TOPIC: Valve shim question

Hi there,
What are the dimensions of the valve shims and what are they made of? Spring steel?
Tom

They are .500" in diameter and the thickness varies from .0900" to .1369", no idea what exactly they are made from. I don't like this setup because you have to remove the cam to replace the shims. I had my cam off three times to get this shimmed properly. My Yamaha XS750 had the shims on top the bucket, with a special tool you could push the bucket down and replace the shim with one of the correct size. I could trade my shims for the correct size at the dealership, no charge. I'm thinking of looking into a replacement to this type. If something from another engine could be found and modified to work It would make this a little easier for adjustment. Wish I still had the leftover engine parts from my XS750 project. Seems everytime I toss crap I end up wishing I hadn't!

I think they are just mild steel puck, almost like they were just cut from a dowel. I rebuilt one of my Homelites and someone along the line had mixed up the spacers so one of the exhaust valves was hanging open just a touch. I just used a flat file and removed about .005 so that the proper gap could be maintained. Probably not the recommended method but it worked well.

Yes they are shim under bucket, which is less prone to spit a shim than shim over bucket, like Kawasaki used. I once had a GS1000 Suzuki with shim over bucket, much larger shim req'd to fit the cam lobe, but it was more convenient to shim with a special tool, still have the tool.
Every shim size ever made is available fast on www.bearcat55.com

When I re-shimmed mine I just measured the clearence and and the shim size to figure out what I needed to make it right. After I got the right shims I put them in and did a recheck before putting everything back together. Seemed to work out OK. It runs fine now.
I know it is a pain to re-shim. But is is worse to re-cam Like I had to do 3 times. Mine was due to broken dist drive keys. (old style).
I now have the newer cam with the nylon dist. drive key.
No more pulling the cam to replace the drive key.

Dave, next time I'll have you do mine! Mine went back together in a different block, all the shims, buckets and cam were from the original block so that was my starting point(1), I then took my measurements and shimmed accordingly(2), rechecked it and needed to do a final shimming to get the correct tolerances(3). Had the same problem when I did the Yamaha, had to do it twice to get it within specs.

Going to a different block probably made it more of a challenge X2. All I was changing was the cam. And you know they are all different.

64_Express said he could file the shims interesting! I guess my thought was that they prehard 4140 steel or something as tough.
I'm a Tool and Die Maker and own a complete machine shop so I was looking for material and dimension specs. I should have made my inquirey more specific.
Thanks guys.
Tom

I'm sure they are hard tool steel. If they weren't they would wear out very quickly. Remember that the cam lobe profiles aren't ground with a flat face. They have a slight angle so the bucket will be forced to rotate during the opening and closing cycle. At 3,500 rpm crank speed, the buckets rotate about 180 degrees 1,500 times per minute. Do the math on that, and you realize that mild steel would fail quickly. Worn valve locks are often an over looked problem regarding valve clearance and unhappy valve train noise. It's essential to get all worn parts replaced and keep the lifter buckets in the correct order, install the correct thrust shim behind the drive gear, torque the cam bolts in the right sequence, and err on the side of caution on the clearances. I'd rather have shims a little loose than the other away around - burned valves ain't no fun.

When I bought out a former Homelite dealer I got about 75 shims in there original Homelite packages with original Homelite part numbers. The shims are mild steel and can be easily filed to reduce the thickness as needed if you do not have the correct thickness. Included was a fixture to hold the shim while it is being filed. I am not sure but I appears to have been provided by Homelite. I would suggest that a person could make there own shims in a pinch if you did not have access to a source. As far as tool steel or mild steel I would think you would want the shims to be mild steel. As the shims and the cam lobe contact many times a second you would want the shim to be the wear item and not the shim and the cam lobe. I would think that is why Homelite suggests valves need to adjusted at 30 hours and then every 100 hours.

Greg Anderson
Wisconsin

Filing the shims is not necessary; I have every size ever produced, including the special thick and thin shims that were not listed in the dealer toolkit.
Go to www.bearcat55.com and shoot me an email or call direct with the sizes you need, we normally exchange them but can sell them outright too.

Bill is right! I sent him the measurments I needed for shimms he sent me what I needed. I put everthing back together. My motor works fine! Thanks Bill!!

Mr. Roberts,
Any chance you might put a flat mill file to the side of one of the thicker shims to see how easy the file will cut?
Tom Peterson

Just so you know - the shims do not touch the cam. The lifter buckets do. The buckets rest on top of the shims which sit on top of the valve stem & spring retainer. Just ask Bill if I know anything about Homelites.....




gdanderson wrote:

When I bought out a former Homelite dealer I got about 75 shims in there original Homelite packages with original Homelite part numbers. The shims are mild steel and can be easily filed to reduce the thickness as needed if you do not have the correct thickness. Included was a fixture to hold the shim while it is being filed. I am not sure but I appears to have been provided by Homelite. I would suggest that a person could make there own shims in a pinch if you did not have access to a source. As far as tool steel or mild steel I would think you would want the shims to be mild steel. As the shims and the cam lobe contact many times a second you would want the shim to be the wear item and not the shim and the cam lobe. I would think that is why Homelite suggests valves need to adjusted at 30 hours and then every 100 hours.

Greg Anderson
Wisconsin

Yes you can file or grind them, but I feel obligated to tell everyone that I have personally dismantled a few blown powerheads that contained filed shims. I believe Bruce has too as there was a container of filed shims in the stuff Bruce had, and I KNOW he didn't use them. It can be done, but I cannot recommend doing it.
I maintain a huge inventory of shims for $2.50 exchange + shipping and they are mic'ed prior to me shipping them out. Worst case $20 + shipping and you're abiding by factory service manual with factory parts. That's what I recommend and Bruce will too.
It's the owner's choice, but I've given my advice.

Dave is right, he bought the factory manual and Illustrated Parts List from me for his exact engine serial number, then he did the valves per the book. He mailed me his old shims, I sent him the requested sizes and he's been fine. He had some issues with his cam (he has a 1962) so we converted him to the later style cam at the same time. He's been running like a clock since. His motor had been modified and is basically back to stock. I like his motor since she's not rebuilt and is nearly as old as I am and still going!
Greg has done a wonderful job on his motors too. Shames us all with his attention to appearance.
Bham Rick up here had a nice Bearcat from me, he too did the fabulous cosmetic restoration.
Dick's run nicely, and Don's been pushing his Skagit 17 with a 55 for years. All are stock aside from some running electric fuel pump and/or electronic ignition, updated cooling etc. (the only modified 55 outboard powerhead I have ever seen done properly was Bruce's project)

All the parts on www.bearcat55.com are brand new unless I specifically state used.

It is true that the Homelite and Bearcat 55 are heavy for their output, but with proper maintenance on the right size boat they perform well, last a long time, are thrifty, and the no smoke thing cannot be overemphasized. They certainly foretold the outboard market!
www.bearcat55.com/READ_THIS__55_COMPARISON.php
Hope this helps.

Alright. So when I do a valve adjustment I'll call Mr. Bill.
Next question regarding shimming. Do you have to bench the engine to adjust valve lash? Is there an easier way? All I got to go on is Scott Stewart's overhaul CD's.
Tom

No need to remove powerhead, just remove valve cover and take measurements.
Do you have the service manual?
if not call me with your engine model and serial number.

Did you guys see the new stern drive forum on FG?