Red_Rocket_1965
Active Member
Hey guys, trying to dial in again after modifying a few things on my Holley 750 DP….I have timing at 16 initial, 33 total with vac advance disconnected. It could use a bit (a lot) more although I haven’t test driven yet since getting it back together and stopped for the night.
PROBLEM: when setting idle and timing, when revving it up to 1500-2500 RPM in park at 180 degree temp, it periodically will hold 1500-2500RPM by itself with throttle completely closed. Most of the time the RPM settles down eventually…but sometimes I have to turn down the curb idle. It seems almost random…
It has always run very rich and has quite a large cam although I don’t know exact specs. It only makes 8-9hg at idle. I now have a 4.5 power valve in front (was a 6.5 PV before, back PV is blocked off) removed the choke assembly and choke horn and drilled the controversial 3/32” holes in front throttle blades only for now so it idles without having to open curb idle so much. I figure if Holley XP carbs have built in adjustable idle air bypass holes I’ll try it and if it doesn’t work I can go back to stock no holes throttle blades. It still has stock jets and pump nozzles and does not have any other adjustable air bleeds.
Could this be the throttle blade holes letting in too much air now? It seems to work for so many…maybe a vacuum leak elsewhere? (I did have intake off)
Electronic mopar ignition box, mopar electronic distributor, 906 heads, headers, 3” exhaust, single plane Holley Street Dominator intake man, solid lifters, and ductile iron rockers, 440 bored 060, 727, 3500 stall, 4.10.
Thx!
PROBLEM: when setting idle and timing, when revving it up to 1500-2500 RPM in park at 180 degree temp, it periodically will hold 1500-2500RPM by itself with throttle completely closed. Most of the time the RPM settles down eventually…but sometimes I have to turn down the curb idle. It seems almost random…
It has always run very rich and has quite a large cam although I don’t know exact specs. It only makes 8-9hg at idle. I now have a 4.5 power valve in front (was a 6.5 PV before, back PV is blocked off) removed the choke assembly and choke horn and drilled the controversial 3/32” holes in front throttle blades only for now so it idles without having to open curb idle so much. I figure if Holley XP carbs have built in adjustable idle air bypass holes I’ll try it and if it doesn’t work I can go back to stock no holes throttle blades. It still has stock jets and pump nozzles and does not have any other adjustable air bleeds.
Could this be the throttle blade holes letting in too much air now? It seems to work for so many…maybe a vacuum leak elsewhere? (I did have intake off)
Electronic mopar ignition box, mopar electronic distributor, 906 heads, headers, 3” exhaust, single plane Holley Street Dominator intake man, solid lifters, and ductile iron rockers, 440 bored 060, 727, 3500 stall, 4.10.
Thx!
