'63 SHP Timing Cover - Which is Correct?

[Douglas C.]

Hi,
I've attached pictures of two timing covers for a '63 SHP (8 inch balancer). The one on the left is the more popular cover sold by many vendors as correct for '63 with the timing tab spot welded from below the tab. The one on the right has an identical tab, except spot welded from above the tab. I'm speculating the one of the right is more correct for a '63 SHP application based on my limited research. Never really seen this addressed, so curious of other opinions.
Thanks,
--Doug
IMG_20250606_205335833~2.jpg IMG_20250606_205259214~2.jpg

[Thomas S.]

Ugly but correct for 327/340 63. Taken before restoration.

[Thomas S.]

Also, in case you were not aware. There were cases in 63, where the timing tab on the SHP timing chain cover were actually for the smaller balancer so the marks are incorrect except for TDC.

see

https://www.forums.ncrs.org/forum/technical-discussion/57566-63-67-sb-timing-tabs-convert-6-cover-to-8

https://www.forums.ncrs.org/forum/technical-discussion/82949-62-340-hp-timing-cover-pointer

[Duke W.]

As above. Since the '63-'65 mechanical lifter engines total WOT advance for best power in in the range of 36-40 degrees, they need 12-16 degrees of initial timing, but you set the timing on the tab at 14, it's really only about 11-12.

Of course it's next to impossible to set initial timing on these engines because the centrifugal starts at 700 and they won't idle stably this low or lower long enough to check and reset the timing if necessary.

The solution to this is to use the total WOT advance method. Rev the engine to a few hundred revs higher than the point of max centrifugal and use a dial back timing light with the value set at 36-40 and rotate the distributor base to bring the balancer notch back to zero on the tab. This sets the timing at what you dialed in on the light and circumvents the timing tab inaccuracy.

The above is easy to do on the 365/375 HP engines because centrifugal, assuming it hasn't been modified, is all in at 2350. OE centrifugal on the '63 distributors is the same 24 degrees, but it doesn't all come in until 4600. The easy way to solve this is install lighter centrifugal degrees.

Another problem with the 340 HP engine is that the OE 201 15 VAC requires about 15" Hg to pull to the limit, but the engine only pulls about 12" at the 800-900 idle speed. This results in loss of idle advance once the engine settles back to idle at a stop light, which causes a loss of idle speed that loses more idle advance with more loss of idle speed and this negative feed back loop continues until the engine stalls or you blip the throttle which causes a vacuum spike pulling the VAC to the limit, and then the process starts over again.

It took me a couple of years to solve this because the dealer and "experts" I talked to were clueless, but circa 1965 I figured out what I now call the "Two Inch Rule" and installed the 365/375 HP 8" VAC and centrifugal springs. This not only solved the idle stability problem, but gave the engine noticeably more low end grunt, which was very useful with a CR trans and 3.08 axle.

The idle stability issue does not effect the '63 FI engine because its OE configuration is ported vacuum advance, so the Two-Inch Rule does not apply, but my recommendation is to change it to full time and install an 8" VAC.

Duke

[Keith B.]

Timing_Chain_Cover_crop.jpg
some one named Mike H sent this to me years ago

[Harry S.]

That would be Michael Hanson.

image.png

[Douglas C.]

Thanks for the responses. I was somewhat aware of the timing tab issue for '63 340 hp cars - which is what I will be building sometime this Fall. But the details here are very helpful. Great write-up and links. I suppose you can chock this up to another '63-only situation, which for me, makes the cars all more interesting.