Electronic Conversion Kit

Just my two cents - my local marine engineer (who has tremendous experience) claims that many marine engines (right up to multi 1000 hp diesels) come with slightly large props to keep rpm down and avoid warranty hassles. He says all the American V8s will happily spin to 5000 and in fact is planning on machining our prop down to achieve higher rpm. Not as big an issue as having to small an engine in too heavy a boat but restricting the rpm with a large prop can actually cause them to run hotter in certain circumstances. I know you guys have been running the damn things at 4400 for at least a quarter century with few problems but something to think about.

THE BOAT CAME WITH A 14X16 BECAUSE OF THE 1.23-1 TRANSMISSION. YOU WILL HAVE A MARGIN OF 10% + OR - READING ON THE TACK. YOU ARE RIGHT ON THE MARK WITH WHAT YOU HAVE NOW. YES THERE IS DIFFERENT COILS FOR POINTS AND ELCTRONIC. BUT YOU CAN USE THE STOCK COIL IF YOU FOLLOW THE INSTRUCTIONS THAT CAME IN THE KIT.

FYI. Tach readings are taken from the negative side of the coil. Tachs read a difference in dwell off/on time within the coil. This signal(dwell) originates in the points on an older system. Your tach is simply a volt meter designed to reconize the variances. Dwell is the measurement of the time ths points are closed, which causes the magnetic field within the coil to collaspe in the primary side of the coil and cause an increase in voltage(spark to the plugs) on the secondary side of the coil. Any increase in dwell will retard the timing & decrease in dwell in increase the timing. This is how on board comtuters adjust the timing electronicly on the car you drive. Just thought you might like this info. PS/ there is no "sound frequency" involved in the ignition system.

I converted to a Mallory Unilite and have noticed some funky readings now and again, especially at idle, I think there's a filter of some sort to correct a points/EI conversion if some part doesn't like the swap.

Tach readings come from the coil, not the ignition module. Points or electronic should nto make any difference in tach display. The coil fires 4 times (isn't that right with four stroke?) per crank revolution regardless of ignition type. The tach uses this pulse interval to determine RPM.

Disclaimer: I think I have this right. Anyway, tach should read the same regardless of ignition type.

Changing the ignition system should not effect the rpm that much. I would check the tachometer for accuracy first before I drop the cash for a prop.It is possible the e-ignition is causing a inaccurate reading or the old system was the cause. Either way check the tach with another unit(handhead is OK) just to verify the possible problem. I have not see a conversion increase RPM very much.

What prop did you have that put you at 5000 rpm's? What motor do you have? You are correct don't get over 4400. If you have a 351. Good luck don't hammer it till you get the right prop on your boat. I would call the guys at SKIDIM. They are great. and they could help with problem

Joel

Hi, I have a '89 Ski Nautique and recently I changed for an electronic ignition, everything seem to be great, the only problem is that the engine is running up to 5000 rpm so it seems that the propeller is too small, I changed for a 14x16 three blade propeller and the rpm got down to 4600, the engine manual says that the maximum rpm must be 4400, I would like to know if any of you had the same problem and if you recommend me to use a bigger propeller, if so please tell me what size and if a three or four blade propeller.