MericaMopar
Member
Hi guys, I got a '64 361 mopar engine that is entirely stock other than a holley street warrior (4160) 600CFM carb, weiand 8008 intake, and 440 heads. It has a push button auto with 2.76 gears.
I had it running ok at factory specs, 12 degrees of BTC timing, and the carb adjusted just using the idle screw and idle mix screws. It lacked power but would scoot about with no issues.
I then started reading and watching things about getting more performance from adding more timing to the distributor, changing the springs in the distributor, and properly setting transfer slots on the carb (idle mix screws weren't really effective when I first set the carb up). This is where I have run into trouble...
I took the carb off and set the primary butterflies using the idle speed screw to show square transfer slots, they were way to far open before, almost half the slot exposed at idle. On the distributor, I took out the stock heavy spring and replaced it with a black spring from the FBO kit and also used the mechanical advance limiter set to 18 degrees of advance. I then added more initial timing to 18 degrees and set the new idle speed at 1000rpm (in neutral...750 in gear) with the secondary stop screw.
I now have an off idle or off cruise bog....with light to moderate press of the pedal. WOT seems fine and has more power than before. Revving in neutral would result in a backfire through the carb once rpms got to around 3000. Bog is really bad under high load and low rpm. For example, taking off from a stop or letting it shift into 2nd or 3rd while going less than 25mph.
Things I have tried so far:
1. increase pump squirter from 31 to 35
2. changed power valve from 6.5 to 8.5 (vacuum in gear is 17)
3. changed pump cam from orange to blue
These changes have alleviated the carb backfire...and now I just have a bog and the car could still definitely stall out if I didn't do some fancy footwork while taking off or manually shift gears. Past 2000rpm it runs great, zero hesitation when pressing the throttle.
Overall I am confused, mainly because everything I see and read....setting the carb up "correctly" and adding timing is a sure fire thing. Do you guys think this is still a carb issue at this point? I have not tried main jets yet. My feeling is its running lean now because of the timing changes and just needs more fuel now which is why I have been going after the carb. On the flip side, most carb issues are electrical, but I feel the way I have mine set up is pretty normal and should work fine. I know I messed up using the shotgun approach. I did try going back to 12 degrees of timing, but I would have to open up the secondaries quite a lot to get back to a good 1000rpm (750 in gear) idle.
I had it running ok at factory specs, 12 degrees of BTC timing, and the carb adjusted just using the idle screw and idle mix screws. It lacked power but would scoot about with no issues.
I then started reading and watching things about getting more performance from adding more timing to the distributor, changing the springs in the distributor, and properly setting transfer slots on the carb (idle mix screws weren't really effective when I first set the carb up). This is where I have run into trouble...
I took the carb off and set the primary butterflies using the idle speed screw to show square transfer slots, they were way to far open before, almost half the slot exposed at idle. On the distributor, I took out the stock heavy spring and replaced it with a black spring from the FBO kit and also used the mechanical advance limiter set to 18 degrees of advance. I then added more initial timing to 18 degrees and set the new idle speed at 1000rpm (in neutral...750 in gear) with the secondary stop screw.
I now have an off idle or off cruise bog....with light to moderate press of the pedal. WOT seems fine and has more power than before. Revving in neutral would result in a backfire through the carb once rpms got to around 3000. Bog is really bad under high load and low rpm. For example, taking off from a stop or letting it shift into 2nd or 3rd while going less than 25mph.
Things I have tried so far:
1. increase pump squirter from 31 to 35
2. changed power valve from 6.5 to 8.5 (vacuum in gear is 17)
3. changed pump cam from orange to blue
These changes have alleviated the carb backfire...and now I just have a bog and the car could still definitely stall out if I didn't do some fancy footwork while taking off or manually shift gears. Past 2000rpm it runs great, zero hesitation when pressing the throttle.
Overall I am confused, mainly because everything I see and read....setting the carb up "correctly" and adding timing is a sure fire thing. Do you guys think this is still a carb issue at this point? I have not tried main jets yet. My feeling is its running lean now because of the timing changes and just needs more fuel now which is why I have been going after the carb. On the flip side, most carb issues are electrical, but I feel the way I have mine set up is pretty normal and should work fine. I know I messed up using the shotgun approach. I did try going back to 12 degrees of timing, but I would have to open up the secondaries quite a lot to get back to a good 1000rpm (750 in gear) idle.
Last edited: