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Scored 3 old Holley carbs today

eclipse

eclipse

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All i've run my 85 k10 is the q-jet and two square bore edelbrocks. I'm not too happy with the one on it now and I wanted try something different. A guy I work with told me he had a few holleys laying around he didn't want, he likes edelbrock/carter square bores.

I ended up trading him a 600 manual choke edelbrock for these 3 holleys. This will give me a winter project, never had a holley so I guess I can found out if I like em.

The first is a double pumper obviously, i'm guessing 650 cfm?
second seems to be a basic 600 cfm.
and the 3rd i'm not sure on, doesn't look like a squarebore to me.

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I just recently threw away about 8 of those carbs. I couldn't find anyone who wanted them.
 
The first is a double pumper obviously, i'm guessing 650 cfm?
second seems to be a basic 600 cfm.
and the 3rd i'm not sure on, doesn't look like a squarebore to me.
Click to expand...

Sorry to say but none of those are double pumpers, the first one has been converted to a dual feed but it's not a double pumper. If you look at the list number on the air horn i'll bet the spreadbore carb is a 3310.

Edit: there is a doubler pumper there, it is the spreadbore carb, the rest are vacuum secondaries.
 
oh yeah, oh well I dont really have a need for a double pumper. I want something mild to run on my 85 k10, its a daily driver with a 320 hp 350.
 
Yes, i beleive that is a list number of 3310. The others should be an 1850 with possibly a (dash) -2 or -3 maybe.
 
looked em up on holleys site..
1st is a 750 cfm street/strip
2nd is a 600 cfm
3rd is a 650 cfm, didn't say anything about being a double pumper, wonder if it was modified.

I'll probably rebuild the 750 for my 85k10. My buddy said I should use the 750 and down jet it. Oh well let the projects begin, guess I'll learn how to rebuild carbs now.
 
My buddy said I should use the 750 and down jet it.
Click to expand...
This is wrong in most cases. You should use the volumetric efficency formula and go from there. If you use too big CFM carb your throttle response will suck.
 
agree with the last statement... i had a 750 on a 350, went down to a BIGS 675 custom carb on a camaro and picked up alot of Thro. Resp.

they were both double pump.

i thought that the Q-Jets were well liked as the carb of choice for the 4x4 community ( i am new to 4xing.. been drag racing for past 10 years or so) due to working angles.????

i have heard that the holley's don't do so well in this area?? correct me if i am wrong...

i also do NOT like edelbrock carb's...

in everyvehicle i have had/worked on i have switched to a holley and immediately picked up a seat of the pants horsepower increase (probably around an average of 10-15 horse power)

JMHO
 
My friend took back his idea on using the down jetted 750. So I have the spreadbore double pumper 650 or the square bore 600 vaccum secondarys to choose from. Since right now my 85 is more of a DD I'll probably do the 600. Just gotta get my work bench built in my garage first.
 
I do a lot of Holley carb work & thought I could lend some info.

A 750 is not too much carb for a 350. On a 350, a properly tuned 750 vac secondary carb will feel better than a 600. I've done many of these & the only way the 600 ran better on a 350 is if the 750 was not tuned properly.
The 750's feel more responsive than the 600 since the primaries are bigger & will allow the engine to accelerate better with less throttle opening.

For reference most q-jets are 750's

Double pumpers are more sensitive to sizing as they open all 4 bbls when the throttle is pressed to the floor. In this case a 750DP could make the truck feel sluggish at full throttle.

Vacuum secondary carbs only open the secondaries when engine demand is there. This way a 750 is only a 375cfm carb on the primary 2 barrels. If your engine does not need 750 cfm the secondaries do not open all the way.

Jetting down is an improper theory here as well. The jets only control the fuel flow, not the carb size which is the air flow potential. The jets proportion the amount of fuel vs. the amount of air drawn in. Contrary to this thought, adding too large of a carb, say a 950 DP on a 350, will have less of a vacuum signal through the large venturi, due to its larger size. This will result in less fuel draw into the carb & require a larger jet to get the air-fuel mixture correct because the carb is too large.

The 650 DP spread bore that you have will fit a q-jet intake, but the mechanical secondaries may not work well with your combo. The mechanical secondaries tend to like light vehicles, or ones with steep gears that allow the engine to rev easily.... not typical truck scenarios.

If you do not have an aftermarket intake, the standard flange 4bbls need an adapter to fit a q-jet intake.

Hope this info helps.

Lonnie Pavtis
Lonnies Performance Automotive
 
The 2nd carb you have there is the one I run on my truck. I must say, once you take the time to tune it right, I guarenty you will never want an Edelbrock carb again.

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Lonnie,
Thanks for the info. I'm leaning towards 600 like chevy305 has on his. But I may just rebuild both the 600 and the 750 and try them both.
 
eclipse said:
Lonnie,
Thanks for the info. I'm leaning towards 600 like chevy305 has on his. But I may just rebuild both the 600 and the 750 and try them both.
Click to expand...

The 600 we both have is a 1460 series carb that the truck avenger is based off of. But of coarse with a more useable cfm range. I DD my truck with the carb and it runs pretty steady. The one thing I'd recomend is going to manual choke over the electric, because the electric just causes problems, and the manual lets you control the high idle.
 
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