Holley running super rich

Reply Subscribe

Thread Tools

Search this Thread

Jul 5, 2022 | 11:45 AM

Jerry_85ford

Thread Starter

Mountain Pass

Joined: Feb 2020

Posts: 101

Likes: 7

Holley running super rich

So I’ve got a 351 Windsor with a 4 barrel 600 cfm Holley and it’s actually in a boat but mechanically speaking it doesn’t make much of a difference and I like this forums page. The thing was running good for the weekend and one day it just started running rich it didn’t even want to idle and had a lope to it I had to keep revving it so it wouldn’t die. I got it home and pulled the carb and pulled the bowls off. Everything was clean and none of the ports and passages were clogged. It had 68 jets in it and I went down to 65s, checked the needle and seats and everything looked okay. (Floats aren’t adjustable on this model) I put it back on the boat and set the primary butterflies and idle mixture screws where they should be for basic startup and it was still rich. I leaned out the mixture screws and messed with the idle but no matter what I do it blows black smoke consistently at an idle but it does idle now at least. The thing loads up so much it gets a miss but will eventually smooth out if I hold the throttle at 4500 rpm. Only thing I can think is power valve? Any suggestions before I just rebuild the whole carb

Jul 5, 2022 | 12:04 PM

88n94

Cargo Master

Joined: Jan 2004

Posts: 3,118

Likes: 149

From: South Dakota

I think you guessed the correct faulty part with the power valve. Have a 500 CFM Holley in an old Ford car(currently not in use) and the power valve would fail on occasion.

Jul 5, 2022 | 12:46 PM

Franklin2

Moderator

Joined: Jan 2001

Posts: 57,023

Likes: 2,754

From: Virginia

No liquid fuel spilling into the engine down the throat of the carb when it's running correct?

Jul 6, 2022 | 03:49 PM

Jerry_85ford

Thread Starter

Mountain Pass

Joined: Feb 2020

Posts: 101

Likes: 7

Quote:

Originally Posted by Franklin2

No liquid fuel spilling into the engine down the throat of the carb when it's running correct?

that’s correct I pulled the air filter off and looked down in it while it was running and didn’t see anything other than the squirters when you blip the throttle obviously. So seems to me that it’s something internal. I ordered a rebuild kit today I figured it won’t hurt seeing as I’ve never touched the carb since I’ve had the boat

Jul 6, 2022 | 04:42 PM

Franklin2

Moderator

Joined: Jan 2001

Posts: 57,023

Likes: 2,754

From: Virginia

Watch this video on Holley carb main body warpage. I have had this on every well used Holley carb I have rebuilt. If you do not fix the warp, it will run ok with the new kit for about a month or so, and then you are back to the same old symptoms.

Jul 13, 2022 | 08:53 PM

Jerry_85ford

Thread Starter

Mountain Pass

Joined: Feb 2020

Posts: 101

Likes: 7

Quote:

Originally Posted by Franklin2

I’ve heard of that even had to file down the warped body on my f150 but I didn’t even check the one on this boat and I’m hoping I don’t kick myself for it in the future. I got the carb rebuilt and it runs great so far but we’ll see if it comes back to bite me

Jul 14, 2022 | 01:55 AM

BigBlue2

Lead Driver

Joined: Apr 2002

Posts: 5,380

Likes: 1,261

Quote:

Originally Posted by Jerry_85ford

This is the first I've heard about carb blocks warping. I'm having a hard time imagining how they would warp. They are relatively thick compared to length and seem pretty robust and stable to me. I've rebuilt several Holleys and all went well with out milling 5 thousandths off. What causes the warp? Heat from the engine? Hard to believe but I learn stuff everyday...

10 Ways Ford is LOSING to the Competition

Joe Kucinski

Top 6 Best Deals Available on New Fords & Lincolns Right Now

Brett Foote

This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level

Verdad Gallardo

Top 10 Fords at 2026 Carlisle Ford Nationals

Joe Kucinski

3 Best / 3 Worst Parts of Modern Ford Ownership

Brett Foote

10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches

Pouria Savadkouei

Every 2026 Ford Engine Explained

Brett Foote

10 Ugly Ford Trucks That We Still Kinda Love

Joe Kucinski

10 Things Every Truck Owner NEEDS (2026 Edition)

Michael S. Palmer

Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath

Verdad Gallardo

Jul 14, 2022 | 11:29 AM

Olds64

Logistics Pro

Joined: Jun 2017

Posts: 3,986

Likes: 515

From: Edmond, OK

Thanks for posting the video Dave. I've had trouble with Holley carbs in the past, I wonder if it had this warping. The gent that did the video posted that he provides this service. Has anyone had this done that cured a Holley carburetor of internal fuel and vacuum leaks?

Jul 14, 2022 | 01:40 PM

#10

Franklin2

Moderator

Joined: Jan 2001

Posts: 57,023

Likes: 2,754

From: Virginia

Quote:

Originally Posted by Olds64

I have done several. The first couple I had access to a lathe. I made a fixture out of flat aluminum and bolted the carb to the aluminum and then clamped the aluminum in the lathe and flattened it out with a fly cutter. The last one I did I used a flat file and did it by hand. It's not as easy as it sounds to get it flat by hand and it was a lot of careful work. And it still wasn't as good as the fly cut on the lathe but it had to be better than doing nothing. You then have to take air and carb cleaner in a can to clean all the passages out.

I saw a picture in part of the video where he was also planning the bottom of the body down. I have never done that before but need to check that the next one I do.