ZZ4 Off Idle Stumble
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7th Gear
Joined: Mar 2010
Posts: 7
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From: Phoenix Arizona
ZZ4 Off Idle Stumble
Happy New Year all!
I have a 1973 4 speed that I recently installed a new ZZ4 crate engine, BG Speed Demon 650 with MSD ignition and setup initial timing with 12Deg resulting in 32Deg all in. Setup idle speed a little on high side at 900rpm(primary and secondary adjusted same) as I have yet to install a choke and mixture screws setup to optimum manifold Vac(all 4 adjusted same to ~17inmg) with Vac advance hooked up to ported. At speed and under moderate acceleration I have no issues, however at partial throttle from stop, the engine stumbles and wants to cut out. I have checked the Acel pump and both sides produce a good stream although I did change the pump cam to be more aggressive however has not helped.
As strange as it sounds, I don't want to have to chirp the tires everytime I pull away from lights. Any thoughts?
A secondary issue I have is switching off the engine it often doesn't shutdown immediately however gives a second run on as if the car is asking how dare I switch the car off. I installed the diode at the alternator per the MSD manual however has not helped.
I have a 1973 4 speed that I recently installed a new ZZ4 crate engine, BG Speed Demon 650 with MSD ignition and setup initial timing with 12Deg resulting in 32Deg all in. Setup idle speed a little on high side at 900rpm(primary and secondary adjusted same) as I have yet to install a choke and mixture screws setup to optimum manifold Vac(all 4 adjusted same to ~17inmg) with Vac advance hooked up to ported. At speed and under moderate acceleration I have no issues, however at partial throttle from stop, the engine stumbles and wants to cut out. I have checked the Acel pump and both sides produce a good stream although I did change the pump cam to be more aggressive however has not helped.
As strange as it sounds, I don't want to have to chirp the tires everytime I pull away from lights. Any thoughts?
A secondary issue I have is switching off the engine it often doesn't shutdown immediately however gives a second run on as if the car is asking how dare I switch the car off. I installed the diode at the alternator per the MSD manual however has not helped.
