I am still at the drawing board for my engine build.( cant make up my mind ) I am about to get a holly 600cfm w/ vac. secondaries and electric choke. Is this a little small for a 383 stroker(or a beefed 350). Or would you suggest a different carb, say a Holly DP or a Q-jet. I still need gas milage but I need performance. Is there a carb where I can adjust back and forth from performance to milage.

 

Carter thermoquad
800 cfm or 1000 cfm model.

 

600 is not enough. Get at least a 750 cfm Holley, DP if you have a manual tranny, VS if you have an automatic.

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

I am not that educated in the mechanics of carburator function. Why would it matter to have DP w/ manual & VS w/ auto tranny. An 800 or a 1000cfm does not sound to economical, 1000cfm seems like overkill, but then take another look at my first sentence.

 

LOOK i aint up to the latest holley jive!!
i reckon the 780vacume will suite you down to the ground,,,we use them here on 351 4V clevelands down under, those things got big heads,valves,,giant ports,,, real good on 350 chevs the good old 780, was a top thing,,it gave easy driving,good idle,good economy,and good for 13 second passes,,,jet it up down whatever,,to me double pumpers,are for racing, do you want a nice quick thing to drive,or ya goin street racing, the vacume carbs are good for performance,,i had heaps,easy to dial in , feel free to e mail me ,,HOLLEY said in many articles a 600 vacume ,,,the old 1850 model will run a 500 cube motor up to 400HP,,

 

I've gotten 400hp out of several 350's with the 1850 holley's, but they were modded to have individual feed bowls (instead of that "feed tube" with the o-rings), etc...

IMO, go with a smaller 600-650 or so carb. You can get PLENY of performance at the cost of a little top-end to have more mileage/drivability. Yeah, you can tune a bigger carb to death, but the smaller carb will work just fine, UNLESS ITS MAINLY A RACE VEHICLE. If just a street toy, IMO, go smaller.

No big/small fighting, please....

 

no matter what a 600 is too small, even the stupid CFM formula will tell you that. But what it won't tell you is that the CFM rating is not directly related to gas mileage.

There i didn't come out and say he should get a bigger one did I?

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I WOULD RATHER PUSH A CAMARO THAN DRIVE AN IMPORT

1983Z28 350w/ edelbrock performer RPM power package with 64cc aluminum heads, dynomax shorty headers, 700R-4 with shift kit, 750cfm carb, edelbrock 3" exhaust system, ASCD SS hood, 16" IROC rims.

future mods:
completely done over suspension, black paint with flames, Hurst shifter, dakota digital gauge package, procharger supercharger.

 

yo no offense, you just might not know this.

an 800cfm thermoquad's primaries are only 1 12/32" diameter.
a 1000cfm thermoquad has primaries only 1 16/32" diameter.
Every thermoquad has special high-gain double boosters for better response & mileage.

the Holley 600vs has larger 1 18/32" primaries and most of them do NOT come with annular discharge boosters.

Holleys are several hundred times more likely to develop fuel leaks and to run overly rich due to powervalve problems.

yes I am very biased, but those are the facts.

 

I agree with you entirely. I personally do not like Holleys that much, I don;t like any carburetor for more than one year for some reason. Seems that after one year, things all change... that's a whole 'nother argument...

I am new to Edelbrock/Carters but have had good performance after moderate tuning with their kits, but agai, whole 'nuther story.

 

hey fastbroker,

almost ALL problems in general with carbs and especially ones that develop over time have to do with dirt in the air or fuel.
A carb is cheap and low maintainence, but they are NOT no-maintainence like most people treat them.
Carbs just want very clean air and very clean fuel, and to be cleaned on a regular basis.
So many people have rusty fuel tanks, or water in their fuel or get some kind of dirt into the airstream that causes nothing but problems with carburetors. At that point carb comparisons & performace comes down to which carb had the better filter.

To me, buying a $1 can of carb cleaner and taking the carb apart & cleaning it is no trouble at all, but you'd be surprised the number of people that simply will not do it. Oh and there are some people that think spraying carb cleaner down the venturies will clean it.

this is all good for me because I can pick up carbs fairly cheap from the people who hate them.

ODB

 

A 750 would work bettter than a 600 if it's tuned correctly.

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Big 454 72 Chevy Nova
383 86 Camaro Z28
10.5:1compression 186 casting Heads,234dur.488lift exh&int,Edelbrock performer intake, Holley750 vac.sec 400 crank,flat top pistons,edelbrock valve springs and lifters,tranny shift kit,2500 stall converter. Will install 3.73's later on and might go with a more aggresive cam.As of 4/01 added Hooker Headers,2.5inchpipes with 40 s. Flowmasters.Ignition upgrade include: MSD Coil and MSD module.

 

I'm with ya, ODB. I'm gonna email you sooner or later if I decide to go with an Edelbrock 750 cfm elecric choke carb, if that's ok, for help in final tuning, if/whenI need it. Later on.

 

Quit pulling each others chains.