Re: ...aaaand more 6 pack problems...
[Re: 68RRFlyer]
#1032500
07/14/11 02:19 PM
07/14/11 02:19 PM
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Joined: Jan 2004
Posts: 27,347 Today? Who Knows?
1_WILD_RT
Management Trainee
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Management Trainee
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Today? Who Knows?
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If the fuel is getting past the needle & seat whether around the o ring or past the needle the level in the float bowl will be to high.... Remove the sight plug & you'll know... Is the fuel dribbling from the booster venturi or is it coming from the accelerator pump squirter nozzles.. If it's from the booster venturis you might want to check your power valve... If it's coming from the squirter nozzles the one way check valve may be hung up allowing pull over...
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
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Re: ...aaaand more 6 pack problems...
[Re: meepmeep70]
#1032502
07/14/11 03:16 PM
07/14/11 03:16 PM
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Joined: Nov 2007
Posts: 450 DFW
68RRFlyer
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It's dribbling from the booster venturis, not the accel pump nozzles. You can see it drip out directly down into the carb. I initially set the float so the level was just at the bottom of the hole then tightened everything up. Thinking it might be the seat, I lowered the level some more to see. No fuel drips out when I remove the sight plug since I lowered it a bunch. So that tells me it's sealing I guess. So, you're thinking the power valve is to blame here? Now that I think about it, the car did "pop" once through the intake upon shutdown and I noticed it was through the center carb. That would be causing fuel to come out of the booster veturis if that's blown, no? That is, if I understand what a power valve does. Never replaced one before since I was an Edelbrock guy before and this is my first Holley to deal with. Unfortunately now, I have to head out on a trip and don't get back until month's end to play around with it again. If you think this is the culprit, I'll order one and have it ready to replace when I get home. Thanks for the help. Cheers
Last edited by 68RRFlyer; 07/14/11 03:28 PM.
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Re: ...aaaand more 6 pack problems...
[Re: GomangoCuda]
#1032504
07/14/11 04:00 PM
07/14/11 04:00 PM
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Joined: Nov 2007
Posts: 450 DFW
68RRFlyer
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Hmmm, I just read some symptoms of a faulty power valve and it does mention crappy idle as a symptom. I don't know if it's this or not, but I can't eliminate that possibility. I understand about the main circuit kicking in if the plates are open too much, but even with the idle set low it still drips. And what will happen is the car may idle for about :20 seconds then all of a sudden drop off and die. For no reason. So to keep the car running I'll goose the throttle which of course, sends a squirt of fuel from the accel pump. But the boosters are wet and dripping, and it's not from the shot. I see the drips form and fall into the carb. When I do get it idling atfer several revs, you can see the drips clearly. Something is not allowing the car to idle correctly and letting fuel through those boosters. But what? The float level is not the problem. Fuel is below the sight port immediately after I shut the car down. What needle/seat part number do you guys recommend? Another member emailed me saying 6-519-2 which eliminates the rubber tip. And that o-ring looks thicker than mine. Maybe I have the wrong one in? But would the leaky o-ring cause the fuel to enter the boosters but not fill the bowl? I'm thinking that may be the problem, but not sure. I'm trying to think of the mechanics that would allow that to happen, and I guess it may be possible. Thoughts on that? Cheers
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Re: ...aaaand more 6 pack problems...
[Re: GomangoCuda]
#1032505
07/14/11 05:04 PM
07/14/11 05:04 PM
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Joined: Dec 2007
Posts: 18,157 Mass
DAYCLONA
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Quote:
Quote:
So, you're thinking the power valve is to blame here?
NO, it is not the power valve. If there is fuel dripping from the boosters either the float level is way high or the throttle plates are open to far at idle. There should only be about .040 of the transfer slot exposed below the plates at idle. Approximately square. Much more than that and the main circuit will start to flow through the boosters.
I'd tend to agree, but to eliminate the power valve from the equation, turn the idle mixture screws on the center carb, located on each side of the metering block, all the way in, both screws, if the motor stalls, the power valve is good, if it continues to run/idle, the Power Valve is toast,...replace it with nothing more than a 6.5 rated valve
Mike
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Re: ...aaaand more 6 pack problems...
[Re: 68RRFlyer]
#1032506
07/14/11 05:12 PM
07/14/11 05:12 PM
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Joined: Jan 2003
Posts: 4,720 Moved to N.E. Tennessee
GomangoCuda
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Quote:
Hmmm, I just read some symptoms of a faulty power valve and it does mention crappy idle as a symptom. I don't know if it's this or not, but I can't eliminate that possibility.
If the Powervalve is blown then the fuel leaks out the bottom of the carb through a manifold vacuum passage causing an extremely rich idle. It does not flow out of the boosters. You can check it using the method described in Dayclona's post. But remember even if it is blown it will NOT cause fuel to flow out of the boosters. If the PV is good but the incorrect value it may just barely be measurable with an O2 meter at idle but it will have a negligible if any effect on the idle quality. Incorrect but otherwise functioning PV will not be the cause of pig rich idle or dripping from the boosters.
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I understand about the main circuit kicking in if the plates are open too much, but even with the idle set low it still drips. And what will happen is the car may idle for about :20 seconds then all of a sudden drop off and die. For no reason. So to keep the car running I'll goose the throttle which of course, sends a squirt of fuel from the accel pump. But the boosters are wet and dripping, and it's not from the shot. I see the drips form and fall into the carb. When I do get it idling atfer several revs, you can see the drips clearly. Something is not allowing the car to idle correctly and letting fuel through those boosters. But what? The float level is not the problem. Fuel is below the sight port immediately after I shut the car down.
How much timing do you have at idle? If you don't have enough then you have to open the throttle plates too far at idle to get your idle speed up. I would take off the center carb and turn it over. Find the transfer slot. Turn out the idle speed screw until the slot appears to be square (Approx .040"). Put the carb back on the engine. It probably wont idle. DO NOT touch the idle speed screw! Instead increase the timing to get the idle speed up. Depending on the size of your cam, it will probably want 16-20 degrees at idle. Your Idle mixture screws should now be functional (probably were not before) adjust them for best idle/vacuum. Never change the Idle speed screw more than about 1/8 turn from the base setting above. There should be no dripping from the boosters. If you still can't idle then let us know, there is another problem. Sometimes it is helpful to richen the idle on the outer carbs, Likely won't need more than 1/8 turn out from the factory setting. Now you will need to check the total timing and if necessary modify the advance curve to keep the total timing where you want it. Probably somewhere between 34 and 38 degrees.
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But would the leaky o-ring cause the fuel to enter the boosters but not fill the bowl? I'm thinking that may be the problem, but not sure. I'm trying to think of the mechanics that would allow that to happen, and I guess it may be possible. Thoughts on that? Cheers
Can't happen. If fuel is leaking past fast enough then the level will raise in the bowl and come out the boosters and ultimately the vent which will definately stall the engine. But it will not be forced out the boosters without raising the fuel level.
Last edited by GomangoCuda; 07/14/11 05:17 PM.
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Re: ...aaaand more 6 pack problems...
[Re: Mr.Yuck]
#1032508
07/14/11 05:44 PM
07/14/11 05:44 PM
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Joined: Dec 2007
Posts: 18,157 Mass
DAYCLONA
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I was going to say something but I really don't know that much and you have a ton of good info...lol I was going to suggest that maybe the outboards are a tad open...carry on
You could very well be right on that,...the linkage may be bound, or not adjusted properly between the two outboards?....the list of mechanical variables to check are endless in a sixpack set-up, nevermind the actual tuning procedures required
one needs to start at the basics of installation set-up, before attempting to tune/diagnose problems
Mike
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Re: ...aaaand more 6 pack problems...
[Re: meepmeep70]
#1032510
07/15/11 08:05 AM
07/15/11 08:05 AM
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Joined: Nov 2007
Posts: 450 DFW
68RRFlyer
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This is all good stuff guys, and I appreciate it! My initial timing is 15. It seems any higher and my temp gauge goes off the chart. Yes, I've adjusted the outer linkages. I did them when I did the outer carb adjustments, but they were set initially OK. The plates are bottomed out, no slop, and the idle screws are set about 1/8th (maybe a tish more) off the stops. No fuel dripping out of the bottom, and yeah, the engine stalls and dies if I turn the enrichment screws on the center carb in. So the PV is not the culprit. I'm out on a trip now and won't get back to the car until the 30th. I'll regroup and see if I can get this sorted out then. It's all helpful and I know I'll get it fixed. Just going to take some work. Cheers
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Re: ...aaaand more 6 pack problems...
[Re: lokalik]
#1032513
07/15/11 11:41 AM
07/15/11 11:41 AM
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68RRFlyer
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could it be fuel pressure? the op did not state mech or elec fuel pump.
Standard, stock mechanical fuel pump. Standard setup with the vapor seperator too. So far as I know, this carb has not been opened up at all. Could debris or something cause this too? The fuel dripping out of the boosters that is? Just curious, as I replaced the filter/seperator and like I always do all my filters, cut it open to take a peek inside. It did have some dirt in there, so maybe a piece got by and clogged a port? Just throwing another suggestion out there.
Cheers
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