Club Cobra

Club Cobra (
-   Weber Tuning (
-   -   Idle Mix cylinders Different (

KirkV 04-14-2018 12:17 PM

Idle Mix cylinders Different

So I have my Inglese IDA system and installed it last fall. I have an issue I don't know how to resolve or if it is really an issue at all?
I set the velocity with the velomiter and got all cylinders balanced ok, but when I go to set the mix screws I started at 1 turn out on all of them.

The front 2 sets of carbs would stumble when starting to screw them in like I would expect. I opened them to about 7/8 open and they come back nicely.

Here is where it got weird, the rear sets of carbs when I screwed them in never went away like I expected. So I opened them more and the engine picked up rpm and idled smoother at about 1.5 to 1.75 turns open. I have tried different jet sizes and get the same results

I checked the air volumes again and they were all even. At this point I thought I had a intake leak so checked the whole thing over with raw propane and found nothing.

I have now pulled the intake and everything looked good on the gaskets and no issues found. I am trying to get rid of my stumble at 2000 to 2500 rpm by adjusting idle jets and air correctors but have a deuce of a time with it.

I am headed out to get new intake gaskets and start all over again, but does anyone have an idea of why the rear 4 pistons want more mix jet?

I have taken the webers off and examined the small holes that feed fuel in above the mix jet needle valve and found all of them to be open. The hole the needle valve screws into is open on all 8 as well.

I will get it reassembled tomorrow and try to set it up again, but I am at a loss??????

Thanks Kirk

Gaz64 04-14-2018 04:10 PM


Can you post some pics of your linkage please?

Can you also supply your carb settings?

What happens when you swap one rear carb with one front carb?


KirkV 04-15-2018 10:12 AM


I have just set the intake manifold gaskets in place and need to let them cure before trimming the excess and starting the reassemble procedure. I have switched 2 of the carburetors to see if the issue travels or stays with the cylinders involved.
I currently have a 100 idle jet holder with a 70 jet and the primary is a F11 with a 170 jet.

Here are a few pics of the linkage.

KirkV 04-15-2018 10:21 AM

FD25CA28-F33C-415C-A65F-2D047CFBD977 - Club Cobra Photo Gallery

Heres the link to my gallery and you can see the linkage. Not sure whats up with posting them here

Gaz64 04-15-2018 03:37 PM


I don't see anything unusual.

Have you got 2 or 3 hole progression?

And now while you are reassembling, we'll wait until you have it running to see what happens next.


KirkV 04-15-2018 05:12 PM

2 hole progression

Gaz64 04-15-2018 07:23 PM

Are all the mixture screws the same shape at the pointed end?

Mixture screws are identical?

You will be swapping one or both rear carbs to the front?

KirkV 04-16-2018 04:42 AM

Yes Gary I checked and the mix screws are the same length and dimensions at the end. I will. E swapping just one carb set from back to front.

Gaz64 04-17-2018 04:02 AM

Ok Kirk.

We'll all be here for your next lot of testing.


KirkV 04-18-2018 08:27 AM

Well Gary it appears the problem has now switched from cylinders 3,4 to 5,6 along with the Weber set. It also seems to have an effect on cylinders 1,2 like it did on 7,8 when it was on 3,4.
So the cylinders directly across the manifold from it need more fuel in the mixing screw as well as the carb in question.
It must be leaking in air from someplace?
I have a call into Jim Inglese and am waiting on a return call from him.
Bummer but at least it is not the engine.

Gaz64 04-19-2018 05:56 PM


I think Jim will say there is a carburetor issue with the carb that is now on 5 and 6.

If you look at your firing order, you can see how a carb that is not quite right at idle, can seem to affect other cylinders, since their individual vacuum levels drop just as they are called upon the produce power at idle.

Hope that makes sense.


KirkV 04-20-2018 09:42 AM

Seem to be having issues getting any responses from Jim hoping all is well with him?

byronpete21 04-21-2018 12:57 PM

I talked with Jim Friday, and have a call scheduled with him Monday so I know he is around. I am following your post closely as I am having a very similar problem with my setup as well. Some of my mixture screws I can adjust to full close with no affect on idle, and some of them change the idle with a very small amount of adjustment. I too have chased air leaks and have yet to find one. My next step I think will be to check my float levels and re-check everything. I am also trying to sort out the same 2500 rpm stumble. Feel free to PM me if you would like. Maybe we can be of some assistance to each other.


All times are GMT -7. The time now is 06:54 AM.

Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting For full policy documentation refer to the following link: