cam alignment question
12-08-2007, 05:45 PM
#22
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just an update guys, i couldn't get it to be perfect like mxt's, but i did the best i could 
these are my cams with the crank pulley put exactly on TDC. thanks for the help guys, i hope all is good, i'm keepin' my fingers crossed.
these are my cams with the crank pulley put exactly on TDC. thanks for the help guys, i hope all is good, i'm keepin' my fingers crossed.
12-08-2007, 06:31 PM
#24
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correct, but mxt's were slightly off also (cam timing retarded slightly i believe) just not to the degree mine seem to be, because he had to move the crank pulley slightly away from the tdc indicator to align the cam marks..... probably because his head was milled.
if anything my exhaust cam might slightly be advanced, but not even a degree.
if anything my exhaust cam might slightly be advanced, but not even a degree.
12-08-2007, 06:57 PM
#25
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From that pic, it still looks like your exhaust cam may still be off a tooth. IIRC, there are marks on the cam chain sprocket (the one in front). If those are aligned with the top of the head, then the marks on the cam gears should align perfectly with the seam between the upper & lower cam journals... no questions asked. There is no room for play here. The crank pully marker might be a bit off due to play in the chain or a relative change caused by milling the head, but the marks on the sprocket and gears should always align exactly like the marks shown in the pic that SpitfireS has in his post above.
Also, I think somebody did the math once, and if you're off a tooth, I believe it's about 6 degrees. I'd be concerned about valve to piston contact when you start getting that far off. Especially if you've installed higher lift cams.
Also, I think somebody did the math once, and if you're off a tooth, I believe it's about 6 degrees. I'd be concerned about valve to piston contact when you start getting that far off. Especially if you've installed higher lift cams.
12-08-2007, 08:29 PM
#26
I just finished putting my rebuilt motor in the car tonight -- hoping to fire it up tomorrow. My outcome was exactly like mxt 77's. The cams were dead on, but the crank was off by about the same amount. I tried re-positioning by one tooth, but it pushed things off further the other way. I'm calling it good and crossing my fingers. 
12-09-2007, 06:40 AM
#29
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Originally Posted by Bigeggroll,Dec 8 2007, 11:36 PM
but don't forget that the cams should be aligned in relation to the crankshaft (crank pulley) because the crankshaft is what drives the pistons up and down affecting piston to valve clearances, so ur's is still off, it seems to be slightly retarded. which makes sense due to ur milled head.
moving 1 tooth down would put me below the mark, i know because i did it. so either way i'm kinda it's gunna be off right at crank TDC. so, i'm about 1/2 tooth off (3 degrees) arghhh!!!! i'll probably go with ur advice and move it 1 tooth down.
moving 1 tooth down would put me below the mark, i know because i did it. so either way i'm kinda it's gunna be off right at crank TDC. so, i'm about 1/2 tooth off (3 degrees) arghhh!!!! i'll probably go with ur advice and move it 1 tooth down.
In the last picture you posted, the cam chain sprocket appears to be aligned with the head properly. Where was the crank pulley indicator (take a pic if you can... also, take another picture where we can see the alignment of the cam chain sprocket with reference to the top of the head). If it was dead-on, then I don't understand why you can't get the exhaust cam to align properly. As I stated, these are gears that are designed to fit together properly. When installed, there is no significant room for play, so if the cam chain sprocket is aligned properly then it should be possible (and necessary) to install the cam gears so they align perfectly with the seam in the cam journals.
Yes, I agree that my crank pulley indicator wasn't perfectly aligned, but the difference is probably less than 1 degree, whereas having a cam gear misaligned by a tooth is a much larger difference.
If your crank pulley isn't aligned properly when your cam gears & the cam chain sprocket are aligned properly, then maybe you didn't install the chain properly.
Edit: It does, in fact, appear that your cam chain is not installed properly. Notice the positioning of the links on the sprocket. Notice that on mine, one of the links cover the tooth on the sprocket that points straight up, however in yours, that tooth is uncovered. So, maybe the chain is off by a tooth on the cam chain sprocket, which causes your crank pulley to be misaligned when the top-end stuff is aligned properly. In my Helms, this is described in step 15ish of the "Cylinder Head Installation" section.
12-09-2007, 01:30 PM
#30
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In his pic the center pulley that drives the cams looks to be misaligned, or is it just me? So maybe if thats not perfect that will directly effect you cam points as well. IMO everything should line up perfect, I've never built an engine without all the marks exactly where they are supposed to line up.