Hardened Valves, Sunk Valves, no-lead, unknown heads whats a feller to do?

[Moparfiend]

I am still wrenching on the 318 Sport Sat and have no history with these heads other than Bubba owned the car previously. So I do not know if the heads were later heat treated. I think I know the answer but have to ask.

Is there anyway to determine the condition of the valves and if they were heat treated while the heads are on the car?

Thanks,
The Moparfeind.....

 

[bm02tj]

Heads had flame harded seats starting in mid 70,s and if you had a valve grind it was gone
put a strait edge across the valves and if some stick up higher you have trouble

 

[Moparfiend]

Its a 1970 so not factory hardend. Don’t know the history on the car. I assume thre is no way to tell.....especially while the heads are mounted....

 

[PP1RT]

Its a 1970 so not factory hardend. Don’t know the history on the car. I assume thre is no way to tell.....especially while the heads are mounted....

Yes. Remove your rockers and put a straight edge across the top of the valve stems. If any are up higher than the rest they have started to sink in the head. If the motor is a 70 it does not have hardened seats and will eventually wear down. If the car hasnt got a ton of miles on it they may not be too bad yet...

 

[Moparfiend]

Yes. Remove your rockers and put a straight edge across the top of the valve stems. If any are up higher than the rest they have started to sink in the head. If the motor is a 70 it does not have hardened seats and will eventually wear down. If the car hasnt got a ton of miles on it they may not be too bad yet...

Thanks PP1RT The car has 114k lots of miles. So it looks like I can detect the wear without pulling the heads by removing the valve covers and removing the rocker arms? Wouldnt the height of the calve stems depend on the position of the valve train and not all be synchronized as you suggest to look at a uniform height across all the stems at one give time/position?

 

[happyjackdaddy54]

Any hardened seat from 40 plus yrs ago , heat treating is gone. The BEST way to fix that problem is to replace them with hardened seats. Any auto machine shop can do that. Figure that cost against new heads. It may be cheaper to update. New heads may be cheaper in long run.

 

[Cranky]

Hydraulic lifters usually will bleed down after sitting awhile and all the valves will close but not always. Have you done a compression test yet? Also, if you have a valve that has sunk a good bit, chances are you will have some slack in the rocker/push rod. The factory lifter preload is usually around .050 so figuring wear over time and mileage, some of the preload will be gone but not that much. So, if your experiencing valve train noise, lower compression on some cylinders, chances are good you may have one or more sunk valves. If Bubba drove the snot out of it....well, that's not easy on unhardened seats either. I guess I've been lucky with all of my junk as I've never had any valves that did that.

 

[Moparfiend]

I have not pulled the valve covers yet will do that today. I have not yet been able to do a compression test yet either but soon. So a compression test is another way to look at possible vaove train issues like sunk valves good to know!

 

[PP1RT]

Thanks PP1RT The car has 114k lots of miles. So it looks like I can detect the wear without pulling the heads by removing the valve covers and removing the rocker arms? Wouldnt the height of the calve stems depend on the position of the valve train and not all be synchronized as you suggest to look at a uniform height across all the stems at one give time/position?

With the rocker arms off the valves will all be returned to their seats. The pushrods will not be even because of the cam lobes

 

[Cranky]

I have not pulled the valve covers yet will do that today. I have not yet been able to do a compression test yet either but soon. So a compression test is another way to look at possible vaove train issues like sunk valves good to know!

If the valves are only sunk a little, it probably won't make much difference in a compression test. 318's are fairly low testing anyways but doing a test is just part of the things you do to find out the health of an engine. Is there a reason you suspect sunk valves like valve noise or rough running??

 

[Moparfiend]

Thanks PP1RT got it look across the valve stems with the rockers off.

Hey Cranky no not suspecting anything just everything. I mean that as I started going through this car everything was a basket case so I am more trying to educate myself gather inputs and inspect as much as I can as I move through the process of rehab. I have not yet got her running but anticipate I will have it all together in about two weeks to get her fired up depending on how mich time I can muster on it.