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Thunderbolt V ignition

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fonseca_air_210

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"Hi everybody.
I usualy run m

"Hi everybody.
I usualy run my Correct Craft Air 210 in Portugal, but I'm now working in Angola and found a huge problem to solve. My boss have a Sea Ray boat with a Mercruiser 5.7 V8, Thunderbolt V ignition and simple corp carb.
The engine had the same piston with a hole two times. Now it's running but not ok. It was a Angolan Mechanic that have rebuilt engine, but he can't do more.
The problem is that after rebuild engine, it run for about 10 hours ok. After 10 hours the WOT max rpm start decresing and now it don't go over 3000 rpm.
If not in charge (transmission not engaged) it accelerates ok to ignition cut rpm (4600), but in charge (cruising) it goes ok until 2800 rpm, with some difficult to 3000 and don't overpass.
I have no tool to measure compression but spark plugs shows good combustion in all cylinders.
In my opinion ignition is not advancing.
I read some posts about ground the purple with white strip wire. I tried that with no results.
How can I check ignition module?
If not possible, where can I buy (e-buy) a complete module and distributor cap?
Thank's for any help!"
 
The timing advance is easy to

The timing advance is easy to check with a timinglight. It will not advance with the purpe/white wire grounded. IS there a knock modual?
Just guessing I think you may have tuliped an intake valve. or possably lost another piston. \Is there a knock modual? It would be mounted next to the Ign. modual.
 
"Yes, I have two modules.
<[i

"Yes, I have two modules.
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Modules"">
The problem is that here in Angola even a timing light is hard to find.
I'm trying to get a tool to check compression and a timming light.
If I have tuliped a intake valve I will get different compression values, right?
Once again Thanks for any help"
 
"Ayuh,...

From your descrip

"Ayuh,...

From your description,...
I think you're looking in the Wrong Place...

The motor is going Lean,...
It sounds like the fuel system is boogered up,+ not flowing properly...
It could be anything from the fuel tank to the Carb...."
 
"I tought that too, but I trie

"I tought that too, but I tried to spray some petrol directly on carb with WOT and I get no changes in engine rpm.
Fuel arrives to carb with pressure.
I heard about a filter in carb but I can't find it."
 
It is behind the large nut fit

It is behind the large nut fitting that screws into the Carb.. The Fuel Line screws into it. Remove the Fuel Line and then remove the large fitting by back-threading it. You can get the manual on this site by searching all posts by Bondo. Hopefully someone will offer the Link. Al W.
 
The coil may be dying. Instal

The coil may be dying. Install a spare and see if the problem goes away. Check the wire connectors on the coil and amplifier module for corrosion.
 
"Carlos, You will need to do

"Carlos, You will need to do the compresion test first thing ,Just to be sure the valves and pistons are still alright.. To go from 4600 rpm to 3000 rpm after ten minutes does not sound good.
After last rebuild, How did the mech. Time the engine? The knock modual works with the Ign modual to achieve the best (advance) timing. I will email you this evening with more Knock modual info.
Do that compresion test, Even if it means using your finger. j/k
L8R allan"
 
"what I have are PDF files and

"what I have are PDF files and I can't figure how to post them on this board.I can email It to you if you want it. 100k file, not big.
Later allan"
 
"Sorry to everybody that are h

"Sorry to everybody that are helping me, but my job don't let me much time to go to the boat and I still haven't news.
Anyway, I continue doing some research and I found that with my ignition control reference I should have a Knock control ref. 806611T. Instead of that I have a bctu 16184069 brand new from GM.
Do you thing that this one from GM do the same that the original one?
I hope to get the compression results this week.
Thanks for your help!"
 
Carlos does the problem come a

Carlos does the problem come and go.


I ran into almost the same problem. Surface rust on the pick-up coil in side the distributor cap.
 
"Hi Alfred.
It is permanent.

"Hi Alfred.
It is permanent.
I have sow the pick-up and it's ok.
I found a timming light and compression tester, I will get some news saturday.
Thank you"
 
"[b]"Can you help me findi

""Can you help me finding them?"

Ayuh,... Just Click on the Link in my last post...."
 
For a fuel test it is easy to

For a fuel test it is easy to connect a 6 gal outboard motor tank in line to eliminate the problem with the tank and fuel lines to the fuel pump.
It sounds like what happened to a friends boat. Bugs and spiders moved into the fuel tank vent line. After a while the motor would do the same thing. Vacumn would build up in the tank not allowing the proper amount of fuel to pass out of the tank. Creating a lean burn condition.(burnt piston)He had the carb rebuilt $400.00 before finding the plugged vent line.
 
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