Holley carb "loading"
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=1819
Printed Date: November-23-2024 at 3:31am
Topic: Holley carb "loading"
Posted By: keuka1
Subject: Holley carb "loading"
Date Posted: June-06-2005 at 11:07am
Hey I was hoping someone here could help with an issue I have with my 1985 Martinique with a 351 and Holley carb.
After "putting" around or idling for about 30 minutes. WHen I try to pull up a skier the engine backfires through the carb and take about 5 minutes to run normally.
Any iseas on what I can do to correct this>
Thank you.
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Replies:
Posted By: Jim_In_Houston
Date Posted: June-06-2005 at 11:26am
Mine did the same thing. I found that after running hard and then going to an idle you could look down into the carb and see fuel dripping into the manifold. I called the carb rebuilder and was told the needle valve was sticking. In my case it turned out to be junk in the float bowl that appearantly interfered with the needle valve being able to close. It was suprisingly easy to remedy. I removed the carb, removed the float bowl, cleaned out the junk (it was a dark fine powdery substance), reassembled, installed an in-line fuel filter and the problem has not returned.
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Happy owner of a '66 and a '68 Mustang
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Posted By: jameski
Date Posted: June-06-2005 at 11:47am
Also, check your idle mixture enrichment screw adjustment. If your mixture is too rich, it will foul your plugs and cause these symptoms. Do you see any black smoke coming from your exhaust when you are idling?
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current boat
http://www.correctcraftfan.com/diaries/details.asp?ID=1977 - 94 Sport Nautique
previous boat
http://www.correctcraftfan.com/diaries/details.asp?ID=601 - 78 Martinique
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Posted By: Guests
Date Posted: June-06-2005 at 11:57am
I do think it is running a little rich via black smoke.
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Posted By: 79nautique
Date Posted: June-06-2005 at 2:21pm
You most likely will need to replace the power valve since it backfiresd thru the carb.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: Tim D
Date Posted: June-06-2005 at 3:25pm
Yeah, one backfire, replace the power valve, that's the one on the inside which screws into the metoring block. I wouldn't rule out a intake leak also.
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Tim D
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Posted By: 79nautique
Date Posted: June-06-2005 at 5:50pm
Well actually I would re-build the carb, it's backfiring (lean condition and/or bad power valve) and then it also has black smoke coming out of the exhaust (rich condition) and takes awhile before it cleans out and runs right which could very well be fouled spark plugs.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: JEFF KOSTIS
Date Posted: June-07-2005 at 1:20am
Aside of the issues listed which are certainly correct, make sure the points(if you have them) are not pitted. Idling for long periods causes the points to track (short themselves out) with a carbon track. They are open/close slowly at idle and doesnt take much spark to run ok. When you hit the gas, the carbon track partially shorts the points and screws up the dwell until the engine is reved to chatter the points clean. My boat does it after idling great for a while(get about 100 hrs per set of points) and just pain dies, but im quick on the gas to release before it backfires. Changed points, all ok!!
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MUSTANG COUNTRY
http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17
http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17
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Posted By: keuka1
Date Posted: June-10-2005 at 5:39am
Thanks for the feedback.
I think I will start with the cheaper stuff...points, plugs, cap, rotor, coil (maybe) condenser and see how it goes. IF that doens not help the porblem then it will be time for a carb rebuild.
Again thanks for the help! :)
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Posted By: SS 201
Date Posted: June-10-2005 at 7:41am
Fords are from the factory 8 degree retarded, as the chain wears it gets more retarded. A backfire thru the carb indicates its on the intake side of the engine,timing,intake valve etc..
Although previous events mentioned are true, Check the timing at 2500 and it should at least be 32 degrees. Whatever the inital is is meaning less the full out timing is.
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Posted By: keuka1
Date Posted: August-11-2005 at 3:16pm
Changed T stat and it is now running at 140 and the carb is not "loading" or backfiring throught the carb any more.
But since I had a few backfires throught the carb I will need to change the powervalve.
ANy thoughts on how hard this is to do?
Thanks for the input.
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Posted By: skyhawkflyer
Date Posted: August-11-2005 at 3:40pm
If it's running OK and you don't notice any problems through mid throttle leave it alone.
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Posted By: Siveck
Date Posted: August-12-2005 at 12:59pm
The power valve is in the front metering block on the carb which is behind the front fuel bowl. You can actually change it without removing the carb. Just unhook the fuel line and remove 4 bolts on the front and you will find it in the metering block. You might need a gasket set though. If you get a gasket set, then you might as well rebuild it. It's really quite simple. And you could even add the check valve kit from Holley that supposedly protects the power valve during a backfire. I added that check valve and its nice to know that maybe my power valve is still good after a couple of backfires while getting the timing right. The correct power valve is a 6.5".
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1975 Ski Nautique
"Small Letter Boat"
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Posted By: JAG459
Date Posted: August-12-2005 at 6:32pm
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There is another carb problem that can cause a rich mixture that is usually overlooked. Inside the low speed float bowel of the carb there is a tube with 2 orings on it that connects the metering block to the carb body. If these orings are not tight fitting it can result in excess fuel to be drawn into the low speed curcuit. As the orings deteriorate it will cause the engeine to run in an ever increasing rich condition. At its worst you will see fuel coming from primary orifices in the carb throat at an idle. The orings are include in rebuild kits.
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Posted By: GottaSki
Date Posted: August-12-2005 at 8:29pm
I agree TJ, the PV is not nearly as fragile as I've heard described.
Witnessed many boats and a 4150EG on a Loadmaster pop repeatedly for poor ignition or lean setup with no ill effect to the PV.
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole
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