355 Heads

Cool!

Why the color difference between intake and exhaust?

Hi Vincent,

the color difference is due to the temperature differences between intake & exhaust valves.

Also note that one set of exhausts is a different color than the rest.

Regards, JRV

JRV So what do you have here, 1 set of normal colored exhaust valves and 3 that are abnormal or 3 normal colored and 1 abnormal? What would cause this difference in color, hotter combustion in 1 cylinder or too cool in the other 3?
Thanks, Just trying to learn> Walt

>>3 normal colored and 1 abnormal<<

once the exhaust gas starts escaping by faulty va;ves it causes the valves to run at a different temp than the others. eventualy leading to crytaiization.

Thanks for the information. It's a learning experience for me.

thanks,

What causes this mechanically? What is the fix?

Vincent.

thanks,

what causes this mechanically? and what is the fix?

vincent

Hi Vincent,


in the case of 355's the bronze valve guides suffer extreme premature wear that causes the valves to fail to spin &amp; seat properly and loose cooling ability....once valves stop spinning they loose their ability to self clean the seats/sealing face &amp; once they become covered in carbon they loose their ability to cool...leading to escaping combustion gas which leads to further worsening complications.

For the 355's the solution is new guides...with an update to the newest version Sintered Steel Guides (the material the Factory switched to mid 98 &amp; newer production) mandatory for longivity imo. The SS guides are very expensive - $55 ea..and with the haeds having 49 guides it ads up fast. When looking to purchase a 355 that has had head work make sure all 40 guides were replaced and not just a few (as I've heard some shops do), as this leaves the engine a ticking time bomb if any Bronze Guides are left.

Regards, JRV