A few 20/2 assembly questions

[playdiesel]

Some roughness will not harm the seal as long as some lube is present and care is exersized while slding it over the shaft however sharp edges will kill it. All I did to my 6/1 was take a flat file and knock back the corners on the key slot, no need for over kill here, if it no longer feels sharp it isnt going to cut the seal. Once that was done I took a strip of 120 emery and did the shoe shine deal on the shaft. Then I again used my fingers (wonderfull tools) and felt for sharp burrs. When installing the seal turn the keyway up and hold up slightly on the seal while rotating it. A dab of motor oil on the shaft wiped around is all you need and grease behind the seal will help retain the spring. Mine installled in the housings with no sweat but we all know Indian tolorances .  Ya'll know I am pretty fresh with these engines but in looking over the design it would seem that a person should also spend a lot of time checking over and finishing the crankcase vent as it will play a big role in preventing leaks IF it is working correctly. My Metro vent looked like it had been assembled by a blind two year old on a bad day. Once all the paint goobers were removed and burrs were filed and stoned down and the valve plate corrected mine pulls a decent vacuam on the crankcase as designed to do. No leaks so far but only 10-15 hours on the rebuild.

[mobile_bob]

at least .002" as a minimum is what i would shoot for
.003" is far safer for a variety of reasons.

although it is best practice to use two shims of equal dimension, if you only have one that puts you
into the range of clearance needed, go ahead and use it.

check the clearance at the top of the brg and then recheck at close to the parting line.

everything i have read tells me that more engine's with this type of lubrication (basically splash)
live longer with wider clearances than they do with tight clearances.

because the bottom end oil temps stay relatively cool on these engine's the oil remains correspondingly thick
and fills the clearance quite easily.

a wider clearance is more tolerant of grit than a tight clearance, if you have .003" clearance and the brg can embed
a .002" pos then technically while running the setup can tolerate a piece of grit of about .0035" which is quite large
relatively speaking.

bottom line, is if you set it up and it comes out at .003" i would call it good and run it there myself.

ymmv, imho and all that jazz

bob g

[veggie]

Yep, I'm with Bob an that one.
2-3 thou is good.
0.0010" is a bit risky. Chance of overheating (expanding) and spinning a bearing during intial run-in.
RPMs are relatively low and a good oil wedge with the proper viscosity oil will do very well with 2-3 thou.

veggie

Disclaimer:
The views expressed herein are the soul opinion of a inexperience CHP jockey who has been breathing
Diesel/WVO fumes for 6 months. Any implied knowledge or expertise in the area of discussion is strickly denied
and unusable as evidence in bearing failure court.  

[Crofter]

Jens, I have kicked around the advice on using variance in squish indications. I disagree with being able to correct it by tilting the cylinder housing with partial gaskets. If the bottom of the cylinder is off square the practice may be legitimate but it is absolutely bogus if the discrepancy comes from uneven top of cyl. geometry.

One reason being that the amount of piston to cylinder clearance limits the amount of cock possible.  ;further out of square base may not give any greater side to side squish variance. The possibility of the top surface being also off square complicates matters. You could have equal squish accomplished by a severely cramped piston in the bore.

An important part of what you are doing may affect cylinder liner protrusion. My initial top surface gage .010 difference corner to corner. The top deck was off square with the liner. You cannot correct for that by placing partial gaskes under one side (or corner in my case) of the base.

My final figure on squish was within .002 side to side but that was after machining both upper and lower surfaces. That comes out to .075 but your spec I think is much less. Whatever you do dont make corrections that attempts to tilt the piston in the bore or at the wrist pin hole.

You lucked out on getting a good big end clearance without too much fiddling. My .003 in the picture was after removing a lot of shims and scraping the insert sides near the split line. I agree that tighter fit may not be better for splash lube.

[Ronmar]

Yes, the half gaskets are only to correct for alignment issues(not perpendicular) between crankshaft and cylinder bore.  They will not help issues with piston, rod or cylinder top and head.  I havn't heard of too many having issues with cylinder and liner, other than the liner being too long/have too much protrusion above the cylinder.  Cylinder and liner being in line are fairly easy to confirm with a flat surface and a dial indicator and magnetic base.  With the inner circular edge held against 2 fixed points/dowels on the table, and the dial indicator setup inside the cylinder or liner, the piece is rotated while maintaining contact with the dowels.  If the bore is not perendicular to the face edge, you will get a varying measurement at the top.  I used a drillpress table for this with 2 bolts installed in the vice mounting slots.

Issues with rod and piston can also be diagnosed by simply measuring differential squish, then unbolting the rod big end and rotating the piston/rod 180 degrees and rechecking differential squish.  If your squish numbers swap ends, then there is an issue with rod or piston.  A machinest's level is also a wonderfull tool for quickly confirming some of these measurements, such as if the piston top is parallel to the crank throughout the crank's rotation.

Since the case is a large piece to machine, that is where I would expect to find more errors, and is where I have heard of most problems, including my own.  My engine had a half gasket under the starting side of the cylinder.  All the topend components measured out fairly true.  Measurement of the lower end showed the crank not inline with the case top, and that one TRB hole was about .015" off, with the starter side being higher than the other side.  I could have very easilly used the half gasket, but opted to true up the TRB mounting situation and bring the crank into line (perpendicular) with the cylinder bore...   

[Crofter]

My crankcase deck was as true with the cranshaft as I could measure, but the cylinder was off just a bit over .010" diagonally across the cylinder faces. Top and bottom were paralell, just not square to the liner bore. I didnt even check to see what that did to squish side to side since the top at least had to be machined to get even liner protrusion.

I guess the 20-2 calls for the same squish as my 10-1 so you are coming in range. I dont remember the recommended range but they should be close to similar chamber volume on each for compression match on a twin. Without measuring the volume of both heads pre combustion chambers etc. it is pretty lucky to be the same anyway.

We will all be waiting for first fire when thumper is reborn!

[veggie]

That light at the end of the tunnel is not a freight train coming your way....it's a running Listeroid !   

Yeeeee Haaaaaa !

veggie

[Crofter]

My manual calls for .075 to .080 piston to deck clearance and .055 to.100 valve head recess into the head. Being 5 or 8 thou shy on squish on the one cylinder would likely only be an interference issue if the valve head depth was considerably less than .055". I thought your original concern was with squish discrepancy side to side of an individual piston.

[Tom T]

Crofter coud you copy and post the parts of the manual on setting up the gear train and torques for us some of the specs are very hard to come by. Tom T

[Crofter]

Crofter coud you copy and post the parts of the manual on setting up the gear train and torques for us some of the specs are very hard to come by. Tom T

It is not much more than a thin pamphlet and very poor print quality. Somewhere I have a bookmark to a PDF file of a similar complete manual you could pull up. Maybe someone else can put their finger on it in the mean time? Will have a look later.

[Tom T]

Ok thanks. Tom T

[JohnF]

Tom;

Have a look at my website www.woodnstuff.ca.  A complete Lister manual is on there.  Follow the link "Articles" to "Lister booklet".

[Crofter]

The link I have no workie no more but was virtually the same as John's site.

Tappet Clearances COLD Inlet 0.017" Exhaust 0.032" for 3/1, 5/1, 6/1, 10/2, 12/2.
Tappet clearances for the 8/1 and 16/2 are 0.008" both valves COLD

Valve heads recessed into cylinder head face by 0.055" Min to 0.100" Max
Bump Clearance 0.045" to 0.050" and on 8/1  10/1 etc. and corresponding twins, .070" to .080"

Valve Timing:-
Inlet Opens 5 Deg before TDC and closes 15 Deg after BDC on all engines. Exhaust Opens 45 Deg before BDC and closes 5 Deg After TDC for types WITH compresion changeover valves (3/1, 5/1, 6/1,10/2, 12/2) Exhaust Opens 55 Deg before BDC and closes 20 Deg After TDC for types WITHOUT compression changeover valves (8/1, 16/2)
Probably the longer durations on these engines are due to the much smaller valve clearance settings rather than any difference in components or gear timing.

The Listeroids use fewer but larger cylinder head studs so their torque value is higher than genuine Lister and I have heard that three grunts tight is about right. The only other very critical torque is on the big end rod nuts and calls for 55 ft lbs  and advance till the next cotter pin hole registers.(dont back off from the 55 ft lb. setting to get the safety cotter in.

[Tom T]

Thanks that heleped a lot. Now need to get back on the 20/2 and get it up and running. Tom T

[billswan]

jens

On the head gasket leaking coolant, did you give the head gasket the liquid floor wax treatment? Or are you using composite gaskets instead of the copper sandwich type.......

On the timing I will let you fight that battle as my memory is getting fuzzy on that subject!

Billswan