Briggs and stratton Model 5s Modification

Nice! Been a month and a bit since this thread was updated, any more progress? Would like to see how the casting goes

I'd be real interested in how you're grinding your cam. I'm building a Kohler K341 that has a huge welded performance cam in it already but I want to tweak it to see how much more I can get out of it. If I can grind it myself I'll be saving a bunch of cash.

I'm going to get back on this project soon but I ran into a snag. I needed bentonite clay to make casting sand, which you can get, but some people just grind cat litter into powder. So That's what I was going to do, but I didn't have a good way to grind it up. I crushed up some and tried mixing up a batch of sand, but couldn't get it to pack like it's supposed to. Either I don't have enough clay in it or the clay I used isn't correct. After that I welded up a really hack job ball mill, which is 90% complete so that I can grind up some more cat litter. Basicly a rotating drum that you put the cat litter in with some ball bearings/bolts. They roll around and crush it into power....eventually. Pics of all that soon.

As for the cam shaft. I'm going to weld it up and then grind and check over and over, first with a regular bench top grinder. After I get it close I'll smooth it out with an air powered die grinder (some people may call it a gasket cleaner ect). Not the best way to do it, but it's do-able. More than anything I think you sacrifice longevity by doing it this way. It's tough to get it perfect and things will wear a lot more than if it was done correctly. To get it close to the specs you want will take a lot of time because of all the checking. That's why I took the time to just cut the side of my test block out, because then I can just slide the cam in quickly to check it without taking the whole engine apart.

Here's a pic of what I'll be using to melt aluminum in. I'll probably get some video of the operation once I get ready to cast the head. Or try to cast it anyway.

I'm kind of lost to see how this works?

MatthewD, how it should work is that he will make a complete hollow block shaped as the head to cast in. (Or he will make a styrofoam or similar material duplicate of the head and put in a packing sand so the aluminum will melt making a cast of it) its not that complicated, just takes a long time to do right.

Ah okay

The plan is to get my casting sand ready. (Damp sand with some clay added). Casting sand in some sort of container to hold it, then take the cast iron cylinder head as seen in this picture and jam it down into the sand. Make sure it's packed in good, then carefully remove the head leaving the imprint of the fins/head in the sand. Then melt down some chunks of old engine block with an oxy/acetylene torch in my crucible thing and pour it into the mold. After cooling, remove rough casting from the mold and see how it came out. If the results are acceptable (doubt it on the first try) then sand the bottom flat and grind out the combustion chamber I want with a dremel. Last drill out the holes for the head bolts and spark plug. Tap the spark plug hole. Clean up any rough spots and we have an aluminum head. At the factory, both sides of the head are cast. That's a bit too complicated for my first ever casting attempt and wouldn't save me much machining on this part, so that's why my mold is going to be only one sided.

Just remembering that I think I seen a 4 cylinder version of one of these on Youtube. I think the guy welded the blocks together so they were one. I think it was painted brown.

Oh yeah. I've actually saw that engine running in person. Those guys go to a small engine show near me. They made a twin cylinder also and last I knew they were making a radial engine out of three of them. They make some pretty nice stuff. Except they won't show anyone how they welded their crankshaft together... Top secret.

I think I seen a video with a couple of these engines welded/somethinged together, but I think they were red?
Id like to see some 5horse flattys put together. That would be a fun project.

I bought 2 or 3 of these(or atleast similar) and a 2 stroke Clinton for $40 years ago. I traded 2 of them off.
If i had something to run with them id be tempted to get them running... but alas, they be stashed away in "the pile"...

Finally got around to taking a couple of pictures of the ball mill I made to grind up cat litter for the casting sand. It will need to be at a little steeper angle to work. Used wheel bearing/hub from a truck and welded a tank to the lugs. An old craftsman drill has a v belt pulley welded to it.


The drill will be held in place with some electrical tape once you shim it out with pieces of cardboard to get enough belt tension. The drill is only a cheap one speed drill, so I bought a $10 plug in light dimmer switch so I can slow it down enough to run this thing. Hopefully the dimmer switch will hold up.


The idea is you put the cat litter in the top with some ball bearings and then let it roll around until it's ground into powder. How well this will work I don't know. I've seen people on youtube make this design work with much lighter dury materials, so it should work. Otherwise I'm not going to waste much more time on it. I'll just order bentonite clay online and have it shipped to me.

I got tired of messing with the cat litter grinder, so I just ordered 5 lbs of bentonite clay powder on amazon. Should be enough to mix quite a bit of casting sand. I think the ratio is like 10-1 or something. Anyway, as of right now I'm busy getting ready for the haspin trip, but after that, I plan on trying to cast the head the week after. The plan is to video the process.

Mixed up a batch of casting sand that seems to clump together pretty good. Figured I would try to see how hard it was to get a decent mold. First of all I'm going to have to make a wooden form instead of the plastic box I have. Plastic box flexes a lot and it's going to mess up the sand. Also, I think the heat might be too close and melt it. Secondly, I'm having issues with the deepest cooling fins getting sand stuck in between them. Somehow I have to figure out how to get the head back out of the sand better. Maybe use some sort of non stick coating on it. Surface of the fins might need to be sanded a little smoother too.


Other than the spots that got messed up, the mold looks pretty good. I need to press it down a bit deeper into the sand when I get ready to do the actual casting. If all goes well I'll try it in a few days. Maybe if the sand had just a little more moisture it would help too.

This guy uses talcum powder to make sure the casting sand separates in his mold. I might be able to brush some onto the 5s head to prevent sand from sticking. Looks like his sand might pack a little better than mine also. He might be using some finer grain sand. Here he I casting a rocker arm for a small hit and miss engine shown at the end of the video.

Made up a quick wood form and finally got the sand mixed so it would pack pretty good. Dusted the original cylinder head with talcum powder to prevent sticking and managed to get a fairly good imprint in the sand. Melting down the aluminum was more of a pain than I expected it to be. I had a lot more slag in my melting can than I thought I would and initially, it melted across the top of everything preventing the flame from my torch from getting to the aluminum chunks in the bottom of the pile. Eventually I got most of it melted down, but I didn't seem to have enough heat to work with. I knew I didn't have enough aluminum melted and couldn't skim the slag off too good with what I had to work with, but I figured the mold wasn't perfect anyway, so I might as well pour in what I had and see how smooth of a surface I get. The liquid aluminum wasn't quite hot enough and some of it cooled before reaching the bottom of the mold, as seen by the cooling fins only about 1/3rd as tall as they should be. But, the couple of fins that did flow in worked out pretty nice. A slight roughness and a few bubbles, but even the cast iron briggs heads have that from the factory. Mostly, I need a better way to melt the aluminum, possibly a larger container to hold it in. Another issue is that, by pushing the head into the sand to form the mold instead of packing sand into it, like you would if I had a real two piece mold, the sand between the fins is not as tightly packed as it should be. I may have to resort to making an actual two piece wooden form that fits together to get a good casting. However, first priority is to find a better way to get the aluminum melted down. I would make a lost foam casting, but I think carving the head from foam would be just as tough as using it to form a mold.

To get more heat, maybe one of those propane torches that is used for melting the snow in the driveway, They put out alot of btu's with the big head on it. You can have the propane torch blowing on the side or bottom while you hit the cup with your other torch to melt the aluminum. Should give you a blanket of 800 degree heat that will surround the cup.

My grandfather has one of those laying around, might be a good idea. Also, I think I might be losing a lot of heat through my thin crucible. One guy on youtube mentioned he uses a 4" piece of threaded plumbing pipe with a cap on one end for aluminum. Of course I should have some sort of actual oven or whatever you call it to hold the heat a little better. I figured for now, just get it to work without building a whole factory, as I don't know how many times I'll need to cast anything. I busted up almost an entire junk opposed twin briggs block this afternoon for more aluminum to melt down. More updates soon.....as long as I don't get side tracked....

Planning on trying to give this casting another shot this weekend if I get a chance. My previous test attempt of course wasn't hot enough, but I decided to cut a slice off of it to see if it had a lot of air bubbles in it. For the most part I think it looks pretty good. Should be plenty strong enough to use as a head for one of these engines if I can just get it to pour right.


Right center you can see two small black specks which I think were tiny air bubbles. I have heard some people throw a small amount of table salt into the aluminum before melting it down, which is supposed to help get rid of air bubbles. No idea, but as far as I can tell this should work good the way it is.

What are you using as your furnace?

Wasn't using anything when I tried it before, just the cutting torch aimed into my rigged up crucible or whatever you call it....melting pot. Lose a lot of heat that way. But I have a larger, wider torch end I can try and maybe set it in a metal can or something too while I'm working to keep the heat in some more. Things are on a temporary basis with this deal, everything is rigged up...

Well, for what its worth... I think you can re-purpose your cat litter grinder into a more substantial furnace.
Some sort of insulation would also help. Maybe if you still have the cat litter, add water and turn it to a paste and line the walls of the tank.
If you can put a hole in the bottom, stick a pipe in there to hook to your shop-vac, or GFs hairdryer, some kind of blower to pump air in the tank. Dump a bag of charcoal in there. That should get your crucible more than hot enough.

Yeah, might be a good idea. I tried melting what was left from last time out of my melting container. Couldn't even get it all out. I think I am going to make a thicker walled one.

A chunk of 2in or so  water pipe with a bottom welded in would probable work good for your crucible I think. Your local hardware, or heating and plumbing store ought to be able to cut you a piece pretty cheap.



One of these days, Ide like to try and case some 2 piece aluminum gokart wheels and some brass 22 actions.
...one of these days...

Turned my old cat litter grinder into a furnace/heat shield as suggested by TheBeal. Still use the acetylene torch aimed into the melting container, but also have some additional heat from a propane burner in the bottom of the can. Just to help hold the heat in. Worked almost good enough this time. Still need a better container.


Propane burner under my melting container


Didn't have a great mold which I knew before I poured, but figured I would give it a try anyway. Was being careful not to spill molten aluminum on myself and was too slow to pour. I think I lost a lot of heat between the flame removal and pouring. Otherwise I might have gotten a semi usable casting.


This time we at least got something which resembles a 5s cylinder head. Some is missing and there are a lot of bad spots, but this is definitely a step in the right direction. You can see some spots are too rough, this is where the sand was not packed down enough. Where the tops of the cooling fins are wavy looking, that's where the aluminum cooled too quickly and did not reach the bottom of the mold before solidifying.  


So there we have the 1st test attempt on the right, which I previously cut in half to check for air bubbles. Top we have our latest attempt which is a nice conversation piece. Maybe I should save all the bad attempts, then line them up on a shelf later.


THE BOTTOM LINE: Need a better melting container that holds heat better and longer. Need a better mold. Next time try to pour faster before the aluminum cools too much. Also should probably get some video...

FUN FACT: Most of what was melted down used to be opposed twin engine block (So the head will still be made by briggs and stratton)

This may help brother... easiest furnace there is

http://www.backyardmetalcasting.com/book_fp.html