mattyg92

i have a holley street dominator 670 vacumm secondary, i just put on a dual plane performer intake, a torker single plain was on there first

i am trying to get the mixture screws adjusted right

how many turns has everyone started at? 3/4 turn out? 1 turn?

one weird thing is that if i have them out too far, like 3 turns, when you hit the throttle, it stays at 1500 rpms for about 20 seconds than comes down

thank you all for the advice

66BlkBB

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Someone else will chime in but I always started with 1 full turn out. But this was based on the fact that the butterfly's were fully closed. If they are partially open it will change. The best thing to do is get the Holley manual that is sold through Barnes and Noble or any other good book shop. They give a great description on how to set the carb. By the way, is yours a street "dominator" or "avenger"?

Steve

mattyg92

its a street avenger style carb

Injected Stingray

There's tons of info in the archives on this subject, but it's fairly simple just use a vacuum gage and adjust until you get the highest vacuum reading. Chris

Coves4me

mattyg92, The first thing to do is get hold of a vacuum gauge to set the idle mixture screws. What you want to do is hook the vacuum gauge to intake manifold vacuum and slowly adjust each mixture screw in on each side of the carb to achieve the highest vacuum possible. Then I intentionally adjust the idle speed screw low and below the normal setting to make sure that no mechanical advance from the distributor comes in to play. Also, when adjust your idle screws, make sure that your distributor is disconnected from any vacuum source. You want to adjust the idle mixture screws with static timing only. Once the highest vacuum reading is obtained, hook up your distributor vacuum and adjust your idle speed screw on the carb for the proper idle speed you need. Good luck.

mattyg92

i will give that a try! thanks

cookie_monster

Old school method...was to back it out the mixture screw 2 turns from fully seated position. Proceed to turn in the mixture screw (clockwise) a quarter turn at a time (pausing a couple of seconds to allow carb and engine to react) until the engine just starts to run rough, then back it out (counter-clockwise) a quarter turn from there.
This is how we did it "back in the days" when nobody could afford fancy tools like vacuum gauges.

mattyg92

i will be doing the adjustment this weekend and will report back

SMR 67

Matt Gruber

a vacuum guage is, ahh, quaint.
http://community.webtv.net/MATTGRU/AFtesting

64con

I used the vacuum gauge technic and it worked well. I used to start with the idle mixture screws 3 turns out then slowly adjusted the screws out until the maximum idle was achieved then set idle but I feel more confident with a gauge, plus when your using the vacuum gauge it will show you when you are @ normal vacuum pressure with happens to coincide with the proper idle mixture. Someone will likely correct me but I think using the vacuum gauge works great

64con

I did use a tach before when I was using the 3 turns out then slowly turn out until max idle was achieved method just to set the record correct

JohnZ

Nope. You want the engine at normal idle configuration when you adjust the idle mixture screws - vacuum advance connected, normal idle rpm.

JohnZ

If you have a Holley, 1-1/2 turns out from lightly seated is a better starting baseline; three turns out is very rich, and is way beyond adjustment range.

Stan's Customs

64con

Your right John, 3 turns is likely too rich. I've always had success with the 3 turns, with only 1 1/2 sometimes the motor wouldn't start. likely because I had something else wrong. Anyways listen to John Z he's the man with so much knowledge that it's scarey.

64con

Hey John . My 64 327 300hp has a edlebrock streetmaster intake with a holley 4360 (450 cfm). The car has lots of poop but I was wondering if you had any suggestions for replacing these components without getting carried away with cams and headers and such

Warren

JohnZ

I pretty much stick with the stock configurations these days. You won't get any significant improvement over what you have now until you at least get into the heads and a cam; an engine is an air pump, and unless you can get more in and more out, it isn't going to make more power.

64con

Thanks for your input John. I thought that you might suggest using a holley 0-2818-1 600 cfm carb and a holley 701R-36 dominator intake or something. The car does have the camel back heads so I thought a 600 cfm carb and different intake would make a considerable difference.

JohnZ

The 327/350hp and 327/365hp used 585CFM Holleys (2818 in '64-'65, 3367 in '66, 3810 in '67) on a high-rise aluminum intake, but they also had the "151" cam to help them out, and larger valves. Just the carb alone won't make a lot of difference. A generic Holley 1850 replacement (600CFM) would work just as well.