My MG's Garage 

Engine rebuild
Home Up 5 Spd Transmission Engine rebuild




Since the engine had to come out anyway for the 5 speed conversion, I decided that I might as well go through it, which hopefully will be the last time in my lifetime that it will ever need to be done.   So here is the final view of the "warp core" with the squirrel drive removed.   Note: all the photos are thumbnail's so click on the picture if you would like to see a larger image 


It was a nice Saturday near the end of June.  Johnny and I were putting the final touches on getting his "B" back on the ground and running.  His nephew Ben offered us the use of an engine hoist, but work and family obligations had delayed him being able to get over to my Garage to pull the engine out of the TD.  So Johnny and I were concentrating on getting the suspension on the red car done.  Johnny's brother Tom, Ben's Dad, and an avid  Model T (of the Ford persuasion) Restorer volunteered to bring an engine hoist, and help pull the engine out.  Since the TD uses British Whitworth (BSW) threads I had to make some bolts for the engine stand, I bought from Northern Tool.  I wanted hardened bolts at least grade 5, preferably Grade 8, but couldn't find any long enough.  Graciously, Mark Brandow, owner of  Quality Coaches lent me a tap and die and told me to buy 5/16th Fine thread, and re-cut them.  So the stand was ready, and I was ready, tomorrow Johnny, Tom and Ben would be over and we would pull the engine.  There was plenty of daylight left, and my wife was out shopping, so I decided to get the honey-do landscaping chores out of the way so I would have more time to play in the engine bay.  Nothing stops a rebuild project like a Coronary, let me tell you.  Needless to say, Tom, Ben, and Johnny didn't make it over that Sunday afternoon as planned.  It was a month before they would even let me twirl a wrench at all, and I only wanted to pull the plugs in my "B" to check them. 

Back in May, Johnny and I removed most of the all the connections between the engine, and car.  So here the car sat with the carburetors, intake and exhaust manifolds off, the prop-shaft removed, etc.  June turned to July, and I managed to sneak some work on the car.  Trust me, it can get real boring sitting around and not doing anything that requires more than 10 pounds of effort.  So I did manage to remove and replace the points to the fuel pump in July.  The fuel pump literally died in my Garage in the fall of 2002, but planning on the rebuild in the spring of 2003, I bought the parts, but let the rest go.  Then August they let me back to work, and finally my Doc raised my lift restrictions (10 pounds is a little more than a half-gallon of milk, you sure can't lift much that way). 

Part I -- Removing the Engine

On a nice Friday evening in the beginning of September  I started taking the car apart.  Following the shop manual instruction, I removed the carpeting as directed.   The carpeting isn't really bad, but it's not so good either.  Eventually, it will get replaced, but it might have to wait till more funds are available.  Those of you out there with wives know exactly what I am talking about.  First priority is the engine, The carpeting, only the piece under the drivers chair is really horrid and will need to be replaced, the rest is worn, but serviceable.  As you can see in the photo, I am just being my picky self.  Next it was time to remove the floorboards The plywood was pretty water damaged on the bottom side, so I have resolved to build new ones this winter.  The previous owner, or factory for that matter used plain 1/2 inch plywood.  I think I will try 3/4 inch marine plywood for this application.  Rather than having a completely flat floorboard, the plywood is cut out to accept a foot well piece.

The next thing to be removed is the transmission tunnel cover and the prop shaft tunnel.  Getting the prop shaft tunnel out was pretty easy, but you have to remove the emergency brake lever, and disconnect the cables before attempting this.  On my first try, I tried not to remove it, and was rewarded as usual by having to reinstall the e-brake, and then remove the bits.  Someday I'll learn.  The boys in the Abingdon Engineering shops did not carefully consider the position of the heater core and box. Well, they only put it there because us soft yanks require them.  Here in Minnesota it will usually get down to -25 F (-32 C)  but us soft yanks need our conveniences.  After removing the heater, the transmission tunnel came off with no problems.  Here you see the entire transmission and the rear of the engine.  On the right, there is a better view of the transmission and the transmission mounts which also act as a rear engine mount as well.  There are two rails on either side of the transmission which act as a tunnel for the prop shaft, that must also be removed.  The shop manual says that on left hand drive cars you must disconnect the steering column which sits right over the oil pump and filter.  I removed the three bolts, and dropped the steering wheel, as directed. Now where do you put the thing?  I just pulled it back and tried to rest it on the rear platform.  Well as you can see in the two pictures the engine is ready to be pulled.  I left the front engine mounts in place until Johnny arrived with the engine lift on Saturday. 

Well Johnny showed up, and we set about to assemble the engine lift.  Johnny showed up with the biggest engine lift in the world.  Ben, who couldn't make it because he had to work, had his small engine lift stolen, and all he had was this thing that was suitable for pulling diesel engines out of trucks.  This thing was rated for four tons (3600 Kg) and could have lifted the car!  After attaching the engine balancer (you should use one -- it saved our butts)  we thought okay we are ready.  For those of you who have done this before, the picture will tell you what we had to learn.  The shop manual doesn't tell you this.  Alf and Nigel, two mythical, employees at the works (factory), that John and I made up to complain about, must have known that this knowledge was widely known and dispensed with the Guinness and Harp at the local pub after work.  There obviously was no need to put such a commonly known thing in the shop manual.  However, this never made it across the pond.  All you Yanks out there please note:  It is advisable to remove the headlights and light bar before extracting the engine!!!  There is a note in the shop manual about pulling the shifter.  This also should be done as it is almost impossible to get the tranny out with the shift lever in place.  While pulling the shift lever is an extremely good idea, later on it does present some problems.  Well we pull the two bolts holding the engine mount to the frame, and start to extract the engine.  At one point  you may be able to notice that we actually lifted the car, front wheels and all about 3 inches off the ground.  With a little care and some fussing here and there, you can actually pull the engine and not hurt the headlights, but it would have been easier if we had removed them.  Finally after about three hours the engine is free as you can see.    As you can see by the photo to the right I was very glad to get the engine out of the car.  We lower it to the floor and start removing the transmission, and bell housing.  In the bottom of the bell housing are all these little bits of brass.  On examining the clutch while there was plenty of material on the clutch disk and pressure plate, obvious signs of wear and some scorching was evident.  It is a good thing I ordered another pressure plate and the Autogear transmission kit comes with a new clutch disk that fits the splines of the Ford type9 transmission.  We split off the transmission, and attempt to reassemble the shift lever -- two hours later we got it back in place.  As Alf and Nigel know, you have to get all the shifting plates into the neutral  before you integrate the gear change lever with the transmission.  That really isn't a devilish expression in the photo to the right, but rather more of an alright what do we do now.  The next section will document the results of the tear down and then hopefully the rebuild and install.

Part II -- the analysis and planning

Well the engine was torn down into its component parts.  After much thought I decided to bring the engine up to MG-TD MkII specifications.  by the time I am done it while it won't be a MkII it will be a MkII 1.75.  I don't think at this time I will opt for either the 4.9 rear end, or the friction shocks.  Everything else will be to MkII specs.  One of my other objectives is to take as little metal as possible off the engine.  I plan for this to be the last time in my life to have to do this, and hopefully in the lifetime of whichever of my kids end up with this thing, in theirs as well.

It looks like there is some blow-by between number 3 Cylinder and number 2.  The heads, pistons tops and plugs are heavily covered with carbon, indicating a chronic over-rich mixture.  The Tappets seem in good shape but will need to be re-ground.  I am told that they are not using as quality material for the tappets as the originals so I am better off  having them reground .  The number 3 Cylinder had a lot more rust, but no pitting, probably from sitting around a lot, the SU  Fuel Pump quit, but has since been fitted with new points.  The diaphragm seemed in good order, and it pulls a lot of air.  The previous owner put a glass pack muffler on, and thus it sounded like a truck, Mark lent me a free flow exhaust for an MGA 1600 and it seems to fit in the space available.  The cam shaft bearings and cam showed some signs of wear, and will be replaced with the Moss crane version.  New MG TD MkII valves have been procured, and will be installed with steel guides, and hardened seats.  This will require some regrind of the combustion chambers, how much will as yet to be seen.  The crank has been previously reground as it is running 0100 bearings in the big-end and mains.  The reason it leaked oil so much is that the cork seals in back and the rope seals in front do not appear to be around.  Also the little aluminum bracket over the rear bearing cap is missing, although the cork seal is still on the bearing cap.  As you can see from the photos, the engine was painted Chevy or Massey Ferguson Orange.  This will be changed to MG Red.  I am considering replacing the oil filter with the Fram Spin-on replacement, and installing the Moss Seal Kit.  I have not been reading great things about it on the web, but I park one MG above the other, and so it is not my garage floor that will collect the oil, but rather the "B," and that is not acceptable.  So if this will cut the leakage to zero, it seems the way to go.

Part III -- Engine Modifications

The complete specifications for this engine mod was done up on an Excell spreadsheet, and will be available for download soon.  Change a few of the numbers for your car, and you can figure out the effect of changes to the engine.  So we begin ...

The head went off to Cylinder Head Service of Minneapolis, MN (612-721-4112) for first hot dipping, and then using Non-Destructive Testing (NDT) to see if there were any cracks in the head structure itself.  The head tested fine, and was totally stock, so I had Tom put in steel guides, and the valves ground out to take MKII valves.  Stellite seats were put in so that using unleaded fuel is no longer an issue.  A Good article on using reformulated (read that lead free) gasoline was published by the Chicagoland MG Club that goes into why you should do this.  I opted for steel guides since the bronze oilite guides do not expand and contract at the same rate as the steel valves, and can bind, causing strain or even damage to the entire valve train.  This was relayed to me by more than one respected source.

The valves were reground to a 3 angle grind.  Research showed that for the XPAG engine better airflow occurred at lower valve seat angles so the valaves were ground to a 15-30-45 degrees rather than the more conventional 30-45-60 used for modern engines.  The head was collected and taken to R&R Performance (Columbia Heights, MN) where the porting and polishing was accomplished. 

Brian was very good to work with, and did excellent work.  However this will be the last XPAG head they he wants to work on.  He doesn't see very many of them, and they have decided to reject working on them since they had to create special jigging to work on the heads.  He gets enough Small Block Chevy engines to work on, so they just don't want to take the extra time that the occasional XPAG engine takes.   When they did return the head it the intake and exhaust ports were widened to just a fraction less than the manifold gaskets, and the ports were ground and polished heavily, but not so much that the shape or valve choke was impaired.  The ports were smoothed and blended into the bowls, and pocket ported to make the airflow smooth into and out of the intake/exhaust valves.  The inlet port outer stud boss was ground away about 0.060 in. to make the ports 1.1875 inches high by 0.65625 inches wide, and the "beak" behind the stud boss was polished and radiused.  The net effect of these modifications were to smooth out the entire airflow to aid the XPAG in breathing in and out.  This engine in my opinion is pretty well choked up, and some additional HP can be gained from this original "tractor" engine.  The combustion chambers were polished but no additional metal was used.   0.0897 inches were removed from the head thickness bringing it to a finished thickness of 2.928 in.  bringing the engine's compression ratio to 8.61:1.  Lastly the combustion chambers were measured to confirm they were 4.5 cc's.  While bringing the engine up to MarkII spec's, except for the porting and polishing, I am endeavoring to remove as little metal as necessary, yet to do the job right.  The head was returned to Tom at Cylinder Head Service and the valves and Mark II valve springs were inserted. and the completed head returned.

The crankshaft was sent to Crankshaft Supply (Minneapolis, MN ) where the crank was magnafluxed, polished,  and ion nitrided for durability. The crank came back 0.020 under, and the correct bearings were ordered through Quality Coaches from Moss.  Additionally new cam bearings, and the Crane standard grind cam and shorter rods were ordered as well.  I picked up a set of used MGA HS4 1-1/2 inch Carbs and ordered the rebuild kit from Moss.  More on the carb rebuild later.  A free flow exhaust for an MGA was recommended by Mark to finish up the breathing package.

The engine has just gone into Competition Engines (Burnsville, MN 651-688-6351).  Randy is currently NDT'ing the engine, hot dipping it to clean it up, and will clean and hone the cylinders.  It seems that the #3 cylinder picked up some rust, (a good justification for fogging the engine prior to putting them away for the winter, since it is highly likely that one valve will be open when the engine stops) and we quickly miked the engine and its seems to be 0.030 over bored.  After the wash, and Magnaflux, Randy will mike the bores and let me know if we can get by with a 0.040 overbore.  I will then be able to order the pistons, rings, gudgion pins and frost plugs for the engine.  and a dynamic balance of all moving engine parts comes next.  The current Tappets are slightly grooved, but Mark thinks that I can get by with resurfacing them -- we will see.

That's it for now --- soon we may have an engine again rather than three boxes of parts.

Last modified: April 26, 2005

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