A tiny 3 Cylinder Holt based engine

[b.lindsey]

It's getting close George!! Amazing work, and I thought the "Tiny" had small parts 

Bill

[jeff l]

Truly amazing such fine work !

[Art K]

George'
Wanted to let you know I'm still following along. Phenomenal work as usual. I have to say the penny for scale on the carb reflects just how small this thing is.
Art

[Kim]

George,
I have nothing meaningful to add other than, "Wow!"
I'm always humbled by your work.
Thank you for sharing it,
Kim

[Ye-Ole Steam Dude]

Beyond belief George, your work is amazing.

Thomas

[Roger B]

Still following along  It looks splendid   

[Doc]

Just catching up again and WOW! I love that little carb!! That is a beautiful little rendition of a Holt she is just amazing. VERY NICE WORK 

[gbritnell]

Gentlemen,

 An update on the Tiny Holt.

 I had an opportunity to take the engine out into the garage for a trial startup a few weeks back. I hooded everything up, put some gas in it and gave it a spin all the while slowly adjusting the carb needle open. I found a spot that it would hit a little but no sustained running. I checked the plugs and they were soaked so I wiped them off and gave it another try. Same thing.
I had some doubts about using plugs that small as I had never done that size before. Not knowing if that was the main problem or not  I opted to disassemble the engine and go the next size up with the plugs, 8-36. I have used those in some of my other engines and know they work.

 I took the heads apart and set them up to machine for the new plugs. I made a little cutter up as I don't like drilling into a hole that already has threads in it. A drill seems to moves all over the place. The holes were tapped and the engine put back together. While I had it apart to simplify all systems I made another carb up. This one is kind of like the one used on the Tiny Hit and Miss engines. Just a venturi and a needle valve.
New plugs were made and the engine was set up for a second attempt. As I was spinning it over and opening the needle valve the engine started right up, for about 5 seconds, then quit. I checked the spark and it was gone. Crud!! I took the distributor apart and reassembled another Hall transistor which is a real pain. Ok, new Hall assembled and out we go for another try. Exactly the same scenario.
Out of all the distributor combinations I have built over the years I have only had one other that would constantly burn out transistors. I have no idea why. The distance from the Hall to any spark is far enough that that it shouldn't get any feedback and I always use 2 ground wired when running my engines. The Hall in my 302 distributor is 6 years old and still works fine.

Ok, back to the drawing board.

 Using my existing dimensions I designed a set of points to replace the Hall setup (photo attached.) The new pieces were installed and once again it was out to the garage for another try.
The engine was fueled up, the ignition hooked up and the engine spun over. As I opened the needle valve the engine started up and ran, this time I got about 12 seconds.
As I looked at the engine I saw that 3 of the pushrods had come loose. Surely the cam couldn't have worn that badly in starting attempts. I tried putting the pushrods back in place but there was way too much clearance. Now as I'm doing this I'm not really looking at anything but the lifters and cylinder heads. Scratching my head I couldn't figure it out. As I took a different vantage point is was then that I noticed the problem. The number 2 and 3 cylinder liners had come loose from the jacket and moved up about .100. (photo attached.)

 When I built the engine the liners had a .001 press fit at the top and bottom of the liners and were coated with Loctite. Now I know that Loctite doesn't like aluminum without using an accelerator but I have used this procedure in the past without any problems. Time for another disassembly.

 When I built the engine the liners were installed into the water jackets then the assembly was mounted in a fixture for drilling the head bolt holes so the port faces would all line up. Now with the liners needing to be pulled out I had to come up with a way of accurately locating them upon reassembling. I made up a dummy head with a flat milled on one side, this corresponded  with a flat milled on the original drilling fixture. The drilling fixture with jacket mounted was clamped onto a solid parallel. The liner was coated with Loctite and with the dummy head mounted was slid into the jacket as far as it would go. The liner and dummy head was lightly clamped to the parallel and the whole thing was set upside down between the jaws of my mill vise. The parallel now resting on the vise jaws with the two parts between the jaws I tightened the jaws and squeezed the two pieces back together.

 With the cylinder assemblies back together I mounted them in the original drilling fixture and redrilled all the head bolt holes down into and through the flange of the outer jacket. I then retapped the 0-80 holes deeper. I had to buy some longer screws to assemble everything but there should be no possibility of it coming apart like that again.

 Any way that's where I'm at. I have been doing a job for someone so that has taken precedent over running the engine again. I hope to have it running for the Zanesville show in 2 weeks.

gbritnell

[Plani]

Thank you for sharing your experience. That's some "interesting behaviour" of this little engine.
But I'm sure you will get it all sorted out. I'll keep my fingers crossed while anxiously waiting for the video ....

Plani

[Vixen]

Is there any possibility that the cylinders had become flooded with fuel, causing the cylinder liners and heads to be lifted hydraulicaly? It may be worth checking to see if the con-rods are still straight

If the liners were a 0.001 press fit, would there be any Loctite in the joint? Would 0.001 clearance be better?

Just thinking

Mike

[Myrickman]

Wow George...! Certainly inspirational. Thanks for sharing the tribulations of trying to get the ignition to work. As always, you never cease to amaze and impress. Paul

[b.lindsey]

Sorry to hear about the issues George, but you seem to be tracking then down one by one. Will Roy Scholl be in Zanesville. Maybe he has a take on the hall sensor issue.

Bill

[Art K]

George,
I was just reading getting caught up really. But it sounds like the cylinder sleeve is holding the head onto the cylinder. Isn't the head bolted to the cylinder? and that would keep the cylinder sleeve in place. I must admit having no knowledge of how a Holt is constructed. But if the head isn't bolted to the cylinder doesn't that put a lot of load onto the joint between the cylinder & sleeve?
Art

[Roger B]

Some interesting challenges    but you are working through them  Hopefully not long until it is running properly 

[steamer]

Glad you found it George.....you'll sort it out I'm sure!!!

Dave