OK, this might be a dumb question. I have a 1973 1.7 with Weber IDF 40s that I've been working on for the last year and a half. Compression test shows 140-150 psi, tested with all plugs out, throttle wide open and engine warm. I just drove up to Northern Wisconsin, about 300 miles round trip, and the car ran great and got 27 MPG.

I know the engine has been apart before because there is blue sealant that has squeezed out from between the case. The PO had no information on if and when the motor was rebuilt. I also think I still have 1.7 heads because they are 4 bolt, with breather tubes.

Is there a way to tell what the cylinder size is and if the cam is stock without opening the engine? I assume that the rebuild was with 1.7L parts but how can you tell?

About the only things I could think of would be to:
Look in the sparkplug hole and if the pistons are flat top (no dish), then the PO likely replaced the pistons with aftermarket, but that wouldnt tell you how big.

If you measured the valve travel, you could tell if it was a stock cam or not (possibly identify what it is). However this would be a bit of a challenge crawling under.

Also based on the car running that well with the current setup, you could see what size venturis you have in the webers.
If they were giant, and the car ran good, then you likely have a big bore.
If you can see any spacers under the cylinders then you have a stroker.