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Yet another 1725 rebuild

Discussion in '"Stock" Alpine' started by spmdr, Nov 26, 2020.

  1. sunalp

    sunalp Platinum Level Sponsor

    I have a couple sets of standard 1725 pistons, used but still goo.
    Let me know if these would work.
  2. spmdr

    spmdr Donation Time

    I have struck out with contacts for Jeff K. So looking for pistons, still. PM sent, sunalp.

    I'm considering a piston order with Moss/ VB, anyone dealt with them since the move?

    Next choice is Ross or another piston co that has slipped my mind...
  3. RootesRacer

    RootesRacer Platinum Level Sponsor

    Years ago, VB didnt seem to know the difference between 1592 and 1725 pistons...
    CP Made my flat top 82.5mm pistons. They are not cheap, but at least they are forged.
  4. spmdr

    spmdr Donation Time

    As it turns out Moss/VB is on hold as far as parts sales, for Sunbeam for an indefinite time.

    I was thinking VB/Moss may be the Easy Button.

    I KNOW the BETTER result would be a custom piston with better ring dimensions.

    I also know that IF I want to build a few Hi-Po Sunbeam short blocks, I need to set up a

    source for custom pistons.
  5. RootesRacer

    RootesRacer Platinum Level Sponsor

    Yeah, I have a feeling that Moss is not that into the Alpine market and may end up not adding it to their line.
    Give CP a call, they do make good pistons. 82.5mm is a good ring size then .25mm steps off of that.
    82mm may be good too, who knows...
  6. bernd_st

    bernd_st Bronze Level Sponsor

  7. spmdr

    spmdr Donation Time

    I finally got around to checking Classic Sunbeam in NY and guess what?

    Curt had a LAST set of Hi compression STD pistons! YAY!!!

    I was thinking CS and SS had mostly the same parts so no need to check CS, WRONG.

    And expecting the pistons to come with only cast iron top rings, I scoured a ring catalog

    to find the best ring I could for the job, Chrome or Moly.

    It looks like early Pinto 1600 Moly rings +.030 will give me a nice oversize to file fit to perfection.

    At least that is the current plan.
    Last edited: Jun 29, 2021
  8. alpine_64

    alpine_64 Donation Time

    DW what do you want std high comp pistons for?
    I have 2 sets NOS jahns 12:1s sitting stateside if you want old school. They are .060 pop ups
  9. spmdr

    spmdr Donation Time

    I have several Engine builds in the works.

    The build of This thread is going to be mostly Stock.

    In this case, HC is only compared to the OTHER stock of LC OEM style pistons on the shelf at SS and CS.

    I am assuming the pistons from CS will have a dish, std 1725 size.

    BUT, as far as I am concerned, HC just lets me unshroud the valves, in a Viszard way.

    So, Bring on the HC pistons (no more than FT for this build)!
    Last edited: Jun 29, 2021
  10. alpine_64

    alpine_64 Donation Time

    If you had slightly longer rods yiu could probably deck the pistons to remove the 7.5cc dish and still have same compression height .. Or deck the block
  11. spmdr

    spmdr Donation Time

    The replacement pistons are correct. Rings are still a bit of a challenge, I really want Moly top rings.

    But they are proving to be harder to find (in the Pinto) than I thought.

    I may have to settle for Chrome.

    BUT, the next question, should I replace the rod bolts?

    This being a mostly stock rebuild, I don't NEED better bolts, But, I'm there.

    So, are there any ARP Rod bolts CURRENTLY available, that fit?

    Has anyone checked out the AMC ARP Rod bolts (114-6001) for an Alpine?
    Last edited: Jul 7, 2021
  12. spmdr

    spmdr Donation Time

  13. spmdr

    spmdr Donation Time

    I have the Pinto 1600 +30 chrome rings (2C5981+30) that look good.

    I have the ability to file fit the top ring.

    Now to pick a ring gap, I'm NOT thrilled with the Factory gap number of .024"

    I'm thinking .016"

    My next challenge is the Cam, the original is done, a regrind core.

    But, what to replace it with?

    I stumbled on an Isky SB2 And a Norris 296S from my cam pile, That I am contemplating.

    I have seen numbers on the SB2, but the Norris is a mystery.

    The Norris cam LOOKS like a smaller grind than the SB2, in spite of the 296 number.

    At this point, I don't know the upper limit (numbers) of what I would call an Alpine "street" cam.

    FYI, the cam grinder I have used for a LOT of years says the Stock 1725 cam has a duration of 219 @.050" tappet lift.

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