Welding on a Briggs 5HP aluminum block

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Flathead Builder

Member
I have a 1972 Briggs 5HP Model 130202 that I am restoring. It needs some repair on a couple of the cylinder fins on the PTO side. Can this be welded without warping or otherwise damaging the cylinder wall/bore? What type of welding would this be? (TIG, MIG, or?) I have a real nice bore right now , within specs, and really do not want to have to rebore it. Any other "head's up" would be greatly appreciated!
Thank you for any help,
Michael
 
I would not repair them, but if you must, TIG. You’ll have to cook the block prior to get most of the impurities out of the aluminum. I used to put mine on top of a kerosene heater for a few days. Clean the area up good with a rotary file and see what you can do. I wouldn’t do a lot at one time. Give it ample time to cool between passes and you should be fine. You may have to weld, grind it off and weld again until you’ve got clean aluminum.
 
Skidude said:
I would not repair them, but if you must, TIG. You’ll have to cook the block prior to get most of the impurities out of the aluminum. I used to put mine on top of a kerosene heater for a few days. Clean the area up good with a rotary file and see what you can do. I wouldn’t do a lot at one time. Give it ample time to cool between passes and you should be fine. You may have to weld, grind it off and weld again until you’ve got clean aluminum.
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Thank you for the reply. Any concerns about the heat from welding causing and warpage of the cylinder/bore? The area of the weld will be on the ends of 2 cylinder fins on the PTO side of the block, each about the size of a small grape. Unfortunately, the cylinder has already been rebored and honed, so I really do not want to have to do it again due too warpage.
Michael
 
I would say there's a chance .
A lot depends on how good and fast the welder is .
Bolt the head and side cover on .
Should probably have a block to practice on . Its been said helium gives better results then argon .
 
Thanks flattop1- understood and duly noted.
if it makes any difference, this engine is a Briggs "Koolbore" (all aluminum), including the bore (no steel sleeve). Is there more likelihood of warpage with aluminum or steel/iron?
Michael
 
Thats a weld engineering question.
I would assume , yes . As the sleeve Should provide some semblance of stiffening.
The thing is all welds shrink and draw .
Why not just reshape the fin ?
 
flattop1 said:
Thats a weld engineering question.
I would assume , yes . As the sleeve Should provide some semblance of stiffening.
The thing is all welds shrink and draw .
Why not just reshape the fin ?
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"Why not just reshape the fin?" That is a fair and valid question.
This is a full-blown restoration that is 100% period correct that will go on a (fully) restored collector-quality minibike of the same timeframe. In this case looks are everything and it has to look identical to the way it came off the Briggs assembly line.
Michael
 
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Flathead Builder said:
I have a 1972 Briggs 5HP Model 130202 that I am restoring. It needs some repair on a couple of the cylinder fins on the PTO side. Can this be welded without warping or otherwise damaging the cylinder wall/bore? What type of welding would this be? (TIG, MIG, or?) I have a real nice bore right now , within specs, and really do not want to have to rebore it. Any other "head's up" would be greatly appreciated!
Thank you for any help,
Michael
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Doesn’t the cover/side tins cover up the fins you are talking about. I know you are being meticulous and period correct and there is certainly nothing wrong with that. That’s how my father is. But if the tins cover it why not reshape and cover it? I personally would reshape the fins so good you would have to be a period correct professor with laser vision to tell if was wrong.
 
Unless its the top two fins . Thats pretty much correct .
I'm no rivet counter , but if its the correct engine for the chassis .
Go ahead and have them welded .
Do you have a welder in mind .
Because a welder capable isn't going to be cheap.
 
Unfortunately the tins do not cover where the repair is needed. Yes, I have a very good local welder. I took the engine to him yesterday for a look-see and he will make the needed repair for $ 70.00 (I think that is pretty reasonable) provided that I do all the prep work (small wire brush wheel on a Dremel) over and all around the repair area.
Michael
 
XXX#40 said:
Check the cylinder for roundness, if it's out send it to Brian Carlson for a bore and steel sleeve.
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We still work on these flathead engines every day in the shop.
Steel sleeve will be the way to go unless you have a Raptor 2 or earlier chromed full round piston to fit your aluminum cylinder. We may have a few left around if you need. Otherwise, the R3 pistons (chromed or not) rock too much in the cylinder due to their barrel design and tear up aluminum bore cylinders very quickly.

If there's anything we can help with, feel free to give us a call at the shop.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
35 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
CarlsonMotorsports said:
We still work on these flathead engines every day in the shop.
Steel sleeve will be the way to go unless you have a Raptor 2 or earlier chromed full round piston to fit your aluminum cylinder. We may have a few left around if you need. Otherwise, the R3 pistons (chromed or not) rock too much in the cylinder due to their barrel design and tear up aluminum bore cylinders very quickly.

If there's anything we can help with, feel free to give us a call at the shop.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
35 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
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Thank you Brian- much appreciated and duly noted! I hope that I do not have to this time, however, it is very nice to know that I can use your services if the welding results in a failure (warpage out of round) of the cylinder. Do you have an opinion as to the chances there will be any warpage for this type of welding repair?
Regards,
Michael
 
Flathead Builder said:
I have a 1972 Briggs 5HP Model 130202 that I am restoring. It needs some repair on a couple of the cylinder fins on the PTO side. Can this be welded without warping or otherwise damaging the cylinder wall/bore? What type of welding would this be? (TIG, MIG, or?) I have a real nice bore right now , within specs, and really do not want to have to rebore it. Any other "head's up" would be greatly appreciated!
Thank you for any help,
Michael
Click to expand...
What is the current out of round measurement. ?
 
Flathead Builder said:
Thank you Brian- much appreciated and duly noted! I hope that I do not have to this time, however, it is very nice to know that I can use your services if the welding results in a failure (warpage out of round) of the cylinder. Do you have an opinion as to the chances there will be any warpage for this type of welding repair?
Regards,
Michael
Click to expand...
More than likely out of round now, it was a problem with cool bore engines.
Our best engines were single bearing cool bores that had been sleeved
 
Much appreciate the interest and replies...
I took precise measurements top, middle, and bottom of the ring travel area. Two in each area at 90 degrees to each other (front to back and side-to-side). The bore was just slightly worn at .0005-.001" and uniform within .0005" from top to bottom. I had it honed (machine shop) and put new standard bore rings in just to give it a "freshen up" as the original rings were also slightly worn. It now has great compression and runs very good. Unfortunately, the "damage" to the cylinder fins happened AFTER that and was done due to my error! Keep in mind that this is not in any way a racing engine- just a standard 1972 Briggs 5 HP.
Michael
 
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Keep in mind, the bottom fins do the least cooling, as the heat source is at the top.

Besides, air cooled engines are largely fuel cooled engines.

Other than outward appearance, what is the reasoning behind trying to weld these?

Edit, went back and read again.

Best bet, find another block, pay to have it honed, and move parts to it.

Jmho
 
Soooooo....
Is the general consensus that I am likely (or it is at least possible) to have the bore warp out of round when the 2 fins are welded? I really do not have anything to lose right now (except the $ 70.00 welding charge) to just go ahead and give it a try. If it fails (warps) I'll just go ahead and find another good block or have this one resized and honed.
Michael
 
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