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Possible coil problem?

G

gpmrozinski

Contributing Member
I have a 92 Carver with two 454 Crusaders (330 Hp). I have recently noticed that at cruise speed (3600 rpms) I am seeing a periodic fluctuation in the sync guage and tach on the starboard side. Sometimes the drop/dip is minor and sometimes it is pretty severe. Really don't notice much in the sound or feel of the engine per say but at that speed I don't think I would. At lower speeds (idle-2500 rpms) everything is fine. I suspect the starboard engine coil is breaking down under load but I wanted to ask for some opinions here first before replacing. Thanks for the help.
 
could be the coil but I'd suspect the plug leads before the coil, especially if they are still original. Could also be an advance weight/spring concern if the 'old' style distributor.
 
Thanks Mark. The needle on the sync gauge flickers very quickly towards the port side of the gauge when it happens and then returns to the middle. Then it will start doing it again shortly after. When it really takes a dive I notice a corresponding dip on the tach also. I was thinking coil because that is where the tach and sync signal comes from. I will check and test the plug wires. Do you have any suggestions on how to check the distributor weight/spring? I have the EST ignition system on these engines and they have about 1000hrs on them. Thanks for your help.
 
Don't think EST has springs. All the advance is in the module. Verify the wires/connectors going to the distributor are clean and tight, too.

Both the sync gauge and the tach work off the pulsing voltage from the coil when it fires. I've found sync gauges to be much more sensiive (faster reaction times).
 
That is what I thought about EST distributors also. Your are right on about the sensitivity of the two. I will go over everything with a fine tooth comb. I am going to be changing plugs, caps and rotors this month anyway. I'll look into new wires as well. Thanks for your help, I really appreciate your time.
 
Hi,
I had a very similar problem affecting twin smallblocks. It turned out to be the aftermarket electronic engine synchronizer which had failed. I disconnected it from the ignition and all was fine. Try disconnecting it .








Hope this helps,
Jon Allen
 
Jon,

Thanks for the thought however my sync gauge is OEM and takes it signal from the coil just like the tach does. I don't have an electronic engine synchronizer on my engines. My engines seem to run fine so no real issues there.
 
So, we are not sure if its an ignition problem or maybe just a tach wire problem?
If there is no diagnostic equipment available (like a portable tach, or an ignition analyzer), it's a bit tougher to analyze. I'd take both engines to WOT for a few minutes; it should be obvious if this is a real power issue. At that point, take out all the plugs and do a visual to home in on the problem cylinder.
 
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