when I rebuilt my car years ago . I started with a 750 double pumper and never seemed to get it right . I then went to a 600 single . its been giving me a lot of problem lately get it running good then it loads up and stalls out 10 minutes later it runs fine then in a week or so it loads up . finally seemed like I got it now on primary ,but not getting or getting very little fuel to secondary so I give up with this carb and don't even want to know how to fix it just don't trust it any more . my question is when I was looking what was on it before I built it up . what I found was that the carb it had and a sub was a edlebrock 1903 which is a 785 cfm carb . so why would I want to go with a 600 like most suggested on a earlier post ? talked to a bunch of people I know and all there doing is confusing me more .want to spend around 400 for one .

 

First of all double pumper carburetors aren't suitable for street use because they're made specifically for applications where the engine remains at 4000 rpm or higher; as in track racing and drag racing with very low gears and/or a very high stall torque converter. For a 350" the only suitable carburetor is a 600 cfm single pumper with a vacuum secondary to prevent bogging or any of the AVS types of carburetors. We'll be glad to walk you thru the process of getting your 600 cfm working correctly.

 

carb R8 4010-1 2901 12R-10546B .where do I start . even though I tried to get the gas up to hole in secondary it seems to be about 1/2inch+ below it . if I take it out it runs fine but if i jump on it, it seems to run out and all most stall .

 

Post a photo of your carb.

Where is the fuel set in the primary????

DUB

 

its right at the hole doesn't run out unless you rock the car .

 

OK ive got it close took it out no stall any where at lest to 90mph . when I brought it back the secondary when I pulled the plug was right were you had to rock the car to get it to come out . the primary was right on the threads so I gave it another 1/8 turn . what else do I need to set . also what rpm should it be at in neutral ( right now its at 1000) and in gear( its at 750) its a auto .

 

Your fuel setting is fine depending on how you drive it. I prefer to have the fuel very lightly trickle out of the hole in the bowl. NOT flowing out...but just enough to get the threads wet in the bowl and barely causes a drip to develop under the bowl.

Fast idle around 1500. Then it should idle in PARK at about 750ish...and when in gear about 550-600ish.

Not knowing anything about your engine...these are just approximates....but will get you close ....because unless you have a wicked cam in the car....1000 RPM at idle is too high...that is for sure.

DUB

 

seems like I have it all working now . hope it stays there . thanks

 

went out to use it today . have ran at least a few tanks of gas through it since I got it adjusted . today started right up and flooded out took off air cleaner and could see it dumping gas in front two barrels taped on it a couple times let it sit for about a hour started it back up had a couple pops out of the carb then ran fine again theres nothing showing in the fuel filter . now what ?

 

Check the fuel pressure.

 

I had a Demon 750 and replaced it with an Edelbrock 600 with Fantastic results

 

And that would be my recommendation for anyone with little or no knowledge of carbs and how they work...

All opinions aside a vacuum secondary carb is better suited for an automatic street vehicle and this is why pretty much all professional advice recommends them. Especially if its an application thats more show than go such as many of the low compression low power smogger c3's out there (my original engine being no exception)... Was the carb correctly jetted for the engine when installed or was it a one size fits all approach? When I replaced my edel 600 with a street avenger 670 I found the jetting (amongst other components) was much too lean out of the box for my engine. I dont really know how wild or mild your application is but from your comments you havent even opened the carb up to clean it with all the issues you've had so that makes me think your not really comfortable with playing with it... If thats the case you will be happier with a 600-670 vacum sec street carb.

Sure you can tune mechanical secondaries to have streetable manors but they will never perform as well or efficiently in a street application as the correct setup unless they are professionally setup and tuned for that exact combo. When you look at how they work it just makes sense that a street carb would work better for a street car and a strip carb would have its own edge for the strip. Most of the time the applications were they work great are because of additional tuning efforts on installation.

 

Robert, it would appear based on your initial post that what you have is an Edelbrock version of a Quadrajet. http://www.edelbrock.com/automotive/.../1000/1904.pdf
#1903 (795 cfm) - Recommended for most small-block Chevrolet/GMC V8s, 305 through 454 c.i.d., in both truck and passenger car applications using a hot air style choke; 1975 to 1985.

However in post #6 you seem to be describing the float adjustment procedure of a Holley carburetor. It would sure help to understand if you could post a picture of the carb you are using.

In 1976, your car would have come with a Quadrajet carburetor.

Good luck... GUSTO

 

its a holley carb . I cant find the papers on when I built the car years ago . but what I remember is I had it rebuilt with a 350 350 hp rebuild kit . and about a year later I had a ping in it so when I had it tore apart I told them let add to it so I went to 11 to 1 pistons 64cc heads world sportsman ,crane roller rockers the block is decked .040 and every thing I could do was balanced . the one thing I cant really remember is the cam but numbers 488/504 or something close to that is what I remember . its got a good lope to it when idling.

 

what's up with your choke? looks like it's not connected to anything. Did you tune it cold with choke wide open like that? No wonder it gets hot and loads up...

there's good reading on Holley proper setup on their site. maybe give that a look.

 

never got around to getting the electric choke I wanted and didn't want to fool around with the manual runs fine after a couple seconds .all the tuning has been done on a hot engine . starts right up and with a little pressure on the pedal it runs on its own in about 20 seconds . don't think ive tried to start it with the outside temp below 60 in years . next carb will have electric choke .