another carb question

[wrenchn2]

Re: another carb question

Crossed plug wires, cracked dist. cap,plugged exhaust, fuel filter,fuel pump,rocker arms to tight,cam lobe? Try setting timing with vac gauge bring it up to max vacumm then down 1 pound at idle. Then set idle mixture to max rpm then down just a little 50 rpm or so then set idle speed. If engine is cold may be the choke settings.

[thevic24]

Re: another carb question

before you pull it off, get it warmed up and spray some carb cleaner aroun the base of the carb, and if it sucks the cleaner in from anywhere other then the throttle rods(maybe) then you have a leak. you can check the intake seal that way also. if you swap the vac line you may have to reset your timing(i did) do that and set it where it should. i don't think a bad pvalve would cause a backfire but i would check it any ways. i seem to have to replace mine every year or so, they just seem to go bad. here is another stupid question, have you tried up jetting the primary side 3 or 4 numbers?

[maw08080]

Re: another carb question

New dist. so no damage there, Wires not crossed to wrong cylinders but could be cross fire throught contact. i'll check that as well. I know the exaust is not pluged i don't even have a cat on it. And the turck runs like a animal on the choke.. for 1/4 mile untill it floods out.

[maw08080]

Re: another carb question

I have tried larger jets. It dosn't help my stumble or popping. I thought if a power valve was bad it would flood an engine, so i will check that too.
I really do appreciate eveyones help, I am about at my wits end here.

[maw08080]

Re: another carb question

I have tryed timing with a vac. gauge thats how i got up to 30 deg. base timing. it gave me 22in of vac. at idle but under any load my engine experanced detonation. so the timing is set with a light right now.

[thevic24]

Re: another carb question

do you have a diffrent carb or one that you could use, mabie yours might have a warped throttle. the carb cleaner trick will find that for you

[maw08080]

Re: another carb question

OK, believe it or not, i do have a differant carb. I have a 570 street avenger vacuum secondaries. I started with that carb on it and bought this one because someone else suggested as a fix for the same problem i have with this one. I couldn't get that one right either.
That's why i will definitely check the plug wires and rocker adj. again.

[thevic24]

Re: another carb question

ah ha keep us posted and good luck

[yellomalibu]

Re: another carb question

Does it do this at wide open throttle? or just partial throttle?

If it's a lean condition, perhaps you have too much vacuum and the power valve isn't opening early enough. If you could plumb your vacuum guage in a way that you can monitor it while you drive, does your vacuum drop below 6.5" when this popping is occuring? If not, try a 7.5 or an 8.5... depending on how much vac you have at part throttle; when it's acting up.

They are available in standard single stage, standard high flow, and two stage in vac ranges from 2.5 to 12.5. I'm not as Holley savvy as others, so I don't know which would be ideal... check them out:

http://www.holley.com/types/Power%20Valves.asp

[maw08080]

Re: another carb question

Sweet, Thanks to thevic24 for suggesting switching to manifold vacuum. that seemed to do the trick. I now have no gross stumble or popping. I now seem a bit to rich, its still a little sluggish but my O2 gauge reads on the rich side. It no longer drops off the lean side. I am left with something that I believe i can tune. I'll now go back down one squinter size and lower my float level a hair to see if it improves throttle response. I'll let ya know how it goes.

Thanks a million, guys.

[chad786]

Re: another carb question

centrifugal advance working?

[thevic24]

Re: another carb question

i dont know why that works with some setups but it dose. it had me baffeled for a time also.
-vic

[wrenchn2]

Re: another carb question

Good job vic, I wonder if his harmonic balancer slipped on the rubber 30 degrees timing sounds like a lot if 22lbs max then back it down to 21. Maybe he can check tdc on the balancer with number 1 plug out and turn engine over slowly by hand both ways with a screwdriver touching top of piston. When they slipp its not even close like 10-20 off.

[thevic24]

Re: another carb question

i dont think he runs it at 30 degres, just testing it out there. the vacume may be high though. some setups may have better economy with higher vacume though.

[maw08080]

Re: another carb question

I'm running a fluid dampener it has pre marked timing marks