Hi all,
Remember I put a post on asking for advice on building up a 230 six in a nice '64 Chevy C10 pickup?
Well we got the recommended cam, full master rebuild kit with Sterling pistons (I won't say from where), Offy 4 barrel manifold, 390 Holley 4 bbl, Langdons headers, small HEI etc.
Had the bock and heads machined - 30 over on the bores, 10 on the crank & rods.
Put it all togther with lots of pre-lube etc, turned it over with the plugs out until we had oil pressure and fired it up Sunday. It ran great for 10 mins at about 1000 rpm then just stopped.
We took it all apart and found the wrist pins had scored the pistons very badly on some and welded themsleves solid in place on the other. Pistons just won't move on the rods.
Some piston skirts have score marks on them from scraping up the bores.
In looking at the pistons I'm not very impressed with them - there are no oil holes at 10 to 2 of the top of the wrist pin bore as on the originals and no expansion gap at the top of the skirt. There is just a small shallow 9 and 3 o'clock groove for oil on the side of the wrist pin bore. Doesn't look nearly enough for oil to me.
Rod bearing ends looked just fine, although we'll probably replace the rod and main bearings to be safe.
At the very least the block needs a rehone.

What happenned? Can anyone shed any light? It looks like major oil starvation of the wrist pins. I've also been reading about the right and wrong way round the rods go in. Any clues?

Thanks all, regards, Nick

Did you dip the pistons & rods in a can of assembly lube or oil before you installed them into the block?

When you break in a new engine & cam, you run it at 2000 RPM for 20 minutes. Not @ 1000 RPMs.

Maybe the piston pin holes were not sized correct?

Did the piston & rod move smoothly & easily after the piston & rods were pressed together.

The rods were heated up on the small end & then the piston pins were pushed in by hand?


MBHD

The cause of many engine failures in the same area you are experiencing is from a lack of proper wrist pin clearance. Many times right out of the box, a wrist pin will fit into the piston bore, but isn't meant to be run "as is", it still needs to be honed to ensure the correct clearance before it is installed on the connecting rod. The scuffing on the piston skirts is directly related to the pins starting to gall or seize within the pin bores as well. This could have been an oversight on the machine shops end to not check or pin fit the pistons, but it doesn't take long to reveal itself. Also, spinning the engine over to prime or build oil pressure is not a good method to do this and can cause problems as well that might not be apparent at first. And as Hank mentioned, you need to run the engine at an RPM at least at 2000 or so for 20 minutes or longer on initial break-in, running it at a lower RPM of even 1000 RPM is much harder on the cam and lifters and can cause lifter failure and cam lobes to disappear. Sounds like you need to start from scratch again.

I agree on the tight pin fit.With pressed in pins it's all to easy to gall up the pin bore during installation if you're not careful..

kinda like running in high gear in town with 3.08 gears, I'd say.

??????????????? what the heck did or does 3:08 gears have to do with the topic?

But anyway xs2 On the others comments.To low of brake in RPMs and it could have had clearance issues right off.

SORRY YOU HAVE TROUBLE, CHECK EVERYTHING TILL YOU FIND THE PROBLEM AND GO FROM THERE, ALSO CLEAN YOUR OIL PUMP COMPLETELY. ALSO MAKE A OIL PRESSURE FEED TANK FOR YOUR ENGINE BUILDS, CONNECT IT TO ENGINE BLOCK WHERE OIL PRESSURE GAUGE CONNECTS, BLOW OIL IN AT LOW AIR PRESSURE UNTILL ALL 5 QTS HAVE ENTERED THE BLOCK AND STOP THEN ( SHUT OFF AIR IMMEDIATLY)THEN ITS SAFE TO TURN ENGINE OVER. THIS IS LIKE THE ENGINE HAS JUST RUN AND SHUT OFF. ALWAYS USE ENGINE BREAK IN OIL AS THIS POLITICALLY CORREST OIL THEY SELL NOW DAYS IS INFERIOR TO THE OLD DAYS OIL, "NO ZINC" ALSO IN ALL THE ENGINES I,VE BUILT I,VE NEVER RAN A NEW ENGINE AT 2K WITHOUT A LOAD ON THEM. JUST MY WAY I GUESS.
BOB
P/S
I,D ALSO CUT THE OIL FILTER ELEMENT OPEN AND SEE WHATS IN IT. ITS A TATTLE TAIL ON PROBLEMS....

Hey Twist,
A thousand rpm is a thousand rpm,
same amount of oil gets on cam, lifter bottoms, and cylinders from rod sling-off at 1000 rpm break-in speed as does running in high gear with 3.08s--anyone realized that before?... its the same engine speed, seems to be topical to me.

how do the wrist pins get lubrication?
how do the cylinder walls get lubrication?

The connecting rods on older motors used to have "spit holes" attop the bottom ends of the connecting rods so that at top dead center some oil would squirt out of these hole aimed at wrist pin bosses (which usually had lube holes drilled thru the bottoms of those bosses). this oil along with the continuous spray from the pressured oil spewing from the con rod and the crank journal cheeks are the sole lubrication the cam, lifter faces, and walls get. Other wristpin lube can come from oil scraped from cyl walls thru the drilled holes behind the oil rings. If the break-in rpms are too low (concences is 2000 rpm min) then the wrist pins, due to the tightest clearance in the engine will suffer, even though the aluminum pistons will "grow" faster than any other engine parts.(I think as the aluminum piston "grows", the wrist pin hole will actually close up and get even tighter). I have built 235s through 409s with cast and forged pistons from Zollinger thru TRW products and never did anything to the "as delivered" wrist pin situations, and never had a similar problem. But I have seen swap meet pistons displaying "blued" wrist pin bosses-maybe I've been lucky. I feel the problem was obviously lack of oil at the wrist pins from too little oil being slung off of the rods during break-in primarily due to too low of break-in lubrication.

Sorry to have been flippant with the 3.08 statement

Sorry to hear of the issues.

I've heard of this more in the last 10 years than before, several engine builder friends of mine say they've noticed it too.

FWIW, I use Permatex Ultra Slick on wrist pins almost exclusively (on rare occasion that the engine is going to sit a long while before initial start, I'll use something else, like Red Line Engine Assembly Paste).

a 1000 Rpm isn't much off Idle.Most idle 600-800 (stock) So In high gear with 3.08 NOT likely. No matter what Tranny You won't even be out of first gear at 1000 rpm. And if you are it isn't by much.With my power glide I could stay in low gear @ 1000 rpm.
in 1972 a 250 idle speed was 700rpm(manual) 600rpm (AT)
1975 250 Idle speed was 850(manual) 550-600 for a AT.
So your saying HIGH gear? What ever.

I mis-spoke , its a 2.73 axle ratio with 27 inch dia tires that give you 29.42 miles per hour per 1000 rpms in high gear(1.0:1.0). High gear like in a standard transmission, you know where the DRIVER controls the transmission, where you have a non-slipping clutch, and synchro and cluster gears etc. You bet'cm Red Ryder, a 1000 rpm in 3rd of a manual three speed, or fourth of a manual four speed, commonly know as "HIGH GEAR" in the old days (1.0:1.0) with 27 in. tires IS 29.42 mph( veeeerrry close to 30 mph). Thats the "high gear" i'm talking about "what ever" squared.

Hi 425 D Q . . .

Oil starvation perhaps . . . but what about the fitment? Are these aluminum or cast pistons? Were the pins provided by the piston manufacturer? Or obtained from somewhere else?

Aluminum expands twice as much as iron so the cold clearance specs are different. Perhaps the pistons may have been to tight in the bores? This would increase the loading on the pins . . . and cause the skirts to scrape . . .

Here's a link to a Q & A about fitment for a model T:
Click the link to Tony's piston tips

he goes so far as to heat a piston in the oven to a known temperature to verify expansion rate.

The guy that taught me to rebuild used say "Measure, then Measure again writing down what you find, then Measure again tomorrow and compare . . . don't rush it"

Sorry to hear that you are going to have to build it again.

regards,
stock49

No matter what tranny STD Or AT I have ran Both with 3.08s with a stock 250 and Bottom line is Still a 1000 rpm is barely Off Idle So your still only in first gear. And I know a 4 std is not going to like being in 4th @ 1000rpm.

Okay Now i'm done with this one.
No wounder I'm pretty much done with all this Head butting Bs.

I'm not!

What do you mean "So your still only in first gear" Do you not know how to shift the standard into high gear? A lot of them have the map right on the shift ball.

Yeah, "...1000 rpm IS barely off idle" (so far so good) "...So your still only in first gear" (ooops the blunder raises its head). What sense can that statement possibly make?

With a stick you can be at 1000 rpm in any gear (all forwards,neutral, as well as reverse).

I'd rather be in fourth at 1000 rpm with a 4.56 axle than in fourth at 1000 rpm with a 3.08 or a 2.73 axle is as close as I will agree with your statement.

I guess its "head butting Bs" when you're losing the argument.