850 water pump

[super bodge]

Hello all, My dad is doing up an old 850cc Minor and bought a new water pump for it but it is not the best and the thread that screws down in for the bypass is not good so I am on a mission to get a tap so a friend can tap it out, We think it is 5/8 unf but I'm not sure what tpi it is, we think It might be 14 as 11 looks to course but I thought it was worth a shout out on here for some info before I head to ebay. Many thanks for any help Andy

[bmcecosse]

850 Minors are very rare! That engine was only fitted to some of the later vans.....where minimum performance with maximum economy was wanted. Yes the thread for the bypass insert in the head is 5/8 UNF - the 'UNF' defines the TPI. So as you can see from the chart - it's 18 TPI.
http://www.carbidedepot.com/formulas-tap-standard.htm

[super bodge]

Many thanks for your quick reply and you made me think when you said it was rare so I had a chat with dad and it seems I have it wrong. Are's is a 803 from 1954 and its a cast iron 4 bolt water pump, would I need to get the same tap or is it different. Andy

[bmcecosse]

Ahhhhhhh - right - 803. Oh well! I didn't know the water pump had a 'screw in' bypass connection. I can only say the the head connection is 5/8 UNF. So IF the pump has a screw in connection I would assume it's the same.

[super bodge]

Thanks again for your reply I will get on ebay and get a tap as a chance is better than not having a tap lol. Ps I will be getting my mum and dad to join the club as you have a grate site and the Morris Minor is for keeps. Many thanks again Andy

[bmcecosse]

Show us a picture of the damaged water pump...

[JOWETTJAVELIN]

803 pumps are scarce and expensive so keep hold of the old one.

[super bodge]

Yeah £90 expensive and it was rubbish we had to get some turning work done to make a piece up to hold the pulley tight as it was lose on the shaft as well. not what you would expect for a new part lol. I will try to get a pick on but I'm doing some long hours in the shed

[JOWETTJAVELIN]

Brian Gostling has some recon 803 pumps, check Minor Matters.

[bmcecosse]

What would it take to fit a 948 pump to an 803? Is there a serious difference?

[JOWETTJAVELIN]

No idea but probably incompatible otherwise it would presumably have been done. I think 803 pump has different block face.

[David53]

Mounting points totally different n the 803 pump, so the 950 not possible. I had the same problem with the pulley on the shaft on a new pump from a very well known supplier. Basically badly made. I had the original rebuilt and no problems since.