Timing tab!
Thread Starter
Heel & Toe
Joined: Apr 2011
Posts: 19
Likes: 0
Timing tab!
Til just recently, my 76 vette had no timing tab! Yesterday, I removed the water pump and behold, it's there! It's attached to the timing chain cover, but what is strange is the 0 degree mark is at 12 o'clock!! This is not the original engine, but I'm still confuse! Anyone got any ideas what goin' on here??
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
where the timing tab is and where 0* is marked is irrelevant. what matters is the relationship of where the harmonic balance index line is to the timing tab and true TDC. these timing tabswere often off to the side so mechanics could see it with a timing light and it shows a relative relationship between the timing tab, index tab and TDC. changing harmonic balancers with the index line in the wrong place or having the outer ring slip makes the timing appear all goofy but the engines can still run very well.
Last edited by bobs77vet; Apr 23, 2012 at 02:51 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
If that timing tab is fixed to the stamped steel cover, it is in correct location....but you don't know for exactly what car??? Someone may have pulled a timing cover from another [SBC] engine, some time in the past.
To be sure, you need to find TDC by another method. If you can verify that 0* on that scale is at the same point as TDC for your crank/pistons, then use it. But, I wouldn't depend on its accuracy until you've verified it.
To be sure, you need to find TDC by another method. If you can verify that 0* on that scale is at the same point as TDC for your crank/pistons, then use it. But, I wouldn't depend on its accuracy until you've verified it.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
you need to verify where TDC is there are lots of threads on how to do this and then see where the harmonic balancer index line is in relationship to the timing tab.....you can also buy a timing tab and mount it where you can see it and make your own index line. nothing really fancy going on there its just an index line pointing to a known timing tab location.
Racer
Joined: May 2011
Posts: 297
Likes: 3
From: Indianapolis
You just need to make sure you know where TDC is regardless of which balancer you have. Check this out:
http://www.corvettefaq.com/c3/TDCPaper.doc
http://www.corvettefaq.com/c3/TDCPaper.doc
