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Thread: 340 mopar

  1. #1
    Junior Member SHOW GUEST
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    340 mopar

    hi guy's,my son bought a 72 dustr,340 stock bottom end,360 heads,purple shaft 484 lift cam--runs o/k,has performer intake,850 holley--any suggestion from u mopar xperts to get more out of it??

  2. #2
    Senior Member MASTER BUILDER
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    Is it a street engine? Maybe mill those heads to get the compression up. Port work. Header size? What rear gear you running, and auto or 4 speed?

  3. #3
    Junior Member SHOW GUEST
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    i think you may be right about compression,we don't know we bought it running,it has a 4.30 gear,727 trans,10" converter.we use an msd with 2-step hooked to the brake light switch & leave at 3000,it runs 8.30 in the 1/8th at 83 mph,60 ft is 1.80--hate to disassemble it to find out whats in it & compression ratio,it runs too good

  4. #4
    Senior Member MASTER BUILDER
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    Your combo sounds pretty good. The 60 foot sounds off for a 4.30 gear. Slicks or street tires? If you want it to haul butt one word (nitrous). But since you don't know the internals that could be dangerous.

  5. #5
    Senior Member DYNO OPERATOR
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    I say, keep it like it is for awhile, play, get used to it, then take it apart and build it up. david.

  6. #6
    Senior Member RACING JUNKIE
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    If not knowing is not killing you I agree with others drive it and get used to it, and this winter do some upgrades.
    High compression 12.5 or higher, roller cam and more converter would really wake that 340 up.
    Right now you sound a bit over carbed for that small a motor a 750 would probably help out better, if you have one to try it and see.
    Goodluck, Charles
    ***IN GOD WE TRUST***

  7. #7
    Junior Member SHOW GUEST
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    thanks for the replies--the rear tires are m/t indy profile ss (soft & sticky) they work good but you have to get them REALLY hot.theyre just about gone.just bought some e-t street drags but were going to have to change axles to get 15" wheels on it to match (has classic cragar ss) they don't offer a 15" in 5 on 4 lug pattern.nothing against nitrous but i'm an "all motor"guy.we tried a 750 & 780 carb,but the 850 still has it beat by a tenth-i'm with you,i thought it was too much--but the #'s dont lie.another odd thing is this motor want's about 52 degr. of total timing,starts o/k like that & any less the e-t goes south--can anybody figure that one out?

  8. #8
    Senior Member RACING JUNKIE
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    Your welcome.
    We are here to help.
    I was just thinking your damper might be off alittle cause there's noway your engine would run right with that much timing. It should be closer to 37 to 39 total for a small block.
    I would take number plug out and turn engine by hand till number one is all way up and see where your pointer is, if it's not pretty close to tdc on the damper, its has spun in the hub some, common problem on older dampers. You can get a replacmenet oem one fairly cheap.
    Goodluck Charles
    ***IN GOD WE TRUST***


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