Holly Carb

[potionmaker]

Hey gang. I just bought a used Performer aluminum intake manifold for my 400sbc swap that's ongoing from a friend. For $50 more he threw in the carb that was sitting on it and said that it was running good when he took it off, but wasn't exactly sure what model it is. Any ideas on the CFM's of this carb? The specs are as follows:

Older Holly Double Pumper
Mechanical Secondaries
Model # 6R-4237B
List # 6853
0990
I have searched all through google and the Holly website, but I cant find any info with these numbers. I'm trying to search here, but I keep getting a "dead" link.

Any and all info would be greatly appreciated!!!

 

[trailblazr81]

Looks like it could be a competition mechanical secondary double pumper 650 cfm. I am not a big fan of mechanical secondary double pumpers on anything other than dedicated race motors. If you "get on it" at the wrong RPM it will stumble or just die since it just pours fuel in. Kinda like a controled fuel leak. Theres charts you can find online that will tell you what RPM you must be at before you can floor it. Depending on carb size, motor size, etc. I ran a Barry Grant Speed Demon vacuum secondary on my 383 Nova. I could tune what RPM the secondaries would be fully open and it was much more driveable than a mechanical secondary double pumper.
But I would still soak it in carb cleaner, bolt er on and have some fun with it

 

[potionmaker]

Thanks for the info. DO you think the stock carb would be a better choice (rebuilt ). The specs are below.

Rochester 4bbl
17085226
List #2335

(hard as heck finding info on this one too. Having old parts SUCK!!!)
The only mods to the engine are Performer dual plane intake manifold, headers, and 3" single exhaust.

 

[trailblazr81]

I would rebuild the Q-Jet. Search the web, theres a few sights that list tips n tricks for 'em. The Q-Jet will easilly do things on the trail that the Holley will stall attempting. Ive had a stock 305 and a built 383 with the same Q-Jet. Just did a little tuning. They can be a little intimidating until you learn about them.

 

[blackblazer717]

in my opinion i think quadrabogs as wicked junk. every truck or car that i have ever owned that had one, was replaced with a holly dbl pumper by me, i dont like Q-bogs at all i say huck it and put the dbl pumper manuel secondarie on that bad boy

LUKE
I:E: if the manuel secondary holly is set up right they will not jerk and bog under hard accel.

 

[BadBob]

Older Holly Double Pumper
Mechanical Secondaries
Model # 6R-4237B

Here's what my book says:

Competition replacement for all Quadra-Jet carbs. on
1965-70 327, 350, 402 C.I.D. engs. Mechanical
secondaries, spread bore, double pump, 650 c.f.m., non
emission, divorced choke

 

[trailblazr81]

If you or the person working on the Q-Jet knows what they are doing you can equal the performance of the Holley and get better mileage out of it. You need to set it up for your motor. Plus Ive been in near rollover instances where my Q-jet kept the engine purring fine and allowed me to get out. Ive had Edelbrocks n Holleys sputter or die doing stuff in 2 wheel drive. And they dont restart easily. If you keep the vehicle pretty level the Holley will do fine, but when you start getting all flexed out and at nasty angles you'll be happy you have a Q-Jet.

 

[potionmaker]

Thanks for the info. I wont be doing any heavy wheelin'. Just when needed (beach, snow, light trail). So would the q'jet (rebuilt) be the better choice? Are the cfm's different between the two? How about power delivery (any affect in get-up-and-go?)
Also, Im running a 700R4. Any worries regarding the Holly swap (kickdown, etc.)?

Thanks again. Just trying to save myselft (and my buddy) some extra work.

 

[trailblazr81]

The Q-Jet flows more cfm, but has smaller primaries n massive secondaries. Gives the better throttle response n mileage. Dont be scared about a Q-Jet being rated at 750-800 cfm, it wont overload your motor. Its more of an on demand carb. With the Holly you would probly need to get some assortment of ball studs to connect the throttle n kick down.