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    Senior Member lbhsbz's Avatar
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    I've degreed cams in on the last 5 engines I've built. Only one of them matched the cam card when set straight up. WTF is the problem with the grinders indexing the cam in such a way that it matches the damn card? Clearly they can index the rest of it correctly...so what's so hard about 3 bolt holes and a dowel pin? The stupid Chinese can get the keyways cut in the correct spot on their cranks, you'd think US cam makers could drill holes in the right spot. One of them was 8° out. 3 of them were 2° out, and this last one, which I'm advancing a bit per CStraubs suggestion, ended up on the 2° retarded slot because 2° advanced put it on a 99° int. centerline.

    :::rant off:::

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    Senior Member GT Jets's Avatar
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    Quote Originally Posted by lbhsbz View Post
    I've degreed cams in on the last 5 engines I've built. Only one of them matched the cam card when set straight up. WTF is the problem with the grinders indexing the cam in such a way that it matches the damn card? Clearly they can index the rest of it correctly...so what's so hard about 3 bolt holes and a dowel pin? The stupid Chinese can get the keyways cut in the correct spot on their cranks, you'd think US cam makers could drill holes in the right spot. One of them was 8° out. 3 of them were 2° out, and this last one, which I'm advancing a bit per CStraubs suggestion, ended up on the 2° retarded slot because 2° advanced put it on a 99° int. centerline.

    :::rant off:::
    How much chain slop are you seeing? The distance from the front main to the cam bearing hole makes this number jump around a bit in my experience...

    Another consideration is how deep the chain rides in the gear. There are too many variables affecting the relationship between the two rotating shafts to be "dead nuts" every time, but that would be nice.......

    Be sure to degree the cam in with the crank going forward every time....I have seen this common sense practice get ignored and a quick recheck proves up to a 4 degree discrepancy...
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    Senior Member lbhsbz's Avatar
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    Quote Originally Posted by GT Jets View Post
    How much chain slop are you seeing? The distance from the front main to the cam bearing hole makes this number jump around a bit in my experience...

    Another consideration is how deep the chain rides in the gear. There are too many variables affecting the relationship between the two rotating shafts to be "dead nuts" every time, but that would be nice.......

    Be sure to degree the cam in with the crank going forward every time....I have seen this common sense practice get ignored and a quick recheck proves up to a 4 degree discrepancy...
    Chain on the new motor is tight like a sumbitch...I like it. Chains on other motors have been a bit on the sloppy side, but not more than 2° or so.

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    gn7
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    Quote Originally Posted by lbhsbz View Post
    I've degreed cams in on the last 5 engines I've built. Only one of them matched the cam card when set straight up. WTF is the problem with the grinders indexing the cam in such a way that it matches the damn card? Clearly they can index the rest of it correctly...so what's so hard about 3 bolt holes and a dowel pin? The stupid Chinese can get the keyways cut in the correct spot on their cranks, you'd think US cam makers could drill holes in the right spot. One of them was 8° out. 3 of them were 2° out, and this last one, which I'm advancing a bit per CStraubs suggestion, ended up on the 2° retarded slot because 2° advanced put it on a 99° int. centerline.

    :::rant off:::
    And you know the "Chinese have the key cut correctly because.....?
    And you know the Chinese timing set your using is cut correctly beacuse..?
    And your certain the timing numbers you using include any "ground in advance" and are not just the LSA number?



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    gn7
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    Quote Originally Posted by GT Jets View Post

    Another consideration is how deep the chain rides in the gear.
    OK, I'll bite. And this effects the timing how? I know what your thinking, and I have had this little discussion more that once. So think about it for a little while first.



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    Senior Member lbhsbz's Avatar
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    Quote Originally Posted by gn7 View Post
    OK, I'll bite. And this effects the timing how? I know what your thinking, and I have had this little discussion more that once. So think about it for a little while first.
    A smaller wheel has less degrees in it right? LOL.

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    Senior Member lbhsbz's Avatar
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    Quote Originally Posted by gn7 View Post
    And you know the "Chinese have the key cut correctly because.....?
    And you know the Chinese timing set your using is cut correctly beacuse..?
    And your certain the timing numbers you using include any "ground in advance" and are not just the LSA number?
    Answer to the first 2: cuz I checked it against 3 other cranks and it all matched, and I tried a few different chains. I've got a pile of old T-sets laying around, and I've compared them in the past to the new Engine Pro unit with same results.

    "Ground in advance"...someone needs to explain this one to me....is this some kinda super secret deal that cam grinders do to trick you? I thought the cam was supposed to match the cam card....if it doesn't, whats the point of a cam card? How are we supposed to know where to put the damn thing? I set 'em up based on either the intake centerline or if supplied, the opening/closing points @.050. Why do they need to grind in advance? Make it match the card straight up, then if you wanna adv. or ret. it you can do that with the timing set....

    As usually, I'm probably missing something here. What is it.

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    Howdy,

    Normally, cam companies (at least the serious ones) beg you to check their work. That is best done with a firm foundation on
    A) An absolute location of TDC
    B) Good resolution degree wheel (bigger is better)
    C) Check by all four timing events and finally
    D) See where the intake lobe max lift point is for reference, but believe C for clarity

    Small degree wheels, poor line up of marker, and misalignment of the dial indicator(s) are common sources of error and so is parallax views of all the above.

    As far as I am concerned using D only is all but wasted unless you are in a hurry or thrashing at the races or on the dyno.

    These are of course my opinions and only that.

    Regards,
    IG

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    gn7
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    Quote Originally Posted by lbhsbz View Post
    Answer to the first 2: cuz I checked it against 3 other cranks and it all matched, and I tried a few different chains. I've got a pile of old T-sets laying around, and I've compared them in the past to the new Engine Pro unit with same results.

    "Ground in advance"...someone needs to explain this one to me....is this some kinda super secret deal that cam grinders do to trick you? I thought the cam was supposed to match the cam card....if it doesn't, whats the point of a cam card? How are we supposed to know where to put the damn thing? I set 'em up based on either the intake centerline or if supplied, the opening/closing points @.050. Why do they need to grind in advance? Make it match the card straight up, then if you wanna adv. or ret. it you can do that with the timing set....

    As usually, I'm probably missing something here. What is it.
    By the time your done reading this, you'll understand why CStraub told you what he did.
    I believe this is the Bullet cam you had that is ground with a 109* LSA. I can assume you have no T card, unless you requisted one from them. So your assumption is based on the 109*. Couple of problems with that approach. First, no gaurantee that the cam is ground in a split overlap condition. I agree, they should all be ground straight up. But this is the real world and the cam companies found out they are dealing with dumb asses, more often than not. So they started advancing the "pin" years ago. Comp Cams made a stinking fortune with that little move when they first started with their "famous" HI ENERGY" cams.

    Another problem is, your assuming the cam is ground symmetrical. That the opening and closing ramps are the same. Which means the max lift point is exactly at 109* or half way between the .020 or .050 numbers. Bad assumption. If I had to pay you 10 cents for every Bullet cam ground with an asymmetrical lobe, I would have to sell my house. Which means the only way to assure that you are in fact at CL, is to find the 2 .020 points and go half way between.


    So why did Chris give you a specific * number to shot for? Because he had no way of knowing if the cam had an advance ground in, or if the cam was symmetrical or not. So by giving you an actual IC number, he ASSUMED you would know how to find it.

    So maybe, just maybe, your really not at XXX* CL, and the T sets aren't as far off as you think



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    Senior Member GT Jets's Avatar
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    Quote Originally Posted by gn7 View Post
    OK, I'll bite. And this effects the timing how? I know what your thinking, and I have had this little discussion more that once. So think about it for a little while first.
    Mix- matching timing gears from cam/crank, I have seen a somewhat worn crank gear with a deeper penetration used with a "newer" cam gear with little/no wear, this will "retard" a known cam timing by a very small amount.

    This came about when we were building a "Junkyard Dog" and were too damn lazy to pull the crank gear and it started a debate that came up with this result;

    We had two cranks, one with a "new" gear and one with a 150,000 mile old gear, we checked it by ultimately swapping the gears on the same crank and new timing chain, we saw a notable difference, can't remember the actual numbers, this was over 10 years ago.

    Different rolling diameters was the final consensus..

    I had always assumed (there's that word again) that if both gears were worn similarly, they would be much closer as far as final result.

    I do remember the crank gears being .045" different in diameter at the bottom of the sprockets using a 6" digital Pretty Close....
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    Quote Originally Posted by GT Jets View Post
    Mix- matching timing gears from cam/crank, I have seen a somewhat worn crank gear with a deeper penetration used with a "newer" cam gear with little/no wear, this will "retard" a known cam timing by a very small amount.

    This came about when we were building a "Junkyard Dog" and were too damn lazy to pull the crank gear and it started a debate that came up with this result;

    We had two cranks, one with a "new" gear and one with a 150,000 mile old gear, we checked it by ultimately swapping the gears on the same crank and new timing chain, we saw a notable difference, can't remember the actual numbers, this was over 10 years ago.

    Different rolling diameters was the final consensus..

    I had always assumed (there's that word again) that if both gears were worn similarly, they would be much closer as far as final result.

    I do remember the crank gears being .045" different in diameter at the bottom of the sprockets using a 6" digital Pretty Close....
    If the chain is tight, it doesn't matter where the chain rides on the gear. If you had a .045 difference, the chain would have to show as either loose or very tight when compared to the other gear. But the "ratio" can't change. The number of teeth determine the ratio. It the ratio "could" somehow be off, then it would get further and further from the correct timing point as you turn the motor over, more and more times. But the "ratio" can't change. the teeth won't allow for it.



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    Quote Originally Posted by gn7 View Post
    If the chain is tight, it doesn't matter where the chain rides on the gear. If you had a .045 difference, the chain would have to show as either loose or very tight when compared to the other gear. But the "ratio" can't change. The number of teeth determine the ratio. It the ratio "could" somehow be off, then it would get further and further from the correct timing point as you turn the motor over, more and more times. But the "ratio" can't change. the teeth won't allow for it.

    As much as I agree with everything in this post, I cannot let the fact there can be a change in V/T with mix matched parts.

    I know where you are going with this and totally agree, however, this is where I was going.

    As the sprocket teeth wear on the crank gear, they only "really" wear the "pulling" side of the teeth, thus changing true "zero"...

    The chain did fit somewhat loose on the worn gear, but as long as the valve timing is checked with the crank going "forward" it is irrelevant IMHO...

    So in short, the ratio cannot change, but straight up 0 does.

    GT
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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