Morris Minor Owners Club

svenedin wrote: ↑Sat Sep 23, 2023 2:13 pm I just might get away without having to go to a machine shop. I cannot measure threads so I do not know what thread the bypass adapter I have is. Whatever it is it does not fit the cylinder head properly (it is too loose) and leaks. It screws in easily (too easily) and is clearly not watertight.

Minispares sell a bypass adapter that they say is 5/8" UNS 18 tpi "Whitworth fine" but they also say some customers fit what is actually a servo adapter that is 5/8" 18 tpi UNF. I have ordered both and will see if they fit. If not, head comes back off and I'll take it to a local engine business.

Phil already told you I previous post
It's whitworth not unf
viewtopic.php?p=691688&hilit=Bypass#p691688
Stephen

Bill_qaz wrote: ↑Sat Sep 23, 2023 4:02 pm

svenedin wrote: ↑Sat Sep 23, 2023 2:13 pm I just might get away without having to go to a machine shop. I cannot measure threads so I do not know what thread the bypass adapter I have is. Whatever it is it does not fit the cylinder head properly (it is too loose) and leaks. It screws in easily (too easily) and is clearly not watertight.

Minispares sell a bypass adapter that they say is 5/8" UNS 18 tpi "Whitworth fine" but they also say some customers fit what is actually a servo adapter that is 5/8" 18 tpi UNF. I have ordered both and will see if they fit. If not, head comes back off and I'll take it to a local engine business.

Phil already told you I previous post
It's whitworth not unf

Stephen

Bill_qaz wrote: ↑Sat Sep 23, 2023 4:34 pm Is that a typo in your previous post? 5/8 uns did you mean 5/8 unf which is 18 tpi
People often get mixed between UNC and whitworth as they are both course thread but not interchangeable the thread in the head should be a corse thread.
Loctite do a thread seal which is good when threading into water jackets

philthehill wrote: ↑Sat Sep 23, 2023 4:52 pm Just to reiterate the correct thread for the bypass hose stub is 5/8" x 16TPI Unified Special which has a Whitworth form.
If you try and cut a 5/8" x 18 TPI in the head to overcome problems with the 5/8" x 16 TPI bypass stub threads you may well end up with no threads.

paul 300358 wrote: ↑Sat Sep 23, 2023 8:10 pm Are you sure that its the by-pass stub that's leaking? I was under the impression that if you try to fit the copper coolant pipe above the head nuts, it was too short to correctly fit the bottom hose.

philthehill wrote: ↑Sun Sep 24, 2023 5:39 pm Yes I would run a 3/8" x 16 TPI UNC parallel/plug tap down the stud holes in the block.
If you have not got a compressed air blow gun to clean out the threads after tapping smear the tap with grease before tapping. The grease picks up the displaced crud.
You should only clean the centre of the piston of carbon. Leaving an outer ring of carbon helps to stem oil usage.

svenedin wrote: ↑Sun Sep 24, 2023 4:08 pm Whilst waiting for the new bypass stub pipe (which may or may not solve the problem), I took the advice given here and cleaned the block up better.

I used liberal WD40, a window scraper (a Stanley blade mounted in a handle designed to remove paint from glass) and a green pot scourer. The WD40 lubricates and loosens the carbon.

Using the scraper blade I could feel that some of the stud holes do indeed have pulled up threads. Phil you are spot on (as usual) and I will lighly countersink as you suggest. Bill: I. cleaned up the piston crowns.

Block is as original and has never been skimmed. Stamped with "2" in various places. Pistons marked "MOWOG". No lip I can feel on the bores but rather polished looking and honing marks hard to see.

Thanks agin for the invaluable advice.

I am not so upset now about the leaking stub pipe because the end result if going to be that I do a much better job and I am learning a lot. Everything happens for a reason they say.......

Stephen


IMG_9362.jpeg

Bill_qaz wrote: ↑Mon Sep 25, 2023 9:44 pm

svenedin wrote: ↑Sun Sep 24, 2023 4:08 pm Whilst waiting for the new bypass stub pipe (which may or may not solve the problem), I took the advice given here and cleaned the block up better.

I used liberal WD40, a window scraper (a Stanley blade mounted in a handle designed to remove paint from glass) and a green pot scourer. The WD40 lubricates and loosens the carbon.

Using the scraper blade I could feel that some of the stud holes do indeed have pulled up threads. Phil you are spot on (as usual) and I will lighly countersink as you suggest. Bill: I. cleaned up the piston crowns.

Block is as original and has never been skimmed. Stamped with "2" in various places. Pistons marked "MOWOG". No lip I can feel on the bores but rather polished looking and honing marks hard to see.

Thanks agin for the invaluable advice.

I am not so upset now about the leaking stub pipe because the end result if going to be that I do a much better job and I am learning a lot. Everything happens for a reason they say.......

Stephen


IMG_9362.jpeg

Confused me Stephen as I never mentioned piston crowns? But the block face looks better after your cleaning.
Hope it all goes back together successfully for you this time.

The number 2 next to the bores is likely the manufacturer grade mark for cylinder bore sizing, even std bore have a tolerance/ range