MTFCA Forum

Hi All

I picked up a '13 block for my '13 Canadian touring project recently. When I took the valve covers off to inspect it I noticed that something appears to be missing inside. See if you can spot what's not present.

And has anyone else run across this missing step in the engine manufacture before.

Drive Safe
Jeff
Nova Scotia

Oil drain hole?

early blocks did not have the oil holes in the valve galley.

I looked at the pictures before looking at someone else's answer. Tried to figure how it had something to do with the wrong oil pan.

I’ve got a 13 Canadian T block in the shop. I will look tomorrow!!

Dan's right, need to drill them on early blocks.

The original tappet bores on early blocks are broached with oil grooves that allow excess oil to drain back into the crankcase and there are no drain holes in the bottom of the valve galleries. If the block ever gets reamed out for oversize tappets the reamer will eliminate the original oil drain grooves and THEN you have to drill a drain hole like the later blocks had.

Not enough personal experience with blocks early enough to have that issue. But I have heard that if/when the valve stems wear a bit too much, the intake leakage through the intake valve stems causes a negative pressure in the valve chambers sufficient to keep the oil from draining down through the lifters. I have heard of people removing the side covers to find them nearly half full of oil! I do suspect a bit of exaggeration on that myself? But still?

I did drill the holes in the engine I put together (but have not yet used).

Wayne Sheldon wrote: ↑

Thu Oct 22, 2020 3:58 am

Not enough personal experience with blocks early enough to have that issue. But I have heard that if/when the valve stems wear a bit too much, the intake leakage through the intake valve stems causes a negative pressure in the valve chambers sufficient to keep the oil from draining down through the lifters. I have heard of people removing the side covers to find them nearly half full of oil! I do suspect a bit of exaggeration on that myself? But still?

I did drill the holes in the engine I put together (but have not yet used).

Wayne,

I've heard of that too. I always wondered what force of nature would pump so much oil "up hill" into those chambers, but I believe you answered that question! "Intake leakage through the valve stems!" Still I wouldn't guess that any more oil could accumulate than that which would reach the tops of the tappet guides, at least after the engine sat a while and the oil could leak back past the tappets. I suppose that right after a long run however, there might be a lot more oil than that.

Hi All

Yes, no oil drain holes in the valve chambers. First time I have run across this myself, although I did see it mentioned in McAuley's book in relation to a 1912 engine.

This engine had sat for 30 plus years and had almost no oil in the pan and was overall dry. Yet when I took off a valve cover out ran a couple ounces of black oily goo. There was oil trapped in the valve chambers.

So oil drain holes are going to be drilled when it gets restored. And as mentioned, if the valve guides become leaky, the valve chamber could become either negative pressure or positive pressure depending on which guides are more worn or even pulsate. But I think more oil tends to get sucked up than can drain back down the lifter guides.

Drive Safe
Jeff
Nova Scotia

I built up a speedster 4 valve rajo for a customer and the block didn’t have the two oil drain holes. The oil built up and would leak out at car shows much to the isners annoyance. So we bought a long drill, removed the inspection pan and drilled the two missing holes from the bottom.
They may not be in quite he correct position but the oil build up has ceased.