Technical 265 Chrysler Flathead 6 Diagnostic

Hey all,
Spent some tyme on a 265 Chrysler Flathead 6 I own.
Had head off and she's not been run in many many years. Guy I bought it off pulled it outta Massey Super 92 combine.
Its been rebuilt once, .040 pistons .020 mains and. 020 rods.
I have no idea how many years or hours it was run after rebuild.
Today I got busy, made an improvised cranking handle on flywheel.
Tried a hand compression test...lol
60 on some 85 on 2 and 20 the lowest in cyl 6. Well I tried...lol
Then I did a cylinder leak down test.
And all cyls 80 percent leaking past rings......ughhh
Thought I might get away as is and fire her up and use in my 55 Fargo.
At the very least a ring and valve lap.
Valves are not burnt, cracked or leaking.

 

Sounds like a connecting rod is hitting a camshaft lobe....

 

Nah not the case at all..

 

run it,it will get better,all it needs is some heat and some time.

 

Hmmm I like the idea. But hate to pull it back out of my truck if it goes south on me...thanx man

 

Question for those who like to build on a budget, or to be more blunt always broke like me got a ?
Okay my nect plan is to pull pistons and inspect rings.
I have a slight ridge, with this can I still cut it and deglaze and rering?
I have no fancy bore dial gauge to do an accurate measurement.
A statement qualifier, this okd truck gets driven 1000 miles a year max, last 2 years drove 300 miles total as life had me busy.
I dont necessarily want to spend the big bucks on complete rebuild.
Thoughts from the choir?

 

I'm fifty-fifty on this. Engine is already out, wouldn't take much to clean the ridge off, deglaze cylinders and install rings. On the other hand, could just put fresh gaskets on, and run the engine. Might just be some sticky rings, or leaking gasket(#6), that is causing low compression numbers. You are turning it by hand after all.

 

It does sound like stuck rings....maybe.

 

If you decide to just run it pour some sea foam if each cylinder and let it set to soften the carbon

 

Take it apart completely

take a good look at everything and clean everything.

you can reuse the rings, bearings etc.
If they look good

lap the valves new seals and a good clean up.

parts are plentiful and cheap for this engine.

I would cut the ridge , hone , rings and lap the valves with new seals and gaskets.

 

A long time ago, I had an old Dodge with a flathead six. I did a ring job out on the street. Got rings from the parts store but since I didn't know what engine I had, I took a wild guess and guessed wrong. Filed a bunch off those rings to get a ring gap. After it was together, I couldn't get it to turn over and had to push start it. After it wore in a bit, it ran great.

Sent from my SM-T350 using The H.A.M.B. mobile app

 

Thanx to all above posters.
This engine was out of a combine.
But its the Holy Grail 265 with 4 3/4 stroke.
Its gonna replace my tired well worn 228 in truck.
It will get these goodies off the 228 too.

 

While you have it out & easily worked on, (& you intend to add those "goodies"), why not "do it right" with a total inspection(like Vandenplas said), definitely hone(lightly!!) & re-ring, check the valve spring tension & shim or replace as needed, grind(or at least lap) the valves, inspect the head(surface as needed, or shave .060" if you want to gain a compression point), so that when you re-assemble & install in the truck, you'll know it's "good-to-go" & won't have that "I shoulda" hanging in the back of your head! Between gasket set & rings you shouldn't be invested much more than $200 +/-(OK : so add $4.98 for a spray-can of your favorite engine enamel!! LOL!)

 

265’s were Chrysler Crowns in a lot old cabin cruiser inboard boats. I knew one with 2. The engines ran the same direction but one often reversed one the gearbox mounted on the rear. It was the first engine I ever used Devon to repair a threaded block on a water pump flange.

 

We're in Canada, so $200 is really $300, and the can of paint is closer to 10 bucks, but we get your point.

 

Okay pulled head and marked tdc for all cyl pairs on flywheel.
I think I was at bdc prior tests.
Cyls all friggin damb well leaking still....ughhh
Cyl 6 has 2 pits up near top.

 

Moved it over to my other shop. Hoping it was gonna test better...lol

 

Following with interest! I have a rebuilt, at some point, engine I picked up for my Fargo. One of these days I'll swap it in along with the Ellis intake I acquired a few years back.

One of the things I like about Canadian posts is noticing all the Princess Auto gear in the background. For example your tire changer and other posts with Powerfist spray paint, English wheels, sandblast cabinets, etc.

 

This outta fix it...Well"doggies"...lol

 

I changed a lotta tires with that piece a crap. Welded up bead braker too.

 

How long should MMO sit on top of pistons before leaking past?
24 hours?

 

Well with cylinder ridge, not a good sign.
Not sure yet if a ring job will suffice on this old block.
Next step will be .060 overbored which is no problem and then she will be a 277 CI....
How do I determine if I could get away with ring job for this engine?

 

Use a ridge reamer, disassemble the rest of it, take it to a machine shop & find out how much taper you have in the bores : if under .010 just hone it w/new rings, but why go .060 unless you have a set readily available. I would check your sources(including the machine shop where you checked the taper) to see if an old auto, truck, farm, or commercial parts house might have a dusty oversize set(& rings?) on a back shelf they'd really want to get rid of. You need to be a bit patient, as it can save you a bunch of money

 

How do the bearings look?
I would pull the Pistons, give them a bath and hit the holes with a ball hone. Throw and $100 worth of new gaskets at it and run it. Typically burnt valves and scored walls are common.

I took a 251 out of an ambulance that had some sort of rebuild at one point then sat for a decade. I poured a cup of WD40 down each hole and let it set for a day or two. I pulled the pan and cleaned up some crud from the oil had left. I ran that engine fast and hard for several thousand miles through mud holes and beaver ponds in an M37 on 38" tires.

I wouldn't spend a lot of money on a rebuild this engine may not need or net you any more power.

The oil pump and assorted tubing is worth checking out for problems. The compression and leakdown will likely smarten up once that poor old girl sees some heat.

 

OK, the poor boy process.
Remove the ring ridge & pull all the pistons. I suspect you probably have some stuck or broken rings.
Take all the rings off of a piston. Pull as many as you need to, until you get one complete ring. Insert that one ring into a cylinder (use the piston top to be sure its square in the cylinder) and push it down to just below where the ring ridge used to be. Now, stack as many flat feeler gauges together and get a good measurement on the ring gap and write it down (as "top". Then push the same ring about 1/2 way down in the stroke with the piston top (so its still square in the cylinder) and re-measure your ring gap and write that number down as "middle". Then push the same ring to the bottom of the piston travel in the cylinder with the piston top (so its still square in the cylinder) and re-measure the same ring gap. Write it down as "bottom". Repeat the process with each cylinder, its important to use the same ring in all the cylinders, and its important to make all the top measurements, all the middle measurements, and all the bottom measurements at the same height in the cylinders to get an accurate picture of the condition of the block.

Compare the top, middle, and bottom numbers of each cylinder to each other. These number will tell you how much tapper each cylinder has. The max amount of tapper is .015 for the flathead 6, according to the 54 Dodge truck factory service manual. They are also concerned about how out of round the cylinders are with a Max out of round being .005, but the only way to check out of round that I know of is with measuring with gauges. I would suspect that if you can see daylight between the ring (square in the cylinder), and the cylinder walls at 90 degrees to the crank line, your probably in need of a bore.

Some out of round and some taper can be honed out, but you need to be careful not to enlarge the bore too much. If the piston slops around in the bore, you probably need bigger pistons already. Piston side clearance at the top ring land is suppose to be .0305 for a normal service 265.
If the taper specs are OK, you can re-ring the motor, install new bearings, lap in the valves, and add fresh gaskets. At the current state of dissembly, anything less then doing the rings and bearings probably would be a waste of effort. Gene

 

Yah Thanx DR
Next step I will pull pistons and see whats going on. I see no sign of burnt valves or any serious cyl scores
The tolerances are quite forgiving at .020 taper and .005 outta round.
Not sure if I will find broken rings or not.
Something is sure wrong as the leakdown test shows a lotta leakage 4 sure.

 

Just for some entertainment purposes only.
MMO had leaked past rings, cranking engine could see a few flakes of carbon left behind.
I for fun bolted on head and gasket.
Then hand cranked compression test.
Best cyl near 90 psi...lol
Most 75 to 80.
Some compression.

 

Okay ran my test after some morning coffee. Wrote it down
My makeshift hand crank

 

That tells me you rings on six are still stuck. 90 psi compression on a flatty is damn good! Put a carb on it and some fresh oil and fire it up!

 

Cyl rings stuck or broken?
Now this is hand cranking and not fast.
My trick was to move bolt so I could pull up on flywheel as hard and fast for test.
MMO oily in cyls might helped seal rings for test.
Gonna make decision on use as is or not soon.
I don't have a bell or manifolds to try running on floor.
If I wanna run it as is either got get those items or install in truck
If it goes bad can do an in chassis ring and valve job or prep my 228 block for another set of 265 rods and crank I have in wings.