Rough running dual quads...any thoughts???

REAL 1 · #1 (**permalink**) 08-12-2013, 06:53 PM

Recently rebuilt my Dual Holley 550s. Put in brass floats new gaskets with the rebuild kit.

Rebuilt in or about May. Ran fine.

Recently, engine runs fine for about 20 minutes and then after it gets thoroughly warm it runs rough at less than 1/5 throttle. Smooth's out when I give it more gas. Idle also drops. If I let sit for a while it is harder to start than normal and have to depress accelerator several times or pump gas with fuel pumps but will start right away once running and shut off and re-start quickly.

Floats seems to be working. Checked through the site hole. I leaned it out a bit and it runs a little better. I was going to lean it out more but thought you guys might have some suggestions.

I use Marvel Mystery oil with my gas. Maybe I'll stop that next fill up and see.

Thoughts

patrickt · #2 (**permalink**) 08-12-2013, 07:14 PM

First, before you even think about doing anything else, clean the air bleeds... all 16 of them. Use carb cleaner and compressed air. I've posted this a zillion times, but if you need pics there's a link to one of my threads that has that in the current "Stumbling" thread.

REAL 1 · #3 (**permalink**) 08-12-2013, 08:24 PM

Thanks. Link?

patrickt · #4 (**permalink**) 08-13-2013, 05:54 AM

Quote:

Originally Posted by REAL 1

Thanks. Link?

Here is the link to my original thread on clogged air bleeds -- this is a very easy treatment, the diagnosis is the tricky part. But, anyone can do it. Holley Carb Woes - DCDoug Pay Attention (Long Post) Here is another thread that you might enjoy as well. Again, it's air bleeds as the culprit: This is new: stumbling/missing at idle/cruise speed

REAL 1 · #5 (**permalink**) 08-13-2013, 06:44 AM

Thanks.

patrickt · #6 (**permalink**) 08-13-2013, 07:50 AM

Quote:

Originally Posted by REAL 1

Thanks.

OK, now you know that if that cures your ills, and if your car then runs better than it ever has before, you will now have to refer to me as "God's Gift to Motorsports."

REAL 1 · #7 (**permalink**) 08-13-2013, 01:16 PM

How about just a hearty thank you and a beer if we ever meet????

rpatton3 · #8 (**permalink**) 08-14-2013, 11:56 AM

Marvel Mystery Oil. I may start using it myself.

27 years ago, we poured that down spark plug holes on sister's V12 E type. Down carbs and in gas. Engine is not locked up.

I did some research on MMO and it is largely laquer thinners and LARD. If it works or not, it won't clog my arteries.

It is not the scam Slick 50 was.