Clearancing Molnar rods for roller cam

Discussion in 'Small Block Tech' started by Mark Demko, Jul 2, 2018.

  1. Mark Demko

    Mark Demko Well-Known Member

    All done, I removed 4.5 grams. I made sure each rod weighed the same.... 622.8 g
    300sbb_overkill likes this.
  2. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    So did you decide if you are going to have the crank rebalanced or run it?
  3. Mark Demko

    Mark Demko Well-Known Member

    Im running it.
    I installed all the pistons, and it turns over like velvet.
    My machinist said it will be off a bit, but nothing to worry about.
    Last edited: Jul 8, 2018
  4. Bens99gtp

    Bens99gtp Well-Known Member

    Did you by chance figure out how clearance you have between the rod and cam. Metal parts do expand when warm and moving........I've heard the top end of rod at high rpm can stretch .020 or more depending on rod. Not sure what the minute rod to cam clearness should be
    Mark Demko likes this.
  5. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    You in good hands with those guys so I’m sure it will be fine...
  6. Mark Demko

    Mark Demko Well-Known Member

    No I haven't checked, I tried looking at the #1 when I gained clearance, I wanted to see "how much" room I had, but DAMN, its tuff to near impossible to see:mad:
  7. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    You need one of those little round mirrors on a stick they sell at the auto parts stores for that, will make life so much easier.;)
    Mark Demko likes this.
  8. Mark Demko

    Mark Demko Well-Known Member

    I have that and an inspection camera (bore scope) Im gonna try again, maybe I can climb in there:p
    300sbb_overkill likes this.
  9. Jim Weise

    Jim Weise GOT AIR?


    To measure your cam to rod clearance, a nice fat roll of solder works well... just align it along the length of the rod and rotate the motor thru the contact zone.. it will compress the solder at the point of minimum clearance.. You might have to pop the piston on the same journal out, to get good access.. then measure the crushed area on the solder with a vernier caliper. Most of us like to see a min of .050 clearance.
    Dwayne B and Mark Demko like this.
  10. Mark Demko

    Mark Demko Well-Known Member

    Thanks Jim!!!!
  11. Mark Demko

    Mark Demko Well-Known Member

    I did #2 rod today with the solder, I measured .032
    Too close or am I ok?
  12. Mart

    Mart '71 350 GS, almost stock

    Don't know about the cam to rods, but Mike at TA thought .020 from crank throw to roller cam lobe was sufficient.
  13. 436'd Skylark

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

    Way too close. .060-.080 minimum. That's a time bomb. Once a little slop develops in the timing chain you'll be sweeping up parts.
  14. walts72

    walts72 Well-Known Member

  15. Fox's Den

    Fox's Den 22 years of racing the same 355 Buick motor

    I would go to .080+ be safe Do it and have the shop re balance.
  16. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    It’s a good idea to degree he can 2 degrees tetarded, ensure rod cleArance and then 2 degrees advanced from your current setting so that if some timing slack develops or you re degree the cam you are still safe. And yes if you need to take more off the rods then re balance forsure.
    300sbb_overkill likes this.
  17. Mark Demko

    Mark Demko Well-Known Member

    Im doing more checking for sure before I put the pan on.
    I don't like the idea of taking more off the rods, but now is the time to do it if need beo_O

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