starting problem on gasser

[smoothmove]

eric,

i hear you with the "33000lbs heavy girl" part. we seem to be in the same ballpark with numbers. i find i need 3150 - 3200 to stay on top without throttle jockeying for wind and tide. in the begining of the season that was 13.5 - 14kts, at the end it is 13.0 - 13.5kts. had her wot yesterday(4000rpm), 19 - 20kts, lost about a knot there. do you have mph/knot reading with these gph and are those from flowscans?

jim

The 3000-3100 range I settled on was with a pretty light load. Add a few pounds, and some wind and I'd be saying about what you are. I couldn't resist the WOT yesterday either. Got 22 on the gps and when I looked over at the tach it was at 4400 rpm. That was a first! I think it was a combination of getting the shaft alignment dead on, polishing the props and switching to mobil 1 synthetic. Don't think a half minute at 4400 is gonna hurt a crossbolted race bred engine but according to my 1968 owners manual, I just voided the Chris Craft warranty.

All figures are from tables and gps readings. To me a "flowscan" means a glimpse at a creek.

Eric

 

[UNIQUE_NAME]

4400? wow, port is 4000 stb goes about 4100. are you turning 4 blades? if so what size? running at wot and 21knts kinda makes me jealous of all the guys repowering and having that as a cruising speed. there is always lotto.

jim

 

[Jackman]

Unique,

It was not cheap to repower but affordable with the cummins special when I did as much as work as possible on my own. (All I had the cummins distributor do was drop the engines in with a crane and linem up..which I could have done but they had the crane. ) Something to think about before they run out of the blocks for the special pricing! Plenty of help on this forum if you decide to do it on your own!

 

[spartonboat1]

I also have pertronix, never her of one going bad but if you have the old model, Pertronix I then if you left the key on for more than 15seconds without motor running then you may have burned it out.

We purchased Pertronix coil, low resistance so we bypassed the resistor. get full voltage to coil.

I think that the pertronixII is a better unit. if you forget to turn off the key then it will shut down and not get damaged.

I thought that the key on/engine not running causing coil burn-out was an old wives tale, but is that true?

I thought sole function of the ballast resistor was during the starting cycle, while turning over the engine. If they burned out, then that created an "open" and the engine would not start.

I haven't heard a capacitor mentioned, but they were only present on the old "points" energized distributors and unnecessary in a reluctor activated distributor. The points were really a crude "relay", opening and closing with every piston stroke, so at half rpm speed. The capacitor acted to reduce/eliminate the spark across the point's gap, when the air capacitance is very low for an instant, while the points are almost closed and the spark tends to jump across the relay gap causing early burnout.

It is interesting that this issue has been so low in curing. I thought since the advent of reluctors, these issues were minimal.

 

[MikeP]

In a standard US-made engine the function of the ballast resistor was to reduce the voltage to the coil during normal operation. This is why, if you measure the voltage at the coil with the engine running or ignition on, you will NOT see battery voltage; you will see around 9 volts. The only time full batt voltage is supplied to the coil is when you are actually starting the engine. At that moment, full available voltage is applied to the coil - the ballast resistor is bypassed but ONLY when the Ign switch is in the "start" position.

In a normal system you cannot burn out a coil by leaving the ignition on; ignition on is the coil's normal operating condition.

 

[Maynard Rupp]

I thought that the key on/engine not running causing coil burn-out was an old wives tale, but is that true?

I thought sole function of the ballast resistor was during the starting cycle, while turning over the engine. If they burned out, then that created an "open" and the engine would not start.

I haven't heard a capacitor mentioned, but they were only present on the old "points" energized distributors and unnecessary in a reluctor activated distributor. The points were really a crude "relay", opening and closing with every piston stroke, so at half rpm speed. The capacitor acted to reduce/eliminate the spark across the point's gap, when the air capacitance is very low for an instant, while the points are almost closed and the spark tends to jump across the relay gap causing early burnout.

It is interesting that this issue has been so low in curing. I thought since the advent of reluctors, these issues were minimal.

The opposite is true of the ballast resistor. You have 2 -12 volt feeds to the coil. Pure 12 volt from the starter button and about 7 volts from the ballast resistor. 12 volts feeds the resistor from the ignition key. When you press the starter you get the full 12 volts; when you release the button you deliver reduced voltage through the resistor. If the engine starts but quits when you release the starter button, your ballast resistor is bad.