Help with confusing engine block

[garreth51]

Hello all,
I have owned an '87 944 for six years. PO did not have maintenance documentation, and the car appeared to have an early replacement motor based on timing belt configuration. I recently started a complete teardown to do timing belt, water pump, bearing, etc... I was curious what motor it was exactly but found no engine code stamp. I became further confused when I removed the belts and covers and found mounting points for the late style spring tensioner, a late style oil pump, and late style balance shafts.





I don't understand why the motor was using the early belt configuration, why the spring tensioner mounting points weren't drilled and tapped, and what happened with the engine code. Any help will be appreciated, I have held off buying parts to do a rebuild as I don't want to assume all late style parts will apply.

[kdjones2000]

That is not an '87 block - more probably an '86 one.

Look for the engine code near the #4 exhaust manifold outlet, on the opposite side near the back, but stamped up on the cylinder head deck.

[garreth51]

just the casting number on that side.

[Stoneguy]

I believe the auto tensioners were mid to late 87. 924,944. Don't quote me on that.
I have an original 86 944 with old cam style tensioner and I also have an 87 engine I bought out of an 87 944 NA that does have the auto tensioner.
Very surprising to me that your engine doesn't have an "M" number stamped on the flat just behind the reference sensor bosses.

[kdjones2000]

I wonder if that is a replacement block...

They still stamped the tolerance group (1) on each cylinder, so they certainly could have put the engine stamping on it if they wanted to.

[garreth51]

Ah so that’s what those markings are. And I had a similar thought about it being replacement. But then it’s a late block that was intended for early cars? I just can’t wrap my head around not prepping for the auto tensioner.

[originalowner]

Porsche probably changed the casting mold, but still supplied replacement blocks for the earlier cars by not drilling and tapping for the tensioner.