Carb Jet Size Advice Request
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Junior User
Joined: Jul 2001
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From: Rockwall, Just East of Da
Carb Jet Size Advice Request
I am very thankful to all who responded to my 1976 390 4v (Holley 4160, 600 cfm) pinging problem a while back. I replaced the factory advance canister with an adjustable one and this solved most of the pinging problems.
One respondant said that my truck was also running too lean and therefore must rejet the carb to further reduce and/ or eliminate the pinging problem. I took the front bowl of the carb off to find that the main jets have "65H" stamped on them. I know what the 65 means but I have never seen the H stamped on a Holley main jet before.
Here are my questions:
1) What does the H mean?
2) What size jets do you guys recommend I use?
Thanks for all your help.
One respondant said that my truck was also running too lean and therefore must rejet the carb to further reduce and/ or eliminate the pinging problem. I took the front bowl of the carb off to find that the main jets have "65H" stamped on them. I know what the 65 means but I have never seen the H stamped on a Holley main jet before.
Here are my questions:
1) What does the H mean?
2) What size jets do you guys recommend I use?
Thanks for all your help.
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
"H" is just for HOLLEY...I think. There are so many peole making parts now I think they put it on there just to denote it's theirs.
I know they list a "tight tolerance" jet, but I dont think they would put it in a std Holley. They are flowed/checked to a tighter tolerance to each other, for more precise jetting control.
I would maybe go up 2-3 sizes and see what happens.
I run 68 jets in my 750 vac. sec Holley on my stock 352 and it actually gets BETTER mileage then my old Autolite. I thought of taking a couple more out(factory is 72 for a 750 cfm). It runs good and does not knock or ping.
Larry
I know they list a "tight tolerance" jet, but I dont think they would put it in a std Holley. They are flowed/checked to a tighter tolerance to each other, for more precise jetting control.
I would maybe go up 2-3 sizes and see what happens.
I run 68 jets in my 750 vac. sec Holley on my stock 352 and it actually gets BETTER mileage then my old Autolite. I thought of taking a couple more out(factory is 72 for a 750 cfm). It runs good and does not knock or ping.
Larry
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