Baseline jetting for blower?
02-06-2003 | 02:25 PM
#1
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Joined: Oct 2002
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From: Cape Coral,Fl.
Baseline jetting for blower?
I'm going to try a holley hp 1000cfm carb on on my 250 blower.
It's going on a 502 with stock 8.75 compression,rec. port heads(just upgraded to inconel valves),
cam specs:
dur:236 int.,246 exh. @.050
lift: .553 int,.571 exh 114 centerline.
gil exhaust.
I only want to run about 5lbs of boost. and 5000rpm max.
This carb comes from the factory with 84 jets all around and 6.5 power valves in front and rear.
Where do you think I should start with the jetting?
The boost referencing thing has been talked about alot,but should I ref. both the p/v's or just the front and plug the secondary one and increase the rear jet size.I belive rule of thumb is 5 sizes up when pluging the p/v.
I know most people running single carbs are using a 1050 dominator but I have the 1000 and would like to make it work.
Please advise,
Thanks,Jeff
It's going on a 502 with stock 8.75 compression,rec. port heads(just upgraded to inconel valves),
cam specs:
dur:236 int.,246 exh. @.050
lift: .553 int,.571 exh 114 centerline.
gil exhaust.
I only want to run about 5lbs of boost. and 5000rpm max.
This carb comes from the factory with 84 jets all around and 6.5 power valves in front and rear.
Where do you think I should start with the jetting?
The boost referencing thing has been talked about alot,but should I ref. both the p/v's or just the front and plug the secondary one and increase the rear jet size.I belive rule of thumb is 5 sizes up when pluging the p/v.
I know most people running single carbs are using a 1050 dominator but I have the 1000 and would like to make it work.
Please advise,
Thanks,Jeff
02-06-2003 | 02:50 PM
#2
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Posts: n/a
PROFILE.
Your carb is big enough. I would start with 3 sizes up on all the jets and 2.5 power valves front and rear, INDEX THE POWER VALVES FRONT AND REAR. It is not difficult. Holley indexes their carbs for blowers. If you do not know how or don't know anyone who can, post and I'll explain.
Happy Boating!!!!!!!!!
Your carb is big enough. I would start with 3 sizes up on all the jets and 2.5 power valves front and rear, INDEX THE POWER VALVES FRONT AND REAR. It is not difficult. Holley indexes their carbs for blowers. If you do not know how or don't know anyone who can, post and I'll explain.
Happy Boating!!!!!!!!!
