Looking for a different distributor than my crab cat dist.

C

c1steve

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Any recommendations? I have a stripped screw holding the rotor in place, so this would be a good time to swap in a different distributor than my crab cap one. Engine is the Merc. 350 Mag MPI Horizon, 2006. The ignition system is 100% electronic, computer controlled.

I have lots of vertical room, so the crab cap is not needed. This unit has nothing electrical inside, it only distributes from the coil wire to the 8 plug wires. Possibly a small diameter distributor, but I do not know if that is a problem with high voltage ignitions. Any recommendations?
 
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alldodge

alldodge

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The stripped screw can be fixed, similar happened with a EST dizzy cap and I just tapped for the next size up. Worked fine

Going with another dizzy should work but you need one which has no mechanical advance. Then need to figure out just how your going to set initial timing. Don't see the voltage as being an issue
 
Scott Danforth

Scott Danforth

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They make billet aluminum dizzys for the GM plastic one with crab caps.

There are a few sources of the cap other than GM
 
Bt Doctur

Bt Doctur

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Any thunderbolt dist can work, just remove the innards. the issue is locating the rotor correctly . its a high voltage switch same as a regular dist cap and rotor. manual shows this and I believe this is #1 rotor position
but I think if you place the motor in TDC #1 compression and set the rotor to number 1 position in the cap you should be fine.The computer should be able to adjust the timing from there
 
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c1steve

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On the tapping, I tried installing a helicoil, but the aluminum was very thin, about 1/8". Timing should not be a problem, this engine has a CP sensor. I just have to make sure the rotor is lined up with right contact. The crab cap has some issues such as very expensive caps, plus laterally it is a very tight fit. I have been searching on the Summit Racing website, there is a huge selection of distributors there, some are marine.

My engine is completely computer controlled, the distributor does nothing except distribute the HV spark to the different contacts. No internal wires. I wish the engine was more modern, with a coil for each cylinder and no distributor. I do not believe this style is available yet for inboards.

Pertronix has some units that would work, are made in USA, but some people have had trouble with internal corrosion.
www.summitracing.com

CHEVROLET PerTronix D200810 PerTronix Flame-Thrower Plug and Play Marine Distributors with Ignitor II® Module | Summit Racing

Free Shipping - PerTronix Flame-Thrower Plug and Play Marine Distributors with Ignitor II® Module with qualifying orders of $109. Shop Distributors at Summit Racing.
www.summitracing.com www.summitracing.com
 
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alldodge

alldodge

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No helicoil needed, just tap the existing hole for next size screw. Then remove existing screw from cap and use larger screw.

Does sound like BT has it down so should be no issue with just replacing the dizzy
 
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c1steve

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I thought that section of aluminum was 3/8" thick, so I tried the helicoil. To oversize now I would need a #10 screw. I should have just kept it simple, and tapped one size up as you suggested. I just tried drilling the rotor out for a #10 screw. The screw head was too large to fit the recess.
 
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Scott06

Scott06

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c1steve said:
On the tapping, I tried installing a helicoil, but the aluminum was very thin, about 1/8". Timing should not be a problem, this engine has a CP sensor. I just have to make sure the rotor is lined up with right contact. The crab cap has some issues such as very expensive caps, plus laterally it is a very tight fit. I have been searching on the Summit Racing website, there is a huge selection of distributors there, some are marine.

My engine is completely computer controlled, the distributor does nothing except distribute the HV spark to the different contacts. No internal wires. I wish the engine was more modern, with a coil for each cylinder and no distributor. I do not believe this style is available yet for inboards.

Pertronix has some units that would work, are made in USA, but some people have had trouble with internal corrosion.
www.summitracing.com

CHEVROLET PerTronix D200810 PerTronix Flame-Thrower Plug and Play Marine Distributors with Ignitor II® Module | Summit Racing

Free Shipping - PerTronix Flame-Thrower Plug and Play Marine Distributors with Ignitor II® Module with qualifying orders of $109. Shop Distributors at Summit Racing.
www.summitracing.com www.summitracing.com
Click to expand...
You seem to hear mixed comments on pertronix componenets.

Why not get a used TB distributor as BT suggested? Seems simplest solution
Additionally can you just put a nut on the backside of where the thread is stripped? Maybe not the most elegant solution but it cap just has to hold the cap on
 
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c1steve

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Okay, just checked ebay for used TB distibutors, $150-200. Not worth it when I can buy a new dist. for $200-$300, and the new one is much simpler. Notice that some distributors have iron gears, and some have steel drive gears. From what I can determine, OEM used an iron gear, but I might use steel for longer life. Cam is a roller camshaft.
 
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Scott06

Scott06

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c1steve said:
Okay, just checked ebay for used TB distibutors, $150-200. Not worth it when I can buy a new dist. for $200-$300, and the new one is much simpler. Notice that some distributors have iron gears, and some have steel drive gears. From what I can determine, OEM used an iron gear, but I might use steel for longer life. Cam is a roller camshaft.
Click to expand...
www.ebay.com

mercruiser thunderbolt IV distributor | eBay

mercruiser thunderbolt IV distributor. Condition is Used. Shipped with USPS Ground Advantage.
www.ebay.com

1699892909702.png

except for cap and rotor the 4.3 dist is the same as smallblock
 
Scott06

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Lou C said:
The dist cam should be different no? I have 2 spare Prestolites for my 4.3 in the garage I’ll take a look…
Click to expand...
On points yes , on thunderbolt the trigger wheel is part of the rotor
 
Scott06

Scott06

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Lou C said:
ah yes that makes sense
I have the stone age points
Click to expand...
Yes, I'm sure you are still happy with your beta max as well...

Seriously if you don't mind cleaning and gaping them there is no issue. Its only if you dont know what a dwell meter is that it is a problem
 
Lou C

Lou C

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So far after 20 years of boating with points I never had an ignition related break down. When the points get burned looking I change em. Never had a carb related break down on the water either…
 
C

c1steve

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That Dorman part is very slick. For me, it was the small screws holding the rotor in place. I should have tapped for a 8-32. But now I have a new billet distributor coming from Summit Racing. No more expensive crab caps.
 
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