MK1a engine in MK1b?

[JamesDaniel80]

Hi again,

Following on from my previous post about my dead engine, I've managed to source a replacement but I've just realised it's coming out of a 1985 MK1a model.

Should it be a straight swap? Or will I need to change some bits to make it work?

Or have I just made a huge mistake and bought something that won't work??

Thanks,

James

[Lauren]

Check whether it's a 3-Rib (blue top) or 7 Rib, (redtop).

The 3 rib is the earlier engine. It will work, but is weaker, but revs better. I'd try and get the ECU to go with it if you can and note different injectors etc, though doubtless it'll work well enough with the injectors of your current engine.

It's a total lottery on how good it will be though on an engine that old.

[JamesDaniel80]

Thank you.

It is a lottery but I figure it can't be worse than my dead engine.

And the replacement only has 76k under its belt so fingers crossed.

Here's a question then...at which point did they change the engine types?

My MR2 was registered on 17/09/1987.

The replacement is coming from a car registered on 11/10/1985.

[Lauren]

It was 1987. I had a D-reg t-bar with the earlier engine. Can't remember when that car was registered in 1987 though. Think it might have been September.

When the transition happened from the MK1a to MK1b, it seemed to do so over a year or from 1986-87.

Hope you get lucky with the engine. I just think running a 30 year old engine, it will only be a question of time before the inevitable rebuild, but YMMV of course.

[Tiamat]

YMMV

?

[Lauren]

An ancient acronym from the early days of the internet, Malcolm.

Your Mileage May Vary.

[jimzzr]

I think there was a difference in flywheel/clutch diameter between mk1a and mk1b. I suspect they may well be swappable, I'm sure someone round here will confirm.

[LimeyMk1]

I think there was a difference in flywheel/clutch diameter between mk1a and mk1b. I suspect they may well be swappable, I'm sure someone round here will confirm.

Flywheel diameter is identical, pretty much the same weight too. Only difference is the clutch on the later spec is a bit bigger as the friction surface in the early flywheel is a smaller diameter.

[kaiowas]

It's also only the very earliest mk1a engines that have the smaller clutch, most have the larger one. It's not really an issue as you can use either as long as you match the appropriate clutch with the same type of flywheel.