Question On Cylinder Head Exhaust Valve

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Stangboi4444

Member

Jul 13, 2016

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Jun 6, 2017

#1

• Jun 6, 2017

• #1

My 289 spun a bearing a month or so ago and I am rebuilding the engine. I pulled off the heads and the intake valves were, as I understand, the normal black carbon color while the exhaust valves were a tannish brown. Is this bad? I am young and this is my first engine rebuild. Any help or advice would be great. Thank you.

 

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tos

Founding Member

Apr 27, 2001

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Cincinnati Ohio

Jun 8, 2017

#2

• Jun 8, 2017

• #2

No it is not "bad" The exhaust valves run at a different temp than the intake. One because they are smaller and get hot quicker and also because they are repeatedly surrounded by hot exhaust. When they open to expel the just ignited fuel it passes over most of the valve (bottom, top and stem) where the intake valve sucks cool air in and is surrounded by that cool air (bottom, top and Stem)

 

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Stangboi4444

Member

Jul 13, 2016

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Jun 8, 2017

#3

• Jun 8, 2017

• #3

Ok thank you. Should the valves and springs be replaced or just cleaned up?

 

rbohm

Founding Member

Apr 12, 2002

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tucson,az

Jun 11, 2017

#4

• Jun 11, 2017

• #4

without seeing he valves out of the head, and checking for damage, i cant advise you to either keep or replace the valves. the tan coloration on the exhaust valves is due to the carbon being thoroughly burned up. its normal.

 

tos

Founding Member

Apr 27, 2001

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Cincinnati Ohio

Jun 19, 2017

#5

• Jun 19, 2017

• #5

In my opinion, since you have it all apart then you should do a total engine rebuild and have the heads gone thru by a machine shop. They can advise you what you should do with the heads. They can test the springs and see if they are weak and need replaced and maybe only regrind the valves. They will need new valve seals for sure. They will also check for cracks in the heads.

 

B

BeastsNMonsters

Member

Jun 25, 2017

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East Texas

Jul 13, 2017

#6

• Jul 13, 2017

• #6

Stangboi4444 said:

Ok thank you. Should the valves and springs be replaced or just cleaned up?

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My advice for engine duration is to replace them with quality stock equivalents. They can degrade over time, and may not be out of spec, but might not last as long as new parts would. just my opinion.