VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 1954 235 valve refacing

I have 1954 235 cylinder head with casting # 3835913 which was a 56-62 replacement head.
My six intake valve sealing surfaces are slightly to moderately rusted due to water that entered through the carb and intake manifold.
The six valve seats in the head are in better condition but in need of something to recondition them

The worst intake valve cleaned up to shiny metal on an old hand tool, a ZIM valve refacer #514 but, i see tiny pits in the sealing surface.
It appeared that the hand-spun tool barely removed any material and left a shiny but irregular chattered looking surface on the valve.

My exhaust valves and seats were basically unharmed, they're not shiny new but they are alot better looking than the intake valves and seats.
All my valves have the required thickness at the edge and the required sealing width and the stems are in great condition so i''m sure they are serviceable.

I am wondering how much material valve grinding compound and the wooden-stick-suction-cup-valve-spinning-hand-tool will remove.
Is there only one grit of valve refacing compound to use?
Since all twelve of my valves and seats need only a little polishing to be like new i want to try the compound and hand tool

However, I read in my shop manual that the valve seats in the head are cut 1 degree more than the angle of the valve, so seats are cut at 31 degrees for intake and 46 degrees for exhaust on my 1954 head.

What is the reason for cutting valve seats in the head at one degree more than the valve angle is cut?

Is valve grinding compound and the hand tool spinning stick potent enough to change the one degree difference between seat and valve?

I would suggest have the valves professionally ground. The seats must be of the correct width and angles.The difference of the angles (only one degree) is to ensure ull contact on the valve on the seat. Kind of a wedge effect.
What you are doing will require aother valve job in 10,000 miles.

The valves were professionally ground two decades ago.
The rust is removable but exposes tiny pinhole pits. The fine machining and precise cut edges of the work from 20 years ago is still visible under the rust. Thats b/c i never drove the car much, i'd say less than 10 miles but, there was lots of idling/coasting and short test drives.
I really only used the engine for power to correct issues in all the other mechanical parts.
Its bad form to reface the valves by hand but i think in my case it will suffice for a short while.
If i get the car in one piece and running again it would take me five years to reach 10,000 miles anyways.

I will agree with that.

There is a course and fine lapping paste that I know of but that isnt to say there arent others.
Lapping valves by hand generally doesnt take much metal off in a hurry but it does upset the 1 degree face to seat angle.
Tony

That answers my question.

Is there a way to tell if hardened seats have already been installed?
I had an excellent report on the head two decades ago and except for the current rust on the valves it couldn't have changed bc i barely ran the engine after the head was rebuilt. So its possible someone already replaced the seats.

Two of three machine shops want to replace my valve seats and i don't want them removed so they're not getting my business.
The third might be more forgiving to the customers wants but i'll do it myself before going to them.

Couldn't i get my half-corroded valves cut to match the angle on my valve seats and use them to resurface my valve seats with compound and a lapping stick.
Then i can purchase six brand new intake valves for my head.
Problem solved for 5 yrs or longer.

Does the lead substitute or as i've read marvel mystery oil actually prevent damage to the unhardened valve seats?

I predict i will barely drive the car, even 1000 miles a year is an overestimate.
That is if i ever get the car in one piece again so future valve seat wear due to unleaded gas is of little concern.

Without checking I think the original seats were part of the head casting (parent metal) and if there is a machined ring seat it is most likely a replacement. 20 years ago down here a lot of machine shops fitted hardened seats in preference to the soft cast iron parent metal as it often saved on the need to refaced valves near as often.
Tony

i cant see or feel any edge of a pressed in valve seat ring.
and the metal of the seat area is the same color, condition and apperance as the metal of the head around it.

it sounds like hardened seats were an upgrade simply to lessen valve maintenance.
i predict i'll barely drive the car so i'm leaving my valve seats alone.
when they're worn out then i'll have them replaced with hardened seats.

As well, i recall the machine shop, which was actually a vocational school engine repair classroom doing the work, confirming with me what the angles were.
i agreed that my manual said they were 30 and 45.
I was unaware of the one degree difference for the seats b/c i hadn't read the repair procedure fully.
so its possible they cut the valve seats at 30 and 45 instead of 31 and 46 as the shop manual states.

it seems impossible for me to determine a 1 degree difference in the seats at present time.
but I wonder if there is a way to determine if the seats and valve are cut at the same degree by using plasti-gauge or similar between the seat and valve.
any ideas?

The 1 degree difference often isnt in the books but most machine shops do it to get a better seal on the combustion side.
Tony

Yes, the 1 degree difference was a common practice to better ensure a full ring of contact between the valve face and the seat. The machine shop would dress the stone that they used for the final grind on the seats to that angle.

I agree that it will take a lot of work with valve grinding compound to make much if any change in the face and seat angles. I also agree that given the limited miles we put on these older vehicles I would not spend the money to install hardened inserts.

My suggestion is to use the valve grinding compound to do what you are doing. Clean things up and make sure there is a full ring of contact between the face and seat. Yes, the pits will slightly reduce the sealing action. You might even lose 2 or 3 horsepower.

Reassemble the head, install it with a new gasket and enjoy driving the car!

One great point that I have learned from this forum is that absolute perfection is not required for these vehicles to run well. You can turn every step of the work you do into a full blown engineering project. I am not sure the results are worth the cost and effort.

Rusty 37 you are right about not needing to be perfect for the limited use these cars are going to get. But being a mechanic I dont want the embarrassment of being stuck on the side of the road because I took a shortcut, I certainly dont on a customers vehicle as the rerepair becomes rather expensive on my pocket.
Tony

that is a good point.
i'm already guilty of turning portions of a fun hobby into a miserable engineering project.

I've never used the compound and wasn't sure what its capable of removing.
i was worried i'd accidentally change the seat or valve angles.
Sounds like its an aggressive polish and what i need to evenly clean rust off intake valves.

Hi Tony,

Thanks for your thoughts and inputs. I agree with your guidance that we do not want to be taking shortcuts to the extent that we reduce reliability and especially safety.

I consider this more of a situation where he is approaching the point of diminishing returns. If the seats were wavy or deeply pitted or the valves were warped or had burned edges then olddominion should be heading to the machine shop for more extensive work.