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I too run CDI's similar ignition system on an old Mark 78. That tiny spark coil of theirs bothered me, so I ran it with the much larger Merc coil (and it worked fine. Have yet to sea trail that...

For heaven's sake don't break this work of art trying to get 300 hp! That would be a real tragedy after all the work you put into it.

I, for one, and damn impressed and would love to see her run...

Kinda hard to bore and stroke a 99 cube motor out to anything meaningful.

Jeff

Could you identify what the gages in the video are representing? Hard to tell otherwise.

Thanks,

Jeff

Is it just me, but it looks like the center electrodes are burnt all to hell.

Jeff

PS: Great HP numbers! Congrats. Have you considered using a data logger?

Ah for the old days of Mark 20Hs, with one carb, adjustable on the fly, and a simple magneto!

Jeff

PS: Impressive work as always.

So, what you're saying is that below all that potting is a bad connection making the distributor inoperative? Worth a try.

Thanks.

Jeff

Too true, Sam. The distributor I bought had decent wires (believe it or not) but was still dead.

Jeff

.."With all due respect, the Merc battery CDI is all any 6 cylinder Mark series deflector will ever need. Anything else is a waste of money. Distributor bodies can found on E Bay most any time. "
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Your math is off: Three cylinders (2 stoke) at 6 grand equals 6 cylinders (4 stroke) at 6 grand. I plan to use two HEI modules, each firing 3 cylinders. Got it?

Jeff

With one HEI running 3 cylinders, and the other running the rest, I should easily get 6,000 rpms (think 6 cylinder 4 stroke at 6,000 rpm). Motor tops out before that in any case.

Jeff

I'm currently using a 4 cylinder unit with the 6 cylinder chopper wheel. It works fine, but I'd love to get a spare distributor in case....you know. Getting hard to find. CDI sells one, but for...

Thanks. Good Keeper File info.

I run one of those belt drive CDI systems on my Mark 78, but I must disagree with you that parts are plentiful. Getting hard to find a good used distributor...

Very interested in your ignition system. I'm running an old Mark 78 using the later Merc electronic distributor. Have several of those switch boxes 'hanging around' and would love to utilize them...

Hear, hear!

Jeff

My late (and damn good buddy) ran a 400 inch SB Chevy on methanol, using a huge Holley 4 barrel. I was stunned by the size of the jets that thing used--must have been a 1/4 inch diameter hole!
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..." I do find the this country has become a nation controlled by lawyers and insurance companies and of course all the levels of government. The things we did as kids that made me have an interest...

We sure are!

Jeff

If they wait that long!

Jeff

Don't agree with that statement at all.

An electric pump PUSHES gas to the motor instead of SUCKING it there, as do vacuum pumps on outboards (and pressure is far more effective; it works with 5...

Wouldn't fixed jets make more sense (or are adjustable jets more common on race engines)? Another (maybe worthless) suggestion when having fuel problems would be an electric fuel pump with a...

Glad to hear it! Love that beast.

Jeff

That's the turbo beast I was asking about! Hope it's operating okay.

Jeff

I pray it stays together this time after so much brilliant work!


Jeff

Properly torqued, the vibration "above 6,000 rpms" is irrelevant. If not, the rod bolts would stretch and break from fatigue--and, yes, with the red Lock Tite still holding the bolt/ nut in place.
...

If you can't keep a rod bolt tight without Lock Tite, its not being properly torqued! Billions of rod bolts in engines, from grocery getters to super cars, are assembled WITHOUT Lock Tite every...

Proper torque readings require a consistent, reproducible thread friction, and cleaned threads, oiled, is very consistent.

Using Lock Tite can cause high friction (or not?) and that's not good....

Not only is the no need for Lock Tite on rod bolts, its use is counter productive. (If a nut and bolt in a stress cycling environment is not sufficiently stretched it will FAIL with the nut still in...

As I understand it, the motor was not at full throttle when it blew. Correct?

Jeff

That bolt on the right suffered a fatigue failure--that's where the problem began. (I was a mechanical failure investigator during my engineering career.) Trust me on this: it's an obvious failure....

I've been using quality Allen bolts instead of those stock Merc bolts on my similar rods.

How about using SPS or ARP fasteners in that 1/4 inch fine thread size?

Jeff

Thank heavens more damage wasn't done!

I hope you pin point WHY it happened to a degree that it won't again.

Jeff

Okay. Didn't want that to be a problem with this jewel.

Jeff

I noticed something that could cause you problems: it appears that you stacked the switch boxes one atop the other. Though a neat installation, the top box needs to contact a slab of 'cool' aluminum...

He's also a damn fine photographer! Just check the quality of his photos.

Jeff

Good pun!

Just WAS (past tense) worried that clamps might fail, and what a disaster that would be.

Jeff

Whew! Feeling relived.

Jeff

Love the work--who wouldn't?--but I'm concerned about the transom clamps you made. The stock Merc parts are forged, which adds considerable strength. Seeing yours are milled from a block of aluminum...

Yeah; got something against Pennsylvania!

(Just kidding.)

Jeff

My buddy talked me into putting the starter solenoid in the boat (vs. on the PH). Makes for a lot less clutter and, since often switch engines, I only need one solenoid. Never seen the coil mounted...

Where this project is concerned, "fabulous work" is the new normal.

Jeff

Your photography is also excellent, by the way.

Jeff

Outstanding explanation!

Thanks.

Jeff

Can anyone explain where all those fuel hoses in the photo are going to/ coming from?

Jeff

Well said.

Jeff

Any idea how much horsepower this gem will produce? The Twister IIs made close to 200 in their all-out factory tune, and they were merely cross flows.

Jeff

May I suggest starting a new thread since this one is now buried on page 3.

Jeff

I'm curious why you went with individual heads (vs. all 6 cyilinders at once, or at least 2 or 3 at once)? The block would be far more rigid that way, which was why engine designers went away from...

This thread "Makes my day!"

Jeff

Like many of us "old geezers" I began my Merc experiences with adjustable jet motors, and they made good sense on a two cylinder Hurricane. When I went to a KG-9 it made a bit less sense, holding on...