Announcement

Collapse
No announcement yet.

R2 cylinder head

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Engine: R2 cylinder head

    What is the problem with the R2 heads cracking in the valve seat area Have one head cracked on my Avanti R2 Found a set off a 62 truck and one head was also cracked Good thing that Jack Vines has a set I ordered that he is willing to rebuild

  • #2
    One theory is that in order to make the combustion chamber larger, the foundry removed cast iron, making the area around the valves thinner. Then, the R2 puts more heat and pressure in there.

    BTW, worked on your heads today. Hard exhaust seats are in and deck is milled.

    jack vins
    PackardV8

    Comment


    • #3
      R2 Heads

      Since the R2 heads are prone to crack over time would it be wise on a rebuild of engine to use a dish type piston and use the R1 heads #1557570
      Thanks for the update on my heads from BTW







      Originally posted by PackardV8 View Post
      One theory is that in order to make the combustion chamber larger, the foundry removed cast iron, making the area around the valves thinner. Then, the R2 puts more heat and pressure in there.

      BTW, worked on your heads today. Hard exhaust seats are in and deck is milled.

      jack vins

      Comment


      • #4
        ALL the latter heads are at risk, imho. I've seen many cracked. A lot of people are running them and don't even know it.

        Comment


        • #5
          Where do these cracks appear? Bowl area, chamber area, port roof area, seat area??? Never have seen a problem of water cracks on any modified heads here.
          Perhaps engines have been overheated and steamed from poor cooling.
          Start and Stage Your Studebakers

          Comment


          • #6
            Originally posted by orecrush View Post
            Since the R2 heads are prone to crack over time would it be wise on a rebuild of engine to use a dish type piston and use the R1 heads #1557570
            Yes, of course!

            If the R2 heads crack, or even if they don't, use the more dependable R1 heads (if they are or you just want to) and get the needed volume in the piston top for the compression ratio you want.

            Just make it a reasonable ratio for the fuel you want to use. 8 1/2 to 1 would be a good choice for just driving around and the occasional stick-your-foot-in-it run. If you have some really good fuel available you can go higher; as high as your fuel will allow.

            If your compression ratio and blower boost are too high and the fuel octane too low, the engine can detonate and be heard as a ping, a rattle or even a rapid, repetitive knock in the extreme case.

            My R2 compression ratio seems a little high for the gasoline generally available today. I drive mine so seldom that I just put in the best gas I can and go easy on the gas pedal. Pinging doesn't seem so bad to hear it but pinging will eat up pistons, crack rings and pound out rod bearings.

            A little dish in the piston top that mirrors the open part of the Stude R1 chamber would be ideal.

            Just keep the top of the piston flat under the flat portion of the R1 head and at least as little head to piston clearance as stock to create a good squish area to get good combustion chamber turbulence at low RPMs to inhibit detonation. High RPMs are little problem as there is plenty of turbulence at high engine speeds.

            The constant ratio drive of the R2 blower as compared to the earlier Golden Hawk variable speed blower helps in that the boost doesn't come on until high engine speeds where the turbulence is higher to help prevent detonation.

            Can someone provide a photo of the crack in an R2 or R3 head?

            Don J

            Comment


            • #7
              A little dish in the piston top that mirrors the open part of the Stude R1 chamber would be ideal.
              Getting OT here, but back when the fast guys were doing the mirror dish thing, I bought into that; spent a bunch of money having custom forged pistons made up for Studebaker and Packard V8s.



              By the time I got those trick mirror dish pistons installed, the fastest guys did some more tests and turns out, a simple round dish was better. Back in 1956, Studebaker engineers got it right with the 289" dished pistons ;>)

              jack vines
              PackardV8

              Comment


              • #8
                Originally posted by PackardV8 View Post
                - - - and turns out, a simple round dish was better. Back in 1956, Studebaker engineers got it right with the 289" dished pistons ;>)

                jack vines
                That's a nice set of pistons you had made, there. Did you have any extra sets made?

                What is the volume of the dish? What compression ratio did you end up with?

                The advantage of this mirror dish combustion chamber is greatest at low engine speed and high load, like when lugging in high gear.

                Your combustion chamber promotes turbulence at low speeds, lowering octane requirement, allowing greater spark advance and giving a little more torque. That advantage diminishes as speed increases.

                At high engine speeds there is plenty of turbulence so is not so critical for the racers.

                Studebaker certainly had production issues in mind with their round dished pistons; fewer rejects with the castings and easier to finish machine than with a more complex dish configuration.

                Regards
                Last edited by Don Jeffers; 02-28-2017, 10:58 AM.

                Comment


                • #9
                  Hey Jack -

                  Wait long enough...someone will prove what you did WAS actually better..!
                  Happens all the time.
                  Me, I'd say it depends on the chamber shape...a good tight squeeze/quench is better than nonmoving air/fuel with a full round dish and a "D" shaped chamber. Many things come into play...

                  Mike

                  Comment

                  Working...
                  X