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-   -   car bogs leaving line (https://www.racingjunk.com/forums/showthread.php?t=18797)

alleyk 11-03-2007 12:10 PM

car bogs leaving line
 
what could cause this problem

rabiddawg 11-03-2007 02:04 PM

does it bog then catch up?
if so it can be your pump shot.
But without knowing what carb you have its gonna be difficult to diagnose.
also engine specs help too.

alleyk 11-03-2007 03:03 PM

yes it doe's pick up afterwards, the carb is a davinci 750,
engine sm blk 414,with 638 roller cam,brodix heads

superstreeter 11-03-2007 03:09 PM

I imagine, you are running jet extensions in the back, right?

alleyk 11-03-2007 03:18 PM

yes i am,with 88 jets

superstreeter 11-03-2007 03:20 PM

What kind of r.gear, compression, and stall ?

alleyk 11-03-2007 03:33 PM

538 gears,12to1 comp,6000 stall.

superstreeter 11-03-2007 05:37 PM

sounds like pump shot, you got lots of everything else! I kind a have a question to add to this, would a power valve in the back cause this same thing ? or would the jet extensions take care of that,,,I`m not exactly sure where the power valve draws its fuel from.I don`t run one so I have never chased that problem.

Tod74 11-03-2007 06:00 PM

aRE YOU FOOT BRAKING? Cause If you run a trans brake it wouldn't be the pump shot since the throttle is already wide open.

cepx111 11-04-2007 06:52 PM

Good point Tod.
Alleyk, we definetly need to know if your footbraking or leaving off a transbrake to help diagnos this problem better.
To answer superstreets question, the power vavle is supplied fuel from the bowls themselves and yes it can be a problem cars that leave real hard since the fuel in the rear (secoundaries) bowls is trying to climb up the back of the fuel bowls away from the jets and power vavle intake. I've always plugged them anyway to eliminate that possiblity and went up a few jet sizes maybe 4 at the most, not ten like everybody says.
Cp

alleyk 11-05-2007 02:33 AM

tod i do both, only happens when foot braking, i leave on a pro brake at 5400 and thiers no problem,just curious to know why on foot braking i have this problem.

alleyk 11-05-2007 02:37 AM

cepx111 my last reply is for u as well

davis419b 11-05-2007 04:04 AM

Im not sure what fuel you are running but can you deck the throttle while just setting in the pits without the hesitation?

alleyk 11-05-2007 02:02 PM

running c14,when i deck throttle in the pits it doe's hesitate

davis419b 11-05-2007 03:59 PM

I run alcohol and when mine wont deck clean i have to adjust the 4 corner ilde screws to richen it up so it will deck clean, shoudnt be any different with gas!

hammertime 11-05-2007 05:34 PM


Originally Posted by davis419b
I run alcohol and when mine wont deck clean i have to adjust the 4 corner ilde screws to richen it up so it will deck clean, shoudnt be any different with gas!

I agree its likely in the idle screws. A guy that pitted next to me @ norwalk this year had same issues and ended up being the idle screws.

alleyk 11-06-2007 01:27 PM

hey thanks guys i'm going to try adjusting the idle screws ,and see what happens.

SST4530 11-06-2007 01:30 PM

I think I would lean more toward accelerator pump, pump cam, and squirter size. Be sure when foot braking your not using all the pump shot when stalling at the line. also if your not running 50 cc accelerator pump on the front get one.

Don't need it with trans brake, but foot brake it's a must.

youtellme 11-26-2007 10:18 AM

spring on the rear pump is too loose.

fishman1 11-26-2007 06:38 PM


Originally Posted by alleyk
538 gears,12to1 comp,6000 stall.

with only 12/1cr why r u running c14 just curious....r u turning high rpms

as i have 13.5 cr and i use c12 will no issues and timing at 40 degrees total


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