Big Block Timing Covers

[bcmiller]

Someone asked me about big block timing covers earlier this morning. I won't put them on the spot, but wanted to get this posted. My mind is not really on car stuff right now. I found out within the last 5 days that 2 friends have pancreatic cancer and it's bad. I also lost my favorite aunt last month.

Anyway, it doesn't seem we have anything on the main site in the engine section about timing covers. If it is there, I apologize. I was asked the differences. specifically when the dowel holes were added in the cover. I was thinking for 1969 but couldn't remember. So I checked into my files and found an old post that I had saved from the Chevelles site. I believe this information to be correct from what I have seen. I am not taking credit for writing up the information pasted in below in italics. That is from Jeff Helms, a highly respected Chevelle expert. There would be no reason for the timing covers on Camaros to be different than on Chevelles.

Kurt, if you want me to work on a section to put into the engine write-up, I can work on it. Just let me know. If you don't feel this post is appropriate, remove it.

Again, credit for the information below belongs to Jeff Helms.

If any of you have different thoughts, post them here in this thread with pics. Thank you.


There were at least 10 different BBC timing covers that were used between 1965 and 1969 (five for the 7-inch balancer and five for the 8-inch balancer).

1. The 1965 - early 66 covers used a non-dowel pin cover with a very small, square timing pointer. They only have A-O on them and not A-O-R like the later covers. They have a captured nut in the bottom center of the cover which matches up with a bolt hole in the front center of the oil pan.

2. The 2nd design 66 cover is identical to the above but has the larger A-O-R timing pointer (angled on the 8" balancer version).

3. They dropped the front center bolt hole in the oil pan at the beginning of 67 production (some say they did so late in 66 production but I have seen no original late 66 car or original and complete late 66 396 or 427 engine that bares that out). As a result, at the beginning of 67 production (or some time after that) they dropped the captured nut and the hole in the bottom of the timing cover. However, the slot for the nut is still there in the U-channel reinforcement piece that goes across the bottom of the cover. There is no indication in the parts books of a new part no. being issued, though, which is odd. (Still no dowel pin holes either).

4. There is another cover that is identical to # 3 above, except it does not have the slot in the reinforcement piece for the captured nut. (Still no dowel pin holes). I do not know when this change occurred, and again there is no indication in the parts books of a new part no. being issued.

5. Then there is the 69 cover which has the dowel pin holes, and no hole, nut or slot in the bottom center. This one finally does get a new part number!

[boomer632]

I have an original GM BB 8" cover that I restored and have some pics of. It has the dowel pin holes and no bolt hole in the bottonm middle of the channel. Timing tab has the AOR marks, spot welded on to the cover and has the angled cut at the corner as well. I can post some pics later.