How best to slow down a car that's too fast
09-12-2010, 03:04 PM
#1
Senior Member
DYNO OPERATOR
Thread Starter
Join Date: Jan 2004
Location: central Illinois
Posts: 459
How best to slow down a car that's too fast
This is the best problem I have ever had with a drag race car, but it is still a problem.
I do not have a NHRA license anymore and don't intend to get one again. My 1980 Chevy Malibu is back halved, big tired with a 496 BBC, 1050 Dominator carb, and Powerglide. It weighs 3150 with me in it. I can go 6.40 seconds in the 1/8 mile without a license.
When it is 90 degrees out and not great track conditions I am able to keep it above 6.40 with just backing off the timing and lowering starting line and shift RPM chips. But on a good day and good traction, it is still too fast.
Right now I have a mechanical stop for the carb and have it slowed down that way, but it hurts the 60 foot time about .10 second . I have the carb shut off to about 60 degrees open. It still runs the same MPH, 106.
I have had an inline throttle stop before but dont have one set up for this car. I didn't really like the throttle opening and closing with that set up.
I was thinking about maybe hooking up a MSD retard module and then use it down track with a timer on my Mega 450 delay box. That way I could have it turned up all the way in first gear and slow it mid track, but have it back full tilt for the finish.
I know there was a rule about down track stutter boxes years ago, but I haven't seen anything about it lately.
Anybody have any success with this or a better idea?
I do not have a NHRA license anymore and don't intend to get one again. My 1980 Chevy Malibu is back halved, big tired with a 496 BBC, 1050 Dominator carb, and Powerglide. It weighs 3150 with me in it. I can go 6.40 seconds in the 1/8 mile without a license.
When it is 90 degrees out and not great track conditions I am able to keep it above 6.40 with just backing off the timing and lowering starting line and shift RPM chips. But on a good day and good traction, it is still too fast.
Right now I have a mechanical stop for the carb and have it slowed down that way, but it hurts the 60 foot time about .10 second . I have the carb shut off to about 60 degrees open. It still runs the same MPH, 106.
I have had an inline throttle stop before but dont have one set up for this car. I didn't really like the throttle opening and closing with that set up.
I was thinking about maybe hooking up a MSD retard module and then use it down track with a timer on my Mega 450 delay box. That way I could have it turned up all the way in first gear and slow it mid track, but have it back full tilt for the finish.
I know there was a rule about down track stutter boxes years ago, but I haven't seen anything about it lately.
Anybody have any success with this or a better idea?
09-12-2010, 06:39 PM
#3
Senior Member
RACING JUNKIE
Join Date: Jan 2006
Location: La.
Posts: 2,890
Mark, if you have a milling machine available, you can make carb restricters. I did this with Jimmy Smiths car about 4 yrs. ago when he was runing the 7.0 class on gas (he's now changed to alcohol). I had/have a number of CNC machines available to me and i took .030 shim stock and made a series of smaller venturie plates to fit between the carb gasket useing 2 gaskets. I made them each in .030 steps/holes, i made about 10 of them he could go from 6.70 to 7.20 by just changing out the shim plate. They didn't hurt the 60' times and didn't effect the 4.0 tree leave and he could run the 7.0 # at every race he went too. He switched to stacks injection, and run at half throttle with a peddle stop screw, people said that wouldn't work also, WRONG, he won 5 of 8 races attended the first yr. with the stacks.
Congrats on letting you NHRA lic. expire, i let mine expire in April 2010, and didn't re-up my membership. My 1980 Malibu is also a backhalfed car certifiable to 8.50, we now only have 1 NHRA track in the state, so it's not worth it (NHRA) Mine only runs 6.50's with the sm/blk in it.
Zip.
Congrats on letting you NHRA lic. expire, i let mine expire in April 2010, and didn't re-up my membership. My 1980 Malibu is also a backhalfed car certifiable to 8.50, we now only have 1 NHRA track in the state, so it's not worth it (NHRA) Mine only runs 6.50's with the sm/blk in it.
Zip.
