I have a mid seventies 440 in my Duster. It has a Holley 750 dual feed, single pump carb with vacuum secondaries, an older Edelbrock dual plane intake, Schumacker headers and factory heads (previous owner claims to have done a home port job on them,but he also made other claims that were proven false, so I don't know if he did or not). I don't know cam size, but it is not radical.
Car idles ok, but stumbles and pops through the carb on hard acceleration. After the stumble and pop, it is fine.
At first I thought this was a timing problem. I figured it must have too much advance, and is firing before the intake valve closes. After retarding the timing ( I don't remember exactly how far, but it was a lot), the problem still exists. So I returned the timing to where it was before(10 BTD).
I replaced the power valve and it made no difference. Vacuum reads about 13 or 14 and the power valve is a 6.5.
I tried changing the squirter, and worked my way from a 31 up to a 37. At this point, the pop was gone, but it smoked when you stepped on it. I went back to a 35 and the pop returned. I went back to the 37 and the pop was still there.
Now I am really getting confused.
I got a 625 AFB from my brother, and a Holley 750 double pumper from a friend of mine to see if this problem is actually a carb problem or not. (Haven't had a chance to try the Carter yet) With the double pumper on, the stumble is gone, but the pop is still there.
At one point I checked the timing chain, and there seems to be about 7 or 8 degrees of slop in it. I don't know if this is too much or not.
Did a compresssion test before putting the engine in the Duster, and everything seemed ok (don't remember the numbers now, but all cylinders were within 5 PSI of each other)
I am lost and frustrated. Can someone give me some guidance on this?
Thanks,
Rob
Car idles ok, but stumbles and pops through the carb on hard acceleration. After the stumble and pop, it is fine.
At first I thought this was a timing problem. I figured it must have too much advance, and is firing before the intake valve closes. After retarding the timing ( I don't remember exactly how far, but it was a lot), the problem still exists. So I returned the timing to where it was before(10 BTD).
I replaced the power valve and it made no difference. Vacuum reads about 13 or 14 and the power valve is a 6.5.
I tried changing the squirter, and worked my way from a 31 up to a 37. At this point, the pop was gone, but it smoked when you stepped on it. I went back to a 35 and the pop returned. I went back to the 37 and the pop was still there.
Now I am really getting confused.
I got a 625 AFB from my brother, and a Holley 750 double pumper from a friend of mine to see if this problem is actually a carb problem or not. (Haven't had a chance to try the Carter yet) With the double pumper on, the stumble is gone, but the pop is still there.
At one point I checked the timing chain, and there seems to be about 7 or 8 degrees of slop in it. I don't know if this is too much or not.
Did a compresssion test before putting the engine in the Duster, and everything seemed ok (don't remember the numbers now, but all cylinders were within 5 PSI of each other)
I am lost and frustrated. Can someone give me some guidance on this?
Thanks,
Rob
