292H Comp Cam, reusable?? How to tell.

Small Block Mopar Engine

  1. chrispy1971gtx

    chrispy1971gtx FABO Gold Member FABO Gold Member

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    Pulling apart a 73-340 I got off craigslist cheap. I had been sitting in a barn for several years and was told they had it in a van at one time. Which must have been true since it had van motor mounts and oil pan.

    So good and bad news. When tearing it down, I found .060 2316 pistons, j-heads with 202 valves, HV oil pump, etc. Bearings, crank, etc, look ok, and when pulling the cam, it has a 292H grind. The heads appear to have knurled valves or worn guides. They move around allot in an assembled state.

    The plan was rings, bearings, gaskets and cam, but now I'm thinking to stick with he cheap build, reusing the cam and installing new lifters. So how do I tell if the camshaft is reusable??


    Build plan: This short block, Promaxx 170/65 CC heads, LD340, headers, in a 66 coronet with 410 gears to do some amature drag racing that I've always wanted to do.

    Thanks
    Chris
     
    Last edited: Mar 16, 2019
  2. nm9stheham

    nm9stheham Well-Known Member

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    Visual inspection is step 1. Can't quite see your cam from here without pix.....LOL

    BTW.. L2316's would be a compression upgrade for a late model 340. What I don't know is the stock piston weight of the late 340 pistons, that were balanced with the cast crank and the weighted damper and TC. So IMHO, I'd examine the crank and damper very closely to see if the crank is cast or forged and if the damper and tC/flexplate are weighted (i.e., intentionally imbalanced to help add external balance weight to the cast crank).

    And of course, measure the bores carefully to see if the block is usable as is. What are you going to do about the sloppy guides?
     
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    • pishta

      pishta I know I'm right....

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      Promaxx 170/65 CC heads

      About the cam...you can mic the lobe height and see if there still is a taper on the nose, you can check the lifters for cupping, and thats about all the measuring you can do out of the car. A regrind is pretty cheap as your getting new lifters. you can get something very close with that cam core.
       
    • chrispy1971gtx

      chrispy1971gtx FABO Gold Member FABO Gold Member

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      On the guides, it was on the J-heads...... I'm switching to a new set of aluminum heads. Which is a splurge, but I figured rebuilding the heads would be 500-700 and the new AL heads are $1000.

      As far as balancing. Yea, they're allot of questions to answer. Its a CAST crank motor for sure. No unusual wear on bearings from what I've seen. No flex plate, so I'm not aware of what was on it, but had factory cast balance I just removed today. I took a picture of the crank what has weld to it that I'm not familiar with, but do have another 73 cast 340 crank to compare to.

      Camshaft: I'll get get pics. Cam has some very light surface rust that I think Evapo-rust will cure. I'm just wondering about any funny/unusual wear patterns. I'll clean up and attach pics. Thanks!
       
    • Dartish

      Dartish Well-Known Member

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      If you reuse that cam, DO NOT USE COMP CAMS hyd lifters!!!!!!! Find anything else. I know of 4 sets of comp lifters in the last year that had bad ones that clattered.
       
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      • chrispy1971gtx

        chrispy1971gtx FABO Gold Member FABO Gold Member

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        Just so happened I was on their website and noticed that there are 2 styles, and one is for adjustable valve train. But from what I've read Johnsons is pretty good brand.
         
      • chrispy1971gtx

        chrispy1971gtx FABO Gold Member FABO Gold Member

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        Pics...Last pic is another 73 340 crank.

        20190316_161703.jpg

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      • chrispy1971gtx

        chrispy1971gtx FABO Gold Member FABO Gold Member

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        @nm9stheham, I think you may have mentioned on the Speedmaster thread about checking the deck clearance, and low and behold there is .015 difference per side. One is at .010, the other at .025, and that's checking 3x and zeroing accordingly each time. So is this typical in production motors?
         
      • famous bob

        famous bob mopar misfit

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      • nm9stheham

        nm9stheham Well-Known Member

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        Maybe not typical, but that amount of difference has definitely been reported here by some of the professional machinists. That''ll make about .3-.4 point difference in compression ratio one side to the other. Not great but not a disaster IMHO.

        I'd take a closer look at the 6th lobe from the back on the cam. Can't quite tell on that one. The surface rust on the cam may be an issue..... I don't know how you get it out of the pores without effecting the lobe surface. And since it is an abrasive, that does not bode well unless it is all removed. I am not sure if the resulting compound when using a rust neutralizer is any less abrasive. I personally would not use it unless I had to. New flat tappet cams don't cost an arm and a leg....

        ON the top crank pix, is that some sort of metal inserted into the middle area of the front counterweight? How about rust/wear in the lifter bores?
         
      • chrispy1971gtx

        chrispy1971gtx FABO Gold Member FABO Gold Member

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        Yes, it appears to have weld in it, and the next throw is drilled. But the main/rod bearings look surprisingly good. Bearings are dated 1990 and are .010 under.

        The plan was to take the block and have it boiled, have the decked surfaced properly, etc. The lifter bores are OK. I pulled all the lifters out and cleaned them up. The cam is cheap enough, I'll go ahead and replace it at this point.
         
      • d55dave

        d55dave Well-Known Member

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        When deciding about the cam, look at the bottom of the old lifters. They should all be convex when you hold a straight edge across them. If they are flat or dished (concave) throw the cam out.
         
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        • high.rev.trev

          high.rev.trev Well-Known Member

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          At least 2 of those Cam lobes show evidence of its mating lifter not rotating anymore. But as you say your replacing the Cam now. ( Competition Products had a Nice SB Hyd Cam : Howards Ground 108LCA. 225°/235°, I picked one up for Future use. Accurately indexed too).
          BTW IMO 10thou diffence in the decks isn't going to add up to near 1/2 a full point in Comp ratio from side - side : ave of 10 thou off a head = about 1cc to maybe 1.6cc if Real Closed Small Chamber head, gee you can get that variation in compressed gasket thickness.Doubt you'll notice any performance difference except helping machine shops balance sheet. But at least all your pushrod lengths etc shouldn't be a worry.
          But each to his own..
          Heads for dug-out: waits for Incoming...
          Goodluck .T

          456159713.jpg
           
        • AJ/FormS

          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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          I could be be talked into reusing that cam,depending on the story the lifters tell; but I'd put a lot more spring on it.
           
        • RustyRatRod

          RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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          Somebody spent a lot of money balancing a cast crank.
           
        • high.rev.trev

          high.rev.trev Well-Known Member

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          Maybe not, ... Just maybe he was lookin' after the Machine shops daughter, in his Van, on the way to the Races ? :p

          IMG_20190318_054918.jpg
           
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          • nm9stheham

            nm9stheham Well-Known Member

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            Yes, you are right.... that 'welded in' button or slug is of interest....not sure it is Mallory metal or not. That is why I mentioned the later, low CR pistons perhaps being different... I do not know if they were lighter than the early 340 pistons or not. If so, that would lead to a re-balance of the crank with L2613F's. But I just don't know for sure.

            You're not going to re-use the lifters. right?
             
          • chrispy1971gtx

            chrispy1971gtx FABO Gold Member FABO Gold Member

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            No, I'll throw the lifters away. I actually may have a couple of old LC-340 pistons, and an old set of 2316's in .030 over.
             
          • chrispy1971gtx

            chrispy1971gtx FABO Gold Member FABO Gold Member

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            Soo...in my pile of 340 junk, I found an ancient standard LC-340 piston with rings installed 929.8 grams (2lbs .8oz on my cheap scale). And on a .030 2316, without rings, it weighs 895.8 oz. (1lb, 15.6oz). Side by side comparison with the pin installed 1/2 / 1/2 to each piston, its basically from the chamfer and up difference in compression height. Info I found said .100".
             
          • nm9stheham

            nm9stheham Well-Known Member

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            LC-340? Not familiar with that.... Badger? OH, I get it... 'Low Compression' LOL. Is that with 4 valve reliefs?

            IIRC, the later pistons had 4 valve reliefs, even from the factory. Others may be able to confirm. But if it is .100" lower on the CH vs. the 2316, then that sounds right for the later piston.
             
          • 340doc

            340doc Well-Known Member

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            I could use that passenger mount bracket if you have no use for it! :)
             
          • Wyrmrider

            Wyrmrider Well-Known Member

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            d55dave nailed it on the cam (lifter) inspection plus check the taper and polish
            however that old 292 is way out of date
            revs and has to to make power but not as much torque as a modern 284 would give you
            Howards, Lunati, and even the Comp HL series
            There are two major lifter makers
            Comp uses one
            Isky and Crower use another (better IMHO)
            you can tell by looking
             
          • pishta

            pishta I know I'm right....

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            see post #3. The wear pattern looks fine if one side is shiny, that means its still turning the lifter. If the wear pattern is shiny all across the nose, there is a good chance that the lifter is cupped (convex) or flat, both not good. Cams are cheap, regrinds are cheaper.
             
          • QuickDart360

            QuickDart360 Well-Known Member

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            Throw out that comp 292! Get the real 292 from mopar. It'll make more power.
             
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            • high.rev.trev

              high.rev.trev Well-Known Member

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              I'd basically covered most of that but I can see it has to get spelt out.
              Yeah Delphi & Johnson...
              Not many Joe Bloggs can check Lobe Crown taper. But visually is lobes look like # 6 & # 11 - your pushing your luck fitting new lifters, if you kept in same order, & only going to be a w/end basher , reuse, or do a late Isky 280 Mega Regrind Or Comp Can Similar on that Aftermarket stick & with the 292H's big lobes good chance you won't break through the induction heat treatment. Pull those LC's in to 108° ( You can generally move ea lobe about 2° either way. When REGRINDING) What about a Copy of a Comp Cams 280'ish 106°LCA longer Dur on the Exh grind ?. If your shooting for new lifters now anyway ?.
              Sometimes, nothing personal, I wonder if some of these questions are 'generic' questions so certain favoured ones can air their knowledge, (I've seen it b4 elsewhere).
              Cheers T
               
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