What is most likely to break when you hit a spark-cut rev limiter?

Discussion in 'Street/strip 400/430/455' started by johnriv67, Jan 7, 2020.

  1. johnriv67

    johnriv67 Well-Known Member

    Do pushrods go through rocker arms? Do pushrods snap?

    This would be at 6000 rpm, not 8000 like Hondas, etc.

    What breaks on our big blocks in the case that a mistake occurs and the bang off the limiter for a second?
     
  2. pbr400

    pbr400 68GS400

    Valves float and bearings spin.
    Patrick
     
  3. Luxus

    Luxus Gold Level Contributor

    Correct me if I'm wrong, but shouldn't a rev limiter prevent that from happening? Though I guess it depends on how you set it. But correctly set it should prevent damage by over revving.

    I guess the question might be better put what happens when an engine over-revs?
     
  4. 1972Mach1

    1972Mach1 Just some M.M.O.G. guy.....

    Your limiter is there to prevent damage. You should be able to hit it (repeatedly) with no problem. That's what it's for.
     
    Last edited: Jan 8, 2020
    DasRottweiler likes this.
  5. Philip66

    Philip66 Well-Known Member

    I thought the idea of a rev limiter was to stop things from breaking.
    Isn't that why your putting a rev limiter into action?!?!

    If it's just pulling spark I wouldn't think it would hurt anything. But if you floored it up against it for 20 seconds or so then you're asking for trouble.
     
    johnriv67 likes this.
  6. Philip66

    Philip66 Well-Known Member

    I guess I type too slow....
    ;)
     
    slimfromnz and 1972Mach1 like this.
  7. johnriv67

    johnriv67 Well-Known Member

    Philip had the exact answer I wanted. Thank you

    I wondered how “safe” it was to bump off the limiter a little, on say a massive burnout for a few seconds
     
  8. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    I always broke an adjustable pushrod..

    If you spend enough time on the rev limiter your mufflers will fill with unburned gas and you'll get a mean backfire. I had that happen with an inaccurate tach..
     
  9. Stevem

    Stevem Well-Known Member

    With out a cylinder firing due to termination of spark output production of cylinder pressure to power the Exh flow is greatly deminshed and if you sit on limiter too long the unused fuel can hydro lock the cylinder and or blow your mufflers off as stated above.
     
  10. bobc455

    bobc455 Well-Known Member

    The biggest risk IMO is that when the spart re-starts, you have a lot of unburnt fuel in the exhaust and can get a backfire (depends on a lot of factors).
     
  11. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The MSD rev limiters eliminate the spark on random cylinders, they call it soft touch rev control. You won't do any damage if you bump up against it occasionally. If you are stupid and stay in it repeatedly for a long time, well it can't be good.:D I know we would never do that though.:)
     
  12. BQUICK

    BQUICK Gold Level Contributor

    I hit neutral one time at full throttle. Rev limiter was set at 7200 because I had been chasing down a missfire so I set it high to rule it out.
    Anyway tach memory showed 7800.....kinda hard to slow a fast spinning engine....rev limiter tried....
    Thought it survived it but about 20 passes later a bearing spun....must have injured it and then later chewed and grabbed it....

    With hydraulic cam usually valves will float before it gets too high especially with weak stock springs......but my cam was solid.
     
  13. 69a-body

    69a-body Well-Known Member

    Some ignitions just start pulling timing instead of an off/on spark. Mine starts soft rev control about 200 rpm before dropping cylinders.
     

Share This Page