badmix
1/2 ton status
When testing, Should vacuum advance diaphram hold vacuum with a handheld vacuum pump with engine off.
CK5
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Help. Truck issue....
- Thread starter badmix
- Start date
Yes it should
If you are only hooked to the advance diaphragm, yes.
Doesn't have to Holley. What model and lust number if any. Highly recommend getting ethenol tolerant neoprene
badmix
1/2 ton status
It's a holley 570 street avenger 0-80570 and Mallory 8548201
https://carburetion.com/index.htm give these guys a call. I also can't find a "kit", truth be told I haven't worked on a new Holley. They may know which individual parts will work. You can change just the accelerator pump with out disturbing the bowl gaskets. Get a new base gasket. You'll need to remove carb from intake, to replace accelerator pump.
edit Holley shows it as 4150 I expect many gaskets will be the same.
edit Holley shows it as 4150 I expect many gaskets will be the same.
badmix
1/2 ton status
Well I disco'd the accelerator plunger from carb (basically took pump out of equation) no change, still have issue. Believe the vacuum advance is broke based on you guys and talking to Holley (they own Mallory)
wait you disabled the accel pump ? An accel pump not working is what may be causing the lean pop in the intake
badmix
1/2 ton status
I disconnected this morning , not previously, only wanted to test truck without it, still got bang thru carb. Just trying to troubleshoot
I wouldn't call that a valid test. Hook it back up look down the primary venturi, work the throttle and watch for gas to squirt in both barrel should be a strong squirt, and start just after you crack the throttle and go at least past a 1/3 opening
badmix
1/2 ton status
Ok,,I'll check it out. Seems most things lead back to distributor
badmix
1/2 ton status
Installed new vacuum advance and cap/rotor. No change.,still popping thru carb when "stab" throttle, if I ease rpm up, it's fine.
That ease into it, tells. Is big lean spot when the throttle is stabbed. Accelerator circuit main suspect
For the third time…
badmix
1/2 ton status
Ok, what to check and/or replace?
Obviously do this with the engine off.
It’s a pretty good mechanical check of the acceleration circuit.
badmix
1/2 ton status
Well carb is old, never been gone thru, so ordered rebuild kit and just yanked carb off.
On a side topic.,want to clean up vacuum lines . The carb has a port for full intake vacuum, the hose connected to back of intake manifold to a full vacuum port there. Does that sound correct? And these lines T off to other things, can I plug the carb port and just use intake port to run whatever it runs?
On a side topic.,want to clean up vacuum lines . The carb has a port for full intake vacuum, the hose connected to back of intake manifold to a full vacuum port there. Does that sound correct? And these lines T off to other things, can I plug the carb port and just use intake port to run whatever it runs?
is redundant, can block off the port at carb and use, the port on intake. Or use the port 3/8" on carb for PCV, and mainifold port for other Manifold vacuum devices. You really only need Th350 vacuum modulator, Power brake booster, Hvac supply, and Dist vacuum advance which can be either ported or manifold, depending on tune.
Been there. Heavy on the foot, pop.
Down on power. Easy on the foot was ok.
Believe it was worn exhaust lobe. Forget if it was 6 or 8. Plain as day with the valve cover off.
Broke a rocker once, similar.
Just a thought.
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