Re: LOST 10mph AND ABOUT 6 TENTHS
 

I forgot about the water pump. My V-6 is a Cam trigger and the magnetic pickup is on top, behind the water pump. I had a pump start leaking as we were loading the car. When we got to Ennis we made one run with a towel taped to the pump. It was leaking too bad so I took the Cheaper brand pump I carried as a spare and put it on. The car popped and missed at high RPM. We looked at plugs and ignition and all the electrical. We had one more shot of qualifying left and as I was doing my burn out the car popped on the chip... It hit me that the pump was what we changed and the problems cropped up. As I staged I turned the pump off. Good run, no 9000 RPM miss. Got back to the trailer and took the other pump apart and robbed the seal out of the electrical gremlin pump. Finished the race with no pump or miss problems. I figure that pump motor was a small radio station tuned to my ignition frequency. It wasn't playing any tunes my ignition liked...It seems like the simplest fixes can be the hardest!

Re: LOST 10mph AND ABOUT 6 TENTHS
 

we had a bad ground on electric water pump slow us down one time.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

You stated earlier that you changed the ignition box and it picked up on one run. Then it returned to the loss of mph and ET.

What box are you running?

Robin

Re: LOST 10mph AND ABOUT 6 TENTHS
 

The car has a MSD 7AL-2

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Make sure the dist pickup wire is away from the other wires, I use a shielded pick up wire.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

our car slowed down over a couple of races. Turns out it was the rubber brake line to the rearend swapped out line at track and picked up instant 5 tenths.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Can you post a net slip from both a fast and slow run? Can you post the race pack info from a good run with a bad one overlaid on it? What sensors do you have on the trace pack? Other thing would be send the race pack files from a good run and a slow one to someone you know who has been using a race pack for a while. Might pick up something.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

I would look at the rear brake hose. I have seen more than one collapse internally and hold the rear brakes on.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

We had a power surge from the alternator, lost et chased our tail, replaced ignition box. First pass was good, and down hill from there. Replaced box again. One more good pass and then fell off again .5 to .6 . In our case it was the alternator.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

We took the coil and ignition box out of the car and ran it on the Dyno made good power[/QUOTE]

Over the course of time the two things that would kill my car was a bad MSD box or a broken converter!
I had a Sprague break in my old Trans Torque converter , that I sent to Mike Munsinger at the time and he said the converter was good - put it in the car - still slow.
I finally sent the converter to Coan , they found a broken sprague , fixed it
Result - car fast again! These bloody things will really make you chase your tail.
Try a converter from a friend ,hopefully a known good piece, I think you might just find the "cure". Bill you might remember my MSD problem from Lebanon Valley a few years back, my car was slow and you said it didn't leave like it used to. We changed a bunch of stuff ( including the converter ) then last time shot on Saturday morning Glenn and I put spare MSD and coil , Result - car fast again. Engine never missed or did anything outwardly stupid just not fast.
I hope this helps, we have all been down this path!

Re: LOST 10mph AND ABOUT 6 TENTHS
 

I had a brake hose do this years ago. A piece of the rubber inside line broke loose and when you pushed the brakes it flipped over and blocked from releasing fluid, just line a line lock but would eventually bleed off. Easy check, push brakes and release, then try and spin the wheel by hand.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Over the course of time the two things that would kill my car was a bad MSD box or a broken converter!
I had a Sprague break in my old Trans Torque converter , that I sent to Mike Munsinger at the time and he said the converter was good - put it in the car - still slow.
I finally sent the converter to Coan , they found a broken sprague , fixed it
Result - car fast again! These bloody things will really make you chase your tail.
Try a converter from a friend ,hopefully a known good piece, I think you might just find the "cure".

This is my thought it could be!

Re: LOST 10mph AND ABOUT 6 TENTHS
 

If you have lightweight brakes on the car and have been heavy on the brake pedal the pads can be worn on an angle and they will drag like crazy. Pull the pads off and measure them. If they are worn on an skew get some new ones.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Have that setup!! Thanks!

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Thank you! You’re absolutely right and although I had the converter cut open and looked at but I know people who said they didn’t take the sprague apart - probably worth shipping it again!!

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Back in the day, when I ran a sprag in my converters, when it broke, the ET really fell off but the MPH didn't fall off as much.
Dan

Re: LOST 10mph AND ABOUT 6 TENTHS
 

It's not the converter.

Also, it seems to me, a choked down brake hose would be noticeable when driving through the pits or coasting into the staging lanes.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

I got a good friend with a 1969 Camaro that had the original rubber brake hose from the hard line on the chassis to the block on the rear end collapse sporadically internally. It caused a similar problem. Did not lock up on him coasting through the pits. Just a cheap easy thing to change if it's old or rubber.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

After years of working around dragstrips I am still surprised at the number of cars that are hard to push. Sometimes a car might not start at the scales and has to be pushed out of the way. A racecar should roll easily. The best example of how easy a racecar should roll belongs to our old friend Al Provoast (RIP). Al could push that big heavy station wagon all by himself. While that may not be the issue in this case, everyone should make it a point throughout the year to see how easily your car can roll. If something is causing it to become harder to push by hand, rest assured it has nothing to do with how the engine is running.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Dang Travis, that is one of my best kept “Speed Secrets”

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Everywhere :(

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Try disconnecting the fuel line at the rear of the car blow it out with a low pressure air hose ---if you have a filter blow the line between rear of car and front of filter make sure its open ---then try from tank to before the filter with line disconnected--- from the rear to front try blowing from tank side of the filter thru the filter --- probably a clogged filter --if you do the 3 step method you will isolate where its "plugged"--- how old are the fuel lines in the car?? are they Aeroquip??? or stock??? if they are more than 2-3 years old might be time to replace them as the lining has maybe deteriorated -also check regulator for any obstructions ----FED 387

Re: LOST 10mph AND ABOUT 6 TENTHS
 

For curiositys sake, did you check the rear end housing and see if its flipping? We straightened out a pinion angle shifting problem and housing binding on a car and it was worth half a second.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Does anybody know if this problem was ever resolved? Curious as to what it ended up being.

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Definitely Check all your battery cables and grounds etc... carefully!

Re: LOST 10mph AND ABOUT 6 TENTHS
 

With a Data Logger, on my car I was able to take my best run and just superimpose one run over the other....

Look at flash, fall back, EGT, fuel pressure and all of your data inputs.

My old AutoMeter logger had this feature, but I don’t know about racepak

Good luck

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Just in case anyone would like an update... it appears as though the electric fan we changed to must’ve been the issue... we went to a water pump/electric fan combo and car ran well - still a few kinks to work out but it appears as though the gremlins have moved on!! Thanks so much for all the ideas and advice!!

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Glad you figured it out!