Holley VS. Edelbrock debacle

UC645

G-Body Guru
Apr 20, 2020
552
93
Kittanning, Pa
I’ll start by saying this is not a “which one is better?” thread (because it’s the Holley), and more of a “Why does one do things the other doesn’t?” thread.

I recently switched from a 1406 Edelbrock to a 4150 Holley (list # 4776-2) and have had a few issues/quirks with the Holley.
For starters, the Edelbrock would idle down to around 600 rpm and would happily allow the engine to sit in gear without dying, at nearly 500 rpm, the Holley does not come close to these numbers. Even at 1000 rpm idle, with the Holley on the car and it sitting in gear it seems to stall out far easier. When the engine is up to operating temp this gets even worse, with me needing to get on the gas within a second to prevent the car stalling. Does anyone have any ideas on why this is the case? I have rebuilt both carbs, the reason for the switch is I think the Edelbrock is damaged, it leaks fuel out of the bowls when it’s sitting. That carb has already cost me quite a chunk of change in oil from the gas seeping into the pan overnight.

Another quirk with the Holley is that it doesn’t like full choke, but runs quite rough without it when I go to start it. I’m using a manual choke setup, and can not find any tips or tricks to adjusting this so I can use it. Currently I have to hold the choke open about this much in order to get the engine to start or run with it on:
5D284568-F36F-4F35-B65C-955A19363BB7.jpeg

Fully closed and the engine dies either due to lack of air or over fueling, I can see fuel pouring out the venturis with the choke on fully. Any tips on fixing this? Or should I stop worrying, leave the choke off, and stick my foot in it a bit while it warms up?

As it stands I know the Holley needs a few things:
A bigger primary squirter
A more aggressive primary accelerator pump cam
A 50cc accelerator pump conversion, or a combination of all 3. I will be taking it back to the bench for by the book adjustments when colder weather hits.
Any advice or suggestions are greatly appreciated, I have been looking for around a week and haven’t turned up any solutions.
 

500/600

Royal Smart Person
Supporting Member
Nov 17, 2018
1,002
113
West Virginia
This will get out of control fast so I’ll hurry up and give my opinion before it gets buried in the ridiculousness that this thread will become.

If I had an engine that didn’t need at least 850cfm, which I don’t right now, I would never ever use a Holley over a Carter/Edelbrock. Edelbrock’s are much more cruising/driving/tuning friendly..........and I’ve owned a bunch of each in 35 years of driving and racing.

OK, Let the ridiculousness begin.
 

bracketchev1221

G-Body Guru
Jan 18, 2018
732
93
Ok I will throw my 2 cents in, #1 if the edelbrock worked so well, I would be hard pressed to not buy a new one to replace the one you had. #2. DId the holley EVER work before you rebuilt it? My experience and this may or may not apply to everyone, is that most Holley's that have sat on the shelf for years are there because they NEVER worked even from new. The ones that did work stayed on cars and are still being used. I have had carburetors that went on and idled like a champ and others that never ran right from day one.
 

UC645

G-Body Guru
Thread starter
Apr 20, 2020
552
93
Kittanning, Pa
This will get out of control fast so I’ll hurry up and give my opinion before it gets buried in the ridiculousness that this thread will become.

If I had an engine that didn’t need at least 850cfm, which I don’t right now, I would never ever use a Holley over a Carter/Edelbrock. Edelbrock’s are much more cruising/driving/tuning friendly..........and I’ve owned a bunch of each in 35 years of driving and racing.

OK, Let the ridiculousness begin.
Without a doubt this will go off the rails fast, just like the Holley 🤪
Ok I will throw my 2 cents in, #1 if the edelbrock worked so well, I would be hard pressed to not buy a new one to replace the one you had. #2. DId the holley EVER work before you rebuilt it? My experience and this may or may not apply to everyone, is that most Holley's that have sat on the shelf for years are there because they NEVER worked even from new. The ones that did work stayed on cars and are still being used. I have had carburetors that went on and idled like a champ and others that never ran right from day one.
Although the Edelbrock worked, it didn’t work well. Even after running the bowls empty (seemingly) I was still ending up with gas in the oil over time. Wether this was from the carb still leaking, or rings not being seated is out of my realm of knowledge. I got paranoid over the gas thinning out my oil and allowing my engine to begin to eat itself, which when I found the Holley, it seemed like a good deal.
The Holley wouldn’t of worked in the condition I got it in, it was fairly beat up.
C80FFD88-503F-4F05-A46D-5722CEC65C0E.jpeg

It’s hard to see, but that choke linkage was bent inwards by an 1/8th of an inch.
I replaced every component save for the big items, it got every gasket and seal, needles and seats, throttle shafts, throttle plates, and every spring. I put the correct squirters in it according to the list number.

The other reason I bought it was because I plan to race the car when I’m done and got sucked into the idea that “every racer has a Holley” :rolleyes:, and I underestimated what it would take to revive this thing.
 
  • Like
Reactions: 500/600

84dragcutlass

G-Body Guru
Supporting Member
Aug 20, 2009
963
93
North Vernon IN
In my experience and the rule that i normally go by is if you want to race go with a holley for ease of rebuilding and a ton of options for them out there. If you want a street friendly carb with super easy tuning and little issues over its life go with the Edelbrock. That being said it sounds like your old edelbrock may have had some issues as well or maybe your rings really arent doing so well, either way some tuning and a deep dive into the root cause might help your situation a bit. The addition of the rebuilt Holley throws an huge amount of new potential problem causes on top of what you were already trying to solve. Usually the best way is to change one thing at a time to find what helps your issue and go from there. I know this doesnt help why your car doesn't run as well now with the rebuilt unit but figuring out why that is the case could now be a pretty deep rabbit hole
 

fleming442

Captain Tenneal
Supporting Member
Dec 26, 2013
11,473
113
First off, carbs are magic voodoo, especially Edelbrocks. Holleys are ridiculously simple, so it should be an easy fix. The 2 biggest lessons I've learned are float levels and transfer slots. Get them in check, and it's easy street. I still have to revisit the 1406 E-brock I rebuilt for a friend. It had a sunk float; I got it to idle after the rebuild, but the rest of the throttle sweep is trash. Holley Barry on the 67 works pretty damned good for a cobbled together mess. I recently "readjusted" the idle screws, only to put them right back where they were. I don't discount q-jets, but I failed on my attempt and I'm not paying $1000 for a good one. That's EFI territory these days.
 

UC645

G-Body Guru
Thread starter
Apr 20, 2020
552
93
Kittanning, Pa
First off, carbs are magic voodoo, especially Edelbrocks. Holleys are ridiculously simple, so it should be an easy fix. The 2 biggest lessons I've learned are float levels and transfer slots. Get them in check, and it's easy street. I still have to revisit the 1406 E-brock I rebuilt for a friend. It had a sunk float; I got it to idle after the rebuild, but the rest of the throttle sweep is trash. Holley Barry on the 67 works pretty damned good for a cobbled together mess. I recently "readjusted" the idle screws, only to put them right back where they were. I don't discount q-jets, but I failed on my attempt and I'm not paying $1000 for a good one. That's EFI territory these days.
Yeah the float level..... let’s just say I had to bend the float arm on the secondary fuel bowl to get the needle and seat to even close, let alone set the fuel to the right level. It can be taken down a bit, but the level right where Holley’s tech articles say it should be.
The transfer slots are another matter, I might have them too far open to get it to idle high enough to keep it running in gear. I did have to crack the secondaries open to get the engine to run to begin with though, so that could be part of the problem.

What’s really stumping me reading article after article is the Motor makes surprisingly good vacuum for the cam, even at 850 rpm. When I had the gauge on it, the engine had around 12-13 hg on the gauge.

I think I’m going to call Holley’s tech line after I’m out of work and see what they say.
 

fleming442

Captain Tenneal
Supporting Member
Dec 26, 2013
11,473
113
What engine is this on? Fuel dribbling at idle is NOT GOOD. Setting the float levels on the bench is the start, then they need to be adjusted on the car. Sight glasses make this a breeze. Otherwise, pull the plugs and set them high enough to just dribble out at idle. The transfer slots have to be set first, though. Those are the foundation of the idle circuit. Bring it down; we'll have it going nice in an hour.
 

lilbowtie

Comic Book Super Hero
Jan 7, 2006
3,272
113
Canton Mi
A carburetor is a carburetor if they are set up properly they work properly. There are a lot of carbs that are built for various applications. As Fleming brought up the idle transfer slot is always messed with. Once you set the blades you don't touch those settings again and sure enough someone uses them for idle. Don't know your engine but I'm pretty sure you don't need 50cc pumps
 

Please support GBodyForum Sponsors

Classic Truck ConsolesDixie Restoration DepotMike's MontesP-S-TSouthside Machine PerformanceUMI Performance

contact[email protected]for info on becoming a sponsor