Sonic test numbers, core shift and the not so good first time engine build experience

Discussion in 'Street/strip 400/430/455' started by 1969RIVI, Jul 14, 2020.

  1. alvareracing

    alvareracing Platinum Level Contributor

    I was going to suggest a 76 blue block I have but just seen where you are at, forget it!
     
  2. 1969RIVI

    1969RIVI Well-Known Member

    Yeh that's a bit too far lol:D thanks for thinking of me though:)
     
  3. Buick

    Buick Ramin Ansari

    How much power are you going to wring out of your combo?

    I just wonder what we did in the days when we (I) were (was) too stupid to know anything about core shift and sonic checking other than starting to look at lifter bore “thinness” and the occasional blow-out.

    Man, I’ve been under a rock for too long.
     
  4. 1969RIVI

    1969RIVI Well-Known Member

    I'm looking for around 500-600 HP when all said and done. I assume that back in the day when guys blew an engine up they probably didn't know that it was a ticking time bomb from day one since they didn't know the block wasn't adequate from the start due to excessive core shift and over boring. As the times went on and things were learned about these engines that's where I think alot of these "specs" come from thanks to the guys that "learned the hard way ". I just don't want to spend all this time and money on something the could be ok or could survive, I'd rather do it right and find another block and make sure it will be ok and survive.
     
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  5. hugger

    hugger Well-Known Member

    Sonic checking is like asking the hot drunk girl too many questions,.....the more you ask the more reasons you find to leave it alone,..which= no fun,.
     
  6. 1969RIVI

    1969RIVI Well-Known Member

    I hear ya Hugger! I just want to do this build just once so I'm trying my hardest to find a very good block to use. The engine in the car has its issues but is still running so I got time to look.
     
  7. Mark Demko

    Mark Demko Well-Known Member

    Drunk girls are fun, except when they barf:eek:
     
  8. BennyK81

    BennyK81 Well-Known Member

    haha went through the same...Jim Weise is building a shortblock now...
     
  9. BennyK81

    BennyK81 Well-Known Member

    I made the mistake and pulled the engine....finding out it was crap rendered me with a non driveable car...but one thing lead to another and now almost the whole car is apart
     
  10. 1969RIVI

    1969RIVI Well-Known Member

    Yeh, not going that route I dont have the time or funds to go down that rabbit hole:p. I'm going to keep driving the car as is until the other engine is ready then I'll pull the other one apart and see what was going on with it. In the meantime I'm working on replacing and upgrading the mounts, bushings and driveline to accept the new engine's power/torque level. Then I'll turn my attention to the body and paint. I did the interior when I bought the car. As much as I want one of JW's engines I want to build it myself as it's something I've always wanted to do. He along with others on here have had a heavy influence on my build plan along with tons of guidance for this project so my confidence is really high that I can pull this off!:)
     
  11. 1969RIVI

    1969RIVI Well-Known Member

    Well here we go again round three!! Bought this sucker and having it shipped tomorrow from Quebec, Ontario Canada. It's from a 74 Electra 225 that was previously rebuilt. It's in pieces but everything's there complete carb to pan. Hopefully this one checks out better and I can carry on with my build.
     

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  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    You know, when they over bored my block, they moved the cylinders around to maximize cylinder wall thickness. That might be a way to save a block.

    Motor2SonicCheckWorkSheet.jpg
     
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  13. 1969RIVI

    1969RIVI Well-Known Member

    Larry, all your numbers are above 100 to start with like JW said they should be. The issues with the blocks I have is the numbers on #6 pin side has been in the 70's so no matter what moving the bores around a bit wont help them.
     
  14. 1969RIVI

    1969RIVI Well-Known Member

    Picked up the engine today and yanked out piston #6 in the back of my trailer in the parking lot of the machine shop:p. I wasn't driving all the way home (1hr) to strip it apart to drive it back down. The machinist brought out the sonic tester and we checked pinside #6...........DING DING WE HAVE A WINNER:):):). The bottom of rear pinside came out at 102, middle 117, top 146 the front pinside of #6 was bottom 139, middle 146, top 176. We checked the bore size and its stock 4.31 so its it's never been rebuilt. The PO said the old guy he bought the car/engine from had it rebuilt, I imagine the old guy was confused on what type of "rebuild" he had done and only had rings and gaskets done. This engine is still sporting its original nylon timing set and it has ALL it's teeth still:D. This engine is definitely low mileage and was taken care of just by looking at most of the parts.I will post up some pics once I start diving into it a bit more.
     
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  15. 1969RIVI

    1969RIVI Well-Known Member

    Well I spent the afternoon in the garage tearing down the engine and I found out that this engine must of came from a Canadian car. This thing is so super clean inside and so little wear that the low mileage claims have got to be true! The cam that I pulled out has no markings or numbers anywhere but does have GMC stamped in between two lobes, anyone know if it's a stock 74 cam or aftermarket GMC? Now that its stripped down bare it's time for some mods then off to the machine shop:)
     

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    Last edited: Sep 9, 2020
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  16. 1969RIVI

    1969RIVI Well-Known Member

    Just dropped the block, crank and rods off at the machine shop for cleaning and checking fingers crossed everything comes back good and I can proceed with the build. I'll report back once I have some info.
     
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  17. mikethegoon

    mikethegoon Well-Known Member

    Now all that's left is to get in line.....
     

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  18. 1969RIVI

    1969RIVI Well-Known Member

    UPDATE: So I spoke with my machine shop today and all is well the block, crank and rods all checked out and I got my sonic test numbers. The crank will clean up with a 10/10. The block will go to a 0.30 over bore, a deck clean up cut around 0.15 and the crank tunnel will be align bored with the ARP bolts torqued down. The machinst mentioned moving cylinders 4&6 slightly to get a bit more thickness to the bottom parts of the cylinder walls as they're currently only 98 and 94. Now it's time to talk to JW about some pistons:)
     

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  19. Bens99gtp

    Bens99gtp Well-Known Member

    You will have a better piston and ring selection by going to 4.350 rather than staying 4.342..........I really don't think the .008 will kill you, and given parts choices you will be glad you did
     
  20. 1969RIVI

    1969RIVI Well-Known Member

    Ben can you elaborate a bit, I'm not quite understanding what you mean by parts choices. Other than pistons and rings and maybe gaskets what else changes from .30 to .38 partswise?
     

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