Rough idle with a Weber

[66musthavea6]

This is my first post. The only upgrades my engine has are an ignitor 2 electronic ignition and a weber 32/36 carb. I idled ok awhile ago. I started messing with the jets and the timing and now it idles horribly and I cannot get it to idle smoothly again. Please help.

 

[CoupeBoy]

I think you should reset everything back to 'stock' as you recieved the carb. You may not remember what was stock, so hopefully somebody will be along shortly to point you toward the thread about 32/36 jetting and tips (I don't remember what it was called right now) you should also check for any loose connections that might be causing a vacuum leak. Also might I ask which distributor are you using?

A stock '66 should have had a Load'O'Matic but when you changed your carburator from the original Autolite 1100 you should have updated to at least a 68+ 200 with mechanical and vacuum advance. If you have not you might be experiencing timing issues as well.

-ron

 

[66musthavea6]

The distributor is meant for a 66. What are the advantages of a 68 or later distributor.

 

[GrantD]

I have a fox mustang with later components but I'll answer as best I can from what I've read on here.

The load o Matic carb that you replaced was designed to work in conjunction with that type of distributor, so when one is changed and not the other it causes problems. If you do a bit of digging on here you'll find some more talk about it.

When you said that you had it idling correctly at one point was it with that carb? or was it with the old one?

Here is the post I was thinking of http://fordsix.com/forum/viewtopic.php?t=15522

I'm not sure if it's why yours is idling rough but it will create timing problems that should be resolved.

 

[CoupeBoy]

Here is the thread I was thinking of
Holley/Weber 32/36 Jetting Tips

-ron

 

[jamyers]

What exactly were the changes you made? Best bet is to try and get it back to where it was before, then make one change at a time.

Read up on the Loadomatic - but just for your information, as you're really going to need to replace it with a later (conventional) distributor. Lotsa info in the sticky-threads on replacement options.

Regarding the idling on a Weber...changing the main jets will have zero effect on the idle, unless you somehow had the rest of the tune so far out of whack that it was "idling" with the throttle way too far open.

Idle Jet - did you change it? If not, the tiniest bit of trash in the idle passage will really cause problems - be *sure* the passages are blown clean (air or carb spray).

 

[66musthavea6]

The engine did idle smoothly (or smooth enough) with the weber at first. One of the first things i changed was just the timing. I set it to about 14 degrees. Thats it. The idle was a little worse, but still decent. I kept playing around with the timing to get it just right and messed around with main, air, and pump jets. Not the idle. I cant remember exactly if the the rough idle started after another timing change or jet change.

 

[jamyers]

The only things on a Weber that will affect the idle are the idle jet(s) and the idle speed (throttle opening).

I'm betting that the real problem lies with your loadomatic distributor.

 

[Ronbo]

any chance you picked up some crud in the process of swapping stuff around? Wouldn't take much to cause a problem.


Ron

 

[66musthavea6]

Hopefully i bought the ignitor system that fits 65-73. I'll check it out this weekend and mostlikely get a later distributor. I know they sell 68+ distributors with single or dual vacuum advance. Which one should I get?

 

[CoupeBoy]

Get the Single Vacuum advance distributor. There may be advantages to the dual vacuum system but to me it seems that the added complexity of vacuum hoses and thermal switches just wouldn't be worth it.

-ron

 

[66musthavea6]

Thanks for your help!