Visit The Dirt Forum for More Information

Author Topic:   Holley alky carb throttle pump
Dirt Maniac

Total posts: 168
posted May 13, 2001 12:22 PM
What color primary throttle pump cams are on your Holley 750 Alky carbs. My carb came with a red cam but it doesn't give me any fuel untill the throttle is open quit far. It is in the hole that would make it quicker but it is still kind of late. Sometimes when I get bogged down on restarts my car hesitates when bad when I try to get on it, I think this might be the problem.

Dirt Freak

Total posts: 218
posted May 13, 2001 12:56 PM
Our's are orange.......on both carbs. Came this way from Barry Grant.....then we sent one off this sinter to another carb place to get freshened up......came back with new orange ones again.......
Never a problem on picking up the throttle...unless there was something else going on with the power valves.

Racer 10
Dirt Newbie

Total posts: 3
posted May 14, 2001 06:08 AM
Since you brought up power valves does alc. use the same power valves as gas or do you need to use the high flow ones - ongoing debate with a buddy of mine since you use twice as much alc. I assume you have to use the high flow ones? At least this stands to reason

Dirt Full Roller

Total posts: 57
posted May 14, 2001 12:50 PM
To answer the last question there, there are alky power valves that flow more fuel, and I recommend them. You can get by without them, but...well, I like to use 'em. Not sure what other builders swear by, but that's what I like to do.
And as for pump cam choices, a lot of that has to do with the specific carb's application, but if the first poster's problem is that the cam isn't even actuating the arm until after the throttle is noticeably open, then there is more than just a cam choice problem. There is also a geometry change needed, i.e., altering arm angle, spring-bolt adjustments, etc.
As for pump cam color, our 4bbls typically use aggressively shaped cams for primaries and long duration, more mild secondary cams, but that's also another variable that changes from one engine application to another.

Hope that helps, and let me know if I can be of any other assistance...


[This message has been edited by KPLugnut (edited May 14, 2001).]

[This message has been edited by KPLugnut (edited May 14, 2001).]

Dirt Roller

Total posts: 23
posted May 16, 2001 11:56 AM
I have always run stock power valves with alky they work fine. I did how ever get a brand new carb once with a 3.5 power valve. Car would not come off corners. Check yours use a 6.5 or 7.5 if they aren't already. Good luck.

Also, if your motor has ever backfired in the past it might have blown the main powervalve out. Might try a new one

[This message has been edited by Flatfoot (edited May 16, 2001).]

Back to the Archives