CLASS RACER FORUM - View Single Post - Thermo-quad Tips

GTX JOHN · 05-03-2017, 06:04 PM

If I run stock needles and seats...................7 to 8 psi

If I run .110 needles and seats.....................6 is it!

I was giving just ball park baseline settings to help out........In some circumstances of real excellent air/Sea Level and a carb that a big Air Door Opening (Modifications sometimes required for Air Flow) I can use a .149. Particularly in 1 1/2 "Big" Carb (Not legal on 340). Although a lot of my smartest competitors disagree on this jet size.

The small carbs have a restriction in Secondaries Metering that effect
jet tuning. I have drilled out jet totally maybe .180 or more and it makes
no difference over a 149 or even a 143 in some carbs in A/F...as crazy as it seems. Not the case in the big carbs (1 1/2 Pri.).

Sorry for long winded reply.......Currently in bed a lot with health issues and time on my hands (Possible Congestive Heart Failure).

05-03-2017, 06:04 PM	#7
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,733 Likes: 2,803 Liked 2,486 Times in 697 Posts	Re: Thermo-quad Tips If I run stock needles and seats...................7 to 8 psi If I run .110 needles and seats.....................6 is it! I was giving just ball park baseline settings to help out........In some circumstances of real excellent air/Sea Level and a carb that a big Air Door Opening (Modifications sometimes required for Air Flow) I can use a .149. Particularly in 1 1/2 "Big" Carb (Not legal on 340). Although a lot of my smartest competitors disagree on this jet size. The small carbs have a restriction in Secondaries Metering that effect jet tuning. I have drilled out jet totally maybe .180 or more and it makes no difference over a 149 or even a 143 in some carbs in A/F...as crazy as it seems. Not the case in the big carbs (1 1/2 Pri.). Sorry for long winded reply.......Currently in bed a lot with health issues and time on my hands (Possible Congestive Heart Failure). __________________ John Irving 741 Stock 741 Super Stock Last edited by GTX JOHN; 05-03-2017 at 06:12 PM.