The Ford Barn

Licensed to kill · 07-30-2020, 04:50 PM

I'm in the process of assembling my engine and find that neither my crank gear nor my cam gear have have timing marks (other than the dimple or TDC). To my hillbilly way of thinking then, when I put the cam gear so that the dimple aligns with the pin hole in the cover, that is TDC firing position for cylinder #1 and is directly across from the crank gear. So, if I put the #1 piston @ TDC and line that dimple up with the crank gear, that should be TDC firing position for #4 (because it is directly across from the pin location) and should be right. However, I've read where to set the cam timing with a crank gear that has no mark that you use the key and line up the mark on the cam gear with that (if you have one) but when #1 is at TDC, the key in the crank is no where near the cam gear. This little tidbit of info casts doubt on what I otherwise think is correct. Any clarification would be appreciated.

johnneilson · 07-30-2020, 05:42 PM

You search this subject up on the site here, your assumption of TDC firing position is incorrect.

The key in the crank is theoretically the centerline of the rod journal.
The mark on the crank gear lines up with the key (helical gear mid tooth on helix)
Since the cam is positioned approximately 43.77 degrees before TDC, it will appear way off time wise with marks lined up.

Good observation, most just take it for granted.

Good luck, John

Licensed to kill · 07-30-2020, 06:03 PM

Sponsored Links (Register now to hide all advertisements)

Found it. Thanks. http://www.fordgarage.com/pages/camcrankalignment.htm

07-30-2020, 05:42 PM	#2
johnneilson Senior Member Join Date: Jun 2010 Location: 34.22 N 118.36 W Posts: 1,053	Re: cam timing. You search this subject up on the site here, your assumption of TDC firing position is incorrect. The key in the crank is theoretically the centerline of the rod journal. The mark on the crank gear lines up with the key (helical gear mid tooth on helix) Since the cam is positioned approximately 43.77 degrees before TDC, it will appear way off time wise with marks lined up. Good observation, most just take it for granted. Good luck, John __________________ As Carroll Smith wrote; All Failures are Human in Origin.

07-30-2020, 06:03 PM	#3
Licensed to kill Senior Member Join Date: Aug 2016 Location: Alberta Posts: 930	Re: cam timing. Sponsored Links (Register now to hide all advertisements) Found it. Thanks. http://www.fordgarage.com/pages/camcrankalignment.htm

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07-30-2020, 04:50 PM	#1
Licensed to kill Senior Member Join Date: Aug 2016 Location: Alberta Posts: 930	cam timing. I'm in the process of assembling my engine and find that neither my crank gear nor my cam gear have have timing marks (other than the dimple or TDC). To my hillbilly way of thinking then, when I put the cam gear so that the dimple aligns with the pin hole in the cover, that is TDC firing position for cylinder #1 and is directly across from the crank gear. So, if I put the #1 piston @ TDC and line that dimple up with the crank gear, that should be TDC firing position for #4 (because it is directly across from the pin location) and should be right. However, I've read where to set the cam timing with a crank gear that has no mark that you use the key and line up the mark on the cam gear with that (if you have one) but when #1 is at TDC, the key in the crank is no where near the cam gear. This little tidbit of info casts doubt on what I otherwise think is correct. Any clarification would be appreciated.