Stihl 066 wise me up

[Cut4fun]

Some NOS pistons are from cylinder/pistons sets sold as a set. They may be marked A or B, not AB. I can't remember which is smaller (piston)... but I think it's the B.

More learning , Thank you.

 

[Jacob J.]

Now what if a 460BB aftermarket piston got slipped into a aftermarket 066 cyl? I read where they are both 52mm but the pin location is different.

The 460/046 Big Bore piston is 54mm but is not compatible with 066/660. The reason for this is the "crown height" of the BB piston is different. Crown height is the distance from the top of the wrist pin boss to the top of the piston. The 046/460 BB piston also has shorter skirts than a standard 066/660 piston. They both use a 12mm wrist pin. Obviously the 046/460 BB piston is timed for the 046/460 engine design which uses a shorter stroke than the 066/660.

All the IPL's I have show the same piston part number....I do know that they beefed up the cylinder base, went to 6mm X 25mm bolts
from the 5mm X 20mm bolts

The 066/660 always had the 6mm x 25mm headbolts. The reason IPLs show the 5mm x 20mm bolts is that those were standard on the 064. Remember that IPls dealing with two models of saws that are very similar will show all of the parts available for models on the same page even if the parts aren't interchangeable or compatible with each other.

 

[Jacob J.]

I was reading where a cly and mixed matched piston created a head slap and then another cylinder and piston was used on the same saw and the squish was perfect. So i havent a clue, but am trying to figure it out.
Also read where a aftermarket cyl was used with a stihl piston and got a head slapper. So something is up, but i bet 04 knows something on this and maybe the Lake.

Part of the reason you get "head slappers" when mixing and matching pistons and cylinders with crankcases is the difference in tolerances of the cases themselves. I have seen differences in squish heights of as much as .045" between two cases on similar aged 066s. This could be due to worn tooling or human error.

 

[Erick]

Andy, as usual

You Da Man!!

Wish I had 1/2 the knowledge that you've forgotten.

Cut, thanks for starting this thread, learned a little something new, my day is now complete and its only a quarter after one.