Cam change question?
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Road Captain
Joined: Dec 2009
Posts: 540
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From: Nooga, TN
Cam change question?
If the timing marks on the cams and the cam and crank sprockets are in alignment, the cams are properly timed. Is there any way the cams can be out of timing, if all the marks are aligned properly? Thanks
Road Master
Joined: Apr 2011
Posts: 1,145
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From: Colorado Springs
No I don't see how, but use a straight edge to check the marks. I've been fooled by 1 tooth off looking like it was in line. Make sure the straight edge not only goes directly through the timing marks but also directly through the centers of the cams and not slightly to one side.
Last edited by ocezam; Feb 8, 2012 at 07:57 AM.
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Road Captain
Joined: Dec 2009
Posts: 540
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From: Nooga, TN
Thanks for the response.. I did check with a straight edge and I understand about being slightly off. Having trouble getting it started after change, but I tried some aftermarket exhaust gaskets and they did not seal the exhaust at all. So took the exhaust off last night and found that problem. Popped the cam cover off again to check the timing marks and all was dead on.
The new 255 cam had very weak/light timing marks. Looked something like marks made with a punch. Did not have the nice drilled marks like the stock cam. Cam came new in the box from lakeshore harley. It was also backfiring out the intake like the timing might be off. This is why I was concerned. Rotated the engine with plugs out after cam swap, no noise, like clicks or clanks and rotated freely. Did this again with the cam cover off last night and still rotates freely with no strange noises coming from the valve train. Sure seems like the valve timing is off, but the timing marks align perfectly. Will try again this evening. Also checked plug wire and coil connections, all seemed good. A little puzzled right now.
The new 255 cam had very weak/light timing marks. Looked something like marks made with a punch. Did not have the nice drilled marks like the stock cam. Cam came new in the box from lakeshore harley. It was also backfiring out the intake like the timing might be off. This is why I was concerned. Rotated the engine with plugs out after cam swap, no noise, like clicks or clanks and rotated freely. Did this again with the cam cover off last night and still rotates freely with no strange noises coming from the valve train. Sure seems like the valve timing is off, but the timing marks align perfectly. Will try again this evening. Also checked plug wire and coil connections, all seemed good. A little puzzled right now.
Advanced
Joined: Oct 2011
Posts: 80
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From: Mount Juliet, Tn.
get the piston at TDC and rotate the cams to where they are exactly between the intake and exhaust stroke, look at the marks,, if they are off they could have been marked wrong,, compare the marks on the new cam with the old cam,, the top of the lobes should be at the same place and the marks will be the same,,thats just where i would start...only way it can backfire through the valves is if they are open when it fires..
so also check that it is firing at the right time and make sure your push rods aint holding the valve open,,, compression check,,,
so also check that it is firing at the right time and make sure your push rods aint holding the valve open,,, compression check,,,
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Road Captain
Joined: Dec 2009
Posts: 540
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From: Nooga, TN
Thanks Jesse,
I was hoping that I would not be the luckiest person in the world and get cams that were not marked correctly. WTF Just wondering if improperly marked cams had happened to any one else. Unfortunately I put the cam cover back on. Guess I will take it off again tonight and do some more checking before putting the exhaust back on and trying again. If the cams are not marked correctly, I am going to give HD some grief. You would hope they have better quality control than that, but I guess we all know how good their QC is.
I was hoping that I would not be the luckiest person in the world and get cams that were not marked correctly. WTF Just wondering if improperly marked cams had happened to any one else. Unfortunately I put the cam cover back on. Guess I will take it off again tonight and do some more checking before putting the exhaust back on and trying again. If the cams are not marked correctly, I am going to give HD some grief. You would hope they have better quality control than that, but I guess we all know how good their QC is.
Road Master
Joined: Jun 2010
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From: Annemasse (border of Geneva-Switzerland) facing Mt-Blanc.
If you are confused, one TDC has the two valves closed for ignition and the next TCD will have both valves slightly open to finish exhaust and begin intake cycle. If you still have unburnt mixture in the cylinder because the compression + ignition didn't happen at the proper moment, your timing is probably off by 1 cycle. Old engines didn't have timing marks 
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Road Captain
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Road Captain
Joined: Dec 2009
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From: Nooga, TN
Thanks Expat,
I do understand the part about base circle TDC and overlap TDC. Trying to get that dead on without timing marks would suck. Guess I should have went with the TW-555's instead.
I do understand the part about base circle TDC and overlap TDC. Trying to get that dead on without timing marks would suck. Guess I should have went with the TW-555's instead.
Road Warrior
Joined: Mar 2007
Posts: 1,377
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From: Atlanta, GA
If the cams are new the timing marks are probably correct.
Edited: I am going to flip flop. If the cam timing dots are as weak as you are saying and you are positive everything is aligned, then IMO the timing dots are suspect.
Edited: I am going to flip flop. If the cam timing dots are as weak as you are saying and you are positive everything is aligned, then IMO the timing dots are suspect.
Last edited by atrain68; Feb 8, 2012 at 09:24 AM.