400 SB Tuninb
Thread Starter
Racer
Joined: Jun 2007
Posts: 291
Likes: 6
From: Delray Beach FL
400 SB Tuninb
I just picked up a 70 Split bumprt Z28 to keep my 70 Corvette company.
Motor is a 400 destroked with a 350 crank. Car has a 4 speed Muncie. Has 186 fuelly heads Holley 750DP, HEI and the following cam specs:
Lift .525 Lobe Seperation 108 Duration 250 Lobe Lift .35 Hydraulic Cam
The problem I have is when I get off the gas at low speeds the motor will basically wind down and stall. Once I restart It will idle fine until I go to move it. Once I take my foot off the gas it will idle down and stall.
I have the idle set at 900 rpm. I read some place that an adjustable dist advance can solve this as when I get off the gas the vacuum drops so much there is little vacuum advance. Looking for any other thoughts
Motor is a 400 destroked with a 350 crank. Car has a 4 speed Muncie. Has 186 fuelly heads Holley 750DP, HEI and the following cam specs:
Lift .525 Lobe Seperation 108 Duration 250 Lobe Lift .35 Hydraulic Cam
The problem I have is when I get off the gas at low speeds the motor will basically wind down and stall. Once I restart It will idle fine until I go to move it. Once I take my foot off the gas it will idle down and stall.
I have the idle set at 900 rpm. I read some place that an adjustable dist advance can solve this as when I get off the gas the vacuum drops so much there is little vacuum advance. Looking for any other thoughts
Race Director
Joined: May 2006
Posts: 18,695
Likes: 2,572
1. Did you check if the float levels are set correctly?
2. You set the idle to 900 rpm but did you adjust the mixture screws?
3. What is your initial advance set for with the vacuum line to the distributor disconnected?
4. is the vacuum line to the distributor connected to manifold vacuum or ported vacuum?
2. You set the idle to 900 rpm but did you adjust the mixture screws?
3. What is your initial advance set for with the vacuum line to the distributor disconnected?
4. is the vacuum line to the distributor connected to manifold vacuum or ported vacuum?
