1986 305 timing tab - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Brad_Olson · 04-15-2005, 06:11 PM

My '86 305's timing tab is pretty dirty and all I can see are the "teeth"; the numbers are covered. I think I know what the teeth indicate but want to be sure so I know I'm setting the timing I think I'm setting.

Think of each tooth point as a high spot and the halfway point between 2 teeth as a low spot. There's one low spot that's wider and deeper than the others; I believe this is TDC. The first tooth counterclockwise from TDC is 2 BTDC, the next one is 6 BTDC, and so on. The low spots represent 4 BTDC, 8 BTDC, etc. Currently at idle the mark corresponds with the 2nd low spot, meaning the engine's initial timing is 8 BTDC.

Does this sound right? Thanks!

Brad

04-15-2005, 06:11 PM	#1
Brad_Olson Active Member Join Date: Mar 2005 Location: Stoughton, WI Posts: 187	1986 305 timing tab My '86 305's timing tab is pretty dirty and all I can see are the "teeth"; the numbers are covered. I think I know what the teeth indicate but want to be sure so I know I'm setting the timing I think I'm setting. Think of each tooth point as a high spot and the halfway point between 2 teeth as a low spot. There's one low spot that's wider and deeper than the others; I believe this is TDC. The first tooth counterclockwise from TDC is 2 BTDC, the next one is 6 BTDC, and so on. The low spots represent 4 BTDC, 8 BTDC, etc. Currently at idle the mark corresponds with the 2nd low spot, meaning the engine's initial timing is 8 BTDC. Does this sound right? Thanks! Brad



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