Another tuning issue

[slamons]

390 FE, C6 Trans. new edelbrock intake, new 4160 holley with new 7.5 power valve, timing is set at 18 btd, still have a lope in the idle, sounds like it has a cam but does not, fluxuates from 15 to 13 on vacuume gauge. not found any vac leaks or other problem. Does not matter how idle is set, can turn rich or lean still same idle and lope. HELP.....

[390F100]

That's a good thing!!! or it can be...How does it run? Is it just the lope that concerns you?

[td]

it doesn't have a cam ? just kidding

[slamons]

Its a little anoing lope, It all started after i replace the power valve, could that have someting to do with it?

[DGrant09]

I have the same carb and have fought this. One adjustment a friend made was the floats which helped a lot. I still can play with the mixture screws without the affects I am told we should have. The second issue was the fuel pump. Even though we replaced it last year, we were lacking a sufficient fuel supply. A new pump did the trick. The easy tell tale on the pump was a see through filter just before the carb.
I am still debating this carb. When pulling a 5500 # trailer the truck really struggles. I honestly feel the 390 should do better and may look into another cam or jetting this carb a bit. Any ideas there would be appreciated.
My timing is at 6, on a fresh re-build.
Dan

[Wes]

Slamons try tightening the float bowl, they get loose and allow unmetered fuel to be drawn into the venturi. Also 18btd is allot of advance for a stock cam. try 10-12btd and recheck your vacuum readings.

1 other problem that occurred to me. The power valve may be loose. Sometime if over tightened the power valve gasket splits. Hope this helps

[slamons]

Thank you guys, All your input has helped, After re adjusting the float level, it helped a little, Still timing has to be around 16 to 18 to run smooth, I did re check all plugs, Found 1 that may be fouled, I will replace it and get back....Thanks again...