boring one cylinder common practice?

C

chopo

Senior Member
was it a common thing to do back in the day? I have 2 motors. my first motor had one cyclinder bored .020 over. Today I changed the head gasket on my 29 motor and number 2 cylinder was bored .040 over. I was wondering if this was due to lack of money back in the day or ??? thanks
 
Sounds like a Depression-era in-chassis repair. There were jigs for boring the block with it installed in the car.

If you were going to go to through trouble of pulling the block and having it machined, why not do all four bores while you're at it ?
 
What I meant was - having one bore oversize suggests it was done with the engine in the vehicle, to save (?) on labor expense / hassle of pulling the entire engine and boring all four cylinders.

I don't see much issue running one bore at .020" oversize, as long as they balanced that new piston / rod to match the other three. Same goes for the .040" jug...

Now, if you're going to boost the compression and run it hard and fast, then you might have some issues.

If you've got the heads and pans off, it would be worthwhile to label and pull all piston & rod assemblies and make sure they are balanced within 1/2 gram of each other. Or at least make sure the Oversized slug is within 1/2 gram of the average of the weight of the other three.

What you do with it also might depend on what sort of driving you plan for the car: putting around the neighborhoods at 20-30 MPH, or long runs at 40-50 MPH ?
 
Balance.

When your cars were 10 -15 years old that was the respect they got. The job solved a problem that if not done would have doomed your car to the wrecking yard.
 
chopo said:
im not gonna pull it. just wondering. do you see any issue running it that way?
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That one piston probably doesn't match the weight of the other 3, and the power should be a hair more from that cylinder, not that you'd notice though. If no other engine work is being done, I'd just run it and enjoy it until it's time for new babbit or a rebore.

That cylinder probably had a snap ring come off the piston, allowing the wrist pin slide to the side and score the cylinder wall.
 
Tom Wesenberg said:
That one piston probably doesn't match the weight of the other 3, and the power should be a hair more from that cylinder, not that you'd notice though. If no other engine work is being done, I'd just run it and enjoy it until it's time for new babbit or a rebore.

That cylinder probably had a snap ring come off the piston, allowing the wrist pin slide to the side and score the cylinder wall.
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My concern would be that the CRANKSHAFT would notice it, and if the engine were being run-hard and/or had its compression boosted, it might result in the crankshaft fracturing / breaking.

If we're just chugging around town at 30 MPH or less, it might never be an issue.
 
I've seen a lot of that around here where the cars were made to run to get you back and forth to work.You could pull your engine down,run the block over to one of a half dozen guys,and they would bore out one or two.They would also size it to whatever piston you had or whatever they had to sell you.You threw it back together and you were off to work for another few months.There was no such thing as balancing,it was a matter of survival for you and your family.My great grandfather or old Arnold would bore out one hole for a dollar,sometimes two.Who knows where the hole was in relation to where it was supposed to be.No car=no ride to work=no pay=no food.Most of the cars this was done to were beyond the scrap stage and were on their last legs.I had a JC Whitney engine with 3@.040 over,and one @.060 over.That engine had never been run.I have a Sears Roebuck engine in my sedan with no two pistons that stick up the same amount up over the deck.That engine was installed over 50 years ago,and was parked for about 30.After I had run it for a year of so the head gasket let go.It was steel and had just rotted out.While cleaning up the deck I noticed one piston protruding more than it's mate.I measured and found no two alike.All four are .020 over though.It also has a bunch of divots around the edge of the block from somebody driving chisels in to remove the head.I really think the rebuilder for Sears had assembled it that way as I picked the head right off it.I put Devcon in the divots and have been running it for years.It doesn't smoke,knock,or leak.It could use a little more power,but that could just be I am now spoiled by the Brumfield heads on my others.
 
Yes sir, People had a hard time just keepin food on the table in some places around the country. Poor people had poor ways. A one hole overhaul wasn`t un-common. In the oilfield in the early 70`s we ran stationary engines such as the big Wauksha. They ran on natural gas if a well could be found within a few miles, otherwise we ran them on propane. They were bad to drop valves thru the pistons and therefore got a one-hole overhaul periodicly.
 
Model T Monte said:
Yes sir, People had a hard time just keepin food on the table in some places around the country. Poor people had poor ways. A one hole overhaul wasn`t un-common. In the oilfield in the early 70`s we ran stationary engines such as the big Wauksha. They ran on natural gas if a well could be found within a few miles, otherwise we ran them on propane. They were bad to drop valves thru the pistons and therefore got a one-hole overhaul periodicly.
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I worked for a farmer that dropped a valve in one cylinder which put a hole through the top of a piston. He put a bolt through the top of the piston and ran it that way all the time I worked there. Sounded kind of funny when that piston fired with more compression on that cylinder.
 
I guess the popular brand stuff now is JB Weld.Devcon had a bunch of products,slow setting,fast,clear,low or high temp,there were probably a dozen to choose from.There was one that we used on the decks of the old Cummins engines when they had some erosion from leaking gaskets.I believe they are still around,I bought some of the stuff I used 30 years ago for the A about 5 years ago.
 
Putting this in proper perspective: do a compression test on a "properly" rebuilt engine with some mileage on it. Did all of the cylinders pump up to identical readings? Likewise, do a leakdown test - did each of the cylinders leak down at the same rate? Now all of these are considered static tests. Consider dynamic pressures inside of each cylinder while an engine is running, especially while under load (working) - is each piston pushing on the crankshaft (through the connecting rod) with the same amount of force as each of the other pistons? 99% unlikely! Formula One Race Engine builders attempt 100% and get closer, much closer to ideal than mass production engines coming off the assembly lines, even in the Model A era.
Comes down to how many dollars one wants to spend in rebuilding a completely blueprinted engine.
Considering all of the variables involved in the components of an engine, one piston/cylinder .020" or .030" larger than the rest (provided the piston is balanced to match the others) will not be significantly detrimental to how well the engine runs.
 
the .040 over piston does have a few dril bit reliefs in the top of it marked with dots. I assume this was there way of removing material to match weights.
 
Just for a point of reference.

Ford factory engines during model A production would have had no more than 4 grams difference in a set of pistons and rods. The assembled rod piston sets were weighed and grouped during production.

A nickel weighs 5 grams.

Page 22 of Know Your Model A Ford by Murray Fahnestock
 
Kevin in NJ said:
Just for a point of reference.

Ford factory engines during model A production would have had no more than 4 grams difference in a set of pistons and rods. The assembled rod piston sets were weighed and grouped during production.

A nickel weighs 5 grams.

Page 22 of Know Your Model A Ford by Murray Fahnestock
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The model A was a percisely made car with percisely made parts. Just so happens that it is also a very forgiving car that alot can be out of wack and it will still run.
 
Many years ago when I got a good scale I weighed my collection of NOS pistons --and the pistons in the aftermarket sets.

The NOS ford pistons --any size, center lock, and end lock were all within 5 grams --these were random pistons not from sets.

Some of the aftermarket sets 4 the same size in the sealed box were 40 grams off, all the sets were more than 10 grams.

The main problem with doing any in the car boring or honing is the metal debris, it is impossible to totally remove all the metal without total diss.

That metal will embed itself into the babbitt and wear the crank very fast ---another reason that old babbitt that looks good can be bad.

Even the factory will build an engine with one bore different, or 1 crank journal a different size ---this is done to cut scrappage rates when a machine gets out of spec , I even have an A cam that the rear bearing was hard chromed and reground
 
I got into an 8.2 GM diesel a couple of years ago.(4 stroke V8) The heads needed work,and the electric starting aid had stuck and dumped a can of ether into the engine.They did not run it,but towed it in and I got into it.The rings were shattered and a couple of pistons were cracked.The walls weren't hurt,I measured half of them and they were in spec.They were .010 over so I bought a set of pistons,rings,had the heads gone over and honed it.Things were good until I got to # 6,the piston wouldn't fit.Seven of the holes were .010 over,and # 6 was standard.I had put this engine in this truck several years ago,it was a GM reman.I picked it up at the Ford dealership in a big plastic case.Why would the GM rebuilders do something like that? Luckily the standard hole was now worn pretty good,I got some coarse stones for the hone and got a pretty good fit for the .010 piston.
 
They do it because it costs less, and they have a big parts room --I have seen many cranks with 1 rod journal smaller, 1 bearing bore oversize, different pistons mixed on each side of the engine ---mostly on GM
 
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