Syco79

I went to the track today for the first time. I launched at 3000rpms got off the line with a .052 reaction time then the car almost stalled then just started hauling *** ran 14.2 at 102mph . On my first run the car did the same thing but worse and I ran 15 at 100mph. It seems to choke up and nearly stall when u get on it at wide open throttle off the line then it recovers slowly. My first thoughts were the carb its a brand new edlebrock 750cfm and the engine is a brand spanking new 383 with 470hp. I know the car has the potential to run in the 12s anyone have any idea why it might be choking up on me?

BigBlockk

The accelerator pump is not functioning properly.

BigBlockk

Later.....

Syco79

is this something that is easily adjusted or can the carb be messed up? its brand new

BKbroiler

You don't have any info in your profile and you don't tell us much about the car in your post.
Manual trans, I guess. What rear axle ratio? Street tires? 1st gear ratio in trans? Info like that would help.

Syco79

its a auto trans freshly rebuilt turbo 350 with a 3000 stall speed converter. Stock 79 rear gears. Differential was rebuilt last year I believe stock is 3.08 or 3.55? Ill have to dig out the build sheet later and post the engine specs. It feels like a fuel problem to me but again im not very mechanical I bring it to the shop for everything :o

another-user

ive got the same problem with my 350/300 Qjet.

i havnt actuall gotten on it yet, but when i take off from a stop its got a dead spot on it. just last week the accl pump was replaced (which looked pretty damn good to begin with but was completly shot) worked fine for about 25 miles or so and hten the car was parked. took it out again friday and it has a dead spot now.

arctic74vette

Advance your timing and then see what happens... It cured mine

BKbroiler

Timing is critical. Your distributor should allow all your advance to be in by 2500 rpm or so. That is, your timing should be at 36 degrees by that point. (Check with vac advance disconnected). If it is, and your new carb is working, and you're running street tires, with 470hp you should be absolutely smoking those tires.

Syco79

its in the shop now getting a new oil pressure gauge put in. I believe the timming was set at 36 degrees but maybe its not. I have to bring it back to engine builder to get it checked out. Im running MT ET street radials it spun some off the line but then it did its famous choke up heh. It really sucks to put a ton of money into a new engine and trans to have them not properly tune it.

sly vette

I never count on any work done by someone else. I do all my own work myself and it's not the money that tells me to do so.

lars

I think your secondaries are flopping open too quickly. Tighten up the secondary airvalve to delay secondary opening rate (I believe the Edlebrock has an adjustable opening rate like a Q-Jet). This will usually cure the type of bog you're describing.

olescarb

I agree with the above if the carb is a thunder series carb with a adjustable secondary air valve but if it is a performer with a weighted air valve it is not adjustable.

we have cured the secondary hesitation problem with edelbrock square bore we have seen by using a 1 inch 4 hole carb spacer on a few problem cars. the 4 hole spacer straightens out the air flow thru the throttle bore and venturi, thus it strengthens the signal to the venturi cluster/jet.

edelbrock also sells a accelerator pump with a stronger duration spring (#1468) so the pump squirt will hit harder.

henry @ oles carb

mkflanagan

C64BOB

Me thinks you better go talk to who ever built the motor. 102 mph equates to about 320 HP. Even if the thing falls completely on it's face on the launch with 470 HP it should still be running in the teens. 470 HP at the flywheel should get you at least 115+.

Syco79

Thanks for the replies folks. It is a performer series and I spoke with the builder today he says ill need to get a kit and rejet it but im also going to try the carb spacer like olse mentioned it seems logical. c64 I think if it didnt fall on its face I would of been in the teens. You may be right but I really wont know until I get the carberation problem solved and back on the track. Thanks for all your help guys I have a pretty good idea of how to attack this problem for now. Though I do see a barry grant in my future if I ever catch up on the bills

chewy

Make sure you aren't all the way through the acc. circuit before you actually launch the car. A lot of the time you must delay the acc. pump opening or it will be used up before you really need it.

Syco79

Chewy im not sure I follow you on this one. How would I do that? Im running a 3000 stall speed convertor so I launch around 3k rpms I think byt then the secondaries are already flopping open and thats why it falls on its face.