We left Bob Butson (owner of TA0844) in the June issue, contemplating the mess that his MPJG engine was in. Clearly, with crankpin journals undersize by as much as 90 thou another crankshaft would have to be sourced. Bob takes up the story from now on:
Continuing with the engine, I had to obtain another crankshaft. After much searching, Andy King offered one with a 40 thou. undersized grind which had been crack tested. Now to clean up the block and oilways, remove the core plugs and check all moving parts.
The front engine mounting plate had some holes with a dished area around them. The front plate was slightly bent, and one engine mount had a cracked weld. Some threads in the block had been mangled. They needed to be helicoiled. The bores needed to be sleeved.
The spacer between the crankshaft timing gear and the pulley is a running surface for the front oil seal and has a scroll to screw oil back into the engine. There was a groove where the rope seal located and the scroll was damaged, (Photo 1)
Photo 1 – showing damaged scroll
I made a replica. The rope seal is not very efficient so I opted for a modern lip seal. The seal I chose was quite substantial but very slightly bigger than the original rope seal and did not quite fit the original cover. I made a new cover turned from solid which very closely resembled the original. The seal and an appropriate cover can be obtained from Brian Rainbow, brian ‘at’ brianjrainbow.free-online.co.uk
The timing gears were in good condition but a new timing chain was needed. The clutch plate was in good condition but needed recorking, I was recommended to send it to Charles Cantrill, Tel. 01215673140 cancork ‘at’ cantrill.fsbusiness.co.uk The flywheel had to be refaced.
Having considered many varied opinions about engine modification, and as the flywheel and head were as standard, I did not modify these, except for re-facing and an unleaded conversion for the head.
All engine components were ready for boring, metaling and balancing. The cam followers will be refaced and hardened, as will the rockers. The work will be done by Cox & Turner Engineering 01935 826816 ian ‘at’ coxnturner.freeserve.co.uk
Other problems were the following:
• The breather pipe exit from the rocker cover had been sawn off and replaced with a smaller diameter pipe. This was easily rectified using a piece of the correct diameter tube. I also made a breather downpipe to fit. The photo (right) shows this and also the oil filter conversion used (see TTT2 Issue 2).
• The camshaft tensioning spring was missing: it was broken off just beyond the rivets. A kind soul on the Yahoo groups.com website group mg-tabc sent a drawing (see photo below).
I obtained a strip of annealed spring steel from model engineers Folkstone Engineering Supplies Tel. 01303 894611. After shaping and drilling they hardened and tempered it.
The head studs needed to be replaced as did the big end nuts. These were supplied by Roger Furneaux roger46tc ‘at’ virgin.net The horseshoe shaped circlip which holds the three springs to the clutch plate was in two pieces. I was fortunate to obtain the last of a small batch which had been made privately.
When I assembled the engine I used bolts of original specification, i.e. metric threads with BSF heads. I have compiled a list of original bolts for the MPJG engine, this can be found on the ttypes.org website under the ‘Publications’ section of the site. Some of these bolts are stocked by Roger Furneaux and some by 251 Products, Tel 08707 664252, email sales ‘at’ 251services.co.uk For the latter, if bolts are required, they should be specified as only setscrews my be available.
Ed’s Note: My understanding is that some of the MPJG engine bolts and XPAG engine bolts are the same. As Roger specialises in XPAG items, these are the ones you can buy from him. Those specific to the MPJG engine (well, most of them), as well as those which are used on the XPAG, can be obtained from 251 Products.
I managed to find three suitable springs which serve to move the clutch plate away from the flywheel, and to restore the thrust bearing retaining nut. I replaced the clutch cross shaft bushes. These were supplied by www.bearingboys.co.uk They appear to be able to supply any type of bearing . They also supplied the cogged V fan belt No. BX44 which I used. A new timing chain, rocker shaft and bearings were obtained from the MG Octagon Car Club.
I had re-faced the oil pump cover and made a new shaft. A static shaft and gears were obtained from the MGOCC. The gears were for a TD but had to be reduced to the correct length.
All the engine components were ready for assembly by Christmas (2006).
On rebuilding the engine I found that the pistons which I had fitted protruded above the top of the block, they were Morris Ten pistons which I mistakenly obtained about twenty years ago. Cox and Turner were able to find the correct set.
The head assembly was quite straightforward but I was advised not to fit the rocker lifting springs. All went well after that. I used ‘Wellseal’ jointing compound for all joints from www.ready2race.co.uk
When fitting the exhaust manifold to the head I found that the centre limb was out of line with the outside limbs, giving about 1.5mm gap at its join with the cylinder head. I thought that tightening this to the head would strain the manifold too much for old cast iron and so I had the mating surfaces ground in line, hoping that too much metal had not been removed.
Good progress being made with the MPJG engine
It was time to sort out the gearbox. The first motion shaft had a worn spigot, a missing spring ring for the bearing and a groove worn where the oil seal had run. A limb had been cracked off the rear cover at a bolt hole and the mounting plate was bent. The selector shafts were in good condition but the forks were worn.
The first motion shaft from my spare gearbox was a bit rusty, as were the selector shafts and the top of the casing. On stripping the spare box I found all gears and both lay shaft and reverse shafts to be in very good condition and so I replaced these in my original box. I replaced the first motion shaft bearing and mainshaft bearing with new. The layshaft cage bearings looked OK, as did the cage bearing in the first motion shaft. I took a chance and did not replace these. After cleaning the original synchro hub it appeared fairly sound. I had no way of ascertaining the wear on the synchromesh cone. (See follow on article on replacing synchro-hub balls).
I repaired the groove caused by the oil seal in the bell housing in the first motion shaft using a Speedy sleeve. This was supplied by www.sealmasters.co.uk. The number to fit was 50SRK118, I took the shaft for their sizing.
The universal joint flange for the mainshaft had a damaged oil scroll and was worn due to poor location with the end cover. I replaced the universal joint flange and the end cover with those from the spare box. The oil scroll seemed insufficient to prevent oil leakage from the gearbox, but that is how it was manufactured. Time will tell.
The gearbox remote was next. It appeared to be in good order, with minor wear on the selector lever and in the holes bored for the operating shaft in the casting. There was rust on the gearshift lever and some play between the ball, at its end, and the socket. I re-sleeved the socket. The domed shift lever anti-rattle spring cover was rusty but not pitted. The anti-rattle spring was broken in half. The spring cover had a round section retaining circlip and, due to the flange on the cover not being quite wide enough, it moved under the circlip when changing gear. This would give an annoying clack. I used a flat circlip no. D1300-058-Pack2/ 1CB41 from Simply Bearings Limited simplybearings.co.uk which solved the problem.
Ed’s note: Thanks for another instalment Bob and thanks for some useful supplier contacts. Your follow on article on replacing synchro-hub balls comes next.
A method of inserting balls into a TA synchro hub
A delicate operation, but it works!
When rebuilding the gearbox on my TA it was necessary to strip and clean the synchro hub. I devised this method of reassembly as no special tools were available.
Tools required: two similar G cramps, a 1 1/2 inch wide strip of aluminium, two 2BA bolts about one inch long, eight 2BA nuts, a piece of flat bar ½ to 1inch wide, a bench vise and two small screwdrivers.
A clamp similar to a piston ring clamp was made from the aluminium strip to fit around the outer hub edge flange with about 3/8 in. spacing, fixed by the two 2BA bolts and two 2BA nuts. Clamp two G cramps in a vise and rest the outer hub on the fixed limbs. Insert the springs in the inner hub, then place in position, partly into the outer hub, then fit the clamp. Place a flat bar about ½ to 1inch wide just long enough to straddle the top of the clamp and tighten the G cramps lightly to the bar.
(This ensures that the aluminium clamp sits squarely on the hub and does not rise up when fitting balls and nuts).
Adjust the clamp screws so that the balls may be placed at the ends of the springs. The balls should locate at the entrance to their housings. Two small screw drivers and some dexterity may now be needed. Allow the aluminium clamp to rise about 3/16inch to clear the outer hub flange, adjusting the 2BA bolts as necessary. Push a nut between the clamp and the ball for each ball. Some more adjustment of the clamp bolts will be required. Dribble a small amount of oil over each ball and tighten the clamp screws, making sure all nuts remain in position. The balls are pushed into the hub just the right amount and at just the right centring by the nuts. The inner hub can now be pushed down leaving the nuts to fall free. Check that all balls were located. If any escape, try again. At least they will be retained within the aluminium clamp.