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Thunderbolt IV ignition module

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bernie42

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I need a new or secondhand ign

I need a new or secondhand ignition module for a 5.7 Mercruiser 1991. Can anyone tell me if there is an automotive equivalent that I can use or a cheaper alternative? It is the type that bolts on to the exhaust outlet via a triangular plate.
Thanks
Bernie
 
"I found one at a local boat w

"I found one at a local boat wreckers in central ontario Canada.I found out I could order one with a 1-2 week delivery.They were available new in Vancouver,wisconson,and florida.I have the same but in a 305.Equivalent to a car,I don't know

dave"
 
There is no automotive equivil

There is no automotive equivilant.
This is a marine product only.

You would have to buy a aftermarket marine ingintion such as MSD for any similarities to automotive ingintions.
 
"I have one of these, not sure

"I have one of these, not sure if it is wat you're looking for?

Ignition Amplifier Box, Mercruiser GM V8 Mounts on Riser
MER15248A1"
 
There are diferences in the am

There are diferences in the amplifiers.

If you look at the number on the amplifier itself I belive the numbers (at least they use to) show the total timing advance.

A small block v8 number would be xxxxxxx32 or xxxxxx34 and hiperformance and bigblocks would be xxxxxx36.

This example is typicle and maynot be 100% acurate as I do not have one in front of me right now.
The 32 or 34 or 36 designates the total degrees advance for the module (including initial timing of course)

I will check when I go home for lunch and repost with more acurate info.

Also be careful not to put a v6 module in place of a v8. Small block and big block modules are ok to switch and the only difference is the total timing advance. There may be some differences as to when the full timing occurs at a specific rpm but for testing a small block one vs a big block one it is ok to swap
 
"Like bernard, I also need an

"Like bernard, I also need an ignition amplifier; mine's for a 305 5.0l engine (Thunderbolt IV ignition) engine s/n starts with 0D0 (the boat is a 1992).

At least, I'm *assuming* this is what I need. No spark from coil, tested the ignition according to the Mercruiser service manual; I'm getting +12v on the positive side of the coil; service manual tells me that the ignition amplifier is bad. Does anyone know of a better troubleshooting guide?

In looking online, I'm finding prices ranging from < $100 to > $300

Anybody have any addt'l info on this? Best place to get it?"
 
"A word of caution, the reason

"A word of caution, the reason I have an extra Ignition Amplifier Box is because that was not the problem, it turned out to be the ignition sensor in the distributor, ouch!

Kit"
 
Thank for the info Kit. That

Thank for the info Kit. That shouldn't happen to me though; I'm not getting *any* spark from the coil.
 
"Dale: Perform the following:

"Dale: Perform the following:

Tests for Thunderbolt Ignition:
W/ignition key on AND BILGE WELL VENTILATED OF GAS FUMES!!!

#1 - Connect your voltmeter neg. lead to the engine ground and pos. lead to the white/red wire terminal at the dist. It should read 12 volts.

#2 - If 12 volts is present, remove the coil spark wire from the distributor and connect it to a spark gap tester to ground. Remove the white/green lead from the dist. terminal. Turn the ign. key to on and strike the white/green lead to ground. If there is spark, replace the ignition sensor in the dist.

#3 - If there is no spark, substitute a new coil and repeat test #2. Now if you get spark, install a new coil. NO SPARK, replace ign. amp.

#4 - In #2, if there is No voltage present, disconnect the white/red wire and check it again for 12 volts. If 12 volts is present, replace the ignition sensor inside the dist. cap. If no 12 volts present w/it disconnected--ignition amplifier is shot and must be replaced."
 
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