Throttle stop

Discussion in 'Race 400/430/455' started by BQUICK, Oct 28, 2020.


    BQUICK Well-Known Member

    A machine shop told me not to use throttle stop as it will change fuel distribution and some cylinder will/could run lean. Trying to slow car to run 10.00 index. I usually add weight but I don't have a legal weight bar setup so I add other ways. But why drag extra weight down the track?
    Tried timing but don't like to go below 26deg total.
    Thoughts on throttle stop?
    Was told restrictor plates better but rather not mess with them.....
  2. Jim Weise

    Jim Weise 1000+HP

    Nonsense... just make sure your not on the lean side to being with. While mixtures will not be as good as at WOT, something so far out of whack that it causes engine damage is unlikely.

    And it sounds like you will use very little stop on time, since your close enough to add weight now.. so that lessens any possibility of issues.

    I ran one for years.. with just the primaries of a 750 Holley running for the first 2 some seconds of the run. Never had any indication of detonation or lean cylinders during freshen up inspections.

    There are so many different types of stops on the market now, a blanket statement like that is silly. Whoever said that probably had some experience with a customer that did not know what they were doing, and used the wrong type of stop, on an engine that was too lean to begin with. Or they used a stop under a carb that did not like partial throttle opening.. not all carbs are created the same, dominators especially don't function correctly at certain throttle blade positions.

    Restrictor plate setups are actually much easier and simpler.. I have one here in the shop, we used it to slow down a 10.80 GS to the mid 11's, due to no roll bar in the car last year. Worked great, and if you want one, I can have one made for you. PM me about it. It will be hundreds of dollars cheaper than buying a good stop, and the timers, unless you already own some of it. You would probably need maybe half a dozen different size plates to keep the car on the index, during varying weather conditions.

    The active throttle stop, while more expensive and complex, does allow full top speed of your car, and is adjustable with just the push of a button.

    Pulling timing to slow the car is a bad idea... That will cause engine damage, due to excessive heat buildup. Late timing causes tons of heat.

  3. Thumper (aka greatscat)

    Thumper (aka greatscat) Well-Known Member

    Dedenbear solenoid throttle stop used on Scat and Thumper for many years,no harmful effect.use the dual throttle blade type. Can slow it down from thousenths to seconds. We sometimes slow them down from running 9s to 10.90 easily done. For 1/4 mile found a .003" movement in the adjustment nut changes et by .01 seconds.

    BQUICK Well-Known Member

    My stop is just an adjustable stop under the gas pedal inside the car and it would be in effect the entire pass. That's what shop was concerned about.....
  5. Thumper (aka greatscat)

    Thumper (aka greatscat) Well-Known Member

    BS mine is in effect entirely, the run,getting in and out of trailer, getting in the garage, washing it,checking tire pressure,fueling,etc etc. Lol
  6. Jim Weise

    Jim Weise 1000+HP

    If your worried about it, get an A/F gauge, put a bung in each header primary, and then check each cylinder for A/F ratio during the run. They make caps that screw in in place of the O2 sensor in unused bungs. In eight runs you will have your answer. How far are you closing the carb to slow it down?

    Sounds like Gary uses his throttle stop like a restrictor plate.. which also works, but gives up the ability to reach top speed in the traps, and to adjust it via on time, from the driver seat. Conversely it does eliminate the transition from on the stop to full throttle, high HP or traction limited cars can spin the tires in that situation.

    Lots of different ways to do it, the key is to find something that works consistently for you.


    BQUICK Well-Known Member

    Well I just looked at the 10.00 rules and it says: "throttle stops/controllers PROHIBITED"
    So I guess I'll be using weight and timing. Or would just something under gas pedal not be what they are talking about?
  8. telriv

    telriv Founders Club Member

    In my mind I think a restrictor plate would be a better choice.
    Jusy MHO
  9. Thumper (aka greatscat)

    Thumper (aka greatscat) Well-Known Member

    I've raced those classes with my stop. If I removed the solenoid it was considered a restrictor plate since it couldn't be controlled by a timer or manually from inside.

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