Ok, I'm sick of the Edelbrock carb I bought for my Maverick, I've done what I can to it, and I still don't like it. (someone told me I wouldn't) So anyways I put my trusty Holley 600 on, started it up, and the idle shot up to 1800 RPM, I backed the curb idle screw all the way out, with no change, turned the idle mixture screws in all the way, with still no change, checked the float levels, they seem fine, there is no binding of the linkages or cable. Everything that could be considered a vacuum port is capped off, the vacuum advance is connected to the ported vacuum port, the choke isn't stuck, the needle and seat is fine, fuel pressure is 6 psi.... So anything I'm missing?? It's driving me nuts!!!
what kind of choke? if its a manual there two extra holes you must plugged. One on the air horn and another on the throttle body its usually plugged by a decal.And try adjusting the fast idle screw. also check for biding on the cable it happend to me and it wouldn't idle under 2k
I just pulled the carb apart, it appears that the power valve has hardened up, and is stuck open, I wonder if that would do it?
I was at the local speed shop this afternoon, and the owners wife said "See you tomorrow, Dave" as I walked out the door, she must know something I don't!!
A blown PV will load up (run eye watering rich). Sounds like a vacuum leak to me. If you didn't disturb anything but the carb to manifold gasket, then: Worn out throttle plate bushings Warped carb base plate. Cracked base plate. Secondaries ajar... think that was mentioned. Choke high idle ajustment stuck. Secondary idle ajustment way too high. (screw under base plate, carb must be off) Secondary vacuum cannister to carb body seals leaking. Secondary diaphram dry rotted/ruptured. Bad carb to manifold gasket. (too easy) Not in any particular order. I can think of more in time... What intake manifold?
thats all a power valve does is add more fuel(but its supposed to activate at a given rpm when vacumm drops) just take a vacumm reading at idle and divide by 2 and buy that size valve
This leak has to be a fairly large one in my mind, to have that kind of effect. The front base plate port being open just doesn't do this sort of thing. Too small a port. There is at least one big vac port on that carb. The one on the back, usually used for PCV or power brakes. If that one has a rubber cap on it, is it possible that it (the rubber cap) cracked or split while you were working with the carb? If you installed a hose to it, could the hose have become jarred loose, or ill seated on either end, while you were working with it? IMO, we are looking for a substantial vac leak.
I second, er, THIRD the vacuum leak. Been there, done that... You will find it, and very likely it will be a "DOH!!!" experience. At least it always has been for me...
There are no vacuum leaks, all ports in the manifold are plugged, the pvc port it capped with a new rubber plug, along with the other port on the carb, I even plugged the one of the vacuum advance, and it didn't change anything. The engine has all new gaskets, ne carb gaskets, she's nice and tight. Unless it's in a manifold gasket? It's a good almost new Weiand intake that was on the engine before, and I never had a problem...I might just pull it off this weekend...
Vacuum leaks are easily found by running it and spraying all around with carb cleaner. Dave's dead on, there are many things that could have happened bolting on a carb that's sat on the shelf with the time needed to dry out the powervalve diaphram. If that's hardened and dried the accellerator pump diaphram is as well.
Dave, I wouldn't go beyond searching the carb and immediate area. Unless you have solid evidence that the manifold gasket or any deeper cause is to blame, I wouldn't go fixing things that aren't broken. If everything ran well with the other carb, and this problem only came with a carb change, then look at the carb. Now, if you had an issue like this with the previous carb, then you should go deeper. However I got the impression that was not the case. So it scares me when you talk about seeking fixes that shouldn't be needed. That can only make things worse. Like Baddad says, if your impression is that the carb sat long enough to rot the PV, then there are likely many gaskets, o rings, diaphrams, and seals in the carb that are shot. Several of which could cause your problem. You might need to throw a kit in it quick, just to put new life into the seals and diaphrams. Edit: For the Holley bashers out there... Even the almighty Holley needs new gaskets now and again!
Oh yeah, if you have checked all else as you posted, put a very reliable straight-edge on the base plate of the carb, and check it from several angles. Warped carb bases can have you chasing ghosts!
