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MG MGB Technical - Engine identification question

I need help in identifying my engine. The engine is rebuilt and has no aluminum engine tag. When I bought my MGA I was told that it had a 1967 10GB engine. Today, while looking for a pesky oil leak, I discovered that the dipstick tube was a press fit in the block. I probed the hole in the block and cannot feel any threads. According to what I have found, the dipstick tube on the 18GB engine should be threaded into the block. The engine runs great and I am very satisfied with it, I’m just concerned about future parts compatibility issues if I need to work on the engine. Given this question, which sump and dip stick are correct for the 18GB engine?

I’m about the drop the sump change the gasket, so I will have access the engine internals if that will help in identification.

I understand that there may be a date code under the oil filter. This engine has a spin-on filter so it will be difficult to get to the numbers, but I can try if that’s the only way.

Frank Bruns
Bruns

If the block has a date code (it seems 50:50 as to whether they do or not) it should be quite clearly visible with everything installed including an inverted spin-on filter. Perhaps a little less easy with a hanging filter, but relatively easy to remove that.

More info on dating the engine here http://www.mgb-stuff.org.uk/enginetext.htm#dating, and on dipsticks, tubes and sumps here http://www.mgb-stuff.org.uk/enginetext.htm#dipstick
paulh4

Paul, thanks for the information. I was very helpful (I think – I may be even more confused and concerned now). The engine does not have a date code. I took off the oil filter and I can clearly see the block. The only 12HXXXX number behind the starter appears to be 12H3503 (I’m looking with an inspection mirror and the casting is not that legible.) I’m definitely concerned about the dip stick and tube combination. The tube is the press fit one (and I can’t feel any threads in the block) and the dip stick in the bent one with the fixed conical stop. Evidently, this is not the correct combination. Looking at the pictures you sent me to, the bent dip stick would stop higher in the taller (press fit) tube and might lead to overfilling the sump. Somehow I need to get to the correct tube, dipstick and sump combination be comfortable with the oil level.
I did drop the oil pan and at least the engine is a 5 bearing engine.
Bruns

Sump capacity always has been confusing as you may have noticed in that second link. About the only thing you can say for sure is that oil level should always be below the rotating parts of the engine, which is something you could check with your dipstick if the sump is still off.
paulh4

Here is my update on the Dipstick situation
It appears that my engine has the press-fit dip stick tube, 5.1’ long (18V Block). It has the bent dipstick with the fixed conical seal (second in the series). And the early 5-main bearing sump with the drain NEAR the right rear corner and dipstick “hump” MG never shipped this configuration, but it seems to work ( I think) The Max oil level is below all the moving parts. And the Min is (just) above the top of the oil intake.
NOW, for all the engine guys out there, I have a question. I have never had occasion to take these measurements, or worry about them, on any engine, American or Brit. Given my measurements, the Min. oil level appears to be a true minimum. Any lower and it looks like the oil pump will suck air. Am I missing something? Just how much “cushion” should the Min. oil level provide?
Bruns

That does seem low from a logical point of view, doesn't give much scope for oil surge on acceleration or cornering. I've never let any of mine get below half-way between Max and Min, but then I have known people who leave it until the oil light (dipstick cars, not those moderns without) comes on before topping-up!
paulh4

The top of the gauze oil pump filter is NOT where the oil gets picked up.

Inside the filter is a tube that goes down almost to the bottom of the sump, it is from the bottom of the tube that oil is sucked from.
Chris at Octarine Services

"Inside the filter is a tube that goes down almost to the bottom of the sump"

That figures from something an MGA chap wrote many years ago, and I had forgotten. In competition he was getting oil starvation at high revs as shown on the gauge and wrecking the bearings. To cut a long story short the pickup tube was so close to the sump that it couldn't pass the volume of oil that the pump was trying to get. He was getting an effect similar to cavitation as the pump was trying to move 90 UK pints per minute at 7000 rpm.
paulh4

Of course, Chris. What was I thinking? Looks like I was caught up in detailed measurements and not looking at the big picture.

Just for the benefit of the archives, based on the press-fit dipstick tube and the blocking plate for the mechanical fuel pump, I do have a 18V block, and this block, coupled with a 2nd generation sump (5-bearing with the dip stick hump) and a 2nd generation dipstick (bent, but with the fixed stop) is a workable configuration.
Bruns

This thread was discussed between 18/11/2017 and 21/11/2017

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