I recently put on a Holley 6211 atop my close to stock 427 and have been having problems getting to run properly since. It has been rebuilt, but I am not ruling out vacuum leaks just yet, becuase I know the idiot that rebuilt it (me )

Right now it idles rough, but at the proper speed and never feels like it is going to stall. It runs acceptably when cruising, but any kind of mild to medium accelleration, it seems to run very unevenly (combination of surges and then bogs, then will surge again) Once Iget into the secondaries, it pulls smooth and pretty strong.

Troubleshooting so far:
I have ~10.5" steady vacuum in the manifold
I KNOW I am running rich, while I don;t get that puff of black smoke from the pipe, my plugs have carbon deposits galore and are as balck as night. They also are soaking wet when I pulled them the day after my last test drive.
I set the carb up to stock set-up, with jets, power valves, etc..
When I come back into the garage after a drive, my primary venturis and inner main body is "glistening" and have get a pretty good haze coming up the body from the manifold. When I start cold and am idling, I can clearly see fuel build-up on the venturis. Now, I never looked at these before installing a new carb, so I'm not sure if this is normal...
I did backfire once or twice on the initial install.

Things I am looking at now:
Is the stock jet too high? Since am seeing the fuel build-up, I was thinking this might be the first place to start.
I am also replacing the power valves, just in case I did blow them out or the are passing....although I thought if I blew them out, they wouldn't leak fuel up to the vanturis, but down through the main body...
Also, Idle mixture is set to 1.5 turns out...would a poor idle mixture effect my acceleration or should I get the jetting/excess fuel situation fixed before even lookin here.

Any support would be helpful. Thanks!
(I've been desparate to get this on the road since Al knoch is supporsed to be installing my new vert top next weekend at carlisle!)

 

We need to know what 427 you have in your car. If it is a 390 horse it should do better than 10.5 vacuum. You may have internal engine problems.

If this thing backfired it may have blown the power valve. This will load the engine up BAD. You need to get this sorted out one way or the other before you can do anything else. You can adjust and modify this carburetor all you want, if that power valve is blown it will all be for nothing.

What is your initial timing advance set at? Just for now set it at 12 (or more) BTDC with the vacuum disconnected.

Do you have a good Holley manual? If not, this would be a good time to get one.

As far as the rich idle goes, run the idle mixture screws in. This will lean the idle circuit. If the idle speed goes down open up on the idle speed screws. This will lean the idle circuit. If it has replaceable idle air bleeds, go to a larger one. This will lean the idle circuit. If all that fails, you'll need to resize the idle channel restriction. The Holley manual will tell you how to do this.

This should give you quite a bit to do. Report back with your findings and results.

BigBlockk

Later.....

 

I have the L36. I figured the manifold vacuum would increase when I get the carb tuned in better. As for internal engine problems, I took another look at the plugs today, and a few still seem a little wet so I figure I got an oil leak somewhere, but I know I have always burned a little oil, so not sure how much that adds to this ne problem.

i am completely on the same page as you. Today at lunch I icked up two new 65 power valves. Put them in, no noticale difference, but I didn't drive too long, so then I replaced the main jets own to a size 60 (stock 62) and thats when I had some real problems. The car stared right up, but quickly degenerated. I saw some smoke coming from the drivers side near the exhaust ports, and then the engine stumbled and died. I restarted it, and the same thing happened. I tried shifting the ide mixture screws from 1 turn out to 2.5 turs at half turn increments, no difference. Thats when i had to stop for the evening for other plans. I plan to re-attach tomorrow.

Unfrtuately I did not check the timing tonight, nor did I before starting this whole project. 9didnt see your post until now) Tomrrow if I can get it started, I'll follow up on timing. As for the books, I have a few of them. They have been very helpful so far, but its hard t converse with the book like I can here and describe symptoms. Thanks for your help.

 

so I just got back in from checking compression and everything seems ok. All cylinders are between 170 and 180 PSI, so I am not longer worried about a blwon head gasket...I'm still not sure hwere the smoke was coming from. I know I have an exhaust leak soemwhere, so I am corssing my fingers on that one....could still use some help on the carb though.