holley carb tuning ?
#1625274
05/26/14 08:40 PM
05/26/14 08:40 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
OP
I Live Here
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OP
I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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We have a 650 holley double pumper 4777 on a 392 SB stroker ported magnum heads 10.2 compresison 222@.050 110 LSA 575 lift ported RPM airgap intake TTI headers, 2.5 dual exhaust 2.94 gears, mallolry ign. 32 degrees total in around 2000 RPM 18* idle around 850 idle, electric fuel pump 904 with low 1st and 2nd gears, stock high stall converter. It runs awesome, pulls like a monster at every RPM from idle to 6500 as long as you don't flat foot it. If you go from idle or even a little off idle to WOT it almost dies for a couple seconds then annihilates the tires almost instantly. It is in a 68 cuda. If you ease into it just a little there is no hesitation, only if you just flat stomp it. Do I need 50CC acc pump? Mabey two 50cc pumps? Different pump cams? They are adjusted to start squirting instantly with any throttle movement. I have the float level set to just barely dribble out the level hole with the engine off and the pump on.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: holley carb tuning ?
[Re: ademon]
#1625278
05/26/14 09:27 PM
05/26/14 09:27 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
OP
I Live Here
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OP
I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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It has 37 front and rear squirters in it.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: holley carb tuning ?
[Re: HotRodDave]
#1625279
05/26/14 09:37 PM
05/26/14 09:37 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
It has 37 front and rear squirters in it.
You could be going dog rich with 37s... drop them to about 32-34
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Re: holley carb tuning ?
[Re: HotRodDave]
#1625282
05/26/14 10:49 PM
05/26/14 10:49 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
OP
I Live Here
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OP
I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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I put a 31 in the front and that seems to help, the only other smaller one I have is a 28, should I throw that in the secondary?
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: holley carb tuning ?
[Re: HotRodDave]
#1625283
05/26/14 10:51 PM
05/26/14 10:51 PM
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Joined: Jan 2003
Posts: 5,894 Florida
Locomotion
master
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master
Joined: Jan 2003
Posts: 5,894
Florida
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What pump cams do you have in it and what # hole? You appear to not be getting enough initial squirt volume. 50cc pumps will simply prolong the length of the squirt with the same squirter size.
Try pink cam with the screw through the #2 hole in the arm and #3 hole in the nylon(?) cam I the primaries.
Secondaries the same, or green #2.
It takes some tinkering, but I try to get both squirt durations to finish squirting at the same time for drag racing only applications. You might need a slightly smaller cam. There are charts out there and pink & green are 2 of the biggest 30cc cams. #1 holes usually squirt less volume than #2/3.
Adjust for instant squirt with any throttle movement but keep about .015" additional compression at the pump housing lever when throttle is fully open.
I'll suggest going the other way on the squirters. If it still hesitates, consider .040"/.042"/.045".
I would suggest a power valve rated about 1.5 - 2 numbers above idle vacuum IN GEAR.
My theory is that your converter and gear isn't allowing the engine to rev up as fast as needed. The load requires more initial fuel until the rpm's and vacuum are high enough to get the main jets to take over.
(I normally use .037 - .040" squirters with pump cams as described with a low gear 904, 4.86 gears and a converter that flashes to 5100 - 5400 before starting to lock up.)
Can't guarantee it, but it's worth a try.
If, by chance, it goes when you flatfoot it, hesitates, then goes again, you may need bigger pump cams to extend the duration.
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Re: holley carb tuning ?
[Re: HotRodDave]
#1625285
05/26/14 11:18 PM
05/26/14 11:18 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
I put a 31 in the front and that seems to help, the only other smaller one I have is a 28, should I throw that in the secondary?
Try it for a test but it might be too small but you should see a change
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Re: holley carb tuning ?
[Re: HotRodDave]
#1625286
05/27/14 11:32 AM
05/27/14 11:32 AM
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Joined: Jan 2003
Posts: 12,071 Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,071
Benton, IL.
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Try a quicker opening power valve first, like a 9.5. Then start the accelerator pump tuning.
Master, again and still
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Re: holley carb tuning ?
[Re: DaveRS23]
#1625287
05/27/14 12:04 PM
05/27/14 12:04 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
Posts: 32,394
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Re: holley carb tuning ?
[Re: Locomotion]
#1625288
05/27/14 12:47 PM
05/27/14 12:47 PM
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Joined: Jul 2004
Posts: 19,317 State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,317
State of confusion
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Quote:
What pump cams do you have in it and what # hole? You appear to not be getting enough initial squirt volume. 50cc pumps will simply prolong the length of the squirt with the same squirter size.
Try pink cam with the screw through the #2 hole in the arm and #3 hole in the nylon(?) cam I the primaries.
Secondaries the same, or green #2.
It takes some tinkering, but I try to get both squirt durations to finish squirting at the same time for drag racing only applications. You might need a slightly smaller cam. There are charts out there and pink & green are 2 of the biggest 30cc cams. #1 holes usually squirt less volume than #2/3.
Adjust for instant squirt with any throttle movement but keep about .015" additional compression at the pump housing lever when throttle is fully open.
I'll suggest going the other way on the squirters. If it still hesitates, consider .040"/.042"/.045".
I would suggest a power valve rated about 1.5 - 2 numbers above idle vacuum IN GEAR.
My theory is that your converter and gear isn't allowing the engine to rev up as fast as needed. The load requires more initial fuel until the rpm's and vacuum are high enough to get the main jets to take over.
(I normally use .037 - .040" squirters with pump cams as described with a low gear 904, 4.86 gears and a converter that flashes to 5100 - 5400 before starting to lock up.)
Can't guarantee it, but it's worth a try.
If, by chance, it goes when you flatfoot it, hesitates, then goes again, you may need bigger pump cams to extend the duration.
Some good ideas except for the p/v at idle deal. That`s old skool bs and even if it`s open at idle, it doesn`t come into play unless your way in the transfer slot on to the enrichment circuit. The proper way to tune p/v is to cruise the car and get a vacuum reading then go from there. Some guys go further for economy and hit a grade measure the reading and p/v it accordingly. I have bet. 9-10 "`s at a steady state cruise and put a 5.5 in and what a difference compared to the "old" idle theory. It get`s way deeper than this but that`s my position on this fwiw.........
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: holley carb tuning ?
[Re: Thumperdart]
#1625289
05/27/14 01:02 PM
05/27/14 01:02 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
Posts: 32,394
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Quote:
Quote:
What pump cams do you have in it and what # hole? You appear to not be getting enough initial squirt volume. 50cc pumps will simply prolong the length of the squirt with the same squirter size.
Try pink cam with the screw through the #2 hole in the arm and #3 hole in the nylon(?) cam I the primaries.
Secondaries the same, or green #2.
It takes some tinkering, but I try to get both squirt durations to finish squirting at the same time for drag racing only applications. You might need a slightly smaller cam. There are charts out there and pink & green are 2 of the biggest 30cc cams. #1 holes usually squirt less volume than #2/3.
Adjust for instant squirt with any throttle movement but keep about .015" additional compression at the pump housing lever when throttle is fully open.
I'll suggest going the other way on the squirters. If it still hesitates, consider .040"/.042"/.045".
I would suggest a power valve rated about 1.5 - 2 numbers above idle vacuum IN GEAR.
My theory is that your converter and gear isn't allowing the engine to rev up as fast as needed. The load requires more initial fuel until the rpm's and vacuum are high enough to get the main jets to take over.
(I normally use .037 - .040" squirters with pump cams as described with a low gear 904, 4.86 gears and a converter that flashes to 5100 - 5400 before starting to lock up.)
Can't guarantee it, but it's worth a try.
If, by chance, it goes when you flatfoot it, hesitates, then goes again, you may need bigger pump cams to extend the duration.
Some good ideas except for the p/v at idle deal. That`s old skool bs and even if it`s open at idle, it doesn`t come into play unless your way in the transfer slot on to the enrichment circuit. The proper way to tune p/v is to cruise the car and get a vacuum reading then go from there. Some guys go further for economy and hit a grade measure the reading and p/v it accordingly. I have bet. 9-10 "`s at a steady state cruise and put a 5.5 in and what a difference compared to the "old" idle theory. It get`s way deeper than this but that`s my position on this fwiw.........
thats the way you would do it for a street car but not drag only
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Re: holley carb tuning ?
[Re: Thumperdart]
#1625291
05/27/14 01:41 PM
05/27/14 01:41 PM
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Joined: Jun 2003
Posts: 9,225 Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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blue cams and 32 squirters. I also wont run a PV lower than a 6.5. I want it to open as soon as I mash the go pedal
Last edited by sixpackgut; 05/27/14 01:45 PM.
Gen 3 power 6.22@110, 9.85@135 Follow @g3hemiswap on instagram
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