||Most likely, you are replacing a powerhead that has probably failed
prematurely, due to excessive combustion chamber temperature. You must find the cause of this failure or face the same problem again, very shortly.
ENGINES DO NOT, normally, FAIL WITHOUT REASON, YOU MUST FIND THIS PROBLEM.
Our experience is that the piston is the part most likely to fail, which is generally caused by detonation and/or overheating.
The following Tips should help REDUCE FURTHER FAILURES.
1. Increase main metering jets by .002.
2. Retard ignition timing by 2 degrees.
3. Check entire fuel system, fuel pump, lines, filters,
carbs, and all related items.
4. Check for proper full throttle RPM.
5. Tune engine and change oil more often.
6. Completely replace water pump and associated plumbing.
7. Use only good quality fuels and lubricants.
8. Reduce full throttle usage.
Unable to find cause of failure...
* Replace all switch boxes and/or ignition modules.
* Remove idle stabilizer and advance module. (Mercury motors and others.)
* Replace and/or service oil and fuel injection systems.
* Replace distributor.
Failure due to faulty cooling.