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  1. #1
    Join Date
    Apr 2008
    Posts
    193

    Default Rod and Main bearing clearance

    Hey guys. Have a question. Just got done assembling engine , and some guys are telling me my bearing clearance is to tight. Its a 350 chevy, ( .040 over) with stock crank, and stock rods that were resized / shotpeened with arp bolts. Its a 2 barrel ( stock rochester) engine , and it probally makes 275 hp max. It is in a 3200 lb street stock, and i and it will be spinning 6700 max, but would like to keep it to 6300 or so. I have the Mahle lightweight pistons,10.1 true comp and its been balanced.My rod clearance is .002 and mains are .025. Side clearance was .011, and end play was .005. My buddies are saying this is to tight. Any opinions are greatly appreciated. I hate to take it back apart if i don't have to, but i will if need be. Thanks in advance.

  2. #2
    Join Date
    May 2007
    Location
    PA
    Posts
    844

    Default

    .0025 rod and .0025-.003 mains is preferred but you should be fine. If you want, purchase a set of "x" brgs and use 1/2 the set to gain .0005 clearance.
    Josh K.

  3. #3
    Join Date
    May 2007
    Location
    west virginia
    Posts
    547

    Default

    what are you useing to ck it with?

  4. #4
    Join Date
    May 2007
    Posts
    1,016

    Default

    Hope it's not plasti gauge..

  5. #5
    Join Date
    Apr 2008
    Posts
    193

    Default

    Thanks for the replies guys.I used a mich and a dial bore gauge. I checked and double checked everything, so im sure its accurate.Gonna fire it tomorrow, so hope it works out. Thanks for the input.

  6. #6
    Join Date
    May 2007
    Location
    PA
    Posts
    844

    Default

    Depending on the dial bore gauge, some tend to dig into the bearing slightly giving you a false reading and appearing to have more clearance then what is really there. keep this in mind.
    Josh K.

  7. #7
    Join Date
    Oct 2008
    Location
    Michigan
    Posts
    102

    Default

    .002 on rods and .0025 on the mains should not be a problem with your application. This would be my ideal goal if I was assembling this stock crank motor. Just do not try to run 50 wt oil in it.

  8. #8
    Join Date
    Apr 2008
    Posts
    193

    Default

    Hey Fast. The one i used has rollers on it, and it didn't mark the bearings, so i don't think it dug into them. I fired it today, and everything looks good so far. No blow by and good oil pressure. Thanks for the reply Ford.I guess the only thing that worries me is the stock rods at 6500 , but we have to run them at this track, so no other choice.I will know after next sunday. hahahaha. Thanks for the replys.

  9. #9

    Arrow

    Quote Originally Posted by sj valley dave View Post
    Hope it's not plasti gauge..
    Some times plasti gauge is more accurate then some of the cheap bore gauges guys use with ridgid fingers as then don't work when checking bearing with eccentricty.

    I have had a lot of bore gauge wars at my shop over the years and those cheap gauges don't compare to my Sunnen. I clearance out a lot of rotators and my circle track customers and street and strip customers check my work with it and its never been a problem.

    Its pretty simple how a peice of wax string works. It has surely bailed alot of guys over the years.

  10. #10
    Join Date
    Feb 2008
    Location
    West Michigan
    Posts
    34

    Default

    Quote Originally Posted by CNC BLOCKS View Post
    Some times plasti gauge is more accurate then some of the cheap bore gauges guys use with ridgid fingers as then don't work when checking bearing with eccentricty.

    I have had a lot of bore gauge wars at my shop over the years and those cheap gauges don't compare to my Sunnen. I clearance out a lot of rotators and my circle track customers and street and strip customers check my work with it and its never been a problem.

    Its pretty simple how a peice of wax string works. It has surely bailed alot of guys over the years.
    Plasti gauge gets a bad rap. It's actually better than some think if used correctly. Last week I compared a clearance check on a sbc. My Sunnen read exactly the same as Plasti gauge everywhere we checked.

  11. #11

    Default

    Quote Originally Posted by Rodz View Post
    Plasti gauge gets a bad rap. It's actually better than some think if used correctly. Last week I compared a clearance check on a sbc. My Sunnen read exactly the same as Plasti gauge everywhere we checked.
    I agree 100 % those cheap bore gauges should not be used for checking bearing clearances period. Just ask the guys at Mahle!!

  12. #12
    Join Date
    May 2007
    Location
    tulsa america
    Posts
    2,686

    Default

    Quote Originally Posted by CNC BLOCKS View Post
    I agree 100 % those cheap bore gauges should not be used for checking bearing clearances period. Just ask the guys at Mahle!!
    so what brands would you suggest. I see sunnen listed. Any others?

  13. #13

    Default

    Quote Originally Posted by powerslide View Post
    so what brands would you suggest. I see sunnen listed. Any others?
    Sunnen bore gauges and setting fixtures are number one when it comes to engine building.

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