Choosing a new cam

Discussion in 'General IH Tech' started by Darrell Tuxworth, Nov 19, 2020.


  1. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    Jim, I think that was actually covered in some detail already. Maybe you missed it. See the posts by Joe Torres and WJA Jr. And some others as well.
     
  2. BinderBookie

    BinderBookie High Wheeler

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    Yeah, and I covered it more and again.
     
  3. Jeff Ismail

    Jeff Ismail High Wheeler

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    My 2 cents worth. Thru the years I have used 3 of the 4 Isky cam grinds and at least 2 of the Comp Cam grinds in various IH rigs. Currently in my 392 powered Travelall (which is used mostly for towing) I am using a 256 grind Isky and am very pleased with it compared to a stock cam that use to be in it. Rest of the drivetrain is Fitech fuel injection, NV4500, 4.56 gears and 35" tall tires. Lots of grunt to pull heavy loads including a recent trip from Oregon where I tipped the scales in excess of 17000 pounds. My white Scout II has a Comp 268 grind in it. Lost lots of bottom end when I went to this cam (compared to a Isky 256/262), but has great power at the top end. Not sure if I helped the discussion but you got my 2 cents worth.
     
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  4. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    Bummer. This morning I received an email from that company advertising the factory-grind cams on ebay:

    "Hello and thank you for your purchase.
    Unfortunately, due to inventory discrepancies in our warehouses we are unable to fulfill your order at this time.
    We apologize for the inconvenience and will be issuing you a full refund."
     
  5. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    Hello Jeff. In your opinion, would there be any downside in putting this Isky 256 cam in an otherwise stock '78 345 engine, 2-barrel carb (H2300-7448)? And would you know happen to know if it affects exhaust emissions in any negative way?

    I was trying to obtain a stock cam from Elgin, but they're proving to be scarce. Maybe extinct? BTW, this isn't an imminent need.
     
  6. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    Anyone used any of Schneider's cams, specifically their milder ones? They still show a lot of selections for IH V8s:

    http://schneidercams.com/hydraulicliftercamshafts-9.aspx

    I'm interested in their 248/256 cam. Their mildest one. Their quoted RPM range for it is 1000 - 3800. Sounds very stock-ish. One thing I don't understand about camshafts, been so long since I was really thinking about this stuff, is the longer exhaust duration with some aftermarket cams, like the 248/256 example. What's the purpose/advantage to that? I ask because the Elgin factory cam specs show the intake valve as having higher lift and longer duration, relative to the exhaust. This is the opposite of what Schneider did with theirs.

    FROM Elgin's site, for reference:
    Elginc_camshaft_specs.png
     
    Last edited: Nov 23, 2020
  7. BinderBookie

    BinderBookie High Wheeler

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    More exhaust duration aids scavenging and is done to improve exhaust flow. Some claim it extends the usable RPM range on engines a little without and effect on low and midrange. That is an oversimplification and overgeneralization because it can be part of a specific formula to overcome a specific problem in a particular engine. Usually assymetric cams (differn profiles on intake and exhaust) are built out of dyno tests to solve a particular problem. Often that comes down to a poor port design and poor flow. Longer exhaust duration is stated to sometime improve fuel economy because of the scavenging improvements. Again, all this is often engine and cylinder head specific.
     
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  8. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    Yep. No doubt. One would hope the cam was designed around an otherwise stock IH engine but that can't just be assumed. Schneider Cams is literally five minutes away. I suppose I could go over there and pick their brains about it. If they don't mind walk-ins these days. I do see that they make cams with that advertised 248-56 profile for a variety of engine makes and types. So they might just be applying some "known formula" (with minor variations) to lots of engines, which is known to work on some engines and just hoping for the best on others.

    Has me curious as to why the stock cam has a longer intake duration than the exhaust. Maybe as you said, to overcome some flaw/limitation with their V8 engines. It does have me curious then how flipping the equation, as Schneider and other have done, affects the engine's behavior.
     
    Last edited: Nov 23, 2020
  9. Ron A

    Ron A High Wheeler

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    Ask them. Howarth and Jones both had Schneider crosses on their racers. They have been grinding them for a while. I ran one in a 345 but it was not one of the milder ones, with low gears and 31s the top end was appreciated. I do miss that vs the stock 392 I am running now.
     
  10. Darrell Tuxworth

    Darrell Tuxworth High Wheeler

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    I don't remember exactly but I think it was .5-1 in/hg. And extremely rapid, like every cylinder was bleeding back into the intake.
    Darrell
     
  11. BinderBookie

    BinderBookie High Wheeler

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    Don't discount the possibility that IH was being lazy or cheap, recycling a cam design from years back. The cam specs for all years would have to be compared to prove it one way or another, but I found documentation that when the IH D282 and D301 diesels were being developed from the similar 242 gas architecture in the mid-late '50s, they designed and tested a new diesel camshaft for it. In the end, they decided the gas cam profile was "good enough." It only cost a few horsepower, but saved production costs.

    Also consider the possibility of an unusual profile having been developed for emissions purposes. Again, someone would need to go part number by part number, match the cam specs and match them to an engine of a particular era.
     
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  12. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    Yeah I'll head over there and ask them one of these days. Getting more curious about it. Especially as stock cams are so elusive.
     
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  13. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    That's funny. Above I'd actually written out, then deleted, that it could just be chalked up to a 1950s cam design, and an older understanding of what would be right for the engines.

    That's another thing. Another reason why I'd want to stick with the stock cam. I'd hate to go through the trouble of putting an 'improved' cam and then find out my Scout can't pass smog anymore.

    I wonder how much variation if any there was in cams for the SV engines over the years. For example, Elgin only makes (made?) one cam, one PN, that seems to cover all of them, right? And IHPA seems to sell only one "stock" cam on their web site.

    ETA: IHPA says that their stock cam "Replaces IH part number 151985R5". That might narrow it down. Anyone know what application(s) that PN maps to?
     
    Last edited: Nov 24, 2020
  14. Ron A

    Ron A High Wheeler

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    Very good possible. Maybe they have some blanks laying around.
     
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  15. Darrel

    Darrel Lives in an IH Dealership

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    Hmm. Maybe jordondoc will chime in with his readings.

    How much vacuum are you pulling at idle and cruise? Is the distributor or ecm controlling timing?


    .
     
  16. Darrell Tuxworth

    Darrell Tuxworth High Wheeler

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    I haven't checked in a while but if IIRC it was 15bat idle, never checked cruise. ECM does all the work for fuel and timing.

    Darrell
     
    Last edited: Nov 24, 2020
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  17. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    This had me wondering, if "stock" camshafts are no longer being made, possibly because the original mfr of the blanks stopped making them and supply has been exhausted, what are the aftermarket companies using to make their cams with? That's another question I should ask Schneider. Do they have a source for IH-specific blanks? Or is the end near even for aftermarket SV camshafts?
     
  18. Ron A

    Ron A High Wheeler

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    That’s what I am afraid of. We are going to be regrinding the old ones before you know it.
     
  19. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    I will try to stop in there next week. Right now on their web site they state that the 4-cyl IH cams are regrinds, but that is not the case for the 8-cyl cams. No idea how long it's been since the web site was updated. I suppose the "©2010" at the bottom of the page might be a clue. In any case, for the 4-cyl cams it says:

    "To get your cam reground you will need to ship it to us along with your name, contact info, and the grind you want."

    I suppose this would be true for 8-cyl cams as well. I also imagine that they'd be able to make a renewed stock profile cam if the customer wants it. I can ask them what process they use for regrinding, i.e. do they add metal as described somewhere above in this thread, will their reground cam be 'good as new' or better, etc.
     
    Last edited: Nov 25, 2020
  20. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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