Holes in piston?????

[Bob Carriere]

What would be the most likely cause of a hole being blown through the piston top ....... occurred on a 216 and a rebuilt 261..... and the same Number 4 piston.......

Both engines are/were being used in the Montreal area..... possibly by the same set of volunteer drivers........

In my limited experience, never having blown one yet!!! ..... lugging and engine in a too high a gear for the road speed and detonation by bad timing and straining the engine from low rpm to higher speed without shifting to a better lower gear......

Can we blame the new ethanol fuel???? It has been lamed for everything else but I do not think that ethanol would cause pre-ignition....... bad timing....... bad springs/weights/ corrosion in the dizzy advance mechanisms under the main plate...... but two different engines in two different CMP trucks .....strange coincidence.

What are the opinions out there....

Curious Bob C

[Paul Singleton]

Hi Bob, it could be lean fuel mixture on the affected cylinder causing pre ignition or excessive combustion heat. I think excessive rpm of the engine could also be a factor. The Chevrolet city delivery trucks I worked on many years ago had a vacuum governor between the carburetor and intake manifold that limited engine speed to between 3200 and 3400 rpm. These were 235 sixes. If I recall the governor was a hoof brand governor. It may be wise to install one if you could find one. One of the trucks you got from me had a 235 engine laying in the box, it may have a governor, the engine was from a delivery truck.

[Lionelgee]

Hello Bob and Paul,

Paul, your reply to Bob prompted me to do an online search. Hoof governors are still around - Accessed 3rd October 2023 from https://hoofgovernors.com

Plus there is at least one related spare parts supplier.
Accessed 3rd October 2023 from https://centuryfuelproducts.com/brands/hoof

I am not sure whether the models or spare parts link back to the 1930-40s though. There would only be one way to find out.

Kudos to your long-term memory recall, Paul!

Now, with the latest gap revealed in my knowledge about Chevy motors filled - I now know what a Hoof governor is! I will exit stage right... and I will return to lurking in the background mode.

Kind regards
Lionel

[Paul Singleton]

Lionel, your reply to my post prompted me to do an image search for a Hoof governor. I found a picture of the governor, although it is on a jeep. The ones I remember looked the same. I seem to remember different coloured springs to raise or lower rpm depending on the application.

[Bob Carriere]

Hi Paul

I do remember that one fo the engines was "odd"..... we did strip it of all usable parts as we usually do for all old blocks ...... had a strange intake that was cracked...... will ask my mobile memory...Grant.... tomorrow if he remembers more than me..... I do not remember taking off a governor....although I have collected a few NOS that will fit the small bolt pattern of the 235 carb.....but would not fit on my 261....

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.......

Over time I have given up mon using a strobe light on a cab 11 engine.... I have transferred the TDC markings from the flywheel to a marked on the bottom of the flywheel with the sheet metal cover removed and also on the top under the small plate bolted on top of the bell housing....... then I go by feel and trial run until I find the sweet spot...... I can drive my C15a in fourth gear going around a normal right or left turn....at 12 to 15 mph on flat ground and pull it up with slow throttle to it's cruising 35 mph with no ping or stumble........ vacuum shows about 4 to 5 inches vacuum to its steady 20 inches to flat out 40 mph...... another 4 to 5 mph if I let it get its wind!!!!! and the road is flat and long enough....

It is impossible to get a a strobe light to fit into the engine compartment ever since all the sheet metal has been installed...... got the tip from Phil W. and went further by marking the flywheel on both spots with center punch and white and yellow paint..... using a hand crank made the job more accurate.

But to have two engines melt a piston top is both cruel and weird!!!!!

I have seen a over revved a 251 dodge 6 (M37) with a big hole in the side of the block driven 20 miles back to the garage..... albeit at slow speed.......

The good old days!!!!!

[Lionelgee]

Hello Bob and Paul,

I came to this forum via my truck a 1940 Chevrolet - Holdens cabin ex-Army General Service 30 CWT truck. Prior to my joining here, I was a member of Stovebolt.com. I just made a post there asking if any of their members have heard of any other Number 4 pistons getting a hole blown through them. Considering I am in Australia and there are different time zones - it might take a while before I receive any replies. and be able to post here.

Oh - I am off work sick today - I am on 'light duties'. I am subsequently bored out of my mind. This might be why I went off searching for Hoof Governors. In relation to Ethanol in petrol - we still have a choice at the pumps. Only one type of petrol has Ethanol in it. No, I do not use that pump.

I wonder if spray painting is considered a 'light duty'? Hmmm ... see ya!

Kind regards
Lionel

[Lionelgee]

Hello All,

Thanks to Dan from the Stovebolt.com forum the correct Hoof Governor is a Hoof Model K-313 Governor Kit CHEV-235 NOS. Range 1500-2800 revs.

There is one for sale on eBay at the moment. Just type in the name of the manufacturer and the model number should get you there.

Kind regards
Lionel

[Grant Bowker]

Photos from the listing attached. MTF
The listing is https://www.ebay.com/itm/38508381244...3ABFBMzvTspN9i The buy it now" price is USD 77.67

[Grant Bowker]

More, as promised

[Grant Bowker]

There was at least one more maker of governors that were used on period Chevrolets - King Seeley.
Based on the attached page (from an ebay listing) it appears that King Seeley provided governors to Chevrolet for the "official" installations, with both King Seeley and Chevrolet part numbers listed.


On edit: an earlier edition of the Master Parts Catalog also lists the Monarch model "S" governor as fitting 1934-1936 Chevrolets so there were at least three makers of governors for Chevrolets.


The GMC 302 cubic inch engine used in the M135/211 series also had a governor on its Holley carburretor. The TM says the engine governor was also a Holley product. There's also a listing for a Zenith "Mechanovac" that was used on trucks with PTO (fuel and water tankers) that provided engine speed regulation separate from the normal governor.



On the M135 the governor could be used as a crude cruise control. Pull out the throttle contol until the governor limited the engine speed at a speed of about 58 mph on the level. Compared to proper cruise controls, this had the unfortunate limitation that if you needed to stop in a hurry, you had to be just as fast to disengage the throttle manually to avoid fighting full power with the brakes.

[Grant Bowker]

https://www.ebay.com/itm/26596530222...Bk9SR6rdx6XfYg
also attached the listing photos, including one that shows both the King Seeley part number V6 259 and the Chevrolet number 3693461. The buy it now" price is USD 99.00. The parts book page above lists this one as suiting 1950 235 engines (another model is listed for COE). I think that the same governor is probably a multi-year fit and that the parts book just cut off at 1950...

[Grant Bowker]

More photos from the same KingSeeley listing

[Hanno Spoelstra]

"Governor" or "Govenor"?

[Paul Singleton]

The COE trucks and some of the delivery truck chassis were equipped with a Carter updraft carburetor, hence the different model of governor.

[Lionelgee]

Originally Posted by Hanno Spoelstra

"Governor" or "Govenor"?

Attachment 136038 Attachment 136039

Hello Hanno,

You ask a very interesting question. When you find the definitive answer please post your findings here

Kind regards
Lionel

[Grant Bowker]

Well, both versions of the Chevrolet Master Parts Catalog I checked use the spelling governor. Does that help or just add confusion?
The Chevrolet Catalogue of Major Assemblies CMA-01 seems consistent in using governor.
Note that the Canadian printed Catalogue of Major Assemblies uses the spelling catalogue and the USA printed Master Parts Catalog uses spelling catalog. The never-ending list of English language "localizations", or should that be "localisations"?

[Mike Kelly]

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