Whether using the numbered plates or the jet block...how does the Secondary side balance out to the primary side without PV assistance?
A 600 Holley will have a 66 primary jet with an additional PV jet and the Secondary plate will have just the .067 hole size.
On my 650 carbs I'm running 68 jets all around on both carbs using the jet plate in Secondary side. A/F is in the 13.10 range at WOT.
Is the secondary side of a 4160 type carb actually leaner than the primary by design or does it actually pull more fuel thru the orifice than the primary side?
Holley 4160 secondary plate jetting?
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Re: Holley 4160 secondary plate jetting?
Well talked with QFT on the 4160 vs. 4150 secondary setup and reply was you want the primary and secondary to be about same all the way around and reason for 7-8 jet steps up on 4150 Secondary is for racing enrichment...safety for the "non-tuners".
My understanding is for lack of Power Valve enrichment on the Secondary side of the 4150. However the 4160 doesn't have one either!
Anyway it all seems to work out in the end with a shared plenum at WOT.
My understanding is for lack of Power Valve enrichment on the Secondary side of the 4150. However the 4160 doesn't have one either!
Anyway it all seems to work out in the end with a shared plenum at WOT.
Re: Holley 4160 secondary plate jetting?
If you want to try richer secondary jetting you can drill extra holes in the sec plate. Block the oem jet hole and use the new drilled holes, in combo, to get the equivelent jet area you want.
You can do it with 2 common drill sizes.
I posted on this before. Search my posts.
You can also swap the sec jet plate for a #21. From a 3310 carb. ='s. 75-76 sec jet
I did this on a 396 i built a custom 650 carb for, using a1850 body and a 3310 base plate. It was on a single plane manifold and liked the richer (than stock)sec jetting.
You can do it with 2 common drill sizes.
I posted on this before. Search my posts.
You can also swap the sec jet plate for a #21. From a 3310 carb. ='s. 75-76 sec jet
I did this on a 396 i built a custom 650 carb for, using a1850 body and a 3310 base plate. It was on a single plane manifold and liked the richer (than stock)sec jetting.
Re: Holley 4160 secondary plate jetting?
When I built the carbs I used the Jet Plate that uses standard jets. If I need to richen things up I would go up a jet or two on the Secondaries.
Right now it's in the ballpark according to my A/F data.
Right now it's in the ballpark according to my A/F data.
Re: Holley 4160 secondary plate jetting?
Good stuff. The oem sec metering plates can also be drilled and tapped for holley main jets. As long as they clear the back float in the bowl.
Re: Holley 4160 secondary plate jetting?
you can drill & tap the existing orifice to 10-32 and use air bleeds and not have float concerns.