Done for the season ?

[AdeV]

Jens, I'm gonna get kicked in the head for this, probably multiple times, but I've seen it too many time for me to change my mind.
Get the rods and crank PERFECT. The rest can be pretty sloppy and work flawlessly.
You would not believe the condition I've seen large bore, slow speed engines in that run perfectly. Even if it's a myth that a lister will run 20,000 hours plus
can you imagine the wear after even 10,000 hours?
IMHO get the bottom end right and do the best you can with the rest.

Well, I for one have to agree with this. Just because it will run in a shabby condition, doesn't mean it'll do it any good. The rod, big & little end bearings and crank are taking the biggest pounding of any part of that engine, the better they are, the better & longer the engine will run.

[mobile_bob]

i couldn't agree more, get the bottom end right
and get rid of that abomination of a lube system (top oiling of the upper shell)
and get the plain shells with hollow dippers.

make sure the bottom end is setup right, everything is clean and the top end is a bunch more forgiving

get a 3 angle valve job, with at least a half degree of interference angle, this is very important if you are burning
stuff that makes carbon.

get a 220 grit bead hone, and use it even on new liners!

wash everything so clean your wife would feed a baby out of it.

i have built hundreds of engine's over the years, everything from early days of small block chevies to KT series cummins
from isuzu's gas burners to 12v-149 detroits, cats, macks, IH etc.etc.

i used to get blasted by fellow mechanics back in the day, for reusing parts from the scrap pile to build engines for folks that
had little money, i got paid for doing so and learned quickly that most of the parts in the scrap pile could be reconditioned and
reused successfully.

after honing a liner if it has a couple minor scratches, that won't hurt generally most especially in low hp engine's (and your 20/2
is a low hp engine)

pistons that for years were scrapped are now routinely reused by CAT in their engine rebuilds, it works just fine.

i have told this story before, and it bears retelling

i once built a 500cc honda single cylinder 4 stroke for a 1/4 midget, all from scrap bin parts,
i honed the living crap out of the best scored jug he had, and emery cloth reconditioned the best of his scuffed pistons
straigtened 4 bent valves with a ball pein hammer in an old head, so that they could be reground.

that engine finished 4th in a 60 lap race, in a car that never finished a single regular season race (they were 8 lap heats) using
all new honda parts every race!

yes it smoked a bit going into corners, but it ran like a house on fire down the straights and never failed. last i heard he kept the same
engine and ran it the next season as well.

believe me i caught all sorts of crap from my fellow mechanics on that build.

sometimes being a little on the loose side can be beneficial



just take the time to get things setup right, deck height, squish, plumb/straight and level
get it clean, assembled correctly, and in my opinion you will have a superior product to what it
was originally.

it really doesn't take that much longer to do it right, than it does to do it wrong!

if you can afford new parts, then use them if you like, and if you are short of funds don't be
afraid to reuse some of those parts

bob g

[JohnF]

Jens;

send me a pm if you are interested in plain bearings, hollow dippers and an improved camshaft.  I "think" (not knowing your engine) that I can get it up to a good standard for you.  I'll wait for your pm.

[vdubnut62]

Jens, the "micro holes" are "diesel pits"  and they are going to be in anything you put in the head eventually.
My Xing Dong had 'em and and so did the Cummins in my pickup, my machinist said "aw them's just diesel pits, don't worry about it. I lapped them out of the seats after I had the valve head ground.
It didn't take much lapping either.
They look a whole lot deeper and much worse than they are. I would worry more about slop in the guides than anything else in the top end, assuming that nothing is wore plum (a southern absolute) out.
Ron

[mobile_bob]

those pits are from a seat that is too wide, and small bits of carbon which are hot as hell get stuck to the face
of those seats which are relatively cooler, over time they will start to build up and the valve will start to leak.

that is why the 3 angle is superior, as long as it has the interference angle, instead of a wide seat you end up with
more of a "line" contact at the intersection of the top angle and the seat angle, there the seat pressure is much higher
than it would otherwise be with a single wide seat that has been lapped.

the advantage is  that the bits of carbon will be chopped up and blown clear instead of sticking.

i will look up a jpeg that illustrates this concept, and as they say a picture is worth a thousand words

bob g

ps there is another advantage to the three angle job, that is the guides can run a bit looser and still the valve will seat
a tight guide with the original wide seat can be problematic, in that any issues with valve warpage will cause the valve to
not be able to seat properly. nobody uses the single angle seat anymore outside of 3rd world countries where they have
to handlap valves to the seat.

[mobile_bob]

in my opinion you don't need hard seats, the engine does not run hot enough to warrant them.

as for the guides, the shop will tell you if they need new ones, just be sure to tell them this is a slowspeed application
they should understand that slowspeed engine's can get away with looser guides than can their higher speed counterparts.

again, tight tolerances are not necessary and often times cause more trouble than they are worth.

the trick is in knowing what needs to be tightly controlled, what doesn't need to be, and knowing the difference.

bob g

[vdubnut62]

Jens, does your engine have cast iron valve guides or bronze?
Maybe it's just me, but if I had cast iron ones and bronze was available (and affordable!) I would opt for the bronze ones.
It caught me off guard to find that a 6BT Cummins just has holes reamed to size in the cast iron head, no inserted guide at all.
At 160k miles , the honing marks were still visible in the cylinder walls, but the valve guides had to be redone.
As usual,Bob's right on target about the 3 angle valve job, I was assuming that the listeroids would have the seats cut that way, sorry!
My Xing Dong did, but I forget that is a completely different animal.
Ron

[veggie]

Jens,
Let's turn this into a game....
Do the rebuild and time yourself on the assembly. Then tear it down again, and see if you can beat your time ! 


veggie

[billswan]

Jens

You wrote "reported 2 month turn around time" Wow they must be real good or have near zero competition.

You might want to check around a little. When the favorite shop in my area that did great work started to get backed up because it was racing season I went down the road to the next best I was not going to wait just to get a flywheel faced just so a bunch of dirt track guys could get there stuff only to go out and bust 1/2 it up in a couple of races. I know high performance work brings in a lot of work but you have to look at it as he just lost my ag business. (RANT)

That crankshaft is the make or break on this engine running again you really need to get it out into the light and to a shop, would be a waste to have the top end ready to reassemble only to find out that the crank will be beyond repair because of a crack.

What brand is the engine I don't recall? Where did you get it have you checked with the importer maybe he is about to bring in more and can add a new crank to his order? If you would have to wait 2 months on machine work my guess is that shop is running at premium pricing a new indian crank might not be any more expensive than a premium rework?

Billswan

[veggie]

Re: $700 CAT Perkins

Perhaps, but if your CAT/Perkins engine had a failure, the parts would be MUCH more expensive (and the cost would be about the same to do the heads)
Then there's the cost of modifying your whole system to accommodate the new engine(s).
Not to mention any missing accessories needed for the engines(stub shaft, mounts etc....)

veggie

[mobile_bob]

assuming the crank journal needs turned undersize

i would have no issue with a single journal being turned and the others polished and left alone

you might ask them how much to magnaflux the effected journal area, particularly the fillet areas
the rest of the crank should be fine.

100 bucks is a bit high to clean up your crankcase in my opinion, so shop around a bit more, or alternatively

take it outside and spray it down with oven cleaner, nice and heavy and cover it up with a plastic trash bag
or set it in a trashbag, spray it down and then pull the bag up and tie if off.  leave it sit in the sun for an hour
or so, then take it out and hose it off with your garden hose.

oven cleaner will strip all the grease, grime, cooked on crap and leave the thing remarkably clean.

so there you go, we saved you a few bucks

bob g

[Apogee]

Jens,

Regarding the head work, they should also be magnafluxing them for that price along with what else you listed.

I'd have the crank welded up and ground back down if it needed it.  Likely wouldn't cost much more, then you'd be able to run std bearings.

Lastly, again, have them polish it first.  I might be that the white metal transferred to the crank and it would polish up fine.  Doubt it, but worth a try.

Finally, you could always have the crank flame hardened and the journals hard-chromed and the thing would be indestructible.

Steve

[vdubnut62]

Try the ovencleaner .
I have done whole tractors with several cans----WEAR A RESPIRATOR PLEASE whichever method you choose!! My Dad is dying from lung damage from doing stuff like this, a little at a time over a bunch of years will do a lot of cumulative damage.
Sorry, didn't mean to rant, just want everybody to know the danger.
Ron

[mike90045]

Lye (oven cleaner, most of the liquid plumber drain cleaners) will quickly damage anything aluminum. Pistons, garbage disposals, window frames....  be aware.

[billswan]

Jens

You wrote "I was reading through the engine manual and found out that one is supposed to mark the orientation of the con rod bearing shell when disassembling. Well I kinda didn't do that Sad 
How important is this when you replace the bearing shells (#1 piston) and how important is that when you don't replace the shells (#2 piston)."

I have always tried to take careful account or all parts orientation when you think it might be reused.
But sometime things happen that messes that approach up. Then you just have to use common sense to carefully examine the parts and try your best to get the puzzle back together the way it came apart.

My best advise is throw away all the bearing shells and use new, but save the used one that you are tempted to reuse. If you reuse the good one remember it has what 1100 hours on it? Rebuild back with new bearing shells.

Billswan