NW_Jim

Kinda interesting, to make a $300 piece of electronic equipment work, you need a machine shop to modify a $10 part. Why don't they include the trigger with the ignition?

MACDAD260

Hey guys, would just replacing the stock coil with that Crane coil do any good on a stock Thunderbolt IV setup? Quicker starting sounds interesting.

formula31

Dont know, I doubt it. I think the multiple discharges from the igntion amp has a lot to do with starting. Although, the higher output voltage from the coil should help if you have good wires that can handle it. Interesting. If you do it, let us know what happens.

turbo2256

I have put one of the hot Jacobs coils on a slightly modified motor with good results. I helped a lot at low speeds.

US1 Fountain

I'm thinking very seriously about this Crane unit also. It appears to help with a slightly rich setup at idle. Do we also have to change over the stock Merc plug wires? The -92 is the coil that I see is recommended to use with the HI-6M unit. Anyone know the difference from the LX-92 vs the PS-92 coils? Also, is it just some tachs that will need the adapter, or all of them? Mine is the original Stewert Warner tach.
I also agree that they ought to come with a rotor!

BTW, I am taking my motor to Bruce for dyno very soon now, with all my stock original Merc distrib and T-bolt ignition installed. We are going to run it thru and then change over to his dyno MSD distrib and ignition and run it again. Should be interesting to see the results.

IRONMAN

To confuse matters worse I just read Dennis Moores article in Famil;y and performance boating, His article seemed to say that below 5500 rpm a good inductive system should be sufficient. The data that US1 Fountain will be very useful, Please let us know what you find. Dennis's article seems to be refering to stock engines and not high compression engines though there may be much more to gain at 9.5:1 as opposed to 8.75:1 with a CD box system. Ironman.

KAAMA

Ironman,

In response to your most recent post, my cousin just finished up dyno testing his 454 today which has been modified with ported heads, Holley 830cfm carb, and performance camshaft. With the stock Merc Thunderbolt iginition system the engine made 514 ft# of torque @3500rpm and 461hp @ 5000rpm. My cousin then tried my Crane HI 6M ignition boxes with PS92 coils and the engine showed absolutely NO GAINS in HP or torque....they even ran the engine up to about 5400rpm...no difference. But we just wanted to check and see for ourselves---that's why we dyno. Funny thing is Tom Earhart who runs/owns the dyno told us (prior to us using the Crane ignition box) that he strongly felt that we would see NO GAIN with the ignition...and he was RIGHT!!!....but we just had to see it with our own eyes.

formula31

I totally agree. There are no gains over a stock ignition in good condition at the top end. I just like them because of the big fat spark it provides for start up and idling. If the carb is a litle fat if wont load up and foul the plugs. But at WOT, no difference.

bck

Summit was giving a free PS-92 coil with some of the autmotive Hi-6 boxes. I would call and see if you can get them to give you the same deal on the marine unit.

US1 Fountain

I'm with formula31.

I'm really only conscerned with the idle quality and the help of burning off the extra gas at idle. If it can keep all the black off the transom, it's worth it just for that.

KAAMA, being the dyno-carb specialist that I am, should there be a difference in the fuel/air mixture at idle between the stock vs the Crane system? Any measurable difference on your cousins dyo results of the 2?
Thanks
Jerry