617 Turbo->240D 4-speed questions
 

I have been reading through all of the threads on this topic I can find, and just want to make sure that I have identified all of the major steps.

1) Pull engines/transmissions
2) Have 240 flywheel balanced and use it to mate 4-speed transmission to 617 engine
3) Shorten drive shaft and shift linkages 4 inches
5) Install 617 engine with 4-speed transmission
6) Splice together electrical and vacuum systems

Some of the threads made the swap seem easy, others like a major pain. Should I expect a major headache? I am trying to decide if I want to attempt this or if I should just find a new 240 engine. Thanks –Bryan

Balance the 240 flywheel to match the "flexplate" from the 617.

It is easy. You can ease the pain even more if you have the donor near by, just in case.

It's a good project for when you have a full weekend to devote to it.

So I should put a reference mark on the flywheel, flexplate, and crank on the turbo engine, then take the flywheel and flexplate into a machine shop for matching? Thanks

Yes, set the 617 to #1 TDC and mark the crank/flexplate with a small punch (not an ink marker).

You don't need to know #1 TDC for the 240 flywheel. The machine shop will find the heavy point and use it as a base point to match balance.
EDIT: Also, you don't need the torque converter to balance. The TC is neutrally balanced on it's own.

the proceedure is described in detail in the factory service manual. an easier method works when the fw is neutrally balanced. which they often are. first check the fw from the engine you want to use. if it is neutrally balanced then make sure the fw you are going to use is neutral also.

also you really should swap out the radiator, speedo and rear end as well. also a second engine shock bracket must be fabricated to do it right.

and if you can do it all in a weekend i will be impressed.

did you mention shortening the driveshaft?

it is a very worth while conversion. not without effort or expense, but you get the simplicity of the 240d with excellent performance. if you do that you will need a speedo to match.

tom w

oh and i would recommend using a 346 rear end from a na 300d to ease taking off with the four speed tranny.

Guess I'll have to hunt for a Factory service manual. Does it detail the addition of the engine mounts too? I'll probably stick with the 240 rear at first. I should have a week or so to attempt it in November, so I have awhile to search for parts. The car was only $400 so I have some extra cash to play with. As for the effort, I guess I am a glutton for punishment. :rolleyes:

Does the drive shaft need to be balanced as well?

Yes, cutting and welding it will change it's balance. While it's out, it is the perfect time to replace the center support and bearing.

While my 240D only had 195k miles at the time, the center support rubber was completely gone. No doubt one reasons the last owner replaced most of the front end trying to fix a bad highway speed vibration.

I guess I should also throw in a set of new motor mounts while I am at it too. How did you get a tach instrument cluster to work while still using the stock 240 rear end? Thanks.

I just kept the right gauge (Tach/clock) from my TD. It should have a two prong plug. One wire is for power (If I remember correctly), the other is signal from the tach amp.

If you study the wiring diagram from a turbo model, you will see just how simple the system is.

Engine swap
 

I have also been thinking about making this switch. There is a place about two hours away from me that specializes in stripping import cars and selling all the good parts off them. When i went there they had at least 4 617 motors with some of them running 400 compression. The motors arnt to expensive however i am a rookie and im not sure exactly how hard this task will be to tackle. I do have access to welders and machinists so im thinking it is do able.

if you dont change out the rear end you will have astounding acceleration but will use a lot of fuel. you will be lucky to get 20 mpg on the highway and 15 arorund town, imho.

good luck

tom w

Fuel milage did not change for me. I got 22mph in my 300TD, and I average 22mpg now in my 240.

I have read several post where members did not have the flywheel matched to the flexplate, they just kept moving the flywheel and checking for vibrations until they got minimal vibration. Is this ok, or is it a MUST that you have the flywheel matched....I have done this without balancing the flywheel and have minimal vibration at idle but no vibration off idle....is this method ok?

Sounds like an exhausting and imprecise procedure. Not to mention time consuming. I'd think you'd be better off just balancing the thing and be done with it.

But I'll have a good time doing it. :D

I think I'm going to go ahead attempt the swap. Looks like the Wife may make me sell the other 240 to do it though. :(