TD engine

[Rickwilson]

Hi All

In my search for a replacement engine for my TC I've come to the conclusion that I will probably have to settle for a TD engine , as TC engines are much harder to find and more expensive too. I have heard reference to "early" and "late" TD's . But never have heard an explanation as to any difference between the engines. Can anyone tell me of any differences between an early TD engine and a late TD engine?

[Steve Simmons]

The biggest differences that you would notice between early and late engines are visual. A lack of a raised MG logo on the side of the block, the engine number plate moving from bell housing to a raised square area on the side of the block, and the water drain moving from the center of the block to the front. Internally the biggest visual change was a change from oval cooling holes to round ones. The water elbow will be the wrong angle for a TC radiator (easily changed) and you will need to source a TC front plate, as the engine mounts are completely different on TD. The valve cover vent is also different, as is the oil sump with a clutch pivot sticking out of the side. The clutch will be larger and starter motor much smaller than TC. The generator is also smaller. The ring gear will have more teeth to match the TD starter. These can all be changed to TC parts. I seem to recall that the intake manifold is slightly different on TD as well. The carbs are basically the same but the bodies are a bit improved and as I recall the pistons went to aluminum with springs instead of brass. The air cleaner and manifold are completely different.

If you want it to look authentic, there is nothing you can do about the block differences, but you can install the TC starter, generator and oil pan to fool most people. There are TC engines out there but as you note they are more expensive. I know of one but I think he wants around $3K for it. By comparison, I just sold a TD engine (long block) needing everything rebuilt for $900.

[Rickwilson]

Does this mean that an EARLY TD engine would be the same as a TC engine except the front plate?

[Steve Simmons]

Now that I think of it, the TD starter used 2 bolts so the block may have changed there. Been a while since I had a TD engine in the garage. Otherwise that I think they are identical. Maybe someone else is more familiar with the TD setup who can either verify or correct my memory. I also remember that the early TD oil pump changed to use a banjo on top rather than the 2-bolt piece the TC used. After about 3,000 engines, they moved the brass plate and all the other things that stand out as making it an obvious TD block.

[Rickwilson]

Steve
I've been told that All TD blocks have 3 starter holes so either starter can be used on a TD block. I'm wondering if a early TD block is the same as a TC block. I.E. oblong water holes, 7 1/4 inch flywheel, engine #location, etc.

if I saw 2 bare blocks. How would tell which one was TC and which one was EARLY TD?

[Steve Simmons]

I think they are the same, and now that you mention it yes they would have the same number of holes, or else it would have been a different casting.

[Rickwilson]

So I'm thinking that although any TD engine can be made to work in a TC, a EARLY TD engine would be an ideal replacement.

[TD4834]

Being the owner of 5 TDs and 8 XPAG/ type TD,TD2 & TD3 engines let me correct some information. All TD blocks have three holes at the starter location. The very earliest TD engine’s (first several hundred) had their tags in the same location as the TCs. Likely to use up TC stock. Early TDs had a smooth oil pan and was later changed to a finned sump with larger capacity. Early heads have the banana water ways while late are round holed. With that came a spark plug reach change, These changes occurred throughout production. Early engine’s also have a remote oil filter as the TC. Engine’s have a horizontal oil filter integrated with the pump. XPAG/TDs will have a 7-1/4” clutch with a 5/8” cross shaft while XPAG /TD2 and TD3s will have 8” clutch and a 3/4 crosss shaft. TD3 was a late MKII engine designator. The 168xxx cylinder head having larger valves and heavier spring. All MK IIs early and late came with H4 1-1/2” carbs. Early intake manifolds were port matched rather crudely while TD3 intake manifolds carried a 168xxx # and were machined to match. All XPAG PN beginning with 168xxx originated with a XPAG TD /c or MARK II as they were known as.

You must use the correct TD starter for either TD flywheel as the tooth count is different. I believe they are also different than the TC flywheels.

Hope this helps a bit. I’m sure Tom Lange can add more to the list of changes

Bill Chasser
TD-4834
TD/c-8151
TD/c-16920
TD-19408
TD-24060