8n valve seat

[michaelthorne75]

I think I need to do some work on my valve seats. Long story but I have a 1951 8n with new valves but the seats were lapped. But low compression and not coming up when I do a wet compression either. So my question is, if I choose to use a valve seat grinder tool, should I be concerned about grinding the seats below the block itself. Not saying I would, but not sure how much clearance there is as far as the valve seat and block being "level" with each other. Hope this makes sense. Hoping to do this without having to replace a valve seat. Thanks for all the help. Mt

 

[Den N Ms]

Michael,You should be able to touch up the seats with no problem with stones or a seat cutter.Unless the seats have been ground many times before,that, I doubt is the case.The seats possibly just need to be narrowed up with 3 different stones or adjustable seat cutter,then lap the valve face in.

 

[Bob]

(quoted from post at 16:04:09 06/16/19) I think I need to do some work on my valve seats. Long story but I have a 1951 8n with new valves but the seats were lapped. But low compression and not coming up when I do a wet compression either. So my question is, if I choose to use a valve seat grinder tool, should I be concerned about grinding the seats below the block itself. Not saying I would, but not sure how much clearance there is as far as the valve seat and block being "level" with each other. Hope this makes sense. Hoping to do this without having to replace a valve seat. Thanks for all the help. Mt

It AMAZES me that in 2019 there's still folks living in the 1920's or 1930's that still attempt to "lap" valves.

I would do a "leakdown test" to verify the valves are not seating before going any further.

Not much metal should have to be removed to touch up the valve seats, unless they are severely pitted or rusted.

If that is the case, new seats may be required.

NOT sure what equipment you have, here's what was used to grind Ford flathead valve seats "back in the day"...

 

[R Geiger]

(quoted from post at 22:45:01 06/16/19)

(quoted from post at 16:04:09 06/16/19) I think I need to do some work on my valve seats. Long story but I have a 1951 8n with new valves but the seats were lapped. But low compression and not coming up when I do a wet compression either. So my question is, if I choose to use a valve seat grinder tool, should I be concerned about grinding the seats below the block itself. Not saying I would, but not sure how much clearance there is as far as the valve seat and block being "level" with each other. Hope this makes sense. Hoping to do this without having to replace a valve seat. Thanks for all the help. Mt

It AMAZES me that in 2019 there's still folks living in the 1920's or 1930's that still attempt to "lap" valves.

I would do a "leakdown test" to verify the valves are not seating before going any further.

Not much metal should have to be removed to touch up the valve seats, unless they are severely pitted or rusted.

If that is the case, new seats may be required.

NOT sure what equipment you have, here's what was used to grind Ford flathead valve seats "back in the day"...

What is there that is available to the average n owner to grind valves?

 

[Dan]

Of course Bob is correct, but I had a mis-cut valve seat in my 52 8N that I could see light through, and of course did not have any fancy valve cutting tools like Bob shows. My solution - chuck the simple hand lapping tool into a drill, slather lapping compound on the seat, and spin that lapping tool at several hundred RPMs until the suction cup can't hold any more - then repeat! Yep, took me days to finally "lap" that seat and valve until it finally sealed "ok", but compression jumped 20 points or so and the tractor ran much better.

You can take to a good local machine shop and get them to pop out the hardened valve seat, put a new one in, and "hopefully" drill it at the correct exact angles - but my "farmerized" solution worked well for me.

YMMV,
Dan

 

[Den N Ms]

R Geiger,Here are some different brands.
Valve seat tools

 

[R Geiger]

(quoted from post at 15:00:41 06/17/19) R Geiger,Here are some different brands.
Valve seat tools

Thanks!

 

[Hobo,NC]

The problem is when the seat becomes to wide to narrow down without cutting into the block... That does not mean it could not be ran that way it means a shorter life for the valve and possible the valve wearing into the block and damaging it beyond repair...

Without seeing it if you were gonna run it 20hr a year are less shine it up and move on with life.. If you want it back to factory spec have the seats replaced it should not be a problem to find someone to do it...

If I rebuild a engine I replace them all I have my local machine shop do it there is no way I can match his work with the equipment I have.... He has the equipment to put it back to original spec and works cheaper than I do ....

 

[Ken(Ark)]

(quoted from post at 16:00:41 06/17/19) R Geiger,Here are some different brands.
Valve seat tools

WOW , My Dad had an automotive machine shop when I was a kid and I loved helping him . Over the last 20 years I have purchased a lot of vintage equipment at what I thought were fair prices . They are now making pretty good quality tools for the hobbyist at fairly low prices . They might not be professional tools , but as Dan has pointed out , if you are willing to spend the time you can have good results .

I got tired of the local machine shops that could not get your parts within .002 of what they needed to be . Most of those shops have gone out of business but now you are looking at $2k to run an N motor through one just to have an $1800 tractor .