carb adjustment

[71chevylongbed]

how can i tell when my carb it perfectly set for max power and low emissions

[MandarinSixSeven]

This is what I have been wondering for a while now...I keep fine tuning it, but I don't know when its at its best.

[71chevylongbed]

do the two adjustment screws on the edelbrock go in opposite or the same direction?

[flip66]

They turn the same way. You really need to have a dwell tach meter to do it right but you can do it by ear may not be accurate. Turn them all the way to the right, or until it almost dies do not do not tighten them down or you will damage the needle, then turn them to the left till the rpm smoothes out usually about 2 to 3 full turns. Below is a link to a tech manual that tells you how to do it with a tach

http://www.edelbrock.com/tech/index.html

http://edelbrock.r-catalog.com/ImgVD/EDE/1400_Inst.pdf

[franko72]

LMC sells a kit that you can adjust your carb by placing a device in the exhaust and tuning your carb until you get a blue color to get an almost perfect mixture.It sells for around $60.00 . I havent tried it yet, dont know if it will work. anyone seen or used it?

[mikej71]

That LMC thing is called a Color Tune. One of my co-workers has always owned and worked on old Fiats, BMWs, etc., and he said that he used to use them all the time. I told him saw it in the LMC catalog, and he said that he'd love to get another one. I'd like to try one, but I'd much rather try it at around $20 - not $60.

Mike

[LudwigTheMad]

I have always been told the best way to adjust a carb without expensive tools is to get a vacume gauge, hook it to the to the steady vacume port, and turn the screws to the right (or in) then to turn each one a half-keep them even..untill you have the greatest vacume read (at some point it will start to go back down) fine tune with quarter turns (remember to keep the # turns even between the two screws)

Have a very experienced friend who swares up and down that you adjust a Holley carb 2 1/2 turns out and leave it.......it's worked so far..(3 different holley carbs 2 different size 4 barrels and a 2 barrel.......hmmmmm well he has been building engines/cars for 35 years.)

[fast71]

Ludwig has the mark ,,That is how I have set all my carbs.
if you have a Holley you also need to set the floats.

[flip66]

I have heard the vacuum pump works really well too, seen guy do it that way. I could not figure it out though probably lack of experience.

[Jeepster376]

Were talking about several different things here. The screws on the edelbrock turn the same way and affect Idle only. They are best adjusted using a tach, a vacuum gauge or both, adjust for highest vacuum signal or RPMs.

Max power is achieved by changing main jets and doing measured acceleration runs, to find best jet. midrange and cruise is adjusted by the metering rods and springs. Best emissions are achieved on a gas analyzer.

I have one of those color tune things, I got it way back when I had a spitfire. It does work, you can see the flame color through the glass, and adjust for all throttle conditions/RPMs. You can really see the flame go from a rich dirty yellow flame on to a nice perfect mix blue flame on up to a lean white flame. You can also see misfires. You can use it to dial in accelerator pump and everything. Not a bad toy for 20 something bux.

[Jeepster376]

Originally Posted by flip66

I have heard the vacuum pump works really well too, seen guy do it that way. I could not figure it out though probably lack of experience.

I think you mean vacuum gauge, its easy just turn the screws slowly while watching the gauge, adjust each screw till you acheive the highest reading. Adjusting by ear is extremely difficult, I never had any luck doing it that way.