finally decided to pull it out and measure it

[jmssaws]

It's a 066 dave. My late 660 is like new and doesn't need a piston.
Someone will need what your offering.
I've got boxes of pistons. Thanks though

 

[huskihl]

Nice thread DD. Truly definitive

 

[Boo Boudreaux]

you have my address, heck if you prefer to reassemble it your self I will cover shipping both ways and send ya the new piston back with the saw, heck as long as you are positive ( we can check serial number to be sure) that it is a 660 and not a 66, I could just use the complete crankcase (with crank installed) to measure the case volume.
I am going to pull the built 1122s down from the shelf tomorrow and see which versions I have up there as ported runners, but I am positive they are all 064 and early 066.
Dave

I love you avatar it looks likes you were waiting for the taxes to go down ~!~!

 

[Deets066]

Cool thread Dave! Now I need to check weather mine is an early or later 066

 

[Brewz]

I hope you didn't use motol 800 in those saws Dave, the zink deposits may have skewed the results.

 

[Brewz]

Now from what I have read, a smaller case volume is desirable as it gives increased velocity, presumably up the transfers.

I have a bit of an idea of why and what this can effect but would love to hear some more detailed information on what case volume effects.

Data acquired, time to learn

 

[Brewz]

late no plug, big bearing 066 serial x614 held 92ml
early oval plug small bearing 066 serial x245 held 76ml

These are the 2 I have which equates to a 21% difference in case volume.

They both run great but run completely differently

The old small baring 066 red light is a bucket of torque but is not as perky as the late big bearing 066 which is very snappy.
I have been wondering if its the alloy vs polly flywheel that may be partly the difference.

With a 21% case volume difference, I am wondering what can be done to the old red light to make it a bit more snappy or am I better off leaving it as is due to the little crank shaft?

 

[Definitive Dave]

A lot of variables in there
Different cylinders/timing.
Different ignition systems.

And let me say my sample size is really dang small, only 6 crank cases .
I am confident in saying that all 1122 series crankcase a DO NOT have the same crankcase volume BUT I wouldn't claim that all crankcase a of these types will match each other in volume. If I measure 50 early 064 crankcases i am not sure they are all the same.
Dave

 

[Brewz]

Yes true but it has to be a given that the early "short case" saws would be lower volume due to being smaller.

I recon castings of saws of like age and make would be very close with the differences being in casting changes as the models progressed through change

 

[Mycamaro_68]

Just thought of this @Definitive Dave. Were all the measurements taken with the crank in the same position? (BDC or TDC) wouldn't the volume of the rod create a difference?

 

[Tractorsaw1]

Great pics to identify these, I believe its a slant top, however its gonna be awhile before its confirmed. Thanks!

 

[ABarrick]

The vast array of different cranks Stihl used I bet plays as much a part of this as actual case volume. Of the dozen or so 064/066/660 I have had apart, I don't think any had identical cranks. I have bought two new 064/6 cranks in the past 4 years and they were both the same but the OE stuff from back in the day changed frequently.

Very cool of you to take your time to do this.

 

[stihl saws]

Anybody got a nice MS660 PHO that needs a new piston?
Mail it to me I will tear it down, fill it with red kool aid and then put a new OEM piston on it, check the squish ( gasket delete if you wish) and send it back to you.

If your still looking I have a good 660 I'd loan you for a few days. I can strip it down this weekend and just send you the bottom half.

 

[Definitive Dave]

All cranks tdc
Stihl sawing i will take you up on that offer
I will pn you from a computer, my thumbs suck

 

[Definitive Dave]

I never checked before but had to pull them off the shelf and peek
Mastermind #1 is a late 064
JMSsaws is a late 064 with a MS660 KS Jug
EC Saws is a early 066 with a MS660 Mahle Jug
Mastermind #2 is a mystery because Fed Ex is hoarding my damn saw - that is my saw to hoard you bastages!!

 

[stihl saws]

All cranks tdc
Stihl sawing i will take you up on that offer
I will pn you from a computer, my thumbs suck

Pics of the 660 that's soon to be a science experiment. Yes, it's dirty. I actually use my saws......sometimes.

 

[Deets066]

I looked at my 64 and 66 today, the 64 is a flat top early case, and the 66 is an oval plug early case.

 

[Deets066]

The 66 has the large bearings and poly flywheel, obviously there are earlier than mine.

Mine is a flat top with decomp

 

[mdavlee]

There's a pin interesting thread going on chainsaw repair about case volume.

 

[Definitive Dave]

Link that thread Mike we ain't skewered