Rebuilding XPAG 9204

[timandgerda]

Hi Steve,
I used G Bland and Sons at Barnsley for all my engine machining last year. They were excellent and went to great lengths to get everything right. I had to have my block line bored for new bearing caps and the cam bearings fitted and bored as they were missing from my spare block (original block was the wrong one). I still have the crank seal tool I made for centering the seal carrier if you need it as mentioned before. Cheers. Tim.

[SteveW]

Hi Tim, thanks for the offer of the crank seal tool. I'll take you up on that when I get to that stage. Hopefully by then I will be allowed to come and collect it. Also, thanks for the recommendation for the engine machining. Their website doesn't mention being closed at the moment so, even though it's an hour from me I'll give them a call.

[SteveW]

I've been taking some measurements today using a dial gauge to work out what needs replacing. The discovery of date stamps on some of the parts has shown that the engine was rebuilt in the latter half of the 1990's. I know that it was off the road for about 10 years since then. This explains why many of the parts look slightly worn, but not excessively so. My measurement results were as follows:

i)The end float on the crank is 7 thou. I think that the recommended float is between 2 and 5 thou, so I'm a bit over, but is it enough to have to replace the shells which otherwise seem in good condition?

ii) The crank has been reground to 30 thou and the surfaces seem in good condition.

iii) End float on the big ends is about 14 thou. I've not seen any discussion of end float for these so I don't know if it matters as presumably the pistons sitting in the bores centre them anyway (plus they must need at least the same end float as the crank to stay centred on the cylinder bores when the crank moves). As near as I can work out, there is 4 thou play between the big end shells and the crank. I need a new set of big end shells anyway, so some of that will probably be taken out.

iv) After I cleaned it up, there was 9 thou play between the camshaft and the front bearing (the one in the earlier pictures). That seems like too much so I'll need a new one, which is a pity as it cleaned up quite well.

I'm going to have to find other jobs to do on the restoration now as I'm stuck on progress with the engine until I find an engine shop that's open.

[SteveW]

I've started the engine rebuild now as the block, head and crank are all back from the engine shop. I had to replace the thin front camshaft bearing but the other two were fine. I did have a little difficulty at first putting the rear bearing back into the block as I couldn't get it to go in square so it kept jamming against the bore in the block after a couple of mm. I eventually found that a much easier way to get it in was to slide the camshaft most of the way in, place the bearing on the camshaft and then push it into the hole. The camshaft kept it perfectly lined up and it went in no problem. My other tip is to put a bit of marker pen on the outside of the bearing and block so that you can get the oil hole and locking hole approximately in the right place. Then poke a screwdriver through the locking hole to move it into the exact position. This prevents accidentally compressing the bearing with the locking screw.

I have a question though. What should the end float on the camshaft be? Mine seems to be quite a lot (say 1mm?), but on the other hand the distributor and oil pump gears will presumably help to stop it moving around too much.

[SteveW]

On further inspection, what seems to be the excess end float is caused by the gap between the circlip and the rear bearing. It's almost as if the rear bearing is not long enough. The diamond end plate is not worn. If someone has a rear bearing on the bench, could they accurately measure how long it is please?

[Gene Gillam]

Earlier in this thread Tom Lange mentioned going to Moss and get an oil pump rebuild kit. If you do please very carefully check the circlip that comes in the kit. Mine failed and caused some expensive damage to the pump and the #2 rod.

[Steve Simmons]

The end float on the camshaft is set at the front. The circlip in the rear is only there to prevent you from accidentally punching out the rear plug as you insert the camshaft into the block. You don't actually need that clip if you're careful. As I recall, end float is spec'd at .005" to .013".

[SteveW]

In that case, I don't understand how the end float is set. I get that the diamond plate stops the camshaft from being pulled out, but what stops movement in the other direction if not the circlip? Maybe something is missing from mine.

[Steve Simmons]

The timing gear is the other stop! So to measure end float, you need to install the gear.

[SteveW]

That sound you probably just heard was the penny dropping. Thank you.

[SteveW]

I cleaned up my flywheel the other day and discovered that it has a crack in it. It looks as though someone has hit it (very) hard with a hammer and crushed the metal whilst installing or trying to get off the ring gear. The crack is oval shaped and disappears under the ring gear but does not emerge on the other side - i.e. it looks as though it would come off as a chip rather than it being a crack that runs through the whole flywheel.

I suspect that I'm looking at getting another one, but has anyone had any experience of having such a thing repaired - either by grinding out and welding in a blob of new metal, or by grinding out the defective bit and also equal mass from the opposite side to keep it in balance. Clearly any repair would have to be professionally done as messing with this amount of angular momentum is potentially dangerous.

Does anyone (UK only due to likely postage costs) have one that they want to sell?

[Ray White]

Hi Steve. I bet that crack has been there for ages and the chance of a chip breaking off is negligible.

I think I would not worry about it.

I have noticed a crack at one of the bolt holes in my sump...but I won't be loosing any sleep over it.

[SteveW]

Since may well have to replace my flywheel and refurbish the rest of the clutch, I was wondering about upgrading to an 8" clutch. With the right flywheel is this just a straight swap?

[Tom Lange, MGT Repair]

I am sailing between Scylla and Charybdis, since I do sell brass Welsh plugs (see mgtrepair.net for details). I can confidently assure you that the steel plugs will and DO rust out internally - probably half of my orders every year come from people who write, "The steel core plug under the exhaust manifold has a pinhole leak from rust..." I believe it is due to areas of poor internal coolant circulation.
Brass Welsh plugs will absolutely last the life of your car. Until I started making brass Welsh plugs, steel plugs were the only option. On a race engine, torn down completely at least once every season, steel core plugs will be no problem. But on a street car, where years can go between engine removals, brass Welsh plugs are well and truly the best ones available. And unlike others available, mine DO fit, are made in the USA, and are precisely custom-made to my specifications.

I make no apology for the fact that the parts I sell are usually a bit more expensive, but are the very best available, to which many satisfied customers can attest. In the last decade I have sold literally thousands of sets of brass Welsh plugs, with universal satisfaction.


Tom Lange
MGT Repair

[bloodysalmon]

Tom, may I ask what are 'brass welsh plugs' got to do with a flywheel ?! ... there are plenty of brass core plug manufactures doing these for the TC (and all British classic cars) in UK, cheaply too.
Who are Scylla and Charybdis anyway ... a rock band or something?!

[Duncan M]

Sounds like Tom is waxing mythological. An old sailor's term, and relevant to a car's cooling system?

[Tom Lange, MGT Repair]

I am certainly late to the party, but the first part of an earlier multi-part question was about whether there was any advantage to brass Welsh plugs over steel ones. I was replying to that, and nothing to do with flywheels. And my mythological reference was because I was trying to balance the fact that I supply brass Welsh plugs, yet strive to be objective in my replies.

Tom Lange

[SteveW]

I took a more literal interpretation - I thought that you were on a sailing holiday between some lesser know Greek islands

[SteveW]

Should there be a screw-in plug in the end of the oil gallery (the large threaded hole in the picture)? There wasn't one in my engine but it doesn't seem right that the hole is only sealed with the clamping force of the engine mounting bracket. I had a look at the picture in the Moss catalogue but couldn't see anything so if there is supposed to be one, does anyone know what the part number is?

[Steve Simmons]

Yes, it's the same type of plug as the rear. I believe the Moss number is 328-020. I'd recommend some sealer on the threads.