Posted by Ken (32.100.87.81) on March 11, 2001 at 21:25:15:
In Reply to: carb problems posted by Maverick73 on March 11, 2001 at 19:26:09:
Congratulations,you just entered the complex world of the Holly carb.
First off the carbs are sold as a unit that has to be custom tuned to the application in that the factory cannot make a carb that is a bolt on perfect operating unit for every engine.
This fact has given Holly carbs an undeserved reputation.
If you look at bores from the bottom, you will see one vertical slot in each bore. There should be about .060 of the slot showing by adjusting the throttle shaft screw to get this setting.
Then install carb back on and start engine till warmed up. Adjust mix screws for bet idle. At this point I don't know what you will get for idle assuming there are no vaccume leaks.
Observe where the mix screws end up.(nearly closed, very far open,or about 1-2 turns out. This dictates what you do next.
For example if the mix screws are in and nearly closed, the idle is to low then the engine is not getting enough air. The throttle plates need to have small holes drilled out near the slots
to allow more air to increase the idle (while not touching the shaft adjusting screw).You would keep enlarging the holes in the plates until you arrive at a point that would be like a stock carb
for idle and mix screw adustment.
This is why 9 out of 10 times just bolting an aftermarket carb on results in less than expected operation.Its a lot of work but worth the end result.
Next then is tayloring the secondary throttle opening by changing springs until the secondarys just open without any hesitation or that belt in the back most mistake as extra power,it must be a smooth
come on then its right. If the spring is to strong the sec. may not open until the RPM is to high or not open at all.
This info is in the Holly hand book and then I have an early issue that details much that in not in the newer issues. When you get to this point the throttle response will get sharper then its time to taylor
the ignition spark advance curve but thats another day!
Now that your confused take it on as a challenge. You will be a Holly expert in your area.
Hope iv'e helped get you started understanding this.
Good luck. Ken