Exhaust valves

[Ricochett]

Hello everybody im new here! i am rebuilding my 1969 corvette 427/390 motor,
after pulling the heads off the motor i notice the valves are white on the exhaust
im concern they might have been ran hot! but im not sure! does anybody have
any reason why the did this?
Thanxs

 

[6880 Mike]

Probably deposits from unleaded gasoline.

 

[Vettehead Mikey]

Sounds normal to me.

 

[Ricochett]

exhaust valves

Hey thanxs guy's! is there a chance of these valves
being weak and could break? i was thinking of increasing to the
next size int/exh valves would this help
Thanxs
Joe

 

[Vettehead Mikey]

No and No.

 

[Ricochett]

exhaust valves

Mike
So your saying stay with the factory size valves?
installing bigger valves wont help!

 

[Hib Halverson]

With the low performance big block, going to bigger valves (the most common change is to use L88 sizes) is only a wise idea if the engine also has cylinder head porting, a camshaft choice and valve train which will compliment the larger valves. If you install big valves, but do nothing else, you may gain a slight amount right near the rev limit of the engine, but you'll loose torque in the low end and mid range.

If you want to do something to improve performance using heads with stock ports and a stock or near stock camshaft profile, I'd have a 3-angle valve job done. The improvement in low- and medium-lift flow will pay off handsomely in mid-range torque...for what the 390-horse 427 is famous.

 

[Ricochett]

motor work

Hib thanxs for the reply! yes i was going to have the port and polishing on the heads with the comp valve job going with a roller cam ( Hyd. ) range from 1500-6500 rpm as well as freshing up the lower end, so by increasing the valves size! is it worth the xtra money? or just go back with stock valves?
also i will be installing a new set of headers to help with the flow! trying to get this big block to have some power
thanxs
Joe

 

[6880 Mike]

Ricochett -- Purchase one of the How To Rebuild Your Big Block Chevrolet books or How To Hot Rod Your Big Block Chevrolet? They're handy.

 

[Hib Halverson]

Hib thanxs for the reply! yes i was going to have the port and polishing on the heads with the comp valve job going with a roller cam ( Hyd. ) range from 1500-6500 rpm as well as freshing up the lower end, so by increasing the valves size! is it worth the xtra money? or just go back with stock valves?
also i will be installing a new set of headers to help with the flow! trying to get this big block to have some power
thanxs
Joe

If you're going to port/polish, 3-angle valve job and go to a roller then I'd go to the rec. port head valve sizes, 2.19 intake and 1.88 exhaust. That's the valve sizes I run in my 71 BBC hot rod. Ported oval port heads with L88 valves work pretty well.

Now...if you're going to run in the 6000-6500 range, you may be safer with a mechanical roller. My opinion is that BBC hydraulic valve gear is iffy above 6000.

 

[Ricochett]

Head work

Hib
Thanxs for the reply! do you have the close chamber heads? to me it dont look like there
enough room to put the 219 intake valve in there? and you mention something hyd gears
not sure if i understanding? are talking about the valve springs?
Thanxs