PDA

View Full Version : Need help carb bog in center of corner!



car23
08-05-2012, 02:53 PM
Carb doesnt do it all the time. It is only for a fraction of a second. It has never done it in the heat race. Always in the main. Sometimes it even helps on dry slick conditions. I have played with jetting and plugs look great. Our track has alot of banking. I thought maybe it was just a little to much bite bogging motor. We run limited lm with a steel motor. Carb is a gearte thanks for any help

perfconn
08-05-2012, 05:41 PM
Check your accelerator pump arm slack.

fast_crew
08-05-2012, 07:02 PM
Does it bog or more like a sputter? Sounds like it could be fuel spitting out of the vent tube (rich sputter). Or as Terry mentioned something with the accelerator pump, squirter to small, to much slack in the arm, incorrect pump cam or setting (lean Bog)

HuckleberryB4
08-05-2012, 09:23 PM
Sounds exactly like the problem I was having earlier this season. The motor ran fine when track was hammer down or I was on the high side, but when I had to slow the car down to run the bottom or when the track went dry slick I had a mid corner stumble when I first picked up the throttle. Ended up being I had the fuel pressure set too high and it was flooding over and spitting fuel out of the vent tube when I wasn't on the throttle using all of the fuel. Backed it down to 3lbs at idle and you shouldn't have any more than 6-7 on the gas down the shoots.

dualdj1
08-06-2012, 08:42 AM
We've been having probs with this as well, though it's happening all the time to us. the guys at braswell said we have the floats set too low, so when he gets back in the throttle, the acc pumps pull out too much fuel and the level is too low for the mains to pull any in, so it stumbles until the level comes back up. We got rained out this week though, so didn't get to see if raising the floats fixed it.

Egoracing
08-06-2012, 08:57 AM
Ours started that one weekend, Nothing changed form one race till the other except it was hotter. After searching everything we dropped the jets one number and the problem was gone.

jedclampit
08-06-2012, 11:48 AM
It could be rich or lean, as the posts here indicate.
Is it clean on starts and warming up tires under caution?
If fit is only with cornering, I'd suspect float levels/fuel pressure. If its anytime you drop the pedal I would suspect the accel pumps.
I have had mid turn blubbering problems that I corrected by opening up the idle mixture screws a half turn each, when all else was correct.
YMMV

car23
08-06-2012, 08:56 PM
i have a kse rear mount pump. i have looked at the fuel levels they are ok. i have a good bit of slack in the arm. i will take some of it up and try that. squirters were the same in my kbr carb that i used to run. i have leaned it down til it popped at the end of the straight and increased it jet size until it is visibly rich by plugs. didnt change at all. i will plug away at it a little more. thanks for the advice

car23
08-06-2012, 08:58 PM
definite bog

dualdj1
08-07-2012, 09:05 AM
what's your fuel pressure at?

car23
08-07-2012, 07:36 PM
i think my pump may be worn. it doesnt have alot of fuel pressure at idle but it goes way up when its reved. too much may be my problem. i have had alot problems with this pump. either the fuel pump or the power steering pump. i will prob can this thing soon

jedclampit
08-07-2012, 10:16 PM
I never had one of those pumps work well, consistently, for me, always some issue.
Regardless, use an external regulator.

dualdj1
08-08-2012, 03:35 PM
Regardless, use an external regulator.

x2. seems to be more of a regulator issue than pump. low at idle is ok, 3-4 psi. you want 6-7 at speed. if it goes over that, you can push too much fuel through/float the needles and flood it out.

RUEF52
08-10-2012, 09:12 PM
Had the same problem, tried everything ended up the carb was too big.Went from an 850 to a 750 runs great no stumble .

jedclampit
08-10-2012, 10:04 PM
x2. seems to be more of a regulator issue than pump. low at idle is ok, 3-4 psi. you want 6-7 at speed. if it goes over that, you can push too much fuel through/float the needles and flood it out.

You will dump fuel with much more than 7 psi at speed (or possibly bend floats/trash adjustments), usually when you lift( high rpm/high fuel pressure/low fuel demand) ....and its really pronounced with integral psi regulation built in the pump.

post back if you get it fixed, you may help someone searching same problem in the future!