Inconsistency

targus · 07-07-2014, 09:32 AM

Is it possible for a converter to cause an issue where my car will make 3 or 4 passes within .04 of each other then out of nowhere make a pass that is .2 slow. On the pass where is slows down it loses ET everywhere starting with the 60'. Everything has been changed on the car trying to solve this issue, wiring, MSD, coil, fuel system, etc... I am of the assumption that if something was wrong in the converter it would continue to slow down, where as once I load up after making this slow pass, the next time to the track the car is right back to making good passes.

3000 lbs car
540" BBC
Ladder Bar Rear Suspension
Powerglide

I installed a data recorder to track engine RPMs this past weekend and on the two passes where the car fell off, the RPMs are very shaky from about .07 into the run. I will try to post a picture of the graph later.

1320racer · 07-07-2014, 07:32 PM

post up all the time slips in order from the day in question.

That said, moving .04 in 3 or 4 passes is a problem no mind 2 tenths.

Consistency starts and end with the one wearing the brain bucket. Are you doing everything exactly the same from the moment you buckle your harness to the moment you cross the stripe?

Ed Wright · 07-08-2014, 05:45 PM

Too rich makes it too sensitive to temp and Baro changes.

targus · 07-08-2014, 07:25 PM

I pay extra attention to my routine for consistency, especially since these issues have come up.

I have the RPM graphs saved as pdfs but am not sure how to post them.

I do not think it is jetting just for the fact that no big change in weather has to happen for the car to make a slow run. No matter what the weather does the 4th or 5th run will be .2 slow and if we make any additional passes after the slow run they are slow as well.

1320racer · 07-08-2014, 09:35 PM

again, post the time slips in order from one day.

Lee Valentine · 07-11-2014, 01:48 PM

Had a car do that once, had one broken roller in converter sprag.

n5ifi · 05-18-2015, 01:00 PM

Quote:

Originally Posted by 1320racer

post up all the time slips in order from the day in question.

That said, moving .04 in 3 or 4 passes is a problem no mind 2 tenths.

Consistency starts and end with the one wearing the brain bucket. Are you doing everything exactly the same from the moment you buckle your harness to the moment you cross the stripe?

Exactly

Wilson1 · 01-01-2016, 11:12 AM

I had a very similar issue. Sent a good converter back to be freshened, when it returned it would do good for the first pass then the car would do weird things. It was a sprag converter. I had it cut twice, chased my tail looking at everything else on the car, finally at the end of the year, tried a different converter, the car went on kill. Both times I had the converter cut I was told that there was nothing wrong with it. There was something wrong with it but they just couldn't find it. One of the trans guys that cut the converter has it in his shop now and he told me he was going to find out just what was wrong. I have called him twice and he still doesn't have any answers.

If you changed the converter and the car is working, my advice is to not send the converter back that was causing you problems if it has been checked once, but junk it and start over. I would go back to the 8" if you still have it and get it tightened up. Good luck, this can be a very frustrating and time consuming problem.

07-07-2014, 09:32 AM	#1
targus Junior Member Join Date: Jul 2014 Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Inconsistency Is it possible for a converter to cause an issue where my car will make 3 or 4 passes within .04 of each other then out of nowhere make a pass that is .2 slow. On the pass where is slows down it loses ET everywhere starting with the 60'. Everything has been changed on the car trying to solve this issue, wiring, MSD, coil, fuel system, etc... I am of the assumption that if something was wrong in the converter it would continue to slow down, where as once I load up after making this slow pass, the next time to the track the car is right back to making good passes. 3000 lbs car 540" BBC Ladder Bar Rear Suspension Powerglide I installed a data recorder to track engine RPMs this past weekend and on the two passes where the car fell off, the RPMs are very shaky from about .07 into the run. I will try to post a picture of the graph later.

07-07-2014, 07:32 PM	#2
1320racer VIP Member Join Date: Nov 2007 Location: New Jersey Posts: 1,778 Likes: 70 Liked 400 Times in 191 Posts	Re: Inconsistency post up all the time slips in order from the day in question. That said, moving .04 in 3 or 4 passes is a problem no mind 2 tenths. Consistency starts and end with the one wearing the brain bucket. Are you doing everything exactly the same from the moment you buckle your harness to the moment you cross the stripe? Last edited by 1320racer; 07-07-2014 at 07:35 PM.

07-08-2014, 05:45 PM	#3
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 389 Times in 168 Posts	Re: Inconsistency Too rich makes it too sensitive to temp and Baro changes. __________________ Ed Wright 4156 SS/JA

07-08-2014, 07:25 PM	#4
targus Junior Member Join Date: Jul 2014 Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Re: Inconsistency I pay extra attention to my routine for consistency, especially since these issues have come up. I have the RPM graphs saved as pdfs but am not sure how to post them. I do not think it is jetting just for the fact that no big change in weather has to happen for the car to make a slow run. No matter what the weather does the 4th or 5th run will be .2 slow and if we make any additional passes after the slow run they are slow as well.

07-08-2014, 09:35 PM	#5
1320racer VIP Member Join Date: Nov 2007 Location: New Jersey Posts: 1,778 Likes: 70 Liked 400 Times in 191 Posts	Re: Inconsistency again, post the time slips in order from one day.

07-11-2014, 01:48 PM	#6
Lee Valentine Senior Member Join Date: May 2004 Location: Brookfield, CT Posts: 708 Likes: 13 Liked 322 Times in 68 Posts	Re: Inconsistency Had a car do that once, had one broken roller in converter sprag. __________________ Lee Valentine 1661 STK

01-01-2016, 11:12 AM	#8
Wilson1 Junior Member Join Date: Sep 2014 Posts: 17 Likes: 0 Liked 0 Times in 0 Posts	Re: Inconsistency I had a very similar issue. Sent a good converter back to be freshened, when it returned it would do good for the first pass then the car would do weird things. It was a sprag converter. I had it cut twice, chased my tail looking at everything else on the car, finally at the end of the year, tried a different converter, the car went on kill. Both times I had the converter cut I was told that there was nothing wrong with it. There was something wrong with it but they just couldn't find it. One of the trans guys that cut the converter has it in his shop now and he told me he was going to find out just what was wrong. I have called him twice and he still doesn't have any answers. If you changed the converter and the car is working, my advice is to not send the converter back that was causing you problems if it has been checked once, but junk it and start over. I would go back to the 8" if you still have it and get it tightened up. Good luck, this can be a very frustrating and time consuming problem.