slammedS10

ok alittle backround bout my engine, 350 bored .020 overe, 480 comp cam, comp lifters, roller tip rockers, 62cc aluminum heads, flat top pistons, scat crank, dual roller timing chain, rpm intake, 1in carb spacer, billet HEI distributer, edelbrock performer 600 cfm carb, and a 3200 stall converter that doesnt flash until 3800 rpm.
My problem is that the car has a terrible misfire under light acceleration, the more I advance my timing the worse it gets, almost sounds like a stutter box. Under wide open throttle it seems to be fine. Now, I will be taking out the stall and replacing it with a 2500 ( better suit the cars performance) and I Have been told that my carb is def the issue with the problems I am having. I was wondering what carb you guys suggest for my application and how much better the car could really run with the correct carb on the car. Thanks for any help and Idea's.
Nick

1 FMF

iTrader: (1)

an edelbrock 600 is a correctly sized carb for that engine,

check out the carb owner's manual
http://www.edelbrock.com/automotive_...ers_manual.pdf
What it can be, given your engine build, is you might need to change the metering rods, you may be too lean, see page 7 calibrating part throttle and the following reference charts. But before you go buy stuff, pulling the top of the carb off to check float level is free, and everything the carb does is based off fuel level in the bowl so make sure that is correct. The other thing is also make sure your idle mixture is correct, and that turning the idle mixture screws in & out causes a change in idle. If they don't then you have dirt in there messing up the circuit. You may also try adjusting the idle mixture slightly richer, it's possible that it's too lean and affecting cruise condition for your engine.

So i would first start by adjusting idle mix screws, make sure they have an affect. If they do, then simply go 1/4 to 1/2 turn counterclockwise (richer) and see if that helps. If that doesn't cure it, then check the float and the fuel level in the bowl of the carb. You may try adjusting it so there's slightly more fuel in the bowl, it may fix the lean condition. If that doesn't do it, then you need to change metering rods. And I'm assuming the carb is new or in excellent condition, if it's used or you don't know its history then it most likely needs a cleaning before anything else will fix it.

1997bird

iTrader: (2)

Which vaccum port do you have your vaccum advance hooked up to on the carb, the port to the passenger side or the port on the driver's side? The port on the passenger side is a full time vaccum port and the port on the driver's side is your part time throttle port. How much total timing to you have right now? What centrifugal weight springs are you useing for your timing curve? Did you make sure that you had the vaccum advance hose disconnected from your distibutor when you set your initial timing?

slammedS10

timing is set at 34 degrees, vaccum port is hooked up to pass vaccum port on carb.

slammedS10

i dont know what to do now. I have you guys telling me carb is right, which is what I thought because of the carb scales, and this other guy that has been building race cars for over 40 years telling me to get rid of the stall converter, and the carb

1997bird

iTrader: (2)

Right now your problem at hand is that you have your vaccum advance from your dist. hooked up to your full time vaccum port on your carb. It is supposed to be hooked up to your part time vaccum port on the carb which is on the drivers side of the carb. This means that you are going to full advance just as soon as your engine is started and your part throttle response is not wanting to function normally. At what rpm did you have the engine to check your total timing?

1 FMF

iTrader: (1)

http://www.hotrodders.com/forum/port...uum-23169.html

http://www.highperformancepontiac.co...ech/index.html

slammedS10

around 3000 rpm

slammedS10

driver side port is full vaccuum not passenger side

1997bird

iTrader: (2)

At 3000 rpm and 34 degree's timing you are going to be about 39-42 degree's at 4000 rpm due to how the centrifigal advance weights work. Sorry about the miscomunication on the vaccum ports, I was going from memory and haven't worked on a Edelbrock in a while.

Hippi

iTrader: (3)

have you checked your hei module to see if it's good?

slammedS10

no I have not, just assumed it was good cause it was brand new. But I think the prob is def, the carb. Call edelbrock today and the carb on my car is only rated to 5200rpm and rec, for stock heads, bla bla bla. So He said to order the thunder series 650. He also said the carb(1406) that is on my car will make it run extremely lean, and its not rec for my intake, and cam set-up. So new carb is on the way . Hopefully tghat will fix my problem!!!!

xx_ED_xx

iTrader: (17)

If you had a wide band you could easily find out... 50 cfm aint going to make it come alive, proper jetting etc will

slammedS10

600cfm for a 350 pulling 6000rpm is the correct rating, It volumetric effeciency that counts.

slammedS10

no worries fellas, put my buddies 800 carb and fuel pump on and blew my rebuilt tranny with 72.8 miles right up. Had to drive home in reverse! New TCI tranny on its way as we speak!!!!