Grey area engines?

[Don R]

 I'll attempt to post some pics, when they download to google. I have two 1970 unnumbered replacement engine cases. Both have the 10 bolt clutch cover, one has the added bolt (3) in the sprocket area and smooth painted cases, the other has a coarser texture that looks just like 5511, a thin frame around the blank number pad, 3 punch marks, and only two bolts in the sprocket area. Both have casting numbers within the hex like a die cast engine.
 I know it isn't a true "sandcast" but I can't help wonder if they continued using the early process to make the updated engine type for a short time. There is a clear difference in the castings.

 One of these engines is destined for 14,100 It's a resto mod, keeping it's Lester mags, the exhaust is still undecided but it should make a nice bookend to 5511. I would love to know how to read the dates in the casting numbers.

[kp]

I can't wait to see the pics 

[4pots1969]

Me too !!

[Don R]

 I'll get better ones but this is on my google photos now, I miss my photobucket account but am too cheap to pay the ransom.
 
 This one has the same appearance and texture as 5511

https://photos.app.goo.gl/2l6982oBkzK02TDh1

 This one looks and feels like all my other 750 engines.

https://photos.app.goo.gl/QNKZCcVGlD4LLew62

[Don R]

   One more that is already in my photos. 2 bolts in the sprocket area. Rough texture.

 
https://photos.app.goo.gl/UhblndxgSm1JscIT2

[kp]

Hi Don
All die cast cases 

[Steve Swan]

i would suggest the difference in surface textures may be due to different casting molds.  these early diecast engines had variances with their respective vin ranges; some of these variances were more distinctive than others.

[Don R]

 I ran a diecast machine in the 70's. I made engine case bottoms and flywheels for lawn boy mowers. The only variance I got resulted in the part going in the melt down basket. lol.
   I did have issues with the die temperature and aluminum temperature. For some reason you could possible shoot the aluminum in before the die closed all the way. That resulted in a squirt of molten metal usually burning you somewhere. Timing was everything, plus the oil/water mix we sprayed the dies with.