1975 1.8 Driver Restoration, Driver quality restoration of a 1975 1.8 Options

[didenpx]

@Montreal914 I really know very little about these engines and am slowly learning as I go. What do you see in the photos that makes you think it may have been used in racing application? Thanks!

Paul

[Montreal914]

I am not an expert either. Your specific 71.76mm number caught my attention. If this is the real stroke, then it was modified. Why would someone go to the trouble of slightly increase the stroke by only 0.76mm? The only reason I can think of is to stay within the boundaries of the 2 liter class.

Now for the 102mm cylinders, these can be problematic and known to warp as their wall are very thin.

Hopefully the real engine experts will chime in. (IMG:style_emoticons/default/smile.gif)

[didenpx]

Thanks!

[930cabman]

I am not an expert either. Your specific 71.76mm number caught my attention. If this is the real stroke, then it was modified. Why would someone go to the trouble of slightly increase the stroke by only 0.76mm? The only reason I can think of is to stay within the boundaries of the 2 liter class.

Now for the 102mm cylinders, these can be problematic and known to warp as their wall are very thin.

Hopefully the real engine experts will chime in. (IMG:style_emoticons/default/smile.gif)

Waiting also,

have wondered why 98 or 100mm pistons are not a thing. If 102 and greater are trouble, why not reduce the size a bit?

[didenpx]

Did some more work on evaluating the engine (with expert assistance).

We learned that the likely cause the 3-4 head was pulled was broken valve spring and loose valve guide on one of the valves. That head came bare (no rocker arm, missing 2 valves) Heads have been ported.

I have pulled the pistons and did a much more careful measurement of stroke and it is 74mm so it’s a stroker crank and the engine displacement should be in the 2.4L range.

Once I get some decent photos put together and we have evaluated the pistons and cylinders (cast iron 102mm cylinders, flat top JE pistons) I am going to start a stand alone thread on the engine in hopes of getting some of the experienced engine builders here to weigh in with advice and information.

But right now the operating theory is that the bottom end is fine and it just needs an oversized valve guide, two new valves (were missing when I got the engine), and reassembly….assuming I can reuse P&Cs.

This is definitely going into the car unless there is something catastrophic that appears during case tear down.

[didenpx]

I've never worked on engines before so working with an experienced engine builder to evaluate the mystery 2.0 has been a humbling experience.

Initially I had the pistons at 102mm (measured at the face). But measured about 1/2" from rings they are 103mm.

Initially I measured the stroke at marginally above 71mm. Then I did a "more careful" measurement (measuring end of rod after pistons were removed) and arrived at 74mm. Yesterday after fitting a jug and piston and using a degree wheel to determine true TDC we determined it is a 71mm stock stroke crank. Duh again.

The crank has welded counterweights so assumption at this point is that it's DPM maybe sourced from European Motoworks (where I'm currently assuming the big bore kit originated).

Based on initial measurements of cam it may be a EMW "S" grind, to be confirmed soon as we prepare to split the case. Looking through the jug holes the engine internals are looking good (near zero wear on the cam lobes).