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  1. noseoil

    Broken spring

    It's running again, but for how long? Ran 7,300 rpm & it was pulling well. Need to run it back up to 8,000 again & see what happens. Thinking the next motor should be a larger displacement, but down-tuned from this type of build for durability.
  2. noseoil

    Broken spring

    "You must have the correct spring height for proper spring pressure on the valve seat," I got that one, but what is it? Still looking for the correct spring height for a Hemi with 26# coils. It's different than the "normal" clone head height, due to the different casting & angled valves from...
  3. noseoil

    Broken spring

    Checked pushrods (chromoly, glass & no click-click) & coil bind is non-issue. It's a good 0.06" between coils with valve fully lifted on the cam. Thinking a bad spring at this point.
  4. noseoil

    Broken spring

    I'm going to check for coil bind this morning, but it's the "Hemi kit" from ARC Racing which has the SS valves, springs & retainers as a complete set, so I need to see if there's a problem with my setup. It's a stock head on top, but ported down below. Otherwise it's basically the factory head.
  5. noseoil

    Broken spring

    Make that 7.2:1, not 72:1, sorry
  6. noseoil

    Broken spring

    No, this was the "fresh" motor with a new bottom end, new SS valves, retainers, lash caps, & the new 26# springs (SS hemi kit from ARC). It has a little over an hour total now, but has run a couple of 8,000 rpm passes prior to this one. I'd changed gearing to keep it from winding up too tight &...
  7. noseoil

    Broken spring

    Just curious, I'm running the Black Mamba cam, stock rockers (1:1 ratio) & all new SS valves, retainers, lash caps & 26 pound springs. Did a test pass today & at 6880 rpm it snapped a spring on the exhaust side. Fortunately, it didn't suck the valve & I've replaced the spring with an older one...
  8. noseoil

    VC 460 rpm range?

    After doing some more reading & looking, it seems like staying under 7,000 is the way these builds need to be done. Above this and things start to break. Below this number with a billet rod & flywheel loolks to be fairly safe for a longer running motor. Guess I need to do a bit more research...
  9. noseoil

    VC 460 rpm range?

    Wondering who has built one of these motors? Which parts, cam, insides etc. & what rpm range is "safe" for pulling good sustained power out of this type of motor?
  10. noseoil

    Balancing?

    Been running a bit more with the new bottom end, changed 1st oil & did a couple of pulls to see how it runs yesterday. Had a slight tuning issue which was resolved. Added a little more fuel in the mid range by changing the needle 2 positions richer, much better transition now to WOT. It was...
  11. noseoil

    Balancing?

    Put the "new" motor back together again. Decided to say screw balancing with my tools & background, just run it & see how it holds up. New HF crank with new ARC bearings is a bit tight, so I'm dropping to 0w-20 oil. Hopefully it will work. It's back running again, so we'll see how long it lasts...
  12. noseoil

    Engine shutting off after revving out.

    Fuel cap & vent issue?
  13. noseoil

    Balancing?

    Best guess, yes, that's what I think was done to fit it into the Predator motor.
  14. noseoil

    Balancing?

    Here's a shot of the bottom of the piston. I just went out to the shop again to look at the bottom of the pin on the edges which look to be fractures. It's just some residue from the stuff floating around the shop & oil, not stress fractures, as it looks at this magnification. The other shot...
  15. noseoil

    Balancing?

    I guess I could set up a router, but it's not safe!Only other way I could do it would be with the drill press & an end mill & start playing, but I'm a wood worker by trade, so having me do this type of stuff might be an expensive way to make a mess. There's lots of meat in there, but the way I...
  16. noseoil

    Balancing?

    It's says "Arias" inside the bottom of the dome. After looking it up online, looks like Bullfrog got an Arias forged piston, then had it machined to their specs for a match to the Predator hemi engine. I think that's why this thing shakes so badly at the wrong rpm range, it's slinging so much...
  17. noseoil

    Balancing?

    Here are the numbers for the ARC rod & Bullfrog piston. Piston is 253g (50 grams heavier than the Predator standard flat top hemi piston at 201g) Arc rod is 149.5g (not much heavier than the 142.3g Predator rod). There's 55 g more with the aftermarket combination. The engine was in pretty good...
  18. noseoil

    General Lee minibike.

    Yes, a "Bully" type of clutch setup for the sliding member of a torque converter would be the way to make it balance & run correctly, but the cost in machining, research & development, trial & error would be staggering. I'm thinking the light flywheel is also a factor, as Delray has said. We...
  19. noseoil

    Balancing?

    Still need to tear into the "old" motor to see what the parts weigh. Popeye, will you be able to get some weights on your motor? I'd be interested to see what the parts are in it. Which motor is it on the bike (the model number)?
  20. noseoil

    Balancing?

    I've just looked at another site with a different explanation of the method & I have left out the "big end" of the rod completely, as Popeye mentioned. I'd still be interested in someone else's numbers as a reality check on my numbers, just to see...
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