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By 1946international - 3 Years Ago
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I'm building a '57 292 for a project and am installing a Comp cams camshaft in it. Spec are, gross lift both I&E .471 Duration @.015 tappet lift 261 Intake & 267 Exhaust LSA 108* . My problem is this, when degreeing the cam I have to "retard" the cam 6*, my multi keyway timing gear set can be adjusted to 8* advance to 8* retarded so I,m not maxed out but 6* sounds a little far. What do you all think? I have checked and rechecked my process 3 times and it comes up the same. The cam card says I need a 108* intake center line.
I did a on-line chat with Comp cams tech guy and he said it "sounds odd but strange things can happen with custom ground cams" & "just put it in and see how it runs" Someone on another site suggested checking the exhaust side to see if the cam was ground right and I guess I could figure out how to do that working off of the cam card but would I have to check each intake and exhaust lobe? Am I just over thinking?
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By Cliff - 3 Years Ago
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You might want to install it at 2 deg advance from what the cam card tells you.
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By Joe-JDC - 3 Years Ago
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We(Ted and I) found the Comp Camshafts for the Y block were ground on the wrong lifter angle and when you advanced or retarded the camshaft, it was off on every lobe from the cam card. Straight up was the only way it matched the cam card. Had 3 Jones camshafts the same problem. Howards, Jones, Comp all use the wrong lifter angle when grinding their camshafts. ISKY uses the correct angle, and you can advance or retard the ISKY with confidence. Just my experience, but I called Mike Jones, and he now has the right angles, and he reground me three camshafts for free. They checked out when degreeing after the modification to correct valve angle. Joe-JDC
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By 55blacktie - 3 Years Ago
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Joe-JDC, I had some knowledge of lifter angle, but I did not know about Howard's using the wrong angle. If that's true, I'm glad I didn't buy a Howard's cam. I hope Schneider got it right.
Thanks for the info.
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By 1946international - 3 Years Ago
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Cliff (3/5/2021)
You might want to install it at 2 deg advance from what the cam card tells you.
how does the cam card say that? am I not seeing something?
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By 1946international - 3 Years Ago
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Joe-JDC (3/5/2021)
We(Ted and I) found the Comp Camshafts for the Y block were ground on the wrong lifter angle and when you advanced or retarded the camshaft, it was off on every lobe from the cam card. Straight up was the only way it matched the cam card. Had 3 Jones camshafts the same problem. Howards, Jones, Comp all use the wrong lifter angle when grinding their camshafts. ISKY uses the correct angle, and you can advance or retard the ISKY with confidence. Just my experience, but I called Mike Jones, and he now has the right angles, and he reground me three camshafts for free. They checked out when degreeing after the modification to correct valve angle. Joe-JDC
So, if I check the valve timing for opening timing and find they are not matching what the cam card says I should try setting it up "straight up" and recheck opening time to see if it then matches the cam card?
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By Ted - 3 Years Ago
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As a general rule, always check both an intake and exhaust lobe on a given cylinder. The two values added together and divided by two is expected to equal the ‘as ground’ lobe centerline. In your case, 108°. Only when the camshaft is installed where both the intake and exhaust lobe centerlines are equal is the camshaft installed straight up. When the intake lobe centerline angle is less than the ‘as ground’ lobe centerline the camshaft is advanced. Likewise when the intake lobe centerline angle is more than the ‘as ground’ centerline angle the camshaft is retarded.
I’ll suggest also checking the cam timing on the #6 cylinder. This will confirm both your checking methodology and if the camshaft is at least the same on those two cylinders. If you find a 2° or more discrepancy, then you may need to check all the cylinders and determine if this is a problem where the left bank does not agree with the right bank. If that’s the case, the camshaft was ground on the incorrect lifter bank angle. By checking the camshaft timing on different cylinders and especially opposite banks you will get a good feel for how good the cam grinder is doing their work.
But back to basics. Being six degrees off on the cam timing is not unheard of. And when I say off, I mean from where the manufacturer or cam grinder recommends where the camshaft is to be initially installed. Most cam grinders specify four degrees of advance and that is typically built into the camshaft so that when the gear marks are properly aligned, the camshaft is close to where it needs to be. In your case and assuming it’s a new timing chain set, then consider installing that camshaft at 104°-106° intake lobe centerline so that as the timing chain loosens up, the camshaft will not be residing in a retarded position. I have found camshafts off as much as 18° off either as retarded or advanced and that’s with the timing gear marks simply aligned as they should be. In those cases, the timing chain is reinstalled with a one tooth offset on the gear marks versus being aligned as was originally designed. In rare instances I have had to broach a new key way slot in the crankshaft gear in which to compensate.
Here are links to the camshaft degreeing articles that were published in The Y-Block Magazine several years ago.
https://www.eatonbalancing.com/2015/09/24/degreeing-in-the-camshaft-part-i-finding-tdc/
https://www.eatonbalancing.com/2015/09/24/degreeing-in-the-camshaft-part-ii-phasing-the-camshaft/
https://www.eatonbalancing.com/2015/09/24/degreeing-in-the-camshaft-part-iii-its-twelve-pins-between-the-marks-for-the-ford-y/
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By BamaBob - 3 Years Ago
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Thanks Ted, for the very informative articles. I do have a question, though. In using the piston stop, does it matter whether the piston is as close to the top as it can be, or can it be just close to the top, as in a half inch or so? I have never used a degree wheel, but am intending to in the near future and need to know all I can learn about its use.
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By Joe-JDC - 3 Years Ago
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The closer to the top you have the piston stop, the smaller the numbers you will work with and less room for error in finding the true TDC. In reality if you do it correctly, the distance doesn't matter. I prefer to work with being close to TDC since it makes reading the degree wheel easier. Joe-JDC
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By 1946international - 3 Years Ago
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Thanks all for the replies. Ted asked if the timing set was new and yes it is. I read those articles earlier today.
So I will check the center line of the exhaust on both #1 & #6 to see where I stand.
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By slumlord444 - 3 Years Ago
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When I put a custom ground Isky cam in my 312 several years ago it was off by quite a bit. Don't remember exactly how much but i got help form Ted setting it up and am sure I got it right. The engine is as strong as I thought it would be when I finally got everything else sorted out. Measure carefully and triple check it to make sure.
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By 1946international - 3 Years Ago
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Slumlord, Thanks for that. I'll do some rechecking today
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By 1946international - 3 Years Ago
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First, thanks for all the help. This is what I came up with.
rechecking the center line on #1 Intake it is 108.75*
I checked #1 Exhaust that is 107*
I checked #6 Intake that is 108.5*
I checked #6 Exhaust that is 108*
Other stuff I checked:
Cam card says Intake should open .050" at 4* BTDC Actual is 2* BTDC for #1 1.5* for #6
card says Exhaust should open .050' at 44* BBDC Actual is 42.5* BBDC for #1 42* for #6
Lobe lift for intake & Exhaust should be .314" Actual for #1 intake is .312" and intake on #6 .315" is Exhaust on #1 is .317" and Exhaust on #6 is .311"
I just checked the lobe lift as I was in there with an dial indicator.
So, if I'm thinking right I should advance the cam 2* to get the opening times better and maybe another 2* to allow for some timing set wear. As it is at 6* retarded now, I should go back to 2* retarted.
Thoughts?
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By Ted - 3 Years Ago
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Unless you also check the closing event side of the camshaft, it’s not a good prtactice to move a camshaft around based only on the opening event side of the camshaft. At this point you don’t know if the lobes are cut exactly right without knowing what the closing event numbers are. In your case use the lobe centerline measurements which you have determined by going to each side of the lobe. Because the camshaft is essentially installed straight up based on the lobe centerline measurements, then you need to advance it about 4°.
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By 1946international - 3 Years Ago
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OK, so I'll move it 4* advance from where it is now. Thanks so much for the help. The other day when I was talking to the Comp Cam guy he said something like "that is a very late opening cam" what are your thoughts on that? is it a late opening cam? Will this make good power for a street car? It's going in a '30 Model A with a 3 speed manual trans with 3.73 gears and 31" tall rear tires.
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By Joe-JDC - 3 Years Ago
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You have to get your opening events, and your closing events, add them together and divide by two to get the actual centerline. Have you done that? Don't move the gears until you follow up like Ted said. Joe-JDC
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By 1946international - 3 Years Ago
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No, I did not do the closing events yet. I thought Ted was saying don't advance it any just because of my "opening stats" but did say " In your case use the lobe centerline measurements which you have determined by going to each side of the lobe. Because the camshaft is essentially installed straight up based on the lobe centerline measurements, then you need to advance it about 4°."
Meaning, don't make changes on the reported opening times but I should make changes based on the centerline numbers.
Please correct me if I'm wrong.
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By Joe-JDC - 3 Years Ago
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That is not how I read it, but I will back out and let Ted answer if he feels he needs to clarify anything. Joe-JDC
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By 1946international - 3 Years Ago
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Joe, you are probably right I just checked the closing times on #1 & #6. This is what I found:
Spec on the cam card for Intake closing is @.050" 40* ABDC actual for #1 @ .050" is 40.5* and actual for #6 is 40.5*
spec on card for Exhaust closing is @.050" 7* ATDC actual for #1 @ .050" is 8* and actual for #6 is 7.5*
and I just brought the opening numbers down to make the comparison easier
Cam card says Intake should open .050" at 4* BTDC Actual is 2* BTDC for #1 1.5* for #6
card says Exhaust should open .050' at 44* BBDC Actual is 42.5* BBDC for #1 42* for #6
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By Ted - 3 Years Ago
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1946international (3/8/2021)
......Meaning, don't make changes on the reported opening times but I should make changes based on the centerline numbers.
Please correct me if I'm wrong.
You’re not wrong and neither is Joe. If you are coming up with different values when doing the cam degree in process by both the lobe centerline method and checking it at 0.050” lifter rise, then attribute that to the cam grinder not matching the actual camshaft grinding to what’s listed on the card. The key here is that all the lobes for the various cylinders measure the same.
There are two different methodologies for checking a camshaft as to where it’s installed in relation to TDC. One of those is the centerline method of which you provided all the lobe centerline values for both the intakes and exhausts for both the #1 and #6 cylinders. This is typically the most accurate method.
If you are actually trying to compare the opening and closing values on the cam card for either verifying the advertised or the 0.050” numbers, then this takes a different approach. This will require zeroing out the dial indicator on the base circle of the camshaft and measuring the crankshaft degrees at specific levels of lobe lift. As a general rule, the hydraulic camshafts use 0.006” lobe lift for measuring advertised duration while solid lifter camshafts use 0.020” lobe lift for the advertised duration. Most cam cards will also provide opening and closing numbers at 0.050” lifts and those values are pretty much universal with all cam grinders while the advertised values may vary somewhat. If attempting to reverse engineer from a camshaft the specs for which there is no information available, then measuring both the advertised and 0.050” lifter rise numbers can get you this information.
So this brings us to the other method of degreeing in the camshaft which is using the advertised or 0.050” opening/closing numbers to check the cam timing. This method will confirm if the cam is indeed matching the specs on the cam card but do not be surprised at some variability with this method. It must also be noted that the measurements when doing this are not complete without doing both the opening and closing sides of a given lobe. Doing only one side and not the other fails to give a complete picture.
If you do enough of these, you’ll find a very consistent discrepancy between what the cam card says and what is actually measured. Part is this is due to the high viscous break-in lube that’s applied to the lobes which will distort the measurements. Another part is due to the cam grinding operation where the pattern being used on the cam grinding machine does not exactly match the cam card either due to that piece becoming worn, slop or wear in the machine itself, or in making a duplicate pattern from a duplicate where errors tend to stack up on each other.
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By 1946international - 3 Years Ago
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Ted, thanks for the explanation, very helpful.
so are you still suggesting to advance the 4* from where it is now?
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By Ted - 3 Years Ago
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1946international (3/9/2021)
...so are you still suggesting to advance the 4* from where it is now?
Yes
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By 1946international - 3 Years Ago
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Great, thanks again for all of your help and the rest of the board's help.
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