Nasty Rich At Idle

[BLOWN HOWARD]

What would cause this if my fuel pressure is good. Wich adjustment on Holley 750's can i make to lean out the idle circuit???

[TIMINATOR]

Is this a new installation? Did you change anything? or did this just happen all by itself? TIMINATOR

[BLOWN HOWARD]

Not a new application. Had the carbs re-done and told the guy it ran perfect and started up no problems. Just to clean up carbs and put all new gaskets. Ever since then it constantly fouls plugs on start up. and when i can get it running it is richer than hell. Once up and running its all fine. But when it sits for awhile and go to start up major pain in the ass usually resulting in fouled plugs.

[IMPATIENT 1]

Not a new application. Had the carbs re-done and told the guy it ran perfect and started up no problems. Just to clean up carbs and put all new gaskets. Ever since then it constantly fouls plugs on start up. and when i can get it running it is richer than hell. Once up and running its all fine. But when it sits for awhile and go to start up major pain in the ass usually resulting in fouled plugs.
did you reset your idle mixture screws? run them all the way in and back them out a full turn, usually a good starting point from there with duals. i think i ended up at 1 1/2 turns on all 8 mixture screws on my 750's. starts within 4-5seconds and idles perfectly, surges but that's expected. my a/f ratio meter shows a good a/f ratio at idle too.

[DMOORE]

Have you checked the float level? If it's set too high, it could also cause hard starting and rich idle.
Darrell.

[BLOWN HOWARD]

did you reset your idle mixture screws? run them all the way in and back them out a full turn, usually a good starting point from there with duals. i think i ended up at 1 1/2 turns on all 8 mixture screws on my 750's. starts within 4-5seconds and idles perfectly, surges but that's expected. my a/f ratio meter shows a good a/f ratio at idle too.
Yeah i did the adjusting with the screws that was one of the first things i did. The floats are all good also.

[IMPATIENT 1]

Yeah i did the adjusting with the screws that was one of the first things i did. The floats are all good also.
any chance it set long enough for a dirt dobber to clog up the bowl vent tubes? it'll pull a shiat load of fuel in if the tubes are clogged, i know from experience:mad: i ran my sj 1 day, parked it, went out the next day and it ran like shiat, damn mud dobber filled in 1 of my vent tubes:mad: :mad: :mad:

[502 JET]

If adjusting the idle mixture doesn't help, check your power valves they may be leaking. Check that the proper gaskets were used in reassembling the carbs. If still not better check for warpage of the metering blocks and main body of the carbs.

[BLOWN HOWARD]

May the Power Valves be bad and cause this from a back fire through the carb??? Because on one of the many attempts at getting it started it would back fire through the carb a bit.

[IMPATIENT 1]

May the Power Valves be bad and cause this from a back fire through the carb??? Because on one of the many attempts at getting it started it would back fire through the carb a bit.
if they're the old style holleys without blow out protection, then yepper the valves are more than likely blown. if they are, buy a protection kit for them.

[BLOWN HOWARD]

Is there a size or p/n on the power valves??? How many is there 2 per carb or one per carb

[IMPATIENT 1]

Is there a size or p/n on the power valves??? How many is there 2 per carb or one per carb
from the factory they have 1 pv in each metering plate(2 per carb)
but most peeps only run 1 pv in the frt and block the rear
yes the pv number should be stamped on it.

[BLOWN HOWARD]

Do the power valves have an affect on the idle circuit and start up?? Is there a way by looking at them to see if they are bad or not?? Thanks for everybody's help on this issue. Was getting ready to have Carb Shop do a rebuild but at 350 a carb hopefully i can find the problem my self. What does a protection kit consisit of for the power valves.
Chris

[IMPATIENT 1]

Do the power valves have an affect on the idle circuit and start up?? Is there a way by looking at them to see if they are bad or not?? Thanks for everybody's help on this issue. Was getting ready to have Carb Shop do a rebuild but at 350 a carb hopefully i can find the problem my self. What does a protection kit consisit of for the power valves.
Chris
the diaphragm is what gets blown, you can take a vaccuum pump and pull on the vaccuum side , if the plunger stays pulled in under vaccuum its good, if it doesn't it bad. most of the pv i've blown , you could look at em and see the diaphragm pieces hangin out the sides.

[V-DRIVE VIDEO]

Do the power valves have an affect on the idle circuit and start up?? Is there a way by looking at them to see if they are bad or not?? Thanks for everybody's help on this issue. Was getting ready to have Carb Shop do a rebuild but at 350 a carb hopefully i can find the problem my self. What does a protection kit consisit of for the power valves.
Chris
Talk to Dave Lange @ Fuel Curve specialties. He's on 9th in Upland.
909-920-3779

[Blown 472]

You might want to see if he put the whistles on the vent for the bowl, white plastic things stuck on the metering blocks, my motor never ran for shit with them on.

[BLOWN HOWARD]

Talk to Dave Lange @ Fuel Curve specialties. He's on 9th in Upland.
909-920-3779
Yeah i was given his number by Peterson Performance also. Might have to hit him up. Will he tune the carbs on the boat?

[JMC]

Are you fouling several plugs or just one side? If he removed the needle assembly you may have a pinched o-ring on it. Have you pulled all the bowl window plugs to see if they are overflowing?

[VDRIVERACING]

Not a new application. Had the carbs re-done and told the guy it ran perfect and started up no problems. Just to clean up carbs and put all new gaskets. Ever since then it constantly fouls plugs on start up. and when i can get it running it is richer than hell. Once up and running its all fine. But when it sits for awhile and go to start up major pain in the ass usually resulting in fouled plugs.
Just curious... what did the vendor who did the carbs have to say about this? Did you take them back to them for inspection?

[jockorace]

Could be a remote chance your "carb guy" put an incorrect metering plate gasket. There are some subtle differences that are hard to notice sometimes.
I once changed gaskets in a hurry, couldn't figure out why fuel was dribbling into venturis. I had used a 4500 (dominator) gasket in a 4150 carb. Jocko

[BLOWN HOWARD]

Dropped the carbs off over at Dave Lange's the guy is full of information. And the best part is he said it will only take 3days.

[BLOWN HOWARD]

Picked up the carbs 3 days later .And put them on today and they work bitchen. He put the all the right parts in them. And started right up. Didnt even have to mess with the idle.

[VDRIVERACING]

Did he tell you what problems he corrected?

[BLOWN HOWARD]

He said it had the wrong floats in it and put marine style vents on the carb. Other than that he said it will run bitchen now. And today i took it out and it did.