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Aluminum cylinder

#1

Scrubcadet10

Scrubcadet10

I was told (from a member on the Jack's small engines forum) that you can only hone aluminum cylinders to oversize, not bore them with a boring machine, but I also heard otherwise. I need the Briggs aluminum cylinder bigger to 20 thousandth s, I'm sure the machine shop would know what to do, but for the sake of me knowing. Can you bore an aluminum cylinder to oversize, or hone or to oversize.
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#2

J

jp1961

Hello,

Honing doesn't remove that much material. I think the general theory behind honing is to put the cross hatch pattern in the cylinder walls, go get the piston rings to seat.

If pistons are available oversize, your best bet would be to bore oversize and hone to final factory recommended dimensions.

There is a YouTube video of a guy boring a Briggs Quantum engine to the next oversize (using a boring head on a Bridgeport).

Regards

Jeff


#3

W

Walt 2002

My recommendation if you have a B&S engine with an aluminum bore is don't waste your money on it. They do or did make a special set of auto type cylinder hones for over-sizing aluminum bores but the success level is very low. Original bore has a special coating which will be removed in oversize process.

I have used an automobile type hone to over size several cast iron bore blocks - not just for deglazing. These are often pictured in the back of Service Manuals. Note that 2 or 3 graduated grits of stones compose the set for doing this job with the first, coarse set, being very aggressive in removing metal as opposed to above statement.

Walt Conner


#4

S

SidecarFlip

Boring will depend on wall thickness of the cylinder and know Briggs, I'd say toss the engine and buy a mew one. Cylinder walls are as thin as the can pressure die cast them to allow for a one time machining.


#5

Scrubcadet10

Scrubcadet10

they offer a .020 over piston for it.
I'm doing this for a longtime friend, who is in a financial pit right now and i told him i'd do what i could.

Or i could mow his yard for some extra :2cents::2cents: he he he he :D


#6

S

SidecarFlip

Mike the cylinder wall thickness and you'll know right away. After boring you need at leas .030 wall thickness. Tell him to buy a cheap goat and can the lawnmower.


#7

Scrubcadet10

Scrubcadet10

Goats, good lawnmower, and when the teeth fall out eat em! lol.


#8

S

SidecarFlip

Reason I mention that (not on thread) is, I have a good friend who leases out his goats for grounds maintenance here in Michigan. They eat everything including poison ivy and fertilize as they munch which is 24/7. I hear they like Kudzu too. No maintenance needed and they make 'new mowers' by themselves. I mow 7 acres myself and I'm considering mowing less and getting a pair of goats.


#9

Scrubcadet10

Scrubcadet10

Goats are very expensive down here, at least more than they used to be. A 2 YO nanny runs around $250.

i remember when we had goats, 6 nannys and 1 billy named Sampson. We'd go out there at night (well lit area) with a big thick trash can and one of us would get in the trash can with 2 wheels, while the other pulled and the billy goat chased us, and butted us. those were the days. And we had one billy before him, Lightning, he was a mean little dude, horns grew behind his head about 2 feet. He was tame most of the part, but if you got him riled up, he was literally a pain in the rear!lol


#10

W

Walt 2002

Scrubcadet10 said:
they offer a .020 over piston for it.
I'm doing this for a longtime friend, who is in a financial pit right now and i told him i'd do what i could.

Or i could mow his yard for some extra :2cents::2cents: he he he he :D
Click to expand...

Cylinder wall thickness is NOT your problem but the very high risk of failure is. You will get a bunch of time and money in this then be plagued to make good when it fails. Better pick up an equivalent engine with cast iron cylinder liner and rebuild it, good chance of getting by with just new rings or even just a decent used running engine. You likely are working with an old 11 hp, 25-- series engine??

Walt Conner


#11

B

bertsmobile1

Walt is quite right , I should not need to "me too" his posts.
Cool bore engine can not be bored out oversize successfully.
Briggs use the same size piston is engine that are all iron, alloy with iron or steel liners, alloy with chrome plated bore and all aluminium
Thus +20's and even + 40's are available.

Boring is done in thous from .5 up to around 15.
Honing is done in hundredths of thous to clean up the ridges left by the boring bar or clean the glaze off worn cylinder walls, replace the cross hatching or to size very accurately.
Honing .010" off a bore wall by honing would be near a whole day of machining and wear out a complete set of stones.


#12

upupandaway

upupandaway

Walt 2002 said:
....don't waste your money on it. ...
Click to expand...

I agree with Walt. An aluminum block is not just bored and honed, it needs treatment for long life. Annodized(or the like) Nikesil(common treatment) or the like original treatment in it is lost when you bore it.
Personally to keep cost down, u can get a used one for 20$ and transplant the motor if u want.


#13

J

jp1961

I've researched Briggs "Kool Bore" technology. From what I gathered on the web, the piston and rings were chrome plated and the cylinder just plain aluminum (sort of opposite of a chrome cylinder/aluminum piston setup).

Anyhow, you could find a good used engine for your friend, or if somebody could reasonably bore the cylinder .020" over, it may make a good winter project.

Regards

Jeff


#14

sgkent

sgkent

honing a cylinder out or boring with a cutter are two forms of oversizing cylinders. The problem with aluminum is that the honing stones load up with aluminum when more than just a little is removed. Keeping the stones wearing evenly is most important when honing. I used a Sunnen cylinder honing machine for years. Back when Chevy tried aluminum blocks the solution to over size was use a cutter then press in a steel cylinder and hone it to size. That won't be cost effective on a small engine unless it is a one of a kind museum piece. Buy a new engine or a low hour used one.


#15

7394

7394

Example: Chevy Vega....................Need I say more..:thumbdown:


#16

S

SidecarFlip

7394 said:
Example: Chevy Vega....................Need I say more..:thumbdown:
Click to expand...

Actually, the Chevrolet Vega had a Nikasil plated bore, not plain aluminum and it worked well so long as the coating didn't get scratched or nicked. If it did, the engine became an oil burner. Nikasil was and is a common liner in motorcycle engines even today. Nikasil (Nickle-Silicone impregnated bores work just fine actually.

Saying more is saying less in your case.


#17

sgkent

sgkent

they sagged and blew head gaskets. The over bore and steel sleeve was to put the steel a few thousands above the desk so it really crushed the head gasket. The trick conversion was a Buick V6. Personally if I wore out an aluminum BS engine I would just hone it to get a cross hatch, gap new rings and pray for the best. The small shop that over bored lawn mower engines died a long time ago. Yes there are people who do it but the cost is high compared to the gain. Usually one can find a used mower, pressure washer, edger etc that is being parted out over a broken drive shaft, pulley, gears, pump yada yada and the same engine as you have is $80 - $125 to take it off the guy's hands.

But if one does bore the aluminum make sure the guy does a lot of them because if the cutting pressure is too high the cylinder will be more wavy when done than it was before it was bored.


#18

S

SidecarFlip

sgkent said:
they sagged and blew head gaskets. The over bore and steel sleeve was to put the steel a few thousands above the desk so it really crushed the head gasket. The trick conversion was a Buick V6. Personally if I wore out an aluminum BS engine I would just hone it to get a cross hatch, gap new rings and pray for the best. The small shop that over bored lawn mower engines died a long time ago. Yes there are people who do it but the cost is high compared to the gain. Usually one can find a used mower, pressure washer, edger etc that is being parted out over a broken drive shaft, pulley, gears, pump yada yada and the same engine as you have is $80 - $125 to take it off the guy's hands.

But if one does bore the aluminum make sure the guy does a lot of them because if the cutting pressure is too high the cylinder will be more wavy when done than it was before it was bored.
Click to expand...

We took a Vega Hatchback, tubbed it, put in a 350 chevy 4 bolt with a hair dryer and a turbo 400 and ran consistent 10's with it. Even drove it on the street once in a while.... Those were the days...lol


#19

7394

7394

SidecarFlip said:
We took a Vega Hatchback, tubbed it, put in a 350 chevy 4 bolt with a hair dryer and a turbo 400 and ran consistent 10's with it. Even drove it on the street once in a while.... Those were the days...lol
Click to expand...


Yep, I put a 327 in my vega wagon, long ago, after it became an oil burner. :thumbsup:


#20

sgkent

sgkent

:) y'all kinda snuck up on folks I bet who thought they were racing a Vega.


#21

7394

7394

Valid point, lil sleepers... :thumbsup:


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