Stihl 070 090 crankcase Question?

[jensen 32000]

Anybody have any success mating two 070/090 crankcase halves from two different saws? If the dowel pin holes are off slighty, I would guess you have to "line up" the cases to the crankshaft bores, (with a machined pilot shaft) and then the cylinder base? I was thinking to re-drill the dowel pin holes a few thou bigger (.250"), to "make up" for the slight misalign on the pins. Could I machine a little off the area where the cylinder sits,(raise compression) to level the two halves? Sorry for all the questions, Hopefully some of you can help. Thank You! Mike.

 

[olyman]

damn mike--youd think they were all machined--and drilled--on the same jig at the factory--and while mines gong to be torn part down this winter--sounds odd the case halves wouldnt match--and the germans are supposed to do it best--uh huh---

 

[PES+]

It seems like he is blending two different halves I it can be done but you have to be very careful to check the plane of the deck that the cylinder bolts down to all things are possible with enough time, money or both

 

[jensen 32000]

Yes Pest, You are correct, I have an 090G that I got "in pieces" from a couple of years back, and the flywheel half of the case is gone. I think those Germans align the halves in a jig and THEN drill the dovel pins. Besides, I'm sure there was more than one factory assembling crankcases. I have access to a full machine shop, and work with some guys with pretty good skills, (one made a crankshaft from scratch for a steam engine for his old boat) so I'm looking to get it really acuratey matched. I just don't want to "re-invent the wheel" if somebody has aready done it successfully and easily. Thank You guys!

 

[Lakeside53]

Most stihl saws (but not all!) have matching crankcase sides. The 090 and 070 cases are only sold as a set.. They are locked together before machining not only the cylinder mount, but the crankshaft bearing bores... get the later even a thou off and you have a big problems.

So.. are you a betting man?

 

[PES+]

Please elaborate

Please do elaborate just what big problems you would have with a 1 thousandth mismatch on the bearing centers lakeside

I'll let you tell itopcorn: