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Hot Rods AD_NAPCO's 39 GMC Rocket 324 Build

Discussion in 'The Hokey Ass Message Board' started by AD_NAPCO, Sep 29, 2011.

  1. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member

    If it is a good block; any ideas on what cam? Very mild to ? hyd? or stock?
     
  2. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    I've been thinking about that, and I know I don't want anything remotely radical... I want this motor to have good street manners. This thing has to run nice on the piss I can pull from the average gas pump.. The best we got in this state is 91 octane. I don't really know anything about cam profiles so that's another area where I'm looking to be schooled. "hyd?" you talking lifters? Hydraulic? I hadn't given any though to changing lifters. I think I read where some guys were putting sbc valves and lifters in the rockets to save money...

    One thing I forgot to post earlier was that my heads show two springs per valve, which I thought was odd. There's an inner spring wound from flat stock inside the normal round stock spring... Ever see that before?
     
  3. Bobert
    Joined: Feb 21, 2005
    Posts: 820

    Bobert
    Member Emeritus

    My 55 heads have the same springs. The inners are really dampeners and not springs. I guess they are to take care of spring harmonics that may set up.
     
  4. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    That's interesting... And here I thought it might be some performance mod!

    Thanks!
     
  5. So? What's happening with this? How'd the sonic testing check out?
     
  6. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Well, the machinist is lagging. he said he'd get it sonic checked by the end of this week... That leaves tomorrow. I'm trying to be patient. I know the heads did check out good so it's really just down to the block being thick enough to bore again... Will update as soon as I know.
     
  7. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Well, bad news, looks like my block has some pretty serious core shift. Minimum spec for cylinder wall thickness on major thrust surfaces is .170 and looks like it's as thin as .103 in a couple spots. I'm on the hunt for a new block. Bummer.
     
  8. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member

    56 block is one year only, unless you are willing to buy the earlier cam that has smaller journals.

    that being 54 and 55 324's have the small journals.
     
  9. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Thanks Frank... I forgot about that. thanks for reminding me. I have a couple options but need to wait to hear back from one guy. Both within driving distance. It's a bummer having a bill at the machine shop for checking out a block that is scrap, and on top of that, gotta buy another block! I guess that's just part of the joy of this hobby, right?

    All I know is somebody had a good bit of fun with this motor back in the day!
     
  10. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Still looking for a good 56 324 block. THought I had one located but I have not heard from the seller in quite a while.
     
  11. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member

    Have you contacted DESOTO? He is old school, and maybe in your town. I think.



    Who would have thought that these would be hard to find someday. They are getting scarce here too, and I have never found an early 371 available...I don't need one, but you know... :)
     
  12. mr50s
    Joined: Jul 26, 2009
    Posts: 59

    mr50s
    Member

    Hey AD NAPCO,

    Can't help you with a replacement block, but HAMBER "Blownolds" of Southern California just started advertising aftermarket early Olds camshafts that he has put up for sale on the HAMB website. Have you seen his 1/29/12 post yet?

    Good luck!!

    mr50s
     
  13. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Well, I finally heard from the guy with the 56 324 today. He says I can come down and get it tomorrow. It's a bit of a roll of the dice. He said the car was wrecked pretty early on in life so the motor has relatively low miles ~50K or so. Freeze plugs look good, and petcocks are out so no coolant in the block. If this turns out to be a good block and heads it's gonna save my bacon. I'm praying my bacon gets saved!




    Frank, I had not contacted DESOTO, about it, but I'll look him up. Thanks for that.

    I did manage to get a dizzy clamp but thanks for thinking of me!

    I had not seen that post but I found it. Looks like he's only got roller cams for 56 but I'll shoot him a message anyway and see if he's got anything he hasn't listed yet.

    I'll let you all know what happens tomorrow!
     
  14. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Well... I'm not real enthusiastic right now. I just spent the whole day going to retrieve the 56 324 from another HAMB member down south. Paid him $300 bucks for the motor. Has been sitting under the hood of the original car for many years, with the air cleaner and everything intact. Thought it was a good bet that the block would be clean inside. Pulled the heads about an hour ago and nearly shit myself. No wonder it wasn't turning over. I was hoping that if the block turned out to be bad that at least I could salvage and sell the #10 heads and recoup my money. I'm doubting that now but would like opinions from those of you who've been around the block a few more times than me. I haven't mic'd the bores yet. They look worse than my other block. At this point, if it looks like they've never been cut, maybe they can go a full .125 over and be clean. I'm scared the heads might be bad too. Valves/combustion chambers look pretty rusty. I wonder if they can be decked slightly to clean up? Tomorrow I'll try to get it clean enough to turn over so that I can remove the slant-pan hydro that's still attached. BTW... Slant pan hydramatic vs. earlier hydramatic? Any appreciable benefit one vs. the other? I just hope to God that if this stuff is all junk that the guy is honest and refunds my money. I can't afford $300 bucks down the toilet not to mention five hours worth of gas in my truck...
     

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  15. GOATROPER02
    Joined: Mar 22, 2006
    Posts: 2,059

    GOATROPER02
    Member
    from OHIO

    Unless I'm missing something... This looks like a typical core engine

    You've seen some of my tricked out powerplants....this is how they start out

    Tony
     
  16. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member


    well that makes me feel a lot better... I'll stay positive. Once I get the trans removed I'll tear it down and take everything to the machinist.

    fingers crossed.
     
  17. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member

    I agree. Don't worry, ...yet.

    My 56 block had broken a rod years ago, and left a divot in one bore on a 60,000 mile motor. I used a bore gauge to try to measure the depth of the divot; and it was about 13 thou, I thought. The now owner of it, sent it for machining, and it cleaned fine at .030 over.

    You probably will need to try to remove the rod and main caps to get the trans off with the crank still attached to the trans. Or try to free the pistons, but that looks iffy.

    The trans in a base cheapy model 88 will be the slant pan. The middle price 88 and the 98 would be the Jetaway trans.

    I need a single good "1956-only" piston if you can save one :)
     
  18. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Okay... This is all encouraging. Frank, if I can save a piston, I'll get it off to you in the mail asap. PM me your address again.
     
  19. I know there's lot of different methods for freeing the stuck pistons, but... When I tore my stuck 324 apart, I had three stuck pistons that were locking the crankshaft. After a week of soaking in diesel, and week of soaking in ATF/Acetone, they were still stuck. I filled the cylinders with good old Coca Cola, left them over night, came back with a 2x4 and a BFH the next morning and got them all to slide.
    Worth a shot!
     
  20. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Well, it was a few hours of cussing and beating with a big brass hammer, a brass drift, a length of 2x4, and various spray lubes, but I managed to get all 8 pistons out, and all of them came in one piece.

    One good thing is that I know for sure the motor has never been cut. All pistons are marked standard on top.

    Frank, I'll box you up the best one, and get it out asap.

    So, after I get a bite to eat, It's out to drain the torus and free this trans from the crank.

    Anyone have any idea what a slant pan hydra-matic core should be worth?

    Update:

    Got the block liberated and taken to the machinist. Gonna have to tank it for a couple days to see how bad the pitting is going to be in #6 and #8. He thinks those two will need sleeving but won't know for sure till it's tanked.

    So... More waiting. Bummer part is that I'm out $360 bucks for the work done on the scrap block.
     
    Last edited: Feb 2, 2012
  21. Blownolds
    Joined: Mar 31, 2001
    Posts: 2,335

    Blownolds
    Member
    from So Cal

    If it's any condolence, I've busted apart a couple dozen early Olds engines over the years... and they all looked just like that, except for a couple old race engines that were garage-kept. These engines just need to be completely built from the ground up. You're dealing with junk that's over 50 years old now....

    I have many dual-range hydramatic tranny cores available in the San Bernardino area. Prices for stock cores are around $50-75 per tranny, and if they have had hot-rod mods the price may be higher depending on what I know about the tranny.
     
  22. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Well, I finally heard back from the machinist today. Looks like the block magged fine, which is good. Number 6 and 8 holes have to be sleeved. The rest of the holes are all standard but have .030 taper. So .060 over it is!

    At least it's gonna work.

    Now I gotta figure out a cam. Not sure if either of the cores I have are good enough to regrind. I'm not looking for anything too snotty. I want good street manners. Anyone have a recommendation on how to proceed with the cam? Should I send the two cores I have out to Isky or Delta and have them tell me what I have and then go from there?

    After that... It's time to start pricing parts for the complete rebuild.

    Probably gonna scrap the slant pan. Apparently no interest in it and I don't have room to store it.
     
  23. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member

    Paul sends his cams out to a local shop, maybe ask him, or Goatroper
     
  24. Congratulations! A little bit extra work, but at least you can make it happen.

    I'd be interested in the kickdown linkage that connects the carb to the hydro if you have it and want it gone... :)
     
  25. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Sorry, i don't have it.


    Here's a question... What do you guys think about installing hardened valve seats? Should I worry about it with these heads or not? Machinist says I should but he has a vested interest in the money. I'm sure he thinks it's necessary but I've heard it both ways...
     
  26. GOATROPER02
    Joined: Mar 22, 2006
    Posts: 2,059

    GOATROPER02
    Member
    from OHIO

    Why does it need sleeved if its not broke?

    And yes to the hard valve seats

    Tony
     
  27. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Tony, all I know is that the machinist said that all cylinders with the exception of 6 and 8 will clean up at .060. The pitting/scaling in 6 and 8 is too deep for an .060 cut so he is suggesting sleeving those two cylinders. I think the idea being that if we cut the minimum on the remaining six cylinders there's probably a couple more rebuilds in the block, where as if we go a full .125 over again this is a one trip block. Is that not a good way to go?
     
    Last edited: Feb 15, 2012
  28. GOATROPER02
    Joined: Mar 22, 2006
    Posts: 2,059

    GOATROPER02
    Member
    from OHIO

    A sleeve is last resort.....use only when cracked or split....Sleeved cylinders never stay as round as stock case will ...even if the block is thin

    Think of it this way... 3.935 finished bore using only a thin wall sleeve of approx .062 per side means outside dia of sleeve is 4.060 or there abouts(I didnt look at my sleeve selection book) but your not going to use any thinner
    That means there is nothing left behind the sleeve for support

    I have piston and ring kits up to 3.945 or .070 over finished bore size......More then that you are in a dead area as far as ring sizes are concerned until 4.00

    At 4.00 there is anywhere from .160-180wall thickness left when I sonic check most 324's .... which is fine because the Olds doesnt have a bad rod angle.... like say a 302 Ford

    How bad is the acne after being bored.....A few pits wont hurt anything

    All this being said ...remember if you sleeve the block to stay at .060 you can never take it to 4.00 anyway because then you have no sleeve left or anywhere else because of the ring sizes available

    And unsleeved at 4.00 you could sqeak it to 4.005 and maybe 4.020( if you have a thick block) at a later date when you wear it out

    Hope how I wrote this makes sence

    Tony
     
    Last edited: Feb 15, 2012
  29. AD_NAPCO
    Joined: Mar 14, 2008
    Posts: 415

    AD_NAPCO
    Member

    Okay Tony... I see. Well, I'll call the machine shop in the morning and find out if he's already cut into the block and ask him how deep the pits are.

    The other block after the 4" bore was too thin to cut again as per what Ross told me when I called there I think it had spots as thin as .107 at major thrust surfaces. This one has .030 taper on standard bores... Would it be safe to guess with that much taper that there could be above average core shift, making it less likely to have more than one rebuild in it after a .125 cut?
     

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