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Thread: .040" Billet rod too much in NON hemi with 14cc head and...

  1. #1
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    .040" Billet rod too much in NON hemi with 14cc head and...

    .040" Billet rod too much in NON hemi with 14cc head and... .009 head gasket shim with CM .265" cam and 1.3 rockers... 26# springs for the required clearance of .345" lift at valve? 26# springs are supposed to be good for .425" lift? I wud run 22# springs so it DOES NOT have to fight the springs and maybe wipe the lobes off cam, but they are only good for ~.315" lift. got new stainless valves, keepers/hats. hate to put .027-.032" head gasket on motor when .009 is so nice, seems counter productive.

    does crank need to be clearanced with the cam i'm running, like I saw on Utube vid for the HEMI and a cam? not that big a deal, I have grinders. do it anyway to lighten up the lower end a little bit, make it smooth for windage. the motor isn't balanced anyway, right?

    NO I didn't measure piston/head/valve distance as I haven't taken it apart, I have too many things that are taken apart already and need to be put back together again. I want to get all the parts together, take it apart, put parts in, and start it back up and it run right without blowing anything up/smashing valves/piston into head. u know.... do it RIGHT the FIRST TIME?

    YES, it has cone air filter, header, scooter muffler but no jet as it runs too rich here with factory jet so it needs more AIR, not more fuel...for now. 390 carb, tuning nightmare? I bored to 17mm factory carb (cut through into low speed idle jet pocket a little bit with 17mm bit, I can epoxy that. got BUSY with the wen grinder and opened up the intake quite a bit... dug into needle and seat bowl there ... I can fix that with epoxy/JB.

    motor is waiting for a candidate to be put on, big wheel mini bike with springs up front for decent price... which is less than the price of used ok MC on CL. 400KZ for $400 but "needed work" and... NO TITLE. Cost as much to get title as it would to get that bike and no telling if it ran/how much it wud cost to get it running?/

  2. #2
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    The +.040 rod should only be used with the .550 compression height piston. Personally I would go with a zero deck height piston/rod combo paired with a .036 MLS headgasket so you maintain your .030 Piston to head clearance and a spare .006 for crank/rod flex. That would be like 13:1 compression, or you could use the fire ring .045 gasket for the best seal and achieve 12.5:1 compression which is nice. For 390 carb, they arnt the best on gas but are hard to beat on alky, and Barry Young is the man to get in touch with for 390 alky carb for sure.

  3. #3
    4 Cycle Advanced User alvin l nunley's Avatar
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    many believe that a 2 to 1 Rod length to stroke ratio is ideal. The clone has about a 1 to 1.5 ratio. Running a stroker crank with the same rod decreases even that ratio. Now more cubic inches might be better, but the unconventional rod to stroke ratio is going to detract from that, and it's going to make it harder on the parts. Side loading on the piston is going to increase tremendously.

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    13:1 would be a little much compression with 91 octane gas? that is all I can get here from local gas stations... right? need.... 93 octane + for 13:1? or not? cuz of higher altitude 3000'+ so 13 psi air pressure instead of 14.7 @ sea level so not as much air is going to go in the motor no matter what, y/n?

    what is compression height of stock NON hemi piston vs HEMI piston... .020" less for the dish NON hemi piston, right? love to run METH, but where to get it and how MUCH $$$$$ IS IT???? $5/a pint? qt? is a little high.... TOO HIGH for me. no E 85 here in oil country.

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    Non Hemis are all over the place for deck height... seen them .07 in the hole to .02

    Just use a .04 rod a, flat top Hemi piston, and a .045 gasket...
    The flat top has .02 lower compression height...

    I have ran 13-1 comp. ratio on 93-94 pump gas no problem...
    You can mix Xylene at 10-30% for a 1-3 point bump in octane...
    you can by Xylene and or Alky at Lowe’s, Home Depot, Walmart...
    Called Methyl hydrate... same thing...

  6. #6
    4 Cycle Advanced User alvin l nunley's Avatar
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    I'm really no expert on the subject, but with less air going into the engine, (less pressure) I would think a lower octane fuel could be used. Wouldn't hurt to try. Detonation is the problem and octane is a measure of a fuels ability to resist detonation. Detonations main cause is excessive heat and/or pressure. You could try a colder plug.

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    Non Hemis are all over the place for deck height... seen them .07 in the hole to .02

    Just use a .04 rod a, flat top Hemi piston, and a .045 gasket...
    The flat top has .02 lower compression height...

    I have ran 13-1 comp. ratio on 93-94 pump gas no problem...
    You can mix Xylene at 10-30% for a 1-3 point bump in octane...
    you can by Xylene and or Alky at HD/WM...
    Called Methyl hydrate... same thing... that stuff in the blue can with FUEL on the label? for $5 for.... a PINT? I cant even do the math on what that would be a gallon.... x 8 pints in gallon? $40/gal? av gas starts to look cheap at....????

    OK, guess I wont know til I get into it, I want to do this once, it work and mostly be done with it. 390's picky on gas, but great on methyl alcohol.... where we get that... xylene 10-30% good as any? with less air... detonation might not be a problem cuz less air in the combustion chamber no matter what @ 3600'

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