Holley Carb Jetting Question.
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Junior User
Joined: Jun 2003
Posts: 93
Likes: 0
Holley Carb Jetting Question.
Hi All.
Need some suggestions for jetting my Holley 750 vacuum secondary. Maybe someone has a simaler setup and has done it before?
I have a 1987 F-250 460 with 9:1 compression, Performer intake, stock exh. manifolds with duals, FMS Cam 216/220 .493" .502".
Also C-6 and 4:1 rear end.
I'd also like to find a hole size to jetsize reference for drilling the rear metering plate.
Thanks, Tim
Need some suggestions for jetting my Holley 750 vacuum secondary. Maybe someone has a simaler setup and has done it before?
I have a 1987 F-250 460 with 9:1 compression, Performer intake, stock exh. manifolds with duals, FMS Cam 216/220 .493" .502".
Also C-6 and 4:1 rear end.
I'd also like to find a hole size to jetsize reference for drilling the rear metering plate.
Thanks, Tim
Elder User
Joined: Sep 2004
Posts: 500
Likes: 0
From: midwest
first, im sure you've heard it but i would get a set of full length headers. a holley is jetted very well from the box and really all you need to compensate for is youre elevation, also temp if youre very serious. holley jets their carb at sea level and about 70 degrees F. for every 2000ft you go up you move down 1 jet size. the 750 will have #72 jets in it and i would stay with them unless your higher elevation then go to a #70. the main things to adjust include the exellerator pump cam, discharge and the secondary springs, power valve. i think it will work fine out of the box. try it and then make adjustments from there. holla if you got any problems with it, ill help you tune it correctly.
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
Did you check the float settings. And if works better with the choke still on, the secondardies are partly blocked when the choke is on. You might want a stiffer spring in the dyaphragm unit.
Elder User
Joined: Sep 2004
Posts: 500
Likes: 0
From: midwest
i would try 72s if they arent enough go to 74s. i think a 72 will be ideal if your not experiencing a bog or stumble with the 70s. try and see, just get the blue, reusable gaskets and while your in there check and change the power valve. it problably has a 6.5 PV in it and if its mostly stock a 8.5 will give you more fuel quicker. the #s are stamped on the back flat side of them.
