timing cover I.D.

[jeepboy45]

Hello all...

I did some research and found a couple of posts regarding this issue but none with any resolution for sure.

I have a 360 that just came back from the machine shop and is being put together over the next week or so.

I havent gotten the cam/timing set/or cover on yet, but it is next on the list. The problem is this: I am not totally sure what year engine I have. The heads and crank are from one year, and the block is from another, all presumably from close to the same era, about 1980 - 1988. While my engine was being machines, they told me one cylinder had to go PAST .060 over to clean it up, so I found a different block at the last minute-------thanks to jimbos76cj)

Anyway, I have 4 timing covers to choose from in my garage.

The problem is that the timing indexes are in 2 different configurations.
Here are two samples of what I have.
Does anyone have imput on what one I should use?

Thanks in advance for any imput...

brian

 

[Purple77CJ7]

The top picture is the same as the one on my 401 which is a 1977, I think. I have never seen the one in the bottom picture.

 

[jeepboy45]

I thought I would update this post with something I discovered. Maybe this information is already widely known by most of the readers, but it was a new discovery for me.

I havent installed the heads on my engine yet, so I can absolutely determine TDC on cylinder #1.

I put each of the two timing covers and balancers on the engine. While turning the crank clockwise I made a mark on the timing index on the case cover when #1 piston stopped its upward travel. Then I went way past TDC to where the piston was moving back down. Then I slowly turned the crank in the opposite direction ---counter clockwise---and noted where the piston stopped its upward travel.

On BOTH timing covers, absolute TDC (splitting the difference between those two marks) lined up with "TDC" on the timing cover index.

My initial concern was I noticed "TDC" on the black timing cover is way up at the top of the index marks, and on the blue timing cover "TDC" is in the middle. I wondered "how am I going to get an accurate timing reading when the scales are so different?"

What I failed to notice is that the index marks are actually in a different location on the cover. "TDC", even though it is in a different location within the index scale, is actually in the same relative location on the cover. On both covers, "TDC" is located roughly 1 3/4 inches below the small bottom water pump bolt.

So, unless there are other casting issues to think about, the timing scale issue seems to be resolved for me. That will allow someone to use whichever cover is in the best condition, providing they have a choice.

On the blue cover, I wonder why anyone would want to have up to 10 degrees of retarded timing.... It seems odd to show a scale with that much retarded timing.

brian

 

[jeepboy45]

After looking closely at both style covers on the bench, trying to determine which is in better condition, I noticed something very different.

I have no idea which one is earlier or later production, but they use very different crank seals.

The black one (in this case) uses a seal that is nearly 7/16 O.D. larger than the blue case uses.

Most of the time when I'm at the parts store, and the parts jockey asks me what year Jeep I'm working with, I just throw a year at him. In this particular case it does seem to matter when getting the appropriate crank timing seal.