Ignition Issue

try 6 btdc , unhook tach wire from coil , autolite 25's , new cap , new coil , new ballast , new alternator , check magnets on rotor , check air gap of rotor and pickup

I suppose your coil and/or spark plug wires could be breaking down. Also make sure all electrical, ignition related, wires have clean and tight connections. Especially the grounds. Check the condition of the wire connections at the ignition switch.

Sporadic missing is a good sign of poor connections being affected by vibration which causes sporadic loose of integrity. Well, poorly said, but I hope you get the idea. It could also be an internal break within a wire.

79 is right on with the champion plugs...ugh.

And those advance numbers don't look right.
Advance should range 10-34 degrees, +/- .

Depends how much you want to spend. If you want the best, take a look at the marine DUI from PerformanceDistributors.com.

I got an additional 200 RPM from the DUI after replacing my stock Prestolite with EI conversion and setting my base timing to ~14 degrees.

Performance Distributors builds a great product that is custom tuned to your motor. You will need to tell them some info about your boat, including weight, heads, cam, and octane of fuel. They will set up a custom advance curve for you, which can be changed by sending the unit back to them (if you ever add some serious upgrades to the motor). Other benefits include a hotter burn (that allows you to open up your spark plug gaps to ~.055"), a more consistent advance curve, and the incorporation of the coil into the distributor. This cleans up the wiring.

Do a search on this site and you will find some good info, there are several of us who have these DUI's.

The one thing you need to note is that you will need to reuse your current distributor gear since your motor is reverse rotation. Klinger_2003 did this modification to his gear to make it work, which you can read about in this thread.

The cost of the DUI is ~$400 with shipping, by the way. The lead time is 2-4 weeks I would guess- mine took about 2.

I recommend going that route if you are going to upgrade your distributor at all. If you dont want to spend that much or wait that long, the best route is to find a new stock replacement distributor and put a Prestolite EI conversion kit in it for another $100.

The Mallory units look nice and are an easy drop in replacement. However, my opinion is that if youre going to consider the Unilite @ $310+, youre probably better off going with a DUI since the performance will certainly be no worse, plus it eliminates the seperate coil and cleans up the wiring on the motor.

You do have to get new sparkplug wires with HEI terminals to run the DUI- not sure what you need for the Mallory's.

The hole that needs to be drilled in your old gear to reuse it on the DUI should only cost $10 at a machine shop.

Just my $.02

Im not an expert on the Mallory's, though I did look into them when I upgraded my distributor. Summit lists the YLU-554-DV as the proper distributor for a reverse rotation 351w. Summit doesnt list a magnetic version for the reverse rotation, though the only real difference should be the gear.

TRBenj wrote: YLU-554-DV as the proper distributor for a reverse rotation 351w.

WRONG, the DV version is the standard rotation and what you don't want. Like I said earlier I have the YLU-554-CV on my reverse rotation engine.

Has far as the Mallory vs. DUI your going to send $150-200 more for the DUI unit once the gear is drilled and you buy new wires. They are both going to perform equally and both are easy to wire up.

79nautique wrote: TRBenj wrote: YLU-554-DV as the proper distributor for a reverse rotation 351w. WRONG, the DV version is the standard rotation and what you don't want. Like I said earlier I have the YLU-554-CV on my reverse rotation engine. Has far as the Mallory vs. DUI your going to send $150-200 more for the DUI unit once the gear is drilled and you buy new wires. They are both going to perform equally and both are easy to wire up.

I said I wasnt an expert on the Mallory's, but Summit clearly lists the DV as the distributor for a reverse rotation 351w. Whether it is incorrect or not, I dont know- I was simply pointing it out.

I disagree that the performance would be the same on the 2 distributors. The DUI has proven dyno results, and it should offer increased performance on a tuned motor. On a stock motor, I agree that there wouldnt be a noticable difference between the 2. There probably wouldnt be a tremendous performance difference between the full upgrade and a simple EI kit either though.

As far as cost goes, the DUI is only $65 more than the Unilite, and it incorporates the coil. The reuse of the gear on a RR motor may not require machining, but if it does that is only an additional $10.

I consider spark plug wires a maintainance item, so that cost is a moot point, IMHO.

Beats me

Thanks for your help! I'm going to buy the optical unit (YLU-554-CV) - I'll let you know how it goes...

isn't Crane, Mallory and Accel all part of the same company?   Mr. gasket owns them all and a hlf dozen more?