Here is the cam card.
This issue is not making sense to me but thanks for the suggestions. I'm going to re-check everything then report back.
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| Cam degreeing https://slantsix.org/forum/viewtopic.php?t=21663 |
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| Author: | sublimed [ Mon Jan 29, 2007 8:36 pm ] |
| Post subject: | Cam degreeing |
Today I degreed my cam and I am confused about the numbers I got. Here is my cam info: Clifford 276 mechanical lift 464 duration 276 at .050 ex opens 49 bbdc ex closes 11atdc in opens 11 btdc in closes 49abdc 108 lobe center With the dots lined up the cam was way off. Here are the numbers I got at .050: ex opens 67 ex closes 12 ex lobe center 128 So I advanced it 2 teeth and I got these numbers: ex lobe center 104 ex opens 37 ex closes 17 in lobe center 99 in opens 1 in closes 51 I don't understand why I'm getting such inconsistent numbers. I thought I was on the right track when I advanced the cam two teeth when I got my exaust numbers. But then the intake was all messed up. I have to admit I am new to this, but my friend who builds motors for a living was degreeing it for me and he does not understand it either. I'm just posting it here to see if anyone can maybe catch something I'm doing wrong or have any ideas Thank you for any help and let me know if you need anymore information. |
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| Author: | BigBlockBanjo [ Wed Jan 31, 2007 7:25 pm ] |
| Post subject: | |
If you could post a pic of the cam card, it might be easier to tell what is going on. From Clifford's card, it looks like a single-pattern cam, but your numbers look like a dual-pattern. A shot of the card would help. |
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| Author: | Doctor Dodge [ Wed Jan 31, 2007 8:53 pm ] |
| Post subject: | |
Quote: ...I thought I was on the right track when I advanced the cam two teeth when I got my exaust numbers. But then the intake was all messed up...
Two teeth is a lot, or did you mean to say 2 degrees?Quote: ...card said at .050:
67 bbdc would mean the the cam is advanced, Ex. valve is opening sooner then the card's 49 bbdc. ex opens 49 bbdc ex closes 11atdc in opens 11 btdc in closes 49abdc 108 lobe center With the dots lined up the cam was way off. Here are the numbers I got at .050: ex opens 67 ex closes 12 ex lobe center 128 Ex closes at 12 atdc means 1 degree late (retarded) so something is not right with the measurements. When in doubt, go to the overlap event at top dead center exhaust stroke (Ex) and see how the overlap is "spaced" (split) over TDCEx. Example, if the cam has 62 degress of total overlap, 31 should be BTDCEx and 31 ATDCEx. DD |
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| Author: | 73NorthernDuster [ Thu Feb 01, 2007 10:16 am ] |
| Post subject: | Cam degreeing |
I had a similar problem with my isky cam. I had to retard mine one tooth and then everything lined up right. Brent |
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| Author: | sublimed [ Thu Feb 01, 2007 4:27 pm ] |
| Post subject: | |
Here is the cam card. This issue is not making sense to me but thanks for the suggestions. I'm going to re-check everything then report back. |
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| Author: | Slant Cecil [ Thu Feb 01, 2007 8:02 pm ] |
| Post subject: | |
Just check the intake centerline, cam card says 108*ATDC. 1-find TDC and set the wheel, turn motor CW till it hits your stop, take a reading, then turn it CCW, take a reading, add both readings, devide by two, put your pointer on this new number, that will be TDC 2-turn motor CW till the int lifter is raised .290, take reading, say it's 98*ATDC 3-turn motor CCW till the int lifter is raised .290, take reading, say it's 116*ATDC 4-add the two readings, then devide by two, 98+116=214, 214/2=107*, you would be advanced by 1* The thing that may make it confusing is the markings on the wheel. Some wheels go to 90*ATDC, then start counting back down to BBDC. Example, your first reading of 98* will be past 90* and on 82*, the second reading of 116* will also be past 90* and on 64*. If your wheel goes to 180*, it's easier not to get confused. Raising the lifter to .290 is not absolute, it depends on the cam lift. Just use a number that is .020-.050 from total lobe lift. Your cam has a .309 lobe, I just picked .290 as it an even number below .309. This method works on symetrical cams, which most are. It will not work on an asymetrical cam. |
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| Author: | Charrlie_S [ Thu Feb 01, 2007 8:08 pm ] |
| Post subject: | |
Why are you even worrying about the exhaut lobe, while degreeing? Concentrat on the intake. When you get that right, then you can check the exhaust, just to satisfy yourself the cam is ground right. Just for info. Moving the sprocket 1 tooth will change the timing just about 9 1/2 degrees, so two teeth would be 19 degrees. Based on your original numbers, if you had advanced the cam 1 tooth, you should have been right on. |
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