What I do.

Hi, I just got a reminder to participate message. I suppose this would be the best place for me to respond.

I have never built an engine, I would like to, I have a nice steamer in mind but I don't believe I have sufficient skill or equipment to do the job in a creditable manner.

What I have always done is maintain and repair the engines on all my lawn and garden equipment. Right now I'm making a serious effort to bore, ream out, and replace with a bronze guide the worn integral intake valve guide on the eleven HP Briggs and Stratton engine for my Snapper lawnmower.

I'm making, or modifying all the tooling for the project. I've been told I can't do it with what I have, that just makes me more determined to it. If I'm successful I'll post here.

Jim

Welcome Jim, it sounds like you are doing some interesting things.

Jim

J Harp said:

Hi, I just got a reminder to participate message. I suppose this would be the best place for me to respond.



I have never built an engine, I would like to, I have a nice steamer in mind but I don't believe I have sufficient skill or equipment to do the job in a creditable manner.

Click to expand...

Ultimately you need to build up your assets. That being tools and tooling.

What I have always done is maintain and repair the engines on all my lawn and garden equipment. Right now I'm making a serious effort to bore, ream out, and replace with a bronze guide the worn integral intake valve guide on the eleven HP Briggs and Stratton engine for my Snapper lawnmower.

Click to expand...

Just realize that the motivation is different with an engine repair. Fixing the engine might be more about getting the grass cut than an enjoyment from building a running engine.

I'm making, or modifying all the tooling for the project. I've been told I can't do it with what I have, that just makes me more determined to it. If I'm successful I'll post here.



Jim

Click to expand...

There will always be somebody to tell you you can't do it! As long as it isn't the law don't get too worried about it. Do take note of all safety suggestions though. Some things done in the pursuit of this hobby have real safety considerations and we don't want to hear about someone going into the hospital or grave.

Given that you need to consider what you have tool wise and what you may acquire to meet your goals in the future. Good tools do make things easier but guys have also gotten started with very little.


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Welcome to the site. You seem to have some mechanical ability and tenacity to get it done.

Here's the old "Hillbilly Blood" type method with a minimum amount of tools. I may or may not work depending on your ability and the tools at hand.

You can replace the valve guide with a few basic tool and materials, if you're careful. You'll need a drill press, drills, level, hone and a spare used valve would be good.

http://www.mcmaster.com/#bronze-sleeve-bearings/=s6cj3i
http://www.mcmaster.com/#ball-hones/=s6ccrq

Have your material in hand for sizing the bore. Set up a drill press table (level both directions).
Center the taper on the drill chuck into the valve seat and lock down the part. Drill out the old guide and and press in the new sleeve, Locktite works good if it's a bit loose or "punch mark" the bore.

Hone the guide to fit the valve (preferably a new one) to a "pop fit". That means it pops when you remove it quickly with your finger covering the back side with a dry fit. Or, .001 to .002" if you have the ability to measure it.

File four equally spaced grooves across the old valve's seat with a file to provide an even scraping surface. With the seat marked with a felt pen, spin the valve lightly on the seat to see if your anywhere close to a viable seating surface (360*). If not, try and use a drill to spin it off the valve stem side to scratch one out. If you by some means actually find a 360* seat, lap the new valve to a finer seating surface.

Good Luck, it can be done!

Welcome to the site. You seem to have some mechanical ability and tenacity to get it done.

Here's the "Hillbilly Blood" method with a minimum amount of tools. It may or may not work depending on your ability and the tools at hand.

You can replace the valve guide with a few basic tool and materials, if you're careful. You'll need a drill press, drills, level, hone and a spare used valve would be good.

http://www.mcmaster.com/#bronze-sleeve-bearings/=s6cj3i
http://www.mcmaster.com/#ball-hones/=s6ccrq

Have your material in hand for sizing the bore. Set up a drill press table (level both directions).
Center the taper on the drill chuck into the valve seat and lock down the part. Drill out the old guide and and press in the new sleeve, Locktite works good if it's a bit loose or use a few punch marks.

Hone the guide to fit the valve (preferably a new one) to a "pop fit". That means it pops when you remove it quickly with your finger covering the back side with a dry fit. Or, .001 to .002" if you have the ability to measure it.

File four equally spaced grooves across the old valve's seat with a file to provide a scraping surface. With the seat marked with a felt pen, spin the valve lightly on the seat to see if your anywhere close to a viable seating surface (360*). If not, use a drill on the valve stem to scratch one out. If you by some means actually find a 360* seat, lap the new valve to a finer seating surface.

Good Luck, it can be done!

Thm:

Thanks Fellows.

I must modify the statement, "making or modifying all tooling", I ordered an adjustable reamer for sizing the guide. I found that the 5/16 reamer I have wasn't going to work. The valve stem is .3095, if I used the .3125 reamer the guide would be just .0005 shy of the wear the limit from the start if what I have read is correct. a neighbor has offered to bring me a B&S manual for the engine.

I have a lathe and a piece of silicon bronze to make the guide. A shrink fit is what I will aim for, I've done a few, but nothing as critical as this, it's been a learning experience which I hope will continue.

A lot of help and advice has come my way on that other site which I sort of consider my home. Nothing against this site. It's just that I started out there, know it better, and often don't have time to read them all.

What I'm working on now is alignment guides for boring and reaming for the new valve guide. I'll have to make a plug gauge to measure the ID of the reamed hole so I can figure how much oversize to make the guide. I'm not at all confident of my ability to hit a critical diameter like that directly by turning, so will have to sneak up on it with file and wet or dry paper. I have enough material for two or three tries. If I fail, I'll still learn something.

Safety, I practiced it today. Only got a couple of hours sleep last night, felt lousy all day. I wouldn't touch the lathe till about 6PM when I drilled one hole in the centering guide, will bore it later.

Jim

Still working on it slowly, lots of things get in the way. Perhaps I should more fully answer your first posts. Wizard69, I have been accumulating tools for 50+ years, have a few pieces I've had since the mid 50's. Some bought new, but most got at flea markets and yard sales, quite a few I have made.

What I lack and keep looking for is an Atlas 7B shaper, and a good small knee mill. It teems that every one I see that looks interesting is on the other side of the country, or it's midwinter and they are in northern Illinois. Not having a mill limits what I can do, and I often have to find alternative ways to go about a job.

Fabricator, thanks for the tip on using the old valve to mark the the valve seat to check the centering of the guide, I hadn't thought of that one.

Jim

Dredging up an old thread, I promised to post the result here, about forgot.

The project I posted about back in the spring worked. The second (Got a tapered bore in the first) bronze guide I made cut the smoking by about half, a new set of rings took care of the rest.

The first job was to prepare the bore in the aluminum cylinder casting to receive the guide. Everything I tried left a taper. I finally got it smooth enough and with just about a thou. taper, and made the OD of the guide with a matching taper

I found the bronze easy to turn, and drill by using a drill with tiny flats on the cutting lips. Finishing the bore was a job, the expanding reamer I bought was useless. I wound up making a D-bit reamer, it cut great for the first 3/8 inch or so, and then started binding, bronze markings on the bit showed that it had warped when hardening.

Removing the warp with a diamond hone left the reamer cutting undersize. Tried a lead lap, but couldn't get it to run true enough that I could trust it not to bell-mouth or taper the bore. It took about two hours with wet or dry on a split dowel with plenty of oil to get the bore sized so the valve stem would pass smoothly through it. I held the dowel with a bushing in the tailstock chuck and fed it back and forth by hand so I could feel where it was cutting.

Having followed Rich Carlstedt's advice to find how much oversize to make the guide, I put it in the freezer overnight while wrapped in cold-packs. I kept it in the cold-packs with a greased installation tool while heating the prepared bore in the casting to about 400F. The guide dropped in about 2/3 of the way, and some gentle tapping on the installation tool with a wooden mallet finished it. It hasn't come loose yet.

Jim

As far as thinking you don't have the skills, you might be surprised. Years ago I wanted to build a Cobra kit car. I had built a couple of race cars but didn't think I was ready for that challenge. Well, my neighbor built what was considered to be the hardest kit out there and he's an accountant who puts on gloves to mow his lawn.
I ended up helping him with a lot of it but 3 years later I had my Cobra and a great deal of satisfaction.
Go for it !