Best way to slow car
 

I have a sbc w/pg and 5.13 rear that runs consistent 5.60's.I am thinking of slowing it down to run a heads up 5.90 class,what is best way to go,if changing rear how far would I go,thanks for any input.

Restrictor plates or add about 300 lbs, if possible. That way you don't have change the tuneup.

JMO

Zip.

Toss out the laundry a little early 8) 8) 8)

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Best way
 

I have had this issue for 2 seasons.

Slowing a 5.90 car down to 6.40+ to avoid having to get a license again and the associated cost.

I went thru 10 ideas.

Finally used a homemade restrictor plate under the carb at a RJ members suggestion. Slowed to 6.28 with a 4 hole 1 3/4" plate for a 2" dominator carb. It works consistanly. Rather than making a few more to get slower and having to pull the carb each change, I bought an E Z Plate system. It has a 1" spacer with a cut out in the side to slide in 1 of 20 supplied plates. A simple 1 bolt cover comes off and a change can be made in 30 seconds. I haven't tried it yet, but a lot of Super class cars use them. It is very high quality looking, but is a little salty at $350. I think this will be the answer.

No changes to your tune up are required.

throttle stop the local engine builder will run a 7.20 flat in 1/4 mile but his chassis not certified for 7.20 so he puts the throttle stop on so he runs like a 7.40

PUT LESS FUEL IN IT ---WHEN IT RUNS OUT AT 200 FEET IT WILL SLOW YOU DOWN !!!!!!! :? :roll: :roll:

I used a pneumatic throttle controller to run IHRA Super Rod 6.40 index. I can slow my e.t. but still run 120 mph.

TS1955

I have the same issue as my car will run in the 5's but is not certified nor am I licensed...just make an adjustable throttle stop to put under the pedal and play with it until you get it right....you could also use a solid stop up on the carb.....the threaded rod under the pedal is cheap and crude but effective.

Some sort of throttle stop under the pedal is something I put on every car i build. The main reason is when you're 'pushing' for that last ounce of speed, you are not stressing out any of the linkage or stretching the cable. I make sure that it is adjusted at WOT and then can have the option of slowing it down if desired.
A lot of stuck throttle issues can be traced back to over-centered, deformed linkage, stuck wide open throttle blades, or frayed cables from over stressing, and no solid stop on the gas pedal.

High gear only should net you almost exactly what you need :)