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-   -   LOST 10mph AND ABOUT 6 TENTHS (https://classracer.com/classforum/showthread.php?t=78007)

bert powell 12-07-2020 10:17 AM

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.

gmeyer 12-07-2020 10:55 AM

Re: LOST 10mph AND ABOUT 6 TENTHS
 
Quote:

Originally Posted by Henrys Toy (Post 629424)
We took the coil and ignition box out of the car and ran it on the Dyno made good power

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!

Mike Pearson 12-07-2020 01:53 PM

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.

monte8616 12-09-2020 08:52 PM

Re: LOST 10mph AND ABOUT 6 TENTHS
 
Quote:

Originally Posted by Greg Hill (Post 629362)
Is this a Quadrajet motor or Holley? If it’s a q-jet I would bet money it’s in the fuel system.
It’s critical to have enough fuel volume and a q-jet on a 454 SS motor would really stress your fuel system. A good pump like a Magnafuel, a #10 line from the cell to the regulator, appropriate return line, and a # 8 line from the regulator to the carb would ne required. Even if it’s a Holley I would do the same thing.

Have that setup!! Thanks!

monte8616 12-09-2020 08:54 PM

Re: LOST 10mph AND ABOUT 6 TENTHS
 
Quote:

Originally Posted by gmeyer (Post 629428)
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!

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!!

voltdr 12-09-2020 09:59 PM

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

Mark Yacavone 12-09-2020 10:42 PM

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.

rboyle 12-09-2020 11:18 PM

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.

Travis Miller 12-09-2020 11:25 PM

Re: LOST 10mph AND ABOUT 6 TENTHS
 
Quote:

Originally Posted by Lee Jordan (3223) A/S (Post 629364)
Is the chassis still lose? Are all the wheels free, brakes bearings? What about the rear end? Could it be getting tight and slowing the car? Just something else to think about.

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.

Larry Hill 12-10-2020 07:54 AM

Re: LOST 10mph AND ABOUT 6 TENTHS
 
Dang Travis, that is one of my best kept “Speed Secrets”


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