ponchopwr70
09-26-2006, 05:13 PM
Sorry if this is long but here it goes,
My combo goes like this 1970 lemans, 3800lbs with me (just a guess), chevy 388, 10.8:1 static cr, ported and polished 2.02 heads, cam is 235@ .050, 507lift, 108 ls,rpm range 2200-6200, 69 z-28 intake port matched to heads. Timing is 13 initial and 34 Total anymore advanced and it will ping. Also rebuilt hei, accel module, hypertech cap, rotor, no vacuum advance. (I tried vacuum adv. and it pinged real bad, so I then retarted till no pinging was herd, ran good on lowend but poor on top.) Th350, 2400 stall, 3.55 gears 26" tire. This is a street car. First carb was an out of the box holley 750 vac. sec. Hesitation when I would get on it (seemed like a lean condition)everytime and very week topend. My engine builder (he is 52 and a very good friend) Gave me an old race carb (because hes not a fan of vac sec. carbs.) He says its and 850. Its a holley double pumper, choke tower milled off and bowls are cleaned up. It has 76jets front with 6.5pv and 93's in back no pv. 30cc pump in front with the white cam and 31 squirter. 50cc pump back with dark colored cam (aggressive) and 32 squirter. Heres the problem, when I'm cruising 1800rpms and get on it a little, it goes up to 2100rpms then hesitates and jumps to 2400 rpm, then everything is smooth. Top end is awesome, the motor revs quick there is no problems when the secondaries come in, no hesitation just revs quicker. This happens in every gear. If I deck it while I'm cruising it will sputter and almost die then kicks in. I pretty much drive around keeping the rpms up or feather it to get them up.How can I fix this? These symptoms are getting worst now that temp is dropping out side, (like 50 degrees out) engine stays around 170,180. Tonight I footbraked it to get the rpms up and wheels to spin and it sputtered, (doesn't do this when its 70 out) then the tires spun and it ran extremly well even on top. Does this carb sound to big? Should I try to improve on my 750vac sec. carb with a sec metering block, secondary springs, and jets? Sorry this is so long just wanted to give enough info. Thanks in advanced.
My combo goes like this 1970 lemans, 3800lbs with me (just a guess), chevy 388, 10.8:1 static cr, ported and polished 2.02 heads, cam is 235@ .050, 507lift, 108 ls,rpm range 2200-6200, 69 z-28 intake port matched to heads. Timing is 13 initial and 34 Total anymore advanced and it will ping. Also rebuilt hei, accel module, hypertech cap, rotor, no vacuum advance. (I tried vacuum adv. and it pinged real bad, so I then retarted till no pinging was herd, ran good on lowend but poor on top.) Th350, 2400 stall, 3.55 gears 26" tire. This is a street car. First carb was an out of the box holley 750 vac. sec. Hesitation when I would get on it (seemed like a lean condition)everytime and very week topend. My engine builder (he is 52 and a very good friend) Gave me an old race carb (because hes not a fan of vac sec. carbs.) He says its and 850. Its a holley double pumper, choke tower milled off and bowls are cleaned up. It has 76jets front with 6.5pv and 93's in back no pv. 30cc pump in front with the white cam and 31 squirter. 50cc pump back with dark colored cam (aggressive) and 32 squirter. Heres the problem, when I'm cruising 1800rpms and get on it a little, it goes up to 2100rpms then hesitates and jumps to 2400 rpm, then everything is smooth. Top end is awesome, the motor revs quick there is no problems when the secondaries come in, no hesitation just revs quicker. This happens in every gear. If I deck it while I'm cruising it will sputter and almost die then kicks in. I pretty much drive around keeping the rpms up or feather it to get them up.How can I fix this? These symptoms are getting worst now that temp is dropping out side, (like 50 degrees out) engine stays around 170,180. Tonight I footbraked it to get the rpms up and wheels to spin and it sputtered, (doesn't do this when its 70 out) then the tires spun and it ran extremly well even on top. Does this carb sound to big? Should I try to improve on my 750vac sec. carb with a sec metering block, secondary springs, and jets? Sorry this is so long just wanted to give enough info. Thanks in advanced.