jetting help. lq9 holley 750.
#1
jetting help. lq9 holley 750.
im having a hell of a time getting my car not to stumble going WOT. i do have a blowthru set up, buy im not even getting in to boost so im pretty sure thats not having alot of an effect on it.
right now i have
mains 73/ 71
squirters 37/45
orange pump cam on primary
pink cam on secondary
ive dropped the secondary mains to 68 no help, ive had the rear squirter from 31-45 no real difference with a bunch of different cams.
if im driving pretty slow and just touch the gas a little i can watch the wideband go slightly lean and there is a small hesitation. it clears up and pulls pretty good drive on just the primary's. if i try to go WOT at any time the car stumbles bad. from a stop it will kill the wideband is off the meter lean when this happens but not sure if its a missfire from rich or actually a lean condition. ive tried all kinds of combination's of squirts and cams. nothing seems to help.
right now i have
mains 73/ 71
squirters 37/45
orange pump cam on primary
pink cam on secondary
ive dropped the secondary mains to 68 no help, ive had the rear squirter from 31-45 no real difference with a bunch of different cams.
if im driving pretty slow and just touch the gas a little i can watch the wideband go slightly lean and there is a small hesitation. it clears up and pulls pretty good drive on just the primary's. if i try to go WOT at any time the car stumbles bad. from a stop it will kill the wideband is off the meter lean when this happens but not sure if its a missfire from rich or actually a lean condition. ive tried all kinds of combination's of squirts and cams. nothing seems to help.
#2
This is what we have been running on non blow thru 6.0's with 317's and stock cam with 750 dbl pumper.
Front 76-78 with power valve 5.5
Rear 83-85 with power valve blocked
squarters 32 or 33 front
31 rear
What size pumps do you have in the front and rear 30cc or 50?
Front 76-78 with power valve 5.5
Rear 83-85 with power valve blocked
squarters 32 or 33 front
31 rear
What size pumps do you have in the front and rear 30cc or 50?
#3
my 6.0l is cam only. plus the turbo. ha
i have 30cc front and rear.
your are running alot more primary jet then me. i had the car running great when i had my procharger on it. then i was only running 73 front and 71 rear.
i have my front power valve blocked and the rear is a boost referenced one so thats not helping me at this point.
i have 30cc front and rear.
your are running alot more primary jet then me. i had the car running great when i had my procharger on it. then i was only running 73 front and 71 rear.
i have my front power valve blocked and the rear is a boost referenced one so thats not helping me at this point.
#5
#6
rear power valve is boost referenced ? what is the PV rated at? if it is too low of spec it will be too lean as you get into the secondarys. I'd have an 8.5 to start out.
I dont understand why you'd have the front blocked and the rear referenced, I'd change it around and have the front referenced and the rear blocked, and add 10 jet sizes to the rear.
I dont understand why you'd have the front blocked and the rear referenced, I'd change it around and have the front referenced and the rear blocked, and add 10 jet sizes to the rear.
#7
Seems a bigger front squirter might help, i am going to try one soon and see if it helps my stumble issue, if i roll into it at low revs it is fine, but a straight WOT stab and it stumbles then screams into the revs.
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#8
rear power valve is boost referenced ? what is the PV rated at? if it is too low of spec it will be too lean as you get into the secondarys. I'd have an 8.5 to start out.
I dont understand why you'd have the front blocked and the rear referenced, I'd change it around and have the front referenced and the rear blocked, and add 10 jet sizes to the rear.
I dont understand why you'd have the front blocked and the rear referenced, I'd change it around and have the front referenced and the rear blocked, and add 10 jet sizes to the rear.
i bumped up the front squirter from a 37 to a 45 it seemed to help a little bit. but still a little hesitation. but if i hit the secondary's it still stumbles and if i stay in it it will die.
#10
one thing i did try was hold the prime button down on my meth/water injection and that didn't help either. im so lost efi? ha! i might try a 47 squirter in the rear(biggest i have) and maybe i should put a blue cam in? to really try to get some fuel in it.
#11
im running a turbo so my PV's work a little different they bring more fuel with boost.
i bumped up the front squirter from a 37 to a 45 it seemed to help a little bit. but still a little hesitation. but if i hit the secondary's it still stumbles and if i stay in it it will die.
i bumped up the front squirter from a 37 to a 45 it seemed to help a little bit. but still a little hesitation. but if i hit the secondary's it still stumbles and if i stay in it it will die.
goodluck
Barrett
#13
ok im going to call rodger at c&s again and see if i can just put a normal PV (vacuum sensitive) in the front of the carb. other wise i will jet the front up a bunch and see if it helps. it idles at 15" where should i start for a pv if i can run one? also how should i just my pvcrs? i have 4 behind the pv that i can jet from .046 to .093
#14
#15
ok im going to call rodger at c&s again and see if i can just put a normal PV (vacuum sensitive) in the front of the carb. other wise i will jet the front up a bunch and see if it helps. it idles at 15" where should i start for a pv if i can run one? also how should i just my pvcrs? i have 4 behind the pv that i can jet from .046 to .093
If the rear PV is a special one that only opens under pressure(never seen that, but its possible i guess) then you still need to jet the secondarys up 10 sizes to get that half of the carb close to where it should be, and under boost it will open and add additional fuel.
15"of vacuum at idle, I would put a 8.5"in the front, leave the primary jet alone.
#16
i talked to rodger again today. and i bumped up my fuel pressure to 6psi. (had a fuel pressure problem with the procharger and never bumped it back up) also raised my front float level a little so it slightly dripping out. then i adjust the rear alot higher. set high as i could then put the plug back in then bumped it up more. was suppose to go untill fuel came out into the carb. then back off 1/2 turn so i might try going a little more. after this i went out and in 1st gear and go WOT it doesn't stumble. it dosn't have the power the D1SC did on the line but im not sure if that is the turbo or if i could get it a little better. but if i put it in 3rd at idle/stop and go WOT it stumbles. its not as bad as it was but it is still there. i tried to kill it by doing this and it wouldn't so it has gotten better.
and yes my PV's are special just for boosted applications. i asked him about the standard PV's and i cant run them because of the modifications done to the carb to make it a blowthru.
after reading your post i think i am going to try upping the secondarys some and see if it helps it a little more? i could always pull fuel out of the pvcr's.
and yes my PV's are special just for boosted applications. i asked him about the standard PV's and i cant run them because of the modifications done to the carb to make it a blowthru.
after reading your post i think i am going to try upping the secondarys some and see if it helps it a little more? i could always pull fuel out of the pvcr's.