440 Help Needed
What’s the carb part number, and how many turns out are the mixture screws?
My experience has been that the “wandering” idle speed can indicate a lean condition.
If you look down into the primary barrels while it’s idling, is there fuel dribbling out from the boosters?
Float levels have been set/checked?
So the part number for the carb is 0-80459SA. Its their classic series carb. 750CFM, 4160, 64 jets, 8.5PV, vacuum secondaries, electric choke.
The idle screws have been turned out one full turn from fully seated. But with as far as the throttle blades are opened, I dont believe the idle screws would add a significant amount of fuel as compared to the overly exposed transfer slots...? correct?
I dont believe there is fuel dripping from the primaries when idling. But I will check again.
Yes the float levels have been set, I set them so there was minimal spillage coming from the ports while idling.
I just have a hard time believing this is carb related. Even if the AVS took a dump, that new 750VS should have been able to bolt on and clean it up at idle. With 72ish jets and even a 10.5PV it should idle with the vacuum he has 10/15.
Maybe it's ignition related, who knows? I know the heat riser is gone, but still seams to me like it's acting like a restriction somewhere. Any chance a baffle in one of the mufflers broke loose? Run it up to 2500 r's or so and see if you have even flow out of both tailpipes?
Ok, that's all i got...:lol:
Yes there is even flow from both tail pipes. Exhaust is new, with new mufflers. Car only has about 1200-1700 miles on it since restoration.
I agree that the engine should idle with less than 25* at idle......but it will certainly idle a whole lot better with 25*....& possibly more. Are any of the lifters bottomed out, which would hold the valve open?
Yea that is my thought exactly, it should idle with less timing at idle, but it doesnt and I am banging my head against the wall ready to send this car over a cliff!! that may be a little dramatic but it is very frustrating.
I did not visually check to see if a lifter was holding a valve opened, or if a lifter collapsed, but when driving the engine is smooth, there doesnt seem to be a miss or anything like that.
Throttle blades are cheap. Are you suggesting he doesn’t now how to close the throttle? Or maybe he has the throttle cable adjusted wrong?
There is enough room in the throttle cable to have the throttle blades closed. Getting it to close isnt the problem, the idle speed screw controls that just fine, its just that when I close the throttle blades the whole engine starts to shake and then just stalls.
I dont think I quoted someone who mentioned a vacuum leak, but by damn I looked!! I sprayed the carb base with carb cleaner, Sprayed where the intake mates to the cylinder heads and nothing! I even tried that with running propane from a propane torch over it and nothing!! :BangHead:
The guy I am working with mentioned rotor phasing to the cap. That appears to be easy enough to inspect, so Ill give that a go next time I am in. I can AGAIN look for a blasted vacuum leak. Ill check to see if there is a hang up somewhere in the throttle cable, but like OldManRick said I dont believe this is a carb issue since I am getting the same issue with two very different carbs.
Now, Some history on the engine. The engine was in a fire. It originally came out of a 68 New Yorker that was in a building that was torched. According to the information we found the fire didnt get hot enough to destroy the engine. Everything on the engine is the same as was in the fire with the exception of the pistons, piston rings, seals, oil pump, carb, cam, lifters. I know the engine block was magnafluxed. The heads also go machine work done, I can only ASSUME they were magnafluxed as well. However the cast iron intake did not go to the machine shop so it was not magnafluxed. Spit balling here, could the intake of developed a crack due to the fire that would allow a vacuum leak?
