Webster I.C. Project.

[djberta]

I found the plans to the Webster IC 4 stroke engine and have started preplanning my build. Some changes I’m looking at making come from others builds. Like ades on YouTube did some changes that are noteworthy. One of which is using a belt drive for the timing and moving the cam much closer to the valve.

I have the spark plug, tap which is an odd one at 10mm x 1.0. Spark board parts. 6v coil. Odds and ends of square and round materials for the build. Sadly I have no brass. Maybe use aluminum for some of those parts. The plans are metric, but obviously based on inches. Lots of off mm’s like 25.4mm and the hardware is all standard. If anyone has inch plans I would be interested.

Has anyone built one? Any recommendations?

When I say preplanning, I’m thinking this may start towards winter. My mill is still in pieces on the floor, both my lathes are also pulled apart for the move which we are now just finishing. Mid move the city of Leduc tore up the street in either direction for two blocks to install a new storm drain. They just finished paving on Monday. We have no back alley. Literally moving by crossing our neighbours lawns. The end is near, which is good. I can finally get back to making things.

 

[PeterT]

Look forward to your build. It seems to be a popular engine. Ive seen it on YouTube but also some model engineering forums so would pay to check there. Lots to learn from others.

I just so happened to be looking into spark ignition systems for my next build so take this as FWIW. Seems like a lot of the prior models that used biggish coils, custom boards, biggish batteries etc. are changing over to CDI modules designed for models. They are much smaller footprint & can keep up to multi-cylinder count & RPM demands power wise with small batteries. There were some custom module makers I was aware of, but some guys are retrofitting these ones from China. They make them for their own engine 'kits' which are kind of $$ screwdriver assembly desktop engines, but they also offer the components themselves. https://www.enginediy.com/search?type=article,page,product&q=CDI*

In terms of spark plugs, same supplier (and many on AliExpress & hobby distributers) offer very nice scale-ish plus in 1/4-32 format so you don't have to use those big plugs. I have seen some custom builds like V8's where people made their own plugs down as low as 10-32 & even 8-32 threads using Corian or machinable ceramic insulators, but that's kind of hard core

The RCEXL type modules you see on RC airplane gasoline engines are another way to go. You can get those in minimum 1/4-32 plugs or larger. These gave grounded sheathed cables because of potential interference issues. They also have hard mapped RPM sensing advance/retard which might be an advantage for the most part on a single cylinder. Makes it easier to start & generally runs better at higher rpm although I don't know much about Webster specifically. They work with a magnet on the crankshaft output & hall sensor. Generally made for 2-stroke but on a 4-stroke, just produces a harmless waste spark on the INT/EXH RDC transition stroke.


You wont have a distributor to contend with which is easier yet, but just know that these same Chinese CD modules are being used on self made distributers which can get quite small (scale). I replicated this design from a guy who built a 1/4 scale V8. Distributer body is ~ 1" diameter which is one of the smallest I've seen (before wayward spark issues start to creep in). It has a disc with magnets (green) which is picked up by hall sensor (pink) and then aligns to conductor rotor (blue), all air gap. The Chinese CD has no dwell/advance which is actually desirable. My goal is to make a bench mockup. Thereis also a reputable USA made module I'm checking into but more expensive.

 

[djberta]

PeterT, great info. So far I’m just working off some of the YouTube builds, the model engine forum builds. They run from simple to super complex. The plans I have which I do not think are the only ones. Has a set of breaker contacts a cap and coil. Like a 60s ignition system. What I was shooting for is using the tim6 ignition board and an rv coil. I love the idea of a distributor. That tho will be much later as the single cylinder is all I am looking at currently. The specs on the engine show 1800rpm as the max with most of the videos I’ve watched getting at most up ton1600rpm.

I saw on one of builds for a very complex 4 cylinder the guy made tiny spark plugs, this to me is on an extreme level. Like some of the builds where guys are building clock like movements. IE some of the guys making fishing reels, some really amazing precision. For me at this time, i look at the entire build as a chance to make a running engine.

Most of my experience with hobby machining has been making project parts like bushings, shafts, pin drivers and all the new guy lathe and mill upgrades we all seem to believe we have to make.

I will look in to the cdi link you posted as the are for sure the smallest option by far.

 

[djberta]

Sorry I should add I am using the plans and YouTube video changes and updates.

 

[PeterT]

I forgot to mention the RCEXL modules with braided (grounded) harnesses have a metal boot that engages the plug. The boots also come in different orientations; straight (180-deg) 120-deg & 90-deg. I learned the hard way that you should ideally order the right one from the get-go because its not quite as simple as snipping the plug off & swapping with another. There is a little inline resistor nestled within the boot/cable area that needs to be re-soldered & then boot re-clasped. Swapping is doable but kind of a PITA. This isn't really common knowledge but there is internet info. Your plug depth & head orientation may dictate the style of boot, but I suspect the Webster is pretty forgiving if it had the bigger plug. Also, the CD modules are cast in epoxy - no looky-looky (or repair).

I would have said for a single cylinder the CDI is the way to go. But now that you mention 1800 RPM max I would say delve into that further. I kept this chart from a guy who somehow back-engineered the timing advance/retard curve which is hard-mapped on the CDI. You cannot alter it. I suppose its kind of intended for the typical 4000 RPM+ types of engines. OTOH it may not make a hill of beans difference put-putting away. Ask some questions on the model engineering forums where guys have built the engine & have some better info. I bet most used the coil & TIM so if you are familiar or game for it & have the hardware, that's another option.

The 2 main sites I frequent

Home Model Engine Machinist Forum

Home model engine machinists & makers forum. Model engine making forums for engine plans, castings, CAD, CNC designs, lathe, Stirling, boilers & steam.

www.homemodelenginemachinist.com

Model Engine Maker - Index

Model Engine Maker - Index

www.modelenginemaker.com

 

[djberta]

I have found the original Webster plans in inch’s. The plans most readily available are metric conversion from the inch ones. I had to follow a post using the way back machine to get them.

Ignition parts are coming together. I should be able to put them together when needed.

Working on getting my lathe and mill in to my basement. Once they are in and set up I can start building parts.

 

[Megar arc 5040dd]

I am hoping to do a webster engine this winter also, though I said that last winter too. But this time I mean it haha.