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My brother-in-law Terry is working on my Mini as he has the time I don't.

The PO had replaced the head and apparently didn't do more than slap a new head and head gasket on. Terry says the head gasket is burned through in 2-3 places. He says the head looks okay, but he is concerned there is damage to the block. He is going to email me some pics in the next day or so.

If the block is damaged, I am thinking about my options. One would be to have the block machined to remove the damage. Is this cost effective? Two would be to find a replacement 850. Anyone know of a good, used, running 850? What kind of dollars can I expect to spend? Three would be to upgrade to a bigger engine. My car is a late 63, early 64 (I think) and has the starter button on the floor. I want to retain this and have been told if I upgrade the engine, I will have to remove it. Is this in fact the case?

Looking for some input here from more experienced Mini minds!

Thanks,
Peter

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I think the issue about loosing the floor mounted starter surfaces if you also change the gearbox type (to a remote or rod-shift). Your '63 850 would have the magic wand shifter. Unless you opt for a replacement engine with the same style gearbox attached you may not have room for the starter button and the gearshift mechanism in the tunnel. Sadly, some of the early 850 boxes are too narrow at the top to provide clearance for the crank of the larger engines. So, you may not be able to use your existing gearbox on anything but another 850 engine.

I'd ask the machine shop how much it would cost to clean up your block. Before you tear it down, check the piston height relative to the top of the block. If you need a lot removed from the block you could run into the problem of the pistons being "too high". You obviously can't live with them hitting the head.

This forum probably does not have a lot of people who have spare 850 blocks. There is "that other board" where you could post a parts wanted note. However, keeping the car original has a lot of merit, particularly early cars. Your car will be more valuable if you keep the original (numbers matching) engine and gearbox.

The sad thing is, if you're like me, once you get into the engine you may not stop with just decking the block (if you have yours machined). While you're in there you'll end up checking everything and replacing more than you set out to do. It costs a lot to rebuild any engine and an 850 won't be proportionally less expensive than a 998 or even a 1275. A complete, drop-in 850 or 998 with a magic wand gearbox would probably be your least expensive option if you're not worried about originality.

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Considering the gigantic effort required (in a Mini)to get the engine out and then stipped down, I think it would be worth a shot to just mill the head (slightly) to make sure it's "true".
Then put a new head gasket on and see if it works.

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My bro-in-law seems to feel the main concern lies in the head, not the block and will indeed be checking to make sure the head is "true". He asked me a question I am not sure of the answer - what color shound the engine be? He has it out and says the head is green, but the rest of the engine is black. I had the impression the engines were all green. Should it be black, green or a combination? To the best of my knowledge, the engine has never been out or messed with before this, so the fact the block is black is probably correct, for my car at least. What say you guys? And if green correct, what paint to use, where do I get it?

Thanks,
Peter

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Your post above said the car is a '63 so the engine, gearbox, and generator would all have been green from the factory.

If you decide to paint the block, sources like Moss will have the green paint in a spray can. However, I chose the Austin-Healey green engine enamel from POR-15. It is excellent paint. You can brush it on the block and head and you will get very good coverage. For smooth parts like brackets and the valve cover, you can thin the enamel with a small amount of mineral spirits and apply with an air brush. I'm very pleased with the appearance of the POR engine enamel and how it's holding up.

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Doug, any situation where the engine would have been black?

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Later blocks (Mk3 and on?) were black. Perhaps the block was repainted during an engine rebuild prior to when you bought the car.

In the early days, the factory assembled all the ancillary components on the engine apart from the distributor and sprayed them as an assembly. So, the only way I can see having a black block and different colored head would be if a previous owner had the engine apart and/or put together a bunch of different components. For example... perhaps the original engine for your car became very worn so a previous owner bought a Mk3 block and reworked his original cylinder head to have a working engine.

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I suspect there will or should be some casting numbers or ID numbers on the block that will tell me if it is an original engine or a later replacement? Where would they be and what "series" should they be? Being that my bro-in-law has the car, I can't go look myself. Do they tie to the vin tag?

Re: Mini up-date

If you are looking at the engine as it sits in the car, there should be a reverse stamped metal tag on the right, front corner of the block. The tag is on the top of the block (the same surface the head sits on). It will be just behind the generator/alternator, slightly to the left of the temperature sending unit. If you don't find an aluminum tag there (and perhaps only two holes for the rivets), it's a good sign that the block has been rebuilt previously. The aluminum tags are frequently damaged during machining or dissolve off when the block is hot-tanked.

It took a while... but I found an image on the net. See:
https://www.minidean.btinternet.co.uk/images/UHR850engine.jpg
The aluminum engine tag on this 850 is just below the spark plug terminal for cylinder #1

If you are concerned about whether this block is original to your car, you can contact Heritage in the U.K. and ask them to run your VIN number. For a fee they will run your VIN number and provide you a certificate confirming the date your car was built, its original color(s), factory options, and the country it was destined for. They will also list on the certificate the original engine and body numbers.

Here's a link to the current Heritage web site. I have not used their services in years so I can't tell you how they handle requests now.
https://www.heritage-motor-centre.co.uk/pages/exhibitions/exhibitions_heritage_certificates.html

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Unfortunately, the response I got from Heritage was that the records for my car are missing.... :frown:

The tag is there, still riveted in place. Terry mentioned it last time I talked with him.

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Peter, if you're looking for an 850cc replacement you might want to contact Steve Gibbs at Coopertune. He might be able to assist in locating one if he doesn't have one.

https://coopertune.com/

He has a Mini forum off his site with some knowledgable folks as well. If you're not already on the forum, I'd sign up as there are some really helpful people that will respond to your questions.

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Thanks Dave! Always good to have multiple sources.

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Peter, do you know Jim Fletcher at Period Performance Specialties in Gilbert IL? He supports a number of the vintage Mini racers. He might be a source for you as he's a little closer to you. I just recently picked up a 67 Austin Cooper S project from him. If you'd like his number send me an email at david.hesse@wi.gov

The best I can do is a full 998 with rod-change gearbox. I don't have any 850 stuff.

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Steve Gibbs is a good friend and he certainly may be able to help. I don't wish to sound like I'm selling him short though when I suggest that if you start looking for a new block, you may be able to find one closer to home than shipping one from Steve who lives near Virginia Beach.

I have a Mini owner friend in Chicago who may be able to help you look at the problem. He will not have an 850 block, but he can probably put you in touch with more local people who do. If you want to discuss this with him, PM me your email address and I'll forward it to my friend.

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I am going to attempt to post the pics Terry took of my engine.
Tell me what you think based on what you can see.

The blue links are additional pictures.

Re: Mini up-date

That certainly is a well burnt through head gasket.

As Nial said earlier, for the effort involved so far it certainly would make sense to have the head surfaced at the minimum.

I can't tell anything from the pictures. If there is bad pitting or burning on the top of the block then it should be decked. If your brother-in-law is working on the engine at home, suggest that he go to the hardware store and get them to cut him a piece of window glass (not plastic) roughly the same size as the head. You can use that as a flat surface and get a rough idea if the top of the block is warped or not. If there is no burning or pitting and the plate glass shows it's reasonably flat (say.. no more than 0.003" out of flat... checking against both sides of the window glass) then I would use the block the way it is.

When you buy a new head gasket, see if you can locate a Payen "black" gasket for the small bore engines. The Payen gaskets have a sealant on their surfaces and they have a reputation for superior performance on street cars.
See: https://www.aptfast.com/APT_Parts/aseries_Parts/a_Gaskets_Seals.htm

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What would cause that head gasket to burn through like that?? Terry wants to know how I want to procede. How much does a decent running 850 go for? Know anyone that has one? Does anyone have a good complete head for an 850? I'd prefer to keep the original components and do what is needed. I mentioned I saw an engine online for $1200. So now he wants to know where to get a $1200 engine as he is seeing prices of double that.

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Peter, the A-series has a reputation for blowing head gaskets. However, it is certainly more common on the large bore engines than on the 850s. I would check what you have for flatness and burned surfaces before giving up on the engine you have.

As for the extent of the gasket damage, that can be very misleading. Once a tongue of flame starts shooting back and forth through even a pin hole leak in a gasket it can disintegrate very quickly. Your engine was probably running fine one moment and within a couple of minutes started feeling very wrong.

Again, look at what you've got and decide if what you have really isn't fixable. My gut feeling is that you need to have a skim cut taken off the head to restore it to flat and you obviously need a new head gasket. If the block isn't burned and measures flat across the top... a little head work is a cheap way to get back on the road.

As for used engines, $1200 for a used 850 sounds expensive. Over the years, countless 850s have bee pulled from early Minis so owners could install 998s and 1275s. I have seen known good runners posted on other boards for as little as $100 (sitting on an early gearbox). If you're seeing prices that are upwards of $2400, I hope the engine is 1) larger than an 850 and 2) at least partially refurbished and offered with a warranty.