Flathead 4 dual spark plug distributor...

So, let's say a guy is bored and wants to build a flathead banger with a dual plug head, could a V8 distributor be adapted to fit to use the extra 4 spark plug terminals on the cap in pairs?...for example: 1,1, 4,4, 2, 2, 3, 3...(Hell, I'm not even sure that's a proper 4 banger firing order, but hopefully you get the point)...

 

Sure, but that second spark might pretty late in the combustion cycle. It might not make much difference by then.

 

Get a 4 cyl dual plug cap and rotor. Use two coils.

Alfa used them, and some Japanese stuff.

 

nissan and ford both did it, I bet you could make that work.

 

Ford Ranger 4 cylinder engines from the early 90s until?? used dual plugs per cylinder. Don't know just how the ignition was configured, though.

 

What I'm looking at is on a mid-level compression (6-7:1) flathead, the flame propagation is going to be fairly slow anyway, I was considering firing the spark plug farthest from the piston first and the spark plug directly above the piston 2nd at normal timing or slightly retarded...for all I know I may be the one that's slightly retarded...

 

Had a conversation with John Bradley years ago when he was running twin HEI distributors in his nitro flathead; he tried all combinations of lead and trail ignition timing and eventually went back to simultaneous ignition; he eventually abandoned the twin plug altogether.The chamber has a large surface area and relatively low compression so the lag time is relatively short as it doesn't take long to reach a measureable pressure above compression. If you consider total ignition timing required to be a measure of combustion efficiency a flathead is good in that it generally only requires around 26 degrees total, most hot rod bangers like around 27-28. It would be cool looking but I think the work required would not be offset by the gain. Even though the "distance" the flame travels appears to be long, flame propagation is that distance divided by the burn time and is better than some modern ohv. stuff, again that is reflected in the total timing.......fats

 

Dual plug heads work best if it is designed with a hemispherical head like an aircraft engine. Each plug is angled in, between a valve port, and 180 degrees from the other. These conditions make it work best. In any other combustion chamber, the benefits are very limited. During magneto drop off checks on preflight you will note a 100 to 200 rpm drop when running normally on one magneto depending on the type of aircraft. When running on one mag in flight there is a noticable drop in power since a single plug design would be right in the top center of the head like a Chrysler hemi is. The redundancy was built in for safety reasons more than for a power increase.

Kerby