Baseline Jetting - HP500 Carb on 454 Magnums
04-08-2018 | 04:59 PM
#1
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From: Denton, MD
Baseline Jetting - HP500 Carb on 454 Magnums
Hello Friends,
Just finished updating the Twin 454 Mags in my Formula.
454 Mags
Aftermarket Mild Cams (Isky) Do not have details...
GIL Offshore Exhaust asystems
Edelbrock Performer RPM Air Gap Dual Plane Intakes
HP500 Carbs (stock staggered jetting)
Spinning Bravo 1 26P to 5100 RPM.
The HP500 carbs have the stock jetting (staggered, etc.), does anyone have any baseline jetting recommendations for my set up before I fire up the engines this weekend? Should I roll with the stock jetting or is it too fat since it’s for an HP500??
Just finished updating the Twin 454 Mags in my Formula.
454 Mags
Aftermarket Mild Cams (Isky) Do not have details...
GIL Offshore Exhaust asystems
Edelbrock Performer RPM Air Gap Dual Plane Intakes
HP500 Carbs (stock staggered jetting)
Spinning Bravo 1 26P to 5100 RPM.
The HP500 carbs have the stock jetting (staggered, etc.), does anyone have any baseline jetting recommendations for my set up before I fire up the engines this weekend? Should I roll with the stock jetting or is it too fat since it’s for an HP500??
04-09-2018 | 12:48 AM
#2
Charter Member # 55
Joined: Oct 2000
Posts: 20,232
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From: Omaha/LOTO
I would get rid of the staggered jetting and use 78 primary and 93 secondary jets.
Pretty sure that's what I used in the HP500 carb I used on a bumped up 454mag that had a long time ago.
I used the stock magnum intake with a 1" open spacer also.
Pretty sure that's what I used in the HP500 carb I used on a bumped up 454mag that had a long time ago.
I used the stock magnum intake with a 1" open spacer also.
04-09-2018 | 03:14 PM
#4
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From: Denton, MD
I can tell ya the Merc 420-440-460 used the 850 holley with 84's all the way around.
04-09-2018 | 10:17 PM
#7
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From: SF Bay Area
He speaks the truth. My tune ran great then the wideband showed a 500rpm lean spot right at maximum torque load.
04-10-2018 | 01:06 AM
#8
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From: Omaha/LOTO
04-10-2018 | 04:17 AM
#9
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From: OFallon,Mo.
I'm talking about the Cyclones back in the 80's. They were 850's with no power valve in the secondaries. Used 84's all the way around. Aluminum high rise dual planes. Their in Manual #9.
