Stuart 600!

[methuselah1]

Good afternoon, folks! My Father has had the good fortune to obtain a set of castings for this engine, and has been poring over the drawings for a week or three, on the basis that you can't f#£k anything up by thinking about it.

However, both he and I are stumped by the workings of the valve block. Does any one here have any experience of a 600? Photographs of a valve block would be even better!

TIA

-Andrew UK

 

[trlvn]

Not mine, but did you see the Youtube video?



Craig

 

[Jasonb]

If it's anything like the 800 then there is the main valve and also a smaller gas valve. When the main valve opens air is drawn into the cylinder and this draws gas through the passage from the smaller gas valve that mixes with the air as it is drawn into the combustion chamber

The one in the video above has been modified to run on petrol, you can see the bronze carb below the intake and the small undrilled boss where the gas valve would have been above the main inlet valve. Also the governor needs to be altered if running on petrol as it acted to stop the gas valve opening on the gas fueled ones by lifting a spacer out of the gap between gas valve and the end of the rocker arm

 

[Jasonb]

What the bits on the block are for. The blanking plate is tapped opposite the gas valve for feed of low pressure gas and has a cylindrical spigot on teh other side that part fills the hole that gives access for machining the main valve seat

 

[methuselah1]

Wow! Thankyou for that, JasonB!

 

[methuselah1]

Not mine, but did you see the Youtube video?



Craig

Thanks, Craig, I've seen that one (petrol) but there's also a clip of a black one, running off a gas cylinder. I'm pretty sure my dad's going to use petrol, but he hasn't started making swarf yet...

Thinking is free- f&£k ups cost money!

Andrew UK

 

[dcurl451]

Good morning all. I'm Andrews father who has the 600 castings; I bought it as a part machined set. The problem with the valve block is I figured out how it works, but the numpty who machined it has made some bad errors. First, the passage from the gas valve to the inlet valve was not machined in, but the valve guides were in, so I've got to remove the inlet guide to machine the passage (the drawings do not give the dimensions for this , but can be figured out). Next, the bore down to the inlet valve head is not right, it must have been done as a secondary setup to the valve guide machining which has left the valve seating on one side of the valve at about 20 thou! this bore is already oversize, probably in an attempt to rectify the valve seat problem. The only way I can see to fix the problem is to enlarge the bore further by about an 1/8" to give a 1/16" valve seat on the (bad) side. The valve will have to be remade, but this will have to be done anyway because the valve I have is 3/16" short. If I could get one (fat chance) I'd machine the block from scratch. I'm finding other errors too, ie. the studs securing the valve block to the head are not vertical to the machined faces so the parts do not meet squarely; I don't know yet if the studs are out or the faces are out. Another pita is that a number of parts have been machined but not finished ie oil grooves on the main bearings, and on the piston. Because of this I will have to check out all machined parts I have. I also need some tech. info. like measurements of valve springs ( wire gauge, No. of coils, unloaded length, diameter etc) Any help with this engine more than welcome. David C.

 

[methuselah1]

Just a thought, why not prepare the block as a patten, and cast a new one in bronze?

 

[dcurl451]

Hello Andrew, basically I wouldn't have a clue how to go about it, if you think it's a good idea you've got yourself a job chap!

 

[Jasonb]

I'd just get a slice of a nice bit of cast iron bar and carve a new one from that, would probably have to drill the gas to main valve passage and plug up the end but should be possible, I've done it for a few engines in the past.

If you are going for the petrol option then that would make it easier as you don't have to worry about the gas valve. On the other hand you need to make a carb which can be done as a brass fabrication and look like the one for the Stuart Lightweight, AE30 and AE60 suitably modified for up draft and then there is the change to the governor too.

This is Gil's 800 with the correct setup for gas and is very similar to a600, you can see the governor working.

 

[dcurl451]

Always an option Jason, but I'd like it to look original if possible. Are there any drawings about for the carburettors do you know?

 

[Dr Jo]

I think it might be worth enquiring where you got these part machined castings from to understand what you may have: I know that Station Road Steam recently purchased two sets of Stuart 600 part machined castings from Eric Offen: One set was an original Stuart 600 casting set and the second set a "known" third party pattern with some interesting "features" (lack of coring under the base making it extremely heavy being the most obvious one of those features).

Yours may be another set which may originate from the "known" third party patterns. In which case the "known" supplier could provide you with another casting so you can make a new one. Eric tried to get additional castings from Stuarts over a number of years without success.

As a "Gas" engine it doesn't need a carb, more of a demand valve. You need a carb if you wish to run one on a different fuel: like Petrol. In which case it is non standard so pick what ever you fancy.

Jo

 

[dcurl451]

Mine was definitely via station road steam as per the search that comes up. the known third party would be a lead for me.

 

[Jasonb]

The "original look" of a carb cut from solid is 95% down to how much time you put into the external shape and only 5% cast texture

Another recast would be the easiest option if they are available just be aware that there will be a bit of shrinkage, may or may not have much in the way of machining allowance and possibly not cored..

Even if you do want to eventually run it on petrol I'd be tempted to do it as propane fueled first as the info is out there and once you know it runs think about making a modified carb and governor.

 

[Jasonb]

If built to drawing and run on propane you won't need a demand valve as the small gas valve will shut off the gas, they are mostly needed when running a petrol carb equipped engine on propane as the gas constantly flows out the needle valve. None of my propane fueled engines use separate demand valves.

A gas bag is not a bad idea as it allows you to set a slow and very low regulator pressure and the bag contains enough gas to supply the engine when it wants it. Graham of Alyn Foundry may be casting up a few of the ones for his Gardner which would fit the bill and he also has some cast exhaust pots that would look the part.

 

[dcurl451]

My thoughts at the moment are to run on gas and petrol would be a "later" version as you suggest. My biggest concern at the moment is checking the quality of all machined parts (after the problems found with the valve box) plus getting the required info on valve springs; I've also got to source the skew gears ( doesn't appear to be a stock item at the suppliers Ive looked at)

 

[dcurl451]

I think it might be worth enquiring where you got these part machined castings from to understand what you may have: I know that Station Road Steam recently purchased two sets of Stuart 600 part machined castings from Eric Offen: One set was an original Stuart 600 casting set and the second set a "known" third party pattern with some interesting "features" (lack of coring under the base making it extremely heavy being the most obvious one of those features).

Yours may be another set which may originate from the "known" third party patterns. In which case the "known" supplier could provide you with another casting so you can make a new one. Eric tried to get additional castings from Stuarts over a number of years without success.

As a "Gas" engine it doesn't need a carb, more of a demand valve. You need a carb if you wish to run one on a different fuel: like Petrol. In which case it is non standard so pick what ever you fancy.

Jo

Jo, do you have a contact for Eric? 'phone No., e-mail, whatever. Doing a search for the 600, the one that comes up from station road steam is for sure the set I have. The "known" party you speak of could be the gentleman I had brief dealings with a good few years ago, he was making patterns for a 600 for himself, and even sent me some 'photos of his work. I've been trying to find out who he was as I lost all my contact lists after a pc crash a while back. Any help really appreciated. David C.