John Builds Kerzel Hit & Miss

[Sprocket]

OK, What type of supplier sells Teflon caps?

You could probably substitute brass or some other plastic. You make the caps. Probably could get Teflon rod from a plastic supplier or maybe McMaster-Carr.
Doug

 

[simister]

OK, that's fine, thanks Doug,

John

 

[doc1955]

Just turn up some plugs they don't need to be pressed on. They are there to keep wrist pin in place and keep wrist pin from making contact with cylinder wall. Usingwrist pin plugs is so you don't need any other means of keeping them in place. Just put a small plug on both sides and no need to drill hole through wrist pin.

 

[simister]

Just turn up some plugs they don't need to be pressed on. They are there to keep wrist pin in place and keep wrist pin from making contact with cylinder wall. Usingwrist pin plugs is so you don't need any other means of keeping them in place. Just put a small plug on both sides and no need to drill hole through wrist pin.

Ok, that makes sense - thanks,

John

 

[simister]

Brian,
I notice that you used a similar setup with the contact points as the Webster. I am thinking of doing the same thing and wondered if you found any problems with the change from the original plans?

Also, I am having trouble getting the Chrysler contact points that I used with the Webster. Do you see any issue with using any other contact points that can be obtained locally? Of course, I understand that the bracketing would need to suit.

John

 

[Brian Rupnow]

Use any points that you can get. Also get a 12 volt condenser to go with the points.

 

[simister]

Thanks Brian,

 

[a41capt]

Use any points that you can get. Also get a 12 volt condenser to go with the points.

Brian, and any other knowledgeable folks, I was gifted a brand new 6 volt automotive coil, but I’m going to run my newest Engine (a Webster) on 12 volts. Does anyone have an opinion on running 12v through a new 6v coil? I’d rather not see the magic smoke appear!

thanks in advance,
John

 

[BaronJ]

Brian, and any other knowledgeable folks, I was gifted a brand new 6 volt automotive coil, but I’m going to run my newest Engine (a Webster) on 12 volts. Does anyone have an opinion on running 12v through a new 6v coil? I’d rather not see the magic smoke appear!

thanks in advance,
John

No you don't want to put much more than about 7.5 volts into a 6 volt coil. You have two options, well maybe three, use a resistor in series or use a voltage regulator to get your 6 volts. If you can get at the half voltage point of a 12 volt battery that would work as well. As far as the condenser across the points is concerned the voltage isn't too important as long as its greater than what ever voltage you are supplying the coil. A 0.1 uf at 100 v will work and should only cost pennies !

A visit to a car scrap yard will get you a suitable coil, though you may have to take it off the car yourself.

 

[doc1955]

Put together a voltage divider. you only need 1k,1.5k and a 4k resistor to divide the voltage to 6.25v

 

[BaronJ]

Put together a voltage divider. you only need 1k,1.5k and a 4k resistor to divide the voltage to 6.25v

Unfortunately doing it this way you wont have enough current to drive a conventional coil !

 

[Jules]

Put together a voltage divider. you only need 1k,1.5k and a 4k resistor to divide the voltage to 6.25v

You would need to measure the current when running on 6v and then calculate the value and power requirement of a series resistor.

R=V/I

 

[a41capt]

Thanks for all the info guys! I don’t want to hijack this very excellent thread any longer, so I’ll take your input and experiment.

John

 

[Steamchick]

Because of the current demand from ignition coil (much more than 4A. Rms... The peak current can be 3 times that!), I suggest 2 x 6V batteries in series for the 12 V. DC Supply. Lead-acid sealed batteries for alarm systems are small and can hande the current delivery for good sparks. Then tap-off 6V for the ignition system from 1 battery. Possibly cheaper than a resistive voltage divider that can handle 4A rms?
Or get a 12V motorcycle coil...?
K

 

[Steamchick]

Because of the current demand from ignition coil (much more than 4A. Rms... The peak current can be 3 times that!), I suggest 2 x 6V batteries in series for the 12 V. DC Supply. Lead-acid sealed batteries for alarm systems are small and can hande the current delivery for good sparks. Then tap-off 6V for the ignition system from 1 battery. Possibly cheaper than a resistive voltage divider that can handle 4A rms?
Or get a 12V motorcycle coil...?
K

 

[Steamchick]

Because of the current demand from ignition coil (much more than 4A. Rms... The peak current can be 3 times that!), I suggest 2 x 6V batteries in series for the 12 V. DC Supply. Lead-acid sealed batteries for alarm systems are small and can hande the current delivery for good sparks. Then tap-off 6V for the ignition system from 1 battery. Possibly cheaper than a resistive voltage divider that can handle 4A rms?
Or get a 12V motorcycle coil...?
K

 

[Steamchick]

Because of the current demand from ignition coil (much more than 4A. Rms... The peak current can be 3 times that!), I suggest 2 x 6V batteries in series for the 12 V. DC Supply. Lead-acid sealed batteries for alarm systems are small and can hande the current delivery for good sparks. Then tap-off 6V for the ignition system from 1 battery. Possibly cheaper than a resistive voltage divider that can handle 4A rms?
Or get a 12V motorcycle coil...?
K

 

[doc1955]

I use a coil pack from an auto and run on 6v with no problem. I use a resistor to bring the resistance to around 2 ohms and run with a hall with ignition boards that I made. You can also use a tm6 board as long as you use a ballist to bring the resistance to around 2ohms. I've ran it on current as low as 4v without an issue (on hit miss engines).


PS on some of my engines I put a plugin and use a USB charger (wall wart) for power.

 

[Steamchick]

Hi doc1955: Just curiosity.... (I worked on engine design for a car manufacturer) what plug-gap are you working with? - What compression ratio is there on your engine? - Of course, I was thinking of typically 10:1 compression with plug gaps of 0.025 ~ 0.040 inch. But maybe you simply don't have that much compression on the models, nor full sized plugs with such large gaps?
Hence you'll manage with lower voltages and the current will be lower as well. - My smallest engine experience is with 50cc Honda engines at around 9:1. Using 0.5mm spark plug gap.
Cheers!
Ken

 

[Steamchick]

A41capt: Is that a James Captain in your photo? - I guess that's why you have a 6V coil?
K