Morris Minor Owners Club

Colleagues, the questions begin (regarding UFN 456).
There has been quite a bit of bodging done to this car and nearly all of the water hose clips were totally slack, the thermostat housing loose and both types of hose installed (for no Water Pump and "with" water pump - later addition).
I think that I need to either clean up the thread in the cast iron housing, that takes the alloy casting or re-cut it to a larger size.
I can't do this without knowing what the original bolt size should be (my screw gauges don't fit the thread profile, but I think it is one of the 5/16" bolts).
Referring to the photograph, the bolt holes, where the housing connects are circled in magenta as is the alloy air pipe bolt that happens to be the same size. Can anyone tell me what size bolt this should be (the unseen left-hand bolt hole is much shallower than the right-hand one and the previous bolt was spaced out by the use of a larger nut!

The fitting circled in yellow, is the throttle cable linkage which is obviously on the wrong side of the dizzy as the air cleaner/silencer steady bracket strap is missing (which carried the throttle guide/stop) - the dizzy has also been mounted with a "later" type pinch bracket (utilizing the hole for the steady bracket bolt) and the original cotter pin is missing (I have bought a replacement pin). I also have the correct strap, taken off a spare 918 engine that I happen to have.
The engine would originally have been fitted with an Oil-bath filter (which was found in the boot), but a UK silencer had been fitted as a replacement. Inerestingly, although the car was manufactured as LHD export (went to Belgium), the engine number doesn't have an "EX" prefix - should it have had?

All information gratefully received, George.

Metric engine so 8mm Metric ought to be the right thread (OUGHT to, be careful).

The carb is right for the later engine (which you have) but the barcket is for the early engine that had the float chamber and the throttle lever on the opposite sides to that one. Either change the carb back to a Lowlight one or extend the steel bracket over to the other side of the dissy.

On this pic you need to extend a bracket from the one bolt that is removed, under the bolt that still sits there and then bend the end up to take that round metal thingy with the hole through it, if that makes sense. I don't have a better pic to hand.

Hello Rob,
The engine, in question is from June 1950 and is the 2nd type that came with a blanking plate, at the front, to take a water pump if a heater was required.
Below is my March 1951 engine that came with water pump already fitted and has the mounting bracket I refer to. The spare engine had the same sort of bracket, which I have now borrowed.
The bolts that hold down the alloy thermostat housing are not M8, nor any other metric size.
It is the same diameter as an M8 bolt, but the thread is a lot finer.
5/16" BSF (wing and seat floor bolts) are very close, but not close enough.
They are also not 5/16" Whitworth and not 5/16th UNF - I don't have anything else to compare with.

M8x1mm is nearly the same as 5/16 BSF (at 7.98mm) and 25.4 TPI against the BSF at 24 TPI. Mteric 8x1.25 is the more common one so maybe you need the M8x1 Metric FINE thread???
After all these years it could be ANYTHING!

Can you slip one of the bolts out that hold the seat down. 5/16 BSF, so if it is just a little finer then it is M8x1

Rob,
I bought new seat/wing bolts and the first thing I did was to do a comparison. The thread on my "unknown" bolts is finer.
I don't have any fine thread M8's - shame none of my TPI gauges fits!
George.

Rob,
Many thanks - you were spot on with the M8x1 size. I went along to a specialist tool and nut & bolt shop in Camberley and they checked my bolt.
I have now bought a further 4 M8x1 set screws (they didn't have any bolts - they also didn't have any M8x1 taps.

Whoever had been botching the engine and ancillary equipment, had fitted floor/wing bolts of 5/16" BSF and that is why the alloy thermostat housing was loose and full of some sort of silicone sealant - luckily, the bolts were very worn and the threads in the cast iron head had not been compromised much. The seat floor bolts have now been replaced by fresh 5/16" BSF ones and I did re-cut the threads in the captive nuts as I do have 5/16"BSF taps (but no dies). All the 5/16" BSF bolts and set screws, that I have removed so far, have very damaged/stripped threads.

I shudder to think what I will find when i attempt to remove the OSF wing, which isn't on too well (not all bolts in place).
Another member, on my original thread about buying the car, has already warned me about the state of the sills when he last saw the car in bits - I do have lots of panel parts and I now have a Mr Grumpy Roll-over Jig - untried so far.

Thanks again for your help,

George.

For all my taps and dies requirements I use Tracy Tools.

https://www.tracytools.com/

High Speed Steel (HSS) taps and dies are best.

Use die nuts for cleaning up male threads. You can purchase taps that do not cut new threads for cleaning up female threads.

I don't have any fine thread M8's - shame none of my TPI gauges fits!

If you lay a ruler against the thread it has one turn every mm, hence 25.4 turns-per-inch. Neat little trick?

This is a most helpful item in determining threads

https://www.ebay.co.uk/itm/Zeus-Precisi ... :rk:1:pf:0

Thanks for the tip Rob and also thanks to Phil for pointing me in the direction of the Zeus book - just bought a copy and it will be delivered next week.
George.