Holes in piston?????

[Mike K]

Originally Posted by Bob Carriere

From what I have read pre-ignition or pinging is the culprit and not over-revving and such a situation is encountered when lugging over long hill.......


The good old days!!!!!

Yes, sounds like the engines were running lean or the timing or grade of fuel was wrong.... the melting is a result of a overheat situation .

I have heard about the Chevy 6 pistons breaking ( more common with the cast iron alloy pistons ) or fracturing apart at the crown or top where the top ring groove is, this was due to over-revving, but that's another issue not a over heating thing.

Alf Howard, a member of the VMVC told me he worked in the SEC just after the war and his work crew were based at Kiewa . The crew used a brand new Chevy C15A, they would drive home to Melbourne each Friday night and the throttle was floored all the way, he said after about 3 months of this abuse the motor was completely worn out.

[Paul Singleton]

In reference to Hoof vs King seeley, I was looking through some manuals and both the 1940 and 1960 Chevrolet manuals both list King Seeley governors. I am sure that they were Hoof governors on the trucks that I worked on but the governors may have been added to the trucks by a dealer or company owner.

[Lynn Eades]

Is there a vacuum tapping at no. 4 cylinder? (#3 and 4 are siamesed?) As Mike said, A lean mixture puts the temp way up. This was the reason Ford built relieved blocks, because vaccuum brakes caused the engines to lean out and cracked the blocks from valve seat to bore. The other likely cause is detonation.

[Bob Carriere]

After Googoling and other web sites plus Stovebolt.....It seems that the culprit to melting a hole in a piston is a lean mixture that creates more "HEAT"..........lots of it....... if sustained the aluminum gets soft like putty

A lean mixture combined with the ignition being to "early" as in in not enough advance....possible defective vacuum advance diaphragm/ poor timing ....but this would also affect all cylinders/piston......

....... but a lean mixture could also be cause by a manifold leak........

...a drop in vacuum by a leak OR by the vacuum connection on the manifold which location would be below the carb in the intake manifold roughly centered on the siamese/twin ports to cylinder 3 and 4.........

Not sure about the 216 and the location of the vacuum outlet on the intake manifold but on MY 261 it was right smack in the middle inline with cyl/pis. 3 and 4....... however when I installed my 261 in the confined engine compartment of the cab 11, the manufacturer vacuum outlet was sticking out so much off the side that the engine sheet metal cover could not be installed.

My solution was to remove the outlet, plugs up the manifold with a glued pipe plug...... and to fabricate a 3/4 thick spacer from a solid piece of steel.....spacer is same size as the phenolic spacer with another gasket. The spacer was then sandwiched between carb and manifold but removes it higher and further away from the 3 and 4 port intake..... the spacer was drilled and tapped for the wipers, vacuum gauge and one vacant for possible brake booster....... it raised the carb slightly but not an issue.

Once the sheet metal engine cover is installed. the passenger side cover is only 3/4 in. away from the red hot exhaust manifold....engine cover was eventually lined with 1/4 inch ceramic felt.

I hope this will help my no 4 piston........

Pic