72 Skylark 350 rebuild.

Discussion in 'Small Block Tech' started by mattd3933, Oct 3, 2018.

  1. mattd3933

    mattd3933 Member

    I have a 72 Skylark that I basically inherited from my stepfather,. He bought it from my great aunt in about 1993. And parked it in his barn/ garage. It likely had a head gasket failure that prompted my aunt to sell. The car was probably last cranked in 95 latest. He died and now I have the Buick.

    Engine was very stuck. Rings stuck bad in 2 cylinders right where head gasket failed. We opened the engine pbblastered the pistons and eventually freed one with no damage. The other one was worse and we ended up bending a connecting rod. ATM the engine is totally apart, crank, camshaft, empty case other than lifters.

    my issue now is the connecting rod. Rock Auto sell s them but only set of 8.. I found one on eBay from a 68 Skylark, . Would the 68 connecting rod work in my 72? They look Very close. Nuts are 12 pt. Wrist pin end looks the same. Will post link to the eBay rod. Thanks in advance.
     

    Attached Files:

  2. MrSony

    MrSony Well-Known Member

    68-73 rods iirc are the same, it wasa 74/75 when the rods changed. It'd be a good idea to have the bottom end rebalanced since its already apart.
     
  3. mattd3933

    mattd3933 Member

  4. MrSony

    MrSony Well-Known Member

    Seems like a good buy. TA also has full sets of reconditioned rods with new bolts for sale, if you go that route. If one rod bent, no telling what shape the others are in you can't tell with the naked eye unless you have them speced by a shop.
     
  5. stk3171

    stk3171 Well-Known Member

    I dint know this till I took a 73 350 apart and it had 4 early and 4 late rods in it. I came out of an Apollo 73 unmolested 350 2 barrel car.

    Dan
     
  6. mattd3933

    mattd3933 Member

    The other rods should be ok,. I have no reason to doubt them. We just really struggled with that one. Used a brass rod and hammer to bang it out thinking the brass would give way before the rod.. the rest came out easily enough, switched to a wooden hammer handle for pushing them out.
     
  7. alec296

    alec296 i need another buick

    Cylinder walls probably pitted bad too. Have them measured for cleanup before getting pistons.
     
  8. mattd3933

    mattd3933 Member

    The walls don't look terrible. Passable I'd say, after we hit em with the cylinder honer. Good advice though, Worst pitting was in cylinder right where the head gasket was leaking. It's just around the top . Today is going to be a clean up, inspect, organize day, since pretty much all the grease monkey work is done for now.
     
  9. alec296

    alec296 i need another buick

    I would suggest replacing the front cam bearing also. A TA backgrooved front cam bearing is best.
     
  10. mattd3933

    mattd3933 Member

    Cam bearings have to be machine pressed in yeah? I'm doing all the rod bearings and main bearings. Replacing the camshaft totally since the overhaul kit I'm getting comes with one. Didn't plan to do cam bearings.

    This is my first rebuild, I mostly work on looms but I'm learning. I don't plan to make a hotrod (not a 2 door). I want it to run good and look good when it's done.
     
  11. MrSony

    MrSony Well-Known Member

    They are hammered in with a special tool that anyone can buy, but once you pound them in, they kinda "form" to the bearing hole, so you damn sure better get it on the 1st try. I rather pay the $50 or so to have them put in, while the block is there, just be SURE to have them installed correctly as per the instructions. Boring, and cam bearings was about $250 when I had my 1st engine done back in 2015. $400 to have cylinder heads cleaned up, three angle valve job, 2 valves replaced, and guides measured. $400 to have cylinder heads cleaned up, three angle valve job, 2 valves replaced, and guides measured, and springs/seals installed. Everything else was just assembly by me.
     
  12. alec296

    alec296 i need another buick

    I hope pistons didn’t come in that kit. Most are ussually lower in compression the the factory 8.2 compression you actually have. Unless they are 340p pistons then they are about 9.2
     
  13. mattd3933

    mattd3933 Member

  14. mattd3933

    mattd3933 Member

    Also checked cylinder width. The we're right on 3.8 if my memory is right
     
  15. alec296

    alec296 i need another buick

    Looks like Chevy 350 parts/Pistons.
    Those pistons listed are not buick specs.
     
  16. MrSony

    MrSony Well-Known Member

    Yeah, don't get those. Those are all chevrolet pistons. even if they would fit in the bores, the compression hegiht is .3 smaller than stock, you'd be at like 5:1 compression or something stupidly low like that. Engine wouldn't even run.
     
  17. MrSony

    MrSony Well-Known Member

    https://www.rockauto.com/en/catalog/buick,1972,skylark,5.7l+350cid+v8,1023028,engine,piston,5620
    3rd ones down are the only Buick pistons. p15048. They are dished though, so some decking would be required, thinner .020 headgasket, etc.
    Go through summit, get 340p pistons. Stock block will get you 9.5:1, good street compression. I don't remember what gasket (.020 or .040 felpro) gives you the 9.5:1, but from one to the other it's about .5 to .7 of a point difference.
    https://www.summitracing.com/parts/slp-340p30/overview/make/buick

    These are .030 340p pistons.
     
  18. alec296

    alec296 i need another buick

    1.805 compression height. Yuck. About.090-.100 below deck for an actual 7.7 compression with felpro gasket.
    I would get the 340p pistons (1.835) and a crower level 3 cam. Do not get a high volume oil pump kit. Booster plate and new pressure relief spring ( I believe the booster kit may come with choice of springs)
    For 60 psi relief.
    Deck block .020 and use felpro gasket. About 9.45 compression. Drill out oil pickup passage and get 77-80 melling pickup tube.
     
    MrSony likes this.
  19. mattd3933

    mattd3933 Member

  20. MrSony

    MrSony Well-Known Member

    All those pistons, except the ones I stated, are for a CHEVROLET ENGINE and will physically not fit. Only the PH15048 pistons will work, but they will give you terrible compression, the engine will be a turd. With the above linked 340p pistons, yes they are more expensive, but they will give you some actual performance and you can still use pump gas, just premium. If you don't do any decking and use a felpro gasket, with a good tune you could run it on mid grade (about 89 octane) fuel if you wanted.
     
    300sbb_overkill likes this.

Share This Page