Holley carb tuning

[vanrah]

Greetings NorthWest rider & all; From the looks of your plug & the previous use it doesn't tell us much. A couple of tid bits I've picked up over the years. First Holley carbs are rich out of the box, they (Holley) don't want you to burn up your engine. Two, for a ball park reference (starting point), look at similar engines GM has produced in the past with said carb (750 CFM list 3310 & 780 CFM from 67-71 are similar), similar cubes, compression & cam. So that being said I would pick a 1971 LT-1 as a reference point. A 1971 LT-1 was 350 inches, 360 HP, 11.25 compression (I don't know the compression of your LQ-9) & the second most aggressive Hyd (flat tappet) cam (from memory 218* duration & .450" lift give or take a little) of the time. We'll test my brain again, I believe they came with 71's pri & 76's sec, check me buy goggling that ol'e LT-1 or some other late 60's early 70's performance engines from that time period. I should mention that if you have a secondary metering block & plug the power valve hole you will need to be 8 to 12 jet sizes larger in the secondary side. Buy a good Holley book & study, you'll end up liking Holley's a lot. They're easy, Bob Jr.

 

[NorthWestRider]

Greetings NorthWest rider & all; From the looks of your plug & the previous use it doesn't tell us much. A couple of tid bits I've picked up over the years. First Holley carbs are rich out of the box, they (Holley) don't want you to burn up your engine. Two, for a ball park reference (starting point), look at similar engines GM has produced in the past with said carb (750 CFM list 3310 & 780 CFM from 67-71 are similar), similar cubes, compression & cam. So that being said I would pick a 1971 LT-1 as a reference point. A 1971 LT-1 was 350 inches, 360 HP, 11.25 compression (I don't know the compression of your LQ-9) & the second most aggressive Hyd (flat tappet) cam (from memory 218* duration & .450" lift give or take a little) of the time. We'll test my brain again, I believe they came with 71's pri & 76's sec, check me buy goggling that ol'e LT-1 or some other late 60's early 70's performance engines from that time period. I should mention that if you have a secondary metering block & plug the power valve hole you will need to be 8 to 12 jet sizes larger in the secondary side. Buy a good Holley book & study, you'll end up liking Holley's a lot. They're easy, Bob Jr.

Cool thanks for the info i am gonna look for that holley book i know people been mentioning that

 

[vanrah]

Greetings NorthWest Rider & all; Your welcome,The books I like are by S.A. Design #SA08 "Super Tuning & Modifying HOLLEY carburetors" by Dave Emanuel. Check it out it will give you lots of confidence. And of course the "HOLLEY Hand Book" by Mike Urich, HP Books. I like your Ls-Lq modern engine with a carb, it's the way I would go if I was starting a new path. When I a banded big blocks back in 72 & switched to SB's my goal was an aluminum block 406 inch light weight Nasty Mouse. Who can tell the future, take care Bob Jr.

 

[NorthWestRider]

Heres a pic of my engine this is actually the old carb still in this pic

 

[NorthWestRider]

Should i mess around with the accelerator pump and nozzles and cam if i dont have the stumble or can this help for better throttle response if i do