we just swapped a holley 4bbl on to a Y block in place of a leaky 4bbl teapot. the car runs ok at rpm, will not idle, runs rough close to idle, new points, condenser, cap, rotor, and plugs. brand new carb. where do we start?
we first changed the ignition parts, ran the car, and it ran as bad as before. then changed the carb, and still no improovment at idle. the teapot was spewing gas from every seam, into the intake, so we assumed that was a big part of the problem
I'd be checking for a vaccumn leak around the base of the carb. With the engine running, spray a LITTLE bit of carb cleaner around the base and see if you hear an increase in idle. If you do, you have a leak.
Vacuum leak? Get it to run as slow as you can and spray some carb cleaner around the bace. If it picks up you have a vacuum leak. Good luck
Did you check and adjust float levels? Once that is done . If the problem was there before , then it is probably below the carb Possibly an air leak . Check vacuum hoses, including booster and booster diaphragm , vacuum advance , vacuum modulator and anything else that is operated by vacuum. then check carb and intake gaskets, pcv ,and anything else connected to the manifold below the carb. Remember worn valve guides are a source of air leak, and damaged or bad fitting intake gaskets can leak into the manifold from inside the valley. If you get a small squirt bottle and trickle some gas into the air horn of the carb while it is running and it runs better, your problem is an air leak, if it runs worse i, the problem is flooding. You can also check air leaks (carefully) with an unlit propane torch if you are vary careful , just point the gas at the suspect areas, if the engine speeds up it there is a leak at that point...Don't get so much gas lying around ( heavier than air) that it blows you up. A bit at a time is the trick. BE CAREFUL OF SPARKS , DON'T use this if there are any loose terminals or bad plug wires etc, in saying that if there are any plug wires "leaking " they need attention anyway .
...same symptoms, but it's easier to spray carb cleaner around the base of the carb and listen for the idle to increase than it is to take the carb apart to change the power valve. And yes, they do blow easily, especially if during your initial fireup you had a backfire thru the carb. One backfire and they're toast.
which carb are you running? is it the cute little bastard with the tube that runs from bowl to bowl? if yes, box it up and take it back-they've been recalled for this very reason. I haven't seen a blown power valve on a holley in quite some time, but what you are describing sounds pretty suspect. how many points of idle adjustment? 2 or 4? either way, start with them out no farther than 1 and 1/4 turns out. Vaccum secondary, or mechanical? and lastly, you're sure the carb is fully sealed against the intake, right?
yes it has the tube, when were they recalled? I have had it sitting in the garage for a while. we did check the float level, would checker have a power valve? I made fresh gaskets for the manifold side of the adapter, and bought a fresh gasket for the carb side. should be no leaks. (brian, you reading this?)
The recall started about 4 months ago to my knowledge. but it is on ALOT of carbs. something to do with the metering blocks not being fully drilled or improperly plugged or something. what it boils down to is, they won't idle por kaka.
Whadda I know, but, I doubt it's the PV. If the carb was made in recent history, Holleys PVs have an escape built in so the PV does not blow (or at least as easily anyway).... Talk to you in the morning my little polish buddy.
Well we got er running a little better. After playing with point gap, and dwell (oh yea and we had two wires crossed in the firing order... Ooops ) it started to come around a bit. The carb still is not right though. We have two adapter plates with two different bore sizes, the top one being larger. Would this cause some type of restricter plate effect? The other problem we are thinking of is the power valve, the carb keeps spittin back and the car has a slight lurching feel going down the road. These things on top of the occasional dying of the car at idle or during take off. We checked for vacuum leaks and carb base leaks and everything checks out OK. If anybody else has any other ideas of what may cause these symptoms it would be a great help! Thanks to all of you for the suggestions! (Thanks Gregg for all of your help today!) Brian
Check the vacuum advance. The only ignition advance the distributors get is from the vacuum advance. It won't run worth shit without proper ignition advance. Start the car & advance the ignition about 20* & see what happens. Tom T.
The Y block over and under intake runners can leak inside the manifold, make sure the manifold gasket is good and the clamping bolts are tight. Have you adjusted the valve clearances? Remember Y blocks are all solid lifters. Check timing mark against true /physical top dead center.
just to bring this back up and say thanks again for the help, part of the problem was the power valve. It is running better than ever now. No vac leaks, idles great, and runs great.
Holly Has A Great Dvd Showing The Operation Of Their Various Carbs.i Just Replaced My 80457 Recently And The Dvd Came With The New One. The Dvd Has A Great Trouble Shooting Guide Included.my New Carb Has No Float Adjustment Or Fuel Bowl Sight Ports. Deucemanab
check that the carbs sparyers. holly will sometimes screw up and put the wrong fuel sprayer in the carb during assembly. Just open up the throtle and make sure their is a steady spary. Also check your point gap and your dwell. check your timing and if you have vacuum advance make sure its disconnected. also make sure you also have a good sorce of vacuum. A big thing with those holly carbs are thier srayers though. good luck and i hope i sum what helped. joe.
I'm not much help but, have a question. What kind of adapter plates and carb did you use? I have a y-block with a tea pot too. I'd like too change it to something else. It's leaky!
Adapter plates? Humm, if they are open from side to side, not 4 hole type, you are probably leaning things out too much, until the flow gets going real good. On a 350 Chevy with a 500 cfm 2 barrel they will bog considerably if the center section is wide open, in the case of using a 2bbl to Qjet adapter. Close the gap up and things get a lot better. I suspect that you started off with part of this problem, which is why you switched carbs. You might check to see if the timing chain has slipped a cog or two. Good Luck.
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