire from blowing the power valve.
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22 years old or older describes every Holley I have. lol
 
Have you gotten the timing sorted out?
 
If you call Holley or QF the first thing they will tell you is check vacuum and size the power valve accordingly. If it's sized over half your vacuum number it will always idle rich and burn your eyes. You could have other issues also but until you get the right power valve it will be rich. They are cheap and easy to change.
 
Wedgexx said:
If you call Holley or QF the first thing they will tell you is check vacuum and size the power valve accordingly. If it's sized over half your vacuum number it will always idle rich and burn your eyes. You could have other issues also but until you get the right power valve it will be rich. They are cheap and easy to change.
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Nope...

Only if tune up is set up improperly.

I always suggest putting a PV plug in when doing idle tuning especially with a big cam.
 
Why is there so much stupidness on this thread? TIMING FIRST. Without that, you will be chasing your tail.
 
crackedback said:
higher idle speed will almost always result in higher vacuum reading. Reset it to your base idle setting and see what you have for vacuum. You need apples to apples comparison.

You need to cure the fuel dripping from the boosters. If it's dripping, you'll never get a decent idle tune on it.

For what you have, i recommend putting a pv plug in both ends and get the idle tune up correct. Once you have it correct, remove the carb and look at the transfer slots to make sure there isn't too much exposed. If they are, you need to rethink.

A pv activated or affecting idle quality means the throttle blades are open too far.

Turn more initial into it and quit screwing around. :)
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x2
 
I have a new powervalve on the way, and as far as timing it now has 25 initial and 38 advance
 
That's a lot of initial but if it takes it without spark knock, more power to you. lol
 
I locked my distributor at 35 degrees and it idled better and cranks just fine. It is 10.9 -1 comp. and runs on 93 octane but it is a small block.
 
well use my example for instance, this motor pulls 8 pounds of vacume at idle, and it has a 6.5 power valve, which means when the vacume drops below 6.5 pounds the power valve opens increasing the fuel flow. so at idle the vacume may be too low to competely close the power valve letting extra fuel into the motor causing it to be too rich

and about the timing, it still cranks just like it did and doesnt seem to knock
 
rednesss said:
I'm still wondering how the power valve can affect the idle?
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The only way is if it's blown.

twayne24365 said:
well use my example for instance, this motor pulls 8 pounds of vacume at idle, and it has a 6.5 power valve, which means when the vacume drops below 6.5 pounds the power valve opens increasing the fuel flow. so at idle the vacume may be too low to competely close the power valve letting extra fuel into the motor causing it to be too rich

and about the timing, it still cranks just like it did and doesnt seem to knock
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When the power valve opens it's feeding the main/high speed circuit, not the idle circuit. Therefore even if you have a 10" power valve (power valves are rated in inches of mercury, AKA vacuum, not psi) installed and it's completely open during idle it will not affect the idle mixture unless the butterflies are open so far it's running on the main circuit.
 
^^^^^^^^^^^^^^^^^^^^
This!!!!!!!! Fuel would have to be coming out of the boosters for the power valve to have any effect.
 
Well go the rich idle fixed, timing is right, now a new problem, when you get on it it runs great, as soon as you let off the car shuts off, got it home and fuel pressure was on 2 pounds, and noticed air bubbles in the float bowls, so must be a leak somewhere in the fuel line. Got some -8an braided line coming and a fuel cell, maybe thattl do the trick
 
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