holley 750 D.P. carb jetting??

66sbcduece · 07-19-2009, 06:42 AM

Well for years my DP 750 holley what i thought was a 4779 turns out to be 6109 tunnel ram carb after Rickster looked up numbers in holley book!(thanks Rick) I was running 76 primary and 84 sec. jets on 9.8 to 1 327 with vic. junior and 1 inch spacer and ported twisted old trickflow heads. Rick came up with 75,76 stock jetting for this 6109 carb so i jetted 72,74 on this single vic intake and took her out and car seems to run smoother with what seems to accel faster at 4 to 5 grand but as we all know sometimes seat of pants fools Ya. Any carb experts here have any advice or experience or set me in right direction OR if i may be in danger zone!!!! Thanks in advance for any feedback. Car has run best of 12.2 with steet BFG touring radials and 11.64 115.5 with hoosier QTP and 5 speed. thanks again, AL

gmonde · 07-19-2009, 07:42 AM

there are a few ways of making sure you are in the ball park as far as jetting is concerned,,,make a pass at the 1320 mark click of the motor and coast on to the ruturn road and check a few plugs,dont make a pass and idle back to the pits you will not get accurate readings,,i also use a stand alone O2 system,you can record your data and save it,review it on a lap top and you can review the whole run,helps trouble shoot problems(fuel presure issues,jetting,power valves,) gmonde

Rich Biebel · 07-19-2009, 02:22 PM

A 750 4779 carb runs best with right around 70 primary jets with a 6.5 power valve and 80 secondary jets and no power valve. You might have to go slightly richer and change the power valve to suit your cam but those are the baseline numbers I always used on a 750 dbl pumper. Accelerator pump squirters and cams is also abig part of tuning one for your application......

BlueOval Ralph · 07-19-2009, 06:00 PM

Plug Power Valve, 77 or 78 main jets change High Speed bleeds from .026 prim, .031 sec to .026 square. Poen idle feed rest in meetring body .002 to .oo3 thou. Red pump cams 330) I think is number on cam.
Ralph

Quote:

Originally Posted by Rich Biebel

A 750 4779 carb runs best with right around 70 primary jets with a 6.5 power valve and 80 secondary jets and no power valve. You might have to go slightly richer and change the power valve to suit your cam but those are the baseline numbers I always used on a 750 dbl pumper. Accelerator pump squirters and cams is also abig part of tuning one for your application......

CrateCamaro · 07-19-2009, 09:14 PM

Quote:

Originally Posted by BlueOval Ralph

Plug Power Valve, 77 or 78 main jets change High Speed bleeds from .026 prim, .031 sec to .026 square. Poen idle feed rest in meetring body .002 to .oo3 thou. Red pump cams 330) I think is number on cam.
Ralph

I just plugged mt pv as well in the front and found some consistancy increase but I picked up a part throttle choppy chug. I run front and rear jets squared and it runs great. This is for a dedicated track car and im not too sure how this would work on the street.

BlueOval Ralph · 07-20-2009, 07:15 AM

This is for track only if you try no powervalve on street it will be sloppy rich down low and fuel mileage will suffer.

Quote:

Originally Posted by CrateCamaro

I just plugged mt pv as well in the front and found some consistancy increase but I picked up a part throttle choppy chug. I run front and rear jets squared and it runs great. This is for a dedicated track car and im not too sure how this would work on the street.

548camaro · 07-26-2009, 05:16 AM

i found most 4779 750 dp's to like around 72/82

07-19-2009, 06:42 AM	#1
66sbcduece Junior Member Join Date: Sep 2005 Location: torrinton , ct. 06790 Posts: 3 Likes: 0 Liked 0 Times in 0 Posts	holley 750 D.P. carb jetting?? Well for years my DP 750 holley what i thought was a 4779 turns out to be 6109 tunnel ram carb after Rickster looked up numbers in holley book!(thanks Rick) I was running 76 primary and 84 sec. jets on 9.8 to 1 327 with vic. junior and 1 inch spacer and ported twisted old trickflow heads. Rick came up with 75,76 stock jetting for this 6109 carb so i jetted 72,74 on this single vic intake and took her out and car seems to run smoother with what seems to accel faster at 4 to 5 grand but as we all know sometimes seat of pants fools Ya. Any carb experts here have any advice or experience or set me in right direction OR if i may be in danger zone!!!! Thanks in advance for any feedback. Car has run best of 12.2 with steet BFG touring radials and 11.64 115.5 with hoosier QTP and 5 speed. thanks again, AL __________________ sbc residential yahoo

07-19-2009, 07:42 AM	#2
gmonde Senior Member Join Date: Nov 2007 Posts: 615 Likes: 56 Liked 165 Times in 59 Posts	Re: holley 750 D.P. carb jetting?? there are a few ways of making sure you are in the ball park as far as jetting is concerned,,,make a pass at the 1320 mark click of the motor and coast on to the ruturn road and check a few plugs,dont make a pass and idle back to the pits you will not get accurate readings,,i also use a stand alone O2 system,you can record your data and save it,review it on a lap top and you can review the whole run,helps trouble shoot problems(fuel presure issues,jetting,power valves,) gmonde

07-19-2009, 02:22 PM	#3
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: holley 750 D.P. carb jetting?? A 750 4779 carb runs best with right around 70 primary jets with a 6.5 power valve and 80 secondary jets and no power valve. You might have to go slightly richer and change the power valve to suit your cam but those are the baseline numbers I always used on a 750 dbl pumper. Accelerator pump squirters and cams is also abig part of tuning one for your application...... __________________ Rich Biebel S/C 1479 Stock 147R

07-26-2009, 05:16 AM	#7
548camaro Junior Member Join Date: Jul 2009 Posts: 13 Likes: 0 Liked 0 Times in 0 Posts	Re: holley 750 D.P. carb jetting?? i found most 4779 750 dp's to like around 72/82