Thoughts on Holley carb

[jtminton]

Any thoughts on a Holley spread bore carb? My dad has one that needs to be rebuilt, and I was wanting to know if anybody had any experience/advice about it. The number I got off the carb is L6210 3, if that helps. It's at home right now, so I can't post any pics. It would be for my 72 C-20 with a 350. I currently have a Quadrajet on it.

Thanks!

[panhandler62]

The Holley doesn't actually meter quite as well as the quadrajet, but it is dramatticaly easier to tune and maintain. Rebuilding Holley carbs is simplicity itself whereas rebuilding Quadrajets is like putting a puzzle together in the dark while you are drunk.

In practice: the Holley will usualy run better simply because you can keep it properly tuned with almost no effort while the Rochester will often be about half a bubble off plumb.

[jtminton]

Originally Posted by panhandler62

In practice: the Holley will usualy run better simply because you can keep it properly tuned with almost no effort while the Rochester will often be about half a bubble off plumb.

Yeah, the QJ leaves an ever-present pool of gas on top of the intake, too. It also bogs down when I floor the pedal. I think it's just old.

[hgs_notes]

I did a quick check and found an 0-6210-3 which is a model 4165, 650 cfm carb. I'm not positive, but pretty sure its the same as my 4160, just flows a bit more.

I have part numbers for kits and stuff too.

There are some good tuning guides out there, I have an extra book if your interested. They are pretty easy to build and run. Personnaly, I had a spreadbore Rochester with mechanical secondaries before this, and it ran great, but a pain to rebuild. I really like the mechanical secondaries. I might change mine after the next rebuild.

HG

[67chevemall]

I really like the mechanical secondaries. I might change mine after the next rebuild.

Never tried mechanical sec. How do they work? Do they open at a set linkage spot?
Vaccum adjusts with springs how do you adjust mechanical ones?

Cheers

[hgs_notes]

"I really like the mechanical secondaries. I might change mine after the next rebuild.

Never tried mechanical sec. How do they work? Do they open at a set linkage spot?
Vaccum adjusts with springs how do you adjust mechanical ones?"

Well, I liked them, but didn't have it long enough to mess with. So adjusting is not something I could help with. But yes, the secondaries open by linkage with the throttle. They start opening at part throttle and then fully open with the primaries. I had it when I was about 20, I'm 38 now and the memory is foggy. Anyway, I don't know enough to say one is better than the other for any particular application. I'm sure there is information available now that would have been difficult to come by back then.

HG

[rage'nrat638]

manual secondarys......
want to lower your gas milage.....just try it......
say your going up a hill and need a bit more pedal.....well ...the rear two are open.....
you get a hell of a lot of power......under your foot.......heck just the sound of the vacuum.......gas sucking is enough to make me sick......
i had mine on for two weeks and removed....
a holley double pumper with manual secondarys has two power valves....

one little back fire.....or run on....there toast....
lighten up the vacuum secondary spring....to get it to open sooner.....

i changed mine to a two barrel....350 3/4 ton.....and am very happy with the power.....the 69 is not a race truck.......i jump in the 85 638 dart engine when gas don't matter......

thats my story and i am sticking to it !!!!!!!!

[Nelson]

I have a Holley 4360 Q-Jet (450cfm) with mechanical secondaries, and I like it! It was easy to rebuild too! I suggest to take some pics of it during disassembly, and use genuine Holley rebuild kit. Just my 2 cents!