[Arceenut]

I am converting a Saito 180 to spark ignition but retaining the use of alcohol fuel. Question arises, Is there a difference in the optimum advance between gasoline and alcohol?

[RAMJET]

tried that years ago, engine will run just as well on glow plugs with a lot less weight and trouble .now if you were to convert to gas that is another story. assuming you are using a auto advance ignition I would start at 28 degrees and do some testing prop /fuel /plane weight will all have an effect on the ignition timing so you will have to play around a bit . the first engine I tried this on wiped out the rod bearing because the timing was off a bit. I found it a lot of work for very little gain. those engines start first flip and run so nice I can't see the need. cheers Roger

[OLD PRAIRIE RED NECK]

I haven't done this myself but have considered doing it for bigger 4 strokes. There are 3 advantages in my mind and 3 disadvantages.

On the plus side:
1) eliminate kick back on hand starting and throwing of props in the air due to better control of timing.
2) more dependable idle.
3) ability to run low or no nitro fuel

Now the down side:
1) added cost to set up (could be offset by mixing your own fuel).
2) added weight (not a big concern on larger planes).
3) added complexity (more stuff to maintain)

To answer you question about timing, I am not sure of the exact numbers but I do know that methanol has a much higher octane rating than gasoline so the timing could indeed be much more advanced. Perhaps others have tried this and know.

Whether or not this conversion is worth the time and money in my view comes down to how much you enjoy tinkering and where personal satisfaction offsets the frustration of experimenting.

Keep posting I am very interested!

[RAMJET]

but then again when was this hobby ever about need LOL. let us know what you come up with .what are your reasons for going spark anyway. cheers Roger

[OLD PRAIRIE RED NECK]

Originally Posted by RAMJET

but then again when was this hobby ever about need LOL. let us know what you come up with .what are your reasons for going spark anyway. cheers Roger

For myself Rodger, if "just because I want to" isn't reason enough and it comes down to "need" or "it's cheaper to..." then maybe I'm taking it too serious.

I get a big charge out of unusual and unconventional projects, but that's just me!

[Arceenut]

I think I have located a set locally. Yet to get them in my hand to see if they are suitable.
Thanks all.

[RAMJET]

Merv ,Don't have to convince me ,I make my own giant scale 4 cycle engines just for the hell of it. that is why I asked his purpose(I am not questioning his purpose ) . some guys are just trying to overcome a problem and others like you and me just like to tinker regardless of the outcome . hell I even made my own ignition systems for a while. I don't think I ever advanced the hobby with my ideas but I sure advanced my own understanding . My home built 106cc twin 4 cycle on glow ran 28 degrees of advance , my 40 cc single ran the same.

[Raymac]

Here is an article related to my experience with spark ignition on the big four-strokes.....

http://www.raysmodels.ca/Technical%2...ps%20index.htm

.....about half-way down the page see "Spark Ignitions"

[OLD PRAIRIE RED NECK]

Originally Posted by RAMJET

Merv ,Don't have to convince me ,I make my own giant scale 4 cycle engines just for the hell of it. that is why I asked his purpose(I am not questioning his purpose ) . some guys are just trying to overcome a problem and others like you and me just like to tinker regardless of the outcome . hell I even made my own ignition systems for a while. I don't think I ever advanced the hobby with my ideas but I sure advanced my own understanding . My home built 106cc twin 4 cycle on glow ran 28 degrees of advance , my 40 cc single ran the same.

Cool!!

[OLD PRAIRIE RED NECK]

Originally Posted by Raymac

Here is an article related to my experience with spark ignition on the big four-strokes.....

http://www.raysmodels.ca/Technical%2...ps%20index.htm

.....about half-way down the page see "Spark Ignitions"

Good article! I printed it off, thanks.