Flathead Valve Job in Car

RusselS

RusselS

Junior Member
Hi everyone,

Long time listener, first time caller.... picked up a '53 Merc 4dr last July I've been going over from front to back and back to front again.

Almost all dialed in... (fuel, brakes, carb, ignition, timing, suspension, interior, electrical, all done)

A low compression problem I've been ignoring is actually an (almost) burnt exhaust valve that's not sealing completely on cylinder 7.

Been collecting all the right tools to do the job (valve grinder, valve refacer, stones, etc) because eventually I will have to tear the whole motor down.. *but*...

Since it's only one valve I really need to address before it eats a piston.. do you have any advice/best practices/tips to dress one valve seat with the engine in the car?

I don't want to blow the whole motor apart in the middle of the summer, but I want to be able to drive the car a few hundred miles without this one hanging over my head.

Any/all tips or feedback/links to older posts that already tell me how to do this welcome.
 
Went thru the same thing years ago. Did not have to grind seat (just hand lap)
Until you remove the offending side head and intake manifold you won't really know what is needed.
But in my case, a new valve and adjustable lifter and all necessary gaskets.
This is a pic of the offending valve.


picture.php
 
Did a complete valve job on my 50 back in high school auto shop with engine in car. This was in 1955. It can easily be done.with the right tools. Pull the head and intake. If you have a valve bar use it to remove the C clip holding the valve guide. Pop the whole valve unit out and disassemble it. Or you can leave everything in and use a valve spring compressor to remove the two keepers from the valve spring retainer and just remove the valve it's self. Either method is doable with the right tools.
 
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Doing the valve and seat are relatively easy in the car with the proper tools, which you seem to have collected.
HOWEVER, and that is a very big however, cleanup is the most important part of that job.
Grinding the seat is going to put grinding grit all over everything. Before you grind the seat, tape slightly oily rags over everything possible to keep the grit out. The oily rags collect the dirt and hold it. After done grinding, pull rags and blow everything possible out till hospital clean. Wipe everythng down with oily rag then dry rag.
After all of that run the vacuum cleaner over everything.
After that, all you can do is hope you got all the grit out.
People have been doing that job like that for a 100 years and getting away with it.
It may not be right, but it works in a pinch.
 
Great advice and I’m at least pleased to hear I’m not the first nor will be the last to do this. Biggest concern is keeping the lifter valley grit free, so I’ll have to be extra careful and use lots of rags…

Time to get out the pickle bar!! …maybe next weekend :)
 
My '40 tudor had a 3/4 race flatmotor in it, but was getting run over by some unworthy cars. Took it to the local mechanical guru who did a valve job in the car on it, found a bent valve in the process. I put the heads back on, but it took us a long time to readjust the Johnson lifters as the reground cam flexed as we got one one right and went to the next one. Out of the street again it was a whole different critter. What a feeling !
 
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