Modifications to GM harmonic dampener to use on 308

GrimGreaser
GrimGreaser Senior Contributor
edited December 2012 in HUDSON
I currently have my 308 down for valve and ring work (still in the car). I have a Chevy small-block dampener just laying around and have seen several used on 308's. Just wondering if anyone can tell me what needs to be done and at what dimensions. I have a spare crank out in storage, but don't have another dampener to compare to. I'm curious, but don't want to tear apart the front of my engine any more than I have too. Thanks.

Comments

  • Park_W
    Park_W Senior Contributor
    Doesn't the damper (characteristics) need to be tailored to the crankshaft it's going to work with?
  • Geoff
    Geoff Senior Contributor
    Jack Clifford had a new dampener for the 308 motors which he reckoned smoothed them out much better. Are these still around?
  • GrimGreaser
    GrimGreaser Senior Contributor
    edited December 2012
    I think internal vs. external balancing is a major point, but I have seen small block dampener on 308's.

    Fluidamper claims they tune each by specific engine, however the GM one covers small blocks, 90deg V6's, and L6's. That's fluid instead of elastomer though.
  • dougson
    dougson Senior Contributor
    edited December 2012
    I have a GM style damper fitted to my 308, I believe the crank had to be milled a bit. The builder built a pointer using aftermarket parts (TCI). The engine doesn't move at idle, easy to time. Second picture shows complete hook up with aluminum pulley.
  • LHudson
    LHudson Expert Adviser
    My son (Hudsonator) had a stroker crank balanced in Memphis and it took the 8.25 GM balancer to deal with the harmonics of the crank. The smaller balancers did not do the job. Hope this helps. L Hud
  • GrimGreaser
    GrimGreaser Senior Contributor
    edited December 2012
    Thanks. I don't suppose anyone out there with a crank handy can give me the dimension of the front snout? I'm lazy and don't want to walk out to the back shed. :) I also keep leaving my calipers at work.
  • SuperDave
    SuperDave Senior Contributor
    What ever you do.. Don't use one from a small block 400. That engine is externally balanced and the balancer (as well as the flywheel) REALLY is a ballancer and has a large counter weight in it.
  • GrimGreaser
    GrimGreaser Senior Contributor
    Yeah - internal balance is the key. I would like to put a Fluidamper on mine down the line, which is kinda why I'm looking to mess around with the GM damper.
  • TwinH
    TwinH Senior Contributor
    Just checked mine,the balancers not on yet. Came up with 1.310" dia. and 1.425" from the
    spacer to the end of the crank snout.
  • maasfhcenturylinknet
    maasfhcenturylinknet Senior Contributor
    Calling fluid damp monday to see if I can get a few made again.
    Randy Maas
  • Lee ODell
    Lee ODell Senior Contributor
    edited December 2012

    GrimGreaser 8:12AM Flag
    Posts: 461Platinum Member
    Yeah - internal balance is the key. I would like to put a Fluidamper on mine down the line, which is kinda why I'm looking to mess around with the GM damper.

    When I took the Chevy balancer off my El Camino's modified blueprinted engine and installed a Fluidamper I noticed that the engine ran smoother than it did with the Chevy balancer.

    The stock balancers remove crank harmonics at a set RPM. Engine modifications can change where the engine RPMs harmonics happpen. The Fluidamer will remove crank harmonics at whatever RPM they appear. I would be surprised if a Chevy engine harmonics would be at the same RPM as the Hudson engine.

    I would be interested in the results you experience with the Fluidamper on your Hudson. I think the results will be better than with a Chevy balancer and I expect better than Hudson balancer also.
    Lee O'Dell
  • GrimGreaser
    GrimGreaser Senior Contributor
    edited December 2012
    No doubt the fluid dampener is the way to go, but I'm not hot rodding the motor beyond the Twin-H and improved ignition right now. I don't have $300 for one right now though. I do have an old GM dampener, and access to a lathe. I had forgot Randy and Russ had fluid dampeners made before.

    Thanks for the measurement Twin-H
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