Carb adjustment

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mullinax95

mullinax95

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I fired my fresh 360 up not long ago. The carb is a Holley 4150 DP with four corner idle system. I have never had a four corner idle system so it is a little mystery to me. I tuned it rich for break in cause I didn't want it going lean on me.

What is the best method of adjusting the rear idle mixture? The same as the front in which I try to achieve the highest vacuum reading?

4150 Carb 003.jpg


4150 Carb 004.jpg


4150 Carb 002.jpg
 
dont think a four corner idle carb is tuned any different than a 2 corner idle carb...tune for the highest vacuum..

i usually start out rich and slowly start turning them in until i get the idle i want....sometimes i stand behind it and smell the fumes...LOL
 
When I've got the carb in the ball park of being tuned correctly should all four screws be turned out about the same?

From the factory the carb's secondaries idle mix screws was turned out less that the front. ???
 
Yes Ax, they (the idle speed screws) should all be about the same. There should be a secondary idle speed screw under the carb body too. Technically, when you adjust your idle speed with the primary idle speed screw, holley says that the secondary plates must be opened the same amount but the screw is under the carb and almost impossible to get at without removing the carb!

That's why I build my carbs with a Quick Fuel baseplate 'cause the secondary idle screw is placed on top right where you can get to it. They're (the secondary idle speed screw) most likely fine where the factory left it so I wouldn't worry too much about it unless your having some really bad idle problems (read: Giant Cam, lol!).

Have fun! :)
 
Thanks ramcharger. This carb is a little different than what I'm accustomed to. LOL! I know that this carb does not seem to be playing around. It is very sensitive and just seems to run healthier than the other type Holleys. And it runs 10x better than the Edlebrock 750 ever had a chance too!
 
The HP series Holleys are a damn good carb! You made an excellent choice.
 
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