CASE VOLUME DISPLACEMENT ? / Introduction

[XP_Slinger]

The idea of running 272xp agains my build would be great.
Unfortunately the only one I have is almost stripped.
It's a complete crankcase from intake to muffler.
If I had a tank/ clutch & cover / starter and other smart parts ,
Then I would have something to co

Be nice if we had all the saws wouldn’t it ...lol. If I had a running 272 I’d send it to ya for the comparison.

 

[SHOVELHEAD]

Hoping to finish work early tomorrow, and start prepping.

 

[SHOVELHEAD]

Randy @Mastermind ,
Do we have a ETA on the piston?

 

[Mastermind]

It hasn't made it to me yet. It's riding in the box with a saw and a few other items I ordered.

 

[SHOVELHEAD]

So I had enough time yesterday to tare down the 2156 & secure everything in the parts washer & set the timer before leaving the shop.
I peaked just before leaving, it's cleaning up nicely.
Today if I finish work early enough, I'll try to get the 272XP in there as well as the 2159.

 

[XP_Slinger]

 

[SHOVELHEAD]

Just finished the wash, the 2159 is clean and ready for final inspection.
The 272xp in torn down as well and still was still turning in the washer when I called it quits tonight.

I wish I knew how to upload photos, but I guess it wouldn't matter phone is so full.

 

[XP_Slinger]

Just finished the wash, the 2159 is clean and ready for final inspection.
The 272xp in torn down as well and still was still turning in the washer when I called it quits tonight.

I wish I knew how to upload photos, but I guess it wouldn't matter phone is so full.

It’s not difficult to upload pics if you’ve never done it. Just hit the “Upload a File” button under the text field you’re typing in and pick which photos you want to upload. Full size is limited to about 5 per post, you can fit more in a single post using thumbnails

 

[SHOVELHEAD]

I don't see the upload file?
I've found the ( Image URL: ) and can not use it?
URL?

 

[SHOVELHEAD]

 

[Marshy]

I don't see the upload file?
I've found the ( Image URL: ) and can not use it?
URL?

No use the upload a file button down by the post reply buttom.

 

[XP_Slinger]

You don’t have the button circled in red in this pic?

 

[SHOVELHEAD]

!!! WARNING !!!


THIS IS A TEST

 

[SHOVELHEAD]

Okay, that's easy using I phone instead of the P C.

Now if I can free up some (storage) on my phone to take some current photos we'll be in business, for a CHAINSAW BUILD-OFF

 

[XP_Slinger]

!!! WARNING !!!

View attachment 112387 View attachment 112388 View attachment 112389 View attachment 112387
THIS IS A TEST

Dem some nice looking red heads

 

[Lightning Performance]

SH,

Thanks for taking the time to do this. I just read Jim’s thread again.

It’s my understanding that the tunnel volume counted in case displacement. Jim opened his tunnels to match the base, that had to help his case to displacement ratio.

I’d have to say, the only accurate way I could see measuring true case volume would be to cut the head off an old or cheap AM 272 head. Bring piston to BDC, tape off both uppers (leaving just enough space to fill/vent air), seal off intake port with skirt with some pressed in clay, and fill the uppers with a burret.

Alternatively, one can use an overflow beaker and a graduated cylinder for measuring or a scale if water is being used. 1cc of water weighs one gram.

With the overflow Beaker, you fill till spills, then you measure what flows out when you add mass. It’s failrly simple.

So measure case without crank or bearing installed.
Dump crank, pin and pin bearing in overflow, measure displacement
Drop 2 bearing in overflow, measure displacement
Mark where the crank sticks out of the seals. Dip each side to line, measure displacement.
Tape off both transfer tunnels, measure with Burette
Dump piston in overflow, measure.
Measure base of cylinder with piston at BDC from crown. Seal uppers, measure.

Do the math on what belongs in calculation and what doesn’t.

At least that’s how I see it. I could be wrong or over complicating it for sure.

(Case + tunnels/uppers + outer crank measures+ cylinder bore at BDC) - (crank/rod/bearing/pin/piston)

That’s how I see it.

That be the way. Too complicated I always thought.

Try this Doc.

Plug intake and exhaust. Fill the motor with gas, kero , ect... Flip it over burp the air out, shake it some more. You can do this with out a vac pump. The hardest part is burping all the air. Once you are sure the whole saw is filled, drain it completely. Catch all your fluid. This is your gross volume including the intake and exhaust ports. They need to be subtracted. Eliminate the exhaust port and intake port volumes. You will need to measure them with the jug off and plug the port. Filling the port to the jug liner will get you very close. Guest-i-mate the rest if you must. This volume measurement comes in handy to tune intake volume.
The only thing left to measure is the combustion chamber+squish including piston dome or dish. The swept volume of the jug and chamber can be subtracted to get case volume at BDC.
This should cover everything you need to know.
One point to note. This includes the transfer volume with the case at any crank angle.

I used a crude method to determine chamber volume @ TDC
Set the squish with some stopper blocks before you drop the piston in. Plug the decomp, fill the chamber with your fluid and slide down a piston with the top ring on. Now, just keep checking and adding fluid till you see the fluid appear through the ring gap. This is the easiest method of CC the whole motor on a blind head or integral head engine I have found. It can be used on others. This worked great for matching old outboard motor two smokes.

If your careful and keep very good track of your fluid use measured in and measured out, it is easy to get close. The more area = more losses to film coatings left behind. Time and low heat will get them thicker lost oils back. It is a PIA and time consuming to do with a complete assembly. That's why I use kero for quick checks ;-) You still lose some.

I thought DD did pretty good at checking 1122 saw cases.

 

[Lightning Performance]

The idea of running 272xp agains my build would be great.
Unfortunately the only one I have is almost stripped.
It's a complete crankcase from intake to muffler.
If I had a tank/ clutch & cover / starter and other smart parts ,
Then I would have something to compare too.

Perfect time to volume check it. You need good seals and a good case gasket. I have wasted cheap seals to do volume checks before full tear-downs.

 

[SHOVELHEAD]

Dem some nice looking red heads

Thanks
I have more.

 

[SHOVELHEAD]

Perfect time to volume check it. You need good seals and a good case gasket. I have wasted cheap seals to do volume checks before full tear-downs.

Yes these will all get new seals and maybe bearings after inspection?

 

[SHOVELHEAD]

I got to have sometime yesterday in the shop to finish prepping the saws to build my hybrids.
So over the past week I've torn down,
( 3 )2159s ( 1 ) 2156 & ( 1) 272xp
I've dismantled everything and hot tanked all parts.
Labelled ziplock bags for each individual saw and bagged the small parts.
When I have time next week I'll start CC ing each saw 2156/2159/272xp