Adjustable ignition plate..

[PAULT50]

Well racing seasons over for me again for 2012 so it's back into the shed days for some winter time tinkering, finally got the little 40 rebuilt and onto the lake for a test and is by far the nicest (and quietest) running one i own. i have an old 100 type gull that i use here for messing with and thought id try making an adjustable ignition base plate, so i extended the locating hole for the base plate into a groove (in the direction of ignition advance) inserted a 5mm ball bearing into the hole in front of the locating bolt and tightened until it just lets the plate turn in the groove without locking it, spring loaded the base plate in the other direction and ran it to a second villiers thumb throttle and cable, results are...flat calm lake, no wind and gps on my phone...standard timing boat done 5mph, rotate thumb throttle round to about +12 degrees adv. boat does 8mph and sound like you've found a second throttle. Any more than 15 degrees and things start to sound pinky so 12 seemed to work best. Anyone else tried this before? I'll dig it out from it's mid week resting place and take a few pics or a youtubey thing if yous like. pics here of the 40

[Hugz]

That's fascinating. Be good to see a utube of what you have done. Huge increase in performance. Looking forward to adjusting timing on an SD as they don't have a dimple. Would there be any advantage in being able to change the mixture in situe easily?

[PAULT50]

video of it, as i said this aint no show engine, built purely from the parts bin ie. td crankcases, square block, the head that no one wanted, you get the picture, its just a base tester to see what makes it work better. http://www.youtube.com/watch?v=Telimlj2dJ4

[metalflake11]

That is really good. I am going to have a bash at that. Well done sir!

[Niander101]

I like that video and the adjustable timing i also notice you have an amal 2 jet carb on it when normally its a villiers
so you made a spacer?
can you video it running?

[Hugz]

Simple but effective. I'm sure some of the racing lads will incorporate this modification.

[Charles uk]

Many have tried it, found no major benefits, apart from lower tickover when retarded.

Elegant solution!

[Horsley-Anarak]

You beat me to it, Charles posted whilst I was writing.

I'm sure some of the racing lads will incorporate this modification.

I know some of the racing lads have looked at this before. I personally have found that you can move the base plate about 30 degrees with little change to engine speed.

The starting and idle properties will be changed, but I am not sure about the high end performance, unless there have been other mods to the engine.

Saying that, with the OMC engines that I have, the base plate moves a large amount as the throttle opens.

So for a Seagull, optimum WOT base plate position could well be different to factory position.

H-A

[PAULT50]

There are a few mods done to the engine already, well spotted on the carb/block combo Niander, i used the block that had the biggest port area but this also has the smallest carb so i reamed out the block to fit the carb bore and made a shim to space up the outside, works well and gives a nice smooth carb to bore surface with no step, ports have been cleaned up, no base gasket, one leaf out of the head gasket, the smallest volume crankcases that i had, turned out to be td56892 along with the largest volume crank/rod and the lightest piston i could find all driving a 100 direct drive and a five blade fan. Advancing the ignition increases the torque the engine produces not so much the outright horse power or revs, meaning,if your engine prop combo is already achieving peak revs then you will have very little if any advantage ideally you will need to over prop your engine to cut peak revs by 500ish rpm running standard ignition giving the grunt room to work when the ignition is advanced, you'll then be able to maintain around peak revs using a prop with a bigger bite. Word of warning...igintion advance loves to eat piston crowns and big ends both of which are doing 4000rpm three feet away from your chin. pistons just seize but conrods always want to see daylight before the die...if it dosen't sound right it isn't.

[The Tinker]

If you raise the compression the timing adjustment could have an advantage

[Loiner1965]

cool....how far can one go tuning these little strokers....would a reed block have any advantage etc

[Charles uk]

You mean like this?

Paul your second post answered every question I could think of, a very well engineered, simple way of getting adjustable timing with a Wipac or Villiers ignition, but it places your Century into the modified class of racing Seagulls, why don't you bring it to Hayling Island next year, we can find you a suitable boat.

H-A do you know anybody with a concrete 12 footer? this Irish bloke could be frightening, he knows what he's doing.

[PAULT50]

I like modified...I got the 2013 race calender for us on Tuesday night and i'll have three weekends off in 8mths so the chances of getting to hayling 2013 is slim, although i was down your way a few times through the year following the BSB circus. If i ever get to go i'd bring the little boat i built last year, just waiting for all these two wheeled rockets to pack up for the winter so i can get it finished off. Long winded answers are the teacher coming out in me, although is much nicer to be discussing some thing of interest among gentlemen of a certain age (ha ha) with a common interest rather than a class full of 16yr olds that would rather be playing with, at best, an xbox rather than an engine... there's a man in the Belfast docks that builds concrete boats Charles,no joke. reed valves most definitely but remember depending on how you mount it it can increase your crankcase volume behind the petals which will have a negative effect.

[Hugz]

The man is a master magician.....

This has to be my favourite utube:

Electric start. http://www.youtube.com/watch?v=lz11j5Mvu9I