I've had this carb sitting on my shelf for quite some time now, it came with an old edelbrock intake I bought many moons ago. The carb is a Holley 650cfm double pumper in a spread bore setup. It's complete with manual choke, etc. Anyone know how long ago holley stopped making these?

I've never heard much about these carbs, do they work as well as the regular square bore holley double pumpers? I've read this carb is considered a 4165 series, will it take all the usual standard issue holley double pumper parts like jets, power valves and accelerator pump nozzles?

Just rebuilt one a few months ago. They were a direct replacement for the Q-J on many GM cars. #6528 fit 68-70 350". 68-71 400,430,455". #6774 fit 1972 350 &455". They take all the standard Holley parts. Not sure on how long they were produced, but I would guess in to the late 70's. They were advertised as the "emission
design/street performance" carb. I guess that would cover most the bases. Only draw back is they just didn't have the cfm of the QJ or TQ of that era. On the plus, lots of parts available for tuning.

Check in the Summit cataloge. They sell a Holley marine spread bore Q-Jet replacement carb for $420. It is a mod 4175 with an electric choke.

Well good to hear they use the standard parts. I know they use their own gasket kit but at least the other stuff is the same. I'll give the carb a try. Anyone ever run one of these on their ride? If so, how well did they perform and how good was normal driving operation with these?

Is it a 6210? There were scads of those things around (at least around here) in the late 70's and 80's. I guess they were popular among the folks who wanted a Holley, had a spread bore intake, and didn't want to buy a new square bore intake back in the day.

They use different metering block gaskets (and, I think, different bowl gaskets) than a 4150/4160. I've got a few new blue Holley gaskets that I never used. I'll give them to you free if you can use them.

Jim

Yes, the idle screws controlled air rather than fuel. They were usually marked on the side of the metering block with an arrow ( pointing counter clock-wise ) with the word LEAN just below the arrow. Also yes, the discharge nozzles were the anti-syphon type ( common on many other Holley carbs )and the metering block housed the accelerator pump discharge check ball - rather than it being below the nozzle. It also took a strange 2 piece base gasket. A thick asbostos gasket went on first, than a stainless plate gasket, then the carb sat right on the plate gasket. This 2 piece gasket was for use with OEM spread bore manifolds that had the exhaust cross-over on the surface of the carb pad.

The reversal of the idle screws was only on a few models of the 4175 carbs.
To answer that we need the number on the air horn.
The regular version of this carb is the 6210, 650 cfm. Very good carbs. Ussually too vean from the box. The vacuum secondary version was the 4175. Most that I have been around were reverse idle design. Some had secondary metering plates, some had metering blocks.
Remember, ussually too lean, so check what is in it and check plug color.
If you need to know what jets were stock, my holley book has a listing, but I need to know the list number on the air horn.

They were considered a Quadrajet replacement back in the 70's and 80's. You could unbolt the Q-jet, chuck it in a garbage can, and bolt on the 6210. Even the fuel line lined up, as compared to a regular Holley which has the line to the float bowl. I've got one on a Brand X, works well, even has a divorced choke. As previously stated, they use a different gasket set than a regular holley.

Here's the one I ran on my 360 for a number of years after I rebuilt it in 1981 or 1982. I generally liked it although I did have to re-jet it as others have mentioned. I would have probably been happier with a 4175 vac secondaries on the street, but when that carb (4165 mechanical secondaries) came on it sure felt good! Once you got used to driving it it ran pretty good. You couldn't mat it off the line as the bog would seemingly last forever (heavy car with small block). You had to ease into it then push the pedal to the floor.

Thanks for the info guys, keep it comming if you've got more. I'll dig the carb out of my storage bin tomorrow and post the list #.

In general I didn't like these carbs. In the mid '70's I swapped a 340 into my '70 RR sixpack body, it was a 71 junkyard engine with a Thermoquad.

I ran two of these Holley's over the years swapped back and forth and finally mostly ran a QJ. That's right, a GM QJ.

After a while with a little dirt, sometimes the back barrels would stick "cracked" open--the mechanical linkage does not close them all the way. This can be VERY upsetting when you lift, and expect the thing to slow down.

These have the traditional power valve problems and between myself and my friends --back then--I've replaced a lot of Holley power valves.

Of the three available, "back then", Thermoquad, Holley SB or Quadrajunk, I'll take the QJ, thank you very much

Okay I found the number, it's

6210-3
3044

What can you tell me about what's in it (or at least was originally)?

I would have to dig out the actual part number, but I ran one on the TT340 for 4 years. Spread bore 650, double pumper, center hung bowls, full metering and power valves on both ends, manual choke. I found it to be an extremely good carb that even worked pretty well (for a carb) after being extremely modified to run blow through boost. Very tuneable with standard parts. Obviously, you need to know how to drive mechanical secondary carb, or you will be severely disappointed.