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J Harp
10-08-2014, 07:14 PM
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 alunimum 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 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.

doctordoctor
10-08-2014, 07:18 PM
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 alunimum 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 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.

What are you working on? Is this for a full size vehicle or a model?

J Harp
10-08-2014, 09:33 PM
Neither, it's an eleven horse Briggs & Stratton on my Snapper mower.

The mower itself is long overdue for replacement, but I like to fix things, this was a just to see if I can type project. If it holds up it should give me another couple of years of mowing and leaf pickup.

doctordoctor
10-08-2014, 09:45 PM
Neither, it's an eleven horse Briggs & Stratton on my Snapper mower.

The mower itself is long overdue for replacement, but I like to fix things, this was a just to see if I can type project. If it holds up it should give me another couple of years of mowing and leaf pickup.

Have you done any work on valve seats? I'm planning on doing some on an aluminum head, I'll probably be doing the oven cooking of it to pop them out and the freeze/oven thing to put new ones in. Do you have any pics of your guide work?

J Harp
10-08-2014, 10:42 PM
Never done any previous valve work other than "grinding them in" with Clover compound, and adjusting clearance. I didn't recut the valve seat. The tool I used to enlarge the bore for the guide was guided top and bottom. A check with blue showed a pretty good fit of valve to seat. I don't hear any hissing from the intake when the piston is brought up slowly on compression.

I have some pictures of some of the tools I made for the job, some of them I forgot to take pictures of. I don't have a photo hosting service, PhotoBucket was a big frustration for me every time I tried it. Picasa is not available for Linux, and I don't have a Windows machine.

If you would care to PM me your email I'll send you the pictures I have and you can post them if you wish.

ironmonger
10-09-2014, 12:20 AM
<snip>
I have some pictures of some of the tools I made for the job, some of them I forgot to take pictures of. I don't have a photo hosting service, PhotoBucket was a big frustration for me every time I tried it. Picasa is not available for Linux, and I don't have a Windows machine.

<<snip>>

Donít know if it's still available, but the screenshot you see here is Picasa you see here is running on Linux Mint. I use Dropbox to host the pics, which is available for Linux. That is where this photo is stored.

https://dl.dropboxusercontent.com/u/37105624/Screenshot-Picasa%203.png

paul

J Harp
10-09-2014, 07:24 AM
Thanks Paul

I haven't been able to install Picasa for about two years, get a msg. something like the Linux OS is no longer supported.
Neither the photos or Dropbox are on this machine. The Pic's are on my 12.04 machine, but I don't use it much as the hardware is so old that I can't get some of the updates for it, can't print for example. It is backed up with JustCloud, but I haven't been able to get JC properly installed on this one so I could transfer the account. Still working on that (my other thread here).