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bigcarguy · 07-03-2002, 10:18 AM

I'm putting an Edelbrock 600cfm carb on the truck and was wondering how to set the air/fuel mixture screws on the front of the carb. It's a 72 307 if that matters.

JimKshortstep4x4 · 07-03-2002, 11:01 AM

There are a few ways to set the idle jets, but I like to set them with a tach. You adjust for the highest rpm and then enrichen 1/8-
1/4 turn. If the idle speed exceeds the recommended rpm then
adjust that down and recheck your settings. Another method is to use a vacuum gauge and set for the highest reading. Lacking gauges, you can set the idle by ear for what runs the smoothest, turning the screws in or out as needed. Start by turning one jet in until the engine starts to slow down, (initial setting of jets is 1 1/2 to 2 turns open), then back it out until the idle picks up. Usually it is an iteration process and you go back and forth from one to the other to obtain the best idle.

The engine needs to be at temperature before setting the jets.

Good luck!

Jim

jlmtrout · 07-06-2002, 07:32 PM

A vacuum guage will tell you the same thing. Turn the screws in one at a time until the needle starts to drop, then back off and do the same to the other screw. You may have to do this a couple of times to acheive the highest vacuum(usually 18-20 inches). Good luck and keep on truckin'!---------Jerry

07-03-2002, 10:18 AM	#1
bigcarguy Finally a Bulldawg Join Date: Apr 2001 Location: Athens, Georgia Posts: 220	Carb tuning I'm putting an Edelbrock 600cfm carb on the truck and was wondering how to set the air/fuel mixture screws on the front of the carb. It's a 72 307 if that matters.

07-03-2002, 11:01 AM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	There are a few ways to set the idle jets, but I like to set them with a tach. You adjust for the highest rpm and then enrichen 1/8- 1/4 turn. If the idle speed exceeds the recommended rpm then adjust that down and recheck your settings. Another method is to use a vacuum gauge and set for the highest reading. Lacking gauges, you can set the idle by ear for what runs the smoothest, turning the screws in or out as needed. Start by turning one jet in until the engine starts to slow down, (initial setting of jets is 1 1/2 to 2 turns open), then back it out until the idle picks up. Usually it is an iteration process and you go back and forth from one to the other to obtain the best idle. The engine needs to be at temperature before setting the jets. Good luck! Jim

07-06-2002, 07:32 PM	#3
jlmtrout Registered User Join Date: Jul 2002 Location: Memphis, Tn Posts: 194	A vacuum guage will tell you the same thing. Turn the screws in one at a time until the needle starts to drop, then back off and do the same to the other screw. You may have to do this a couple of times to acheive the highest vacuum(usually 18-20 inches). Good luck and keep on truckin'!---------Jerry



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