I just rebuilt my Q-jet and noted that the shafts were very sloppy... Where can I get a bushing kit/ reamer to rebush it? I also note that, while the rebuild took care of the bog/ carb sneeze on acceleration I still have a midrange/ WOT miss... is this likely due to the vac leak at the shafts or something else?
Worn shaft bushings would show up as a lean condition at idle and lower speeds. If you have a misfire under load at midrange and higher RPM's I would look at the ignition. Carbon tracking on the cap or coil tower, worn distributor shaft bushings, or maybe try a new set of spark plugs. :bglasses:
Hi Joe, I should have mentioned that I just did the plugs, wires, cap, rotor and points. Plug gap, timing and dwell all factory spec. The distributor is questionable as there is lots of slop in the gear, it's getting swapped soon. I drove the car today and noted that the motor seems to load up with fuel till it sneezes through the carb then runs almost ok for awhile. If I hammer it I get a big bog and although it will haul a$$ acceleration is not at all crisp and it stutters with anything more than 1/4 throttle. Choke opens all the way and stays there, the secondary air valves never seem to open as I work the throttle manually w/ air cleaner open. Any other hints? Seems really rich to me, float height is dead on, metering rods and jets are all stock.
30 deg. Factory spec. per the manual. I also found out today how loud a 455 is without pipes on it! My exhaust pipes have slowly been giving up so I removed them today as patterns for the bender... beautiful noise!
Check your choke pull off diaphragms.........your carb may have either 1 or 2 of them, but one of them limits the speed at which the secondaries open. If it has a leak they will fall open too fast and cause a major bog. If you have a vacuum pump tester pump it down and it should hold vacuum. :bglasses:
Cool, I'll do that... There are two of them. Autozone has an inexpensive vacuum pump I've been wanting anyway.
Food for thought... vacuum leaks can only occur at throttle settings causing relatively high manifold vacuums. Heavy throttle conditions lower vacuum. Does this condition only occur when using the secondaries? You may be experiencing a problem where the air horn gasket is not properly installed and it is binding the power piston, which controls the metering rods. This can cause a lean condition, creating your problem. Try this... using a very long narrow screwdriver or similar tool, try locating the power piston under the vent stack. Using a flashlight makes the job easier. You are looking for a shiny brass colored line running fore and aft on the vehicle. This is the link holding the metering rods. Gently push down; do they quickly return? Do they push down? If they are not free to move, lean out or excessive richness will occur. Let me know... Ray
