December tends to be a quiet month in the way of major engine restoration projects.
The Stationary Engine Mailing list is preoccupied with two events, our annual on-line charity auction and the annual
world-wide crank-up for New Year. The auction of items often only loosely connected with engines generally raises
about $2,500 for various charities, depending on the level of rivalry between the engine and tractor lists which
are hosted by ATIS, the Antique Tractor Internet Service. stationary-engine@atis.net
The crank-up is held in memory of engine friends past. The first report is usually from Sydney, Australia where
enthusiasts are running their engines before the fireworks over Sydney Harbor Bridge have died down. In deference
to our neighbors, we don't run our engines at midnight, but instead have an all day party on New Year's Day, dragging
out and running a selection of engines. I'm delighted to report this year that included a flawless performance
from Tillie, the Tillinghast half-breed oilfield engine. Finally, we get the news from coast to coast of America
about how the engines have run there.
Maybe the lack of serious work on engines is that this time of year brings exact opposites of a barrier to working
in the shop. In many places in the US, it is just too cold to work out there, unless it's a well-heated shop, and
in Australia, temperatures have been too high at over 100°F for comfortable working conditions. In England
it's just dark and miserable!!
I also noted that, although some folk received engine-related Christmas gifts, no-one received a whole engine.
In a few cases, this has been remedied with list members going out to buy themselves a New Year treat in the form
of an engine. Several of these have been unusual engines in one way or another, with features listed in historical
sources as only appearing on high quality forms of the engine, or on larger sizes only. It seems that some manufacturers
positively delighted in breaking their own specifications!
I've taken a quick look back at my collection of previous articles and see that the subject of valve guides has
been sorely neglected, so I'll take this opportunity to rectify my mistake.
* At what point should one install valve guides? The 5HP. Sawrig Galloway
is
coming apart nicely. Big massive valves, not pitted and in pretty good shape, but there is a lot of radial play
in the OEM guides. I'd say 7/16"stems, both worn about the same.
I can only imagine the size of the massive valves in the "Sweet 16." Whew!!
These valves are HUGE. Not so much valve OD but they've got to be a half inch thick!! That coupled with ~7/16"
valve stems is pretty impressive. And it's a two piece valve. The stem is peened onto the valve.
I don't care too much for valve guides...maybe knurling the stems is the way to go?
These stems are very soft, not like modern era stuff. I plan on it being a "working engine" so I want
it done right.
* You knurl the guides not the stems.
* I don't think much of the idea of knurling the stems of valves. It greatly reduces the contact area and will
probably wear very poorly. Why not just bore out the head and press new guides in, then do whatever is needed to
the valves?
Do it right and do it once.
* I have put valve guides in most (all?) of the engines that I've restored. Have had no trouble with them at all!
* True up the holes and make oversize stems for the valves.
* Many of the old engines used two piece valves. Iif you take one of the valves apart you will find that the stem
is stepped in order to accommodate the smaller hole in the valve head.
* Knurling valve guides consists of running a roller equipped device through the guides - it creates a "spiral
groove" and displaces material, effectively reducing the size of the guide hole.
Used to work with a complete set of "knurlers" and pilots and all, took a damned heavy duty drill to
run through an automotive head.
Works in cars because the knurling was well lubricated with the automotive system - not sure how it would fair
with an engine like we have. The knurling held oil and actually improved efficiency. You reduced oil consumption
past the valve guides if done properly.
I'd ream it out and put in new guides. I used to do that a lot as well, never had a lick of trouble. (Those that
did, well, it's typically due to a poorly done job!)
If the guides are worn unevenly, like egg-shaped, knurling isn't the best answer, fitting with new guides is. Another
advantage of going with replacement guides - you put the thing back to "specs" and can use standard or
stock parts.
On piston knurling, you do the piston because it lends itself better to it.
It's softer (in most cases) and is the replaceable part. Also because you run rings against the cylinder wall,
gee, you couldn't knurl the cylinder!
However, the valve guides, that's a very common practice and the tools are readily available, but not cheap.
* Easy answer, knurl the stems and you make a file that is moved around a lot during use. Knurl the guides on an
engine that lubes them good and the knurling helps trap oil and lessens wear.
Overall knurling is a waste of time though. It is actually easier to drill out the guides and replace them or sleeve
them, and better in the long run.
* If you're striving for perfection, keep in mind that your valve stems are going to be worn as well as your guides.
Going to extreme measures to make the guides perfect will be a waste unless you repair the valves.
There's no reason to hesitate to bush the guides. You could probably buy the a couple reamers and the guides and
do it yourself for cheaper than it would cost to hire a machinist.
I've done some pretty close work using a reamer in a drill press and turning the drill press over by hand because
the motor drives it too fast.
* I have done this plenty of times and it was always the hot ticket. Removable stems is the key, otherwise you
have to make a complete new valve - which is still do-able. I have got away without having to put guides in anything
so far, but they get rustier every year!
I try to avoid putting links to web pages in these articles, for those of you who don't have computers, but it
seems that more and more engine folk are realizing the potential of computers and the internet as a resource. If
you are debating buying a computer, the website mentioned here alone is worth taking the plunge!
* If you haven't seen Craig Prucha's web page, it's certainly worth a
visit. He photographically documents the restoration of engines, step by step, including the fabrication of new
parts.
Somewhere on the web page he makes new valves, starting with chunks of metal and ending up with gorgeous valves.
He makes it look like child's play.
Go here to browse around:
http://www.antique-engine.com/
* Yes, Craig makes great looking and functioning valves---BUT he makes them for engines that are MUCH larger than
those with which most of us play.
Valves of the size needed for that 5 HP Galloway can be purchased VERY inexpensively. Others (for a 1 1/2 HP Hercules
for example) can be had for nothing from most machine shops. Just ask them for a used (ie one that they took out)
valve from a 1987 Toyota. It simply needs an inch or so cut off the stem and the valve face ground/lapped in!
* Worth looking at cast iron or phosphor bronze guides and doing it right, bearing in mind that any leakage past
the inlet guide and stem will affect carburation etc.
Also, if there is little/no lubrication then cast iron will last longer that bronze in the same place.
Boring out the block for guides where there were none before is a major job and the bores have to be at right angles
to the valve seats or you're in big trouble.
Worth getting an engine shop to do that bit, as drilling into an oval hole could mean all sorts of alignment problems
later.
* Excellent point you make about both stem and "guide" being
worn!
Years ago I needed to repair the throttle butterfly shafts in some old MG SU carburetors. There is not enough meat
in an SU carb to rebush them so I bought an adjustable reamer and opened the worn bores up to clean up nice and
round. Then made brass shafts to match the new bore size. They worked great.
Could you do the same with your cylinder head? You can buy inexpensive reamers at less than $10 each, and clean
up your valve stem bores in the head. Then make new valve stems to match whatever new size you wind up with.
Basically for $10 or $20 you can fix your head and the valve stems are a piece of cake. Make the stems long enough
so you can center drill and use a live center. Then cut the center drilled portion off when turned to size.
* I just had to make new valve spring "towers" on a 3 hp M head.
They were broken off and the valve holes were oval like eggs. So I decided to make new valve guides and spring
"towers" in one. Boring and milling and tapping the threads, I did it in one go per stem hole and aligned
the whole setup with the help of a center hole I made in the valve head; that way I was always in the middle of
the "groove".
Then I will bore the final stem hole and will use a long reamer for the exact measurement. Finally, I will mill
off the top with the wrench slot. I thought this was the only way to save this head.
* I have just finished doing the valves on a Lister L. The guides and stems were badly worn. I was able to buy
one new valve. I picked the best of the worn pair and put it in the lathe and ground the stem with a home made
tool post grinder till it cleaned up. I removed the worn guides and reamed the bores in the head to get them round
again and then got some nice soft cast iron and made new guides with the ID to suit the individual valves. I made
the guides 1 thou bigger than the bores and they hammered in nice. I have had new inserts put in the seats and
everything has come up like new.
As usual, the List came up with several ways to achieve the same end result, depending on the initial damage, level
of machinist skill, and tools and material available.
With warmer weather just around the corner, it's time to get the winter projects completed ready for a new show
season!
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©FBI 2004