42WLA valve seat questions

[17thairborne]

I've got a 42WLA type V with the original motor. I've been having some issues with it not starting when hot, (has not compression when checked hot) so we took off the heads and cylinders to have a look. It appears I'm getting a leak at the rear cylinder exhaust valve. The seat has been ground so deep that it is recessed below the original height about 1/8" or more. I'm not sure why this happened, but the point is its very deep and leaves little room for adjustment between the tappet lock nut and the tappet adjustment screw (since the valve sits so deep in the port). It cannot be ground again in its current state as it would be far too deep.

Is it possible to weld the seat up to an original height and grind the bevel again? WHo would you recommend to do this work?

thanks

[T. Cotten]

17thAirborne!

The simplest remedy is a valve with an oversized head. The next simplest is to find an extinct cast iron seat, and have it installed.

Cast iron doesn't weld in a friendly manner, and at flatty temperatures, any heat spike at all can cause a modern hardened seat to shrink, and "fall out".

Good luck!

....Cotten

[17thairborne]

Cotten,
Thanks for the advice. I did not know about an oversize valve. I'll see what I can find.

[17thairborne]

Here is a pic of the cylinder and the depth issue

IMG_3189 arrow.jpg

[17thairborne]

I cleaned up the cylinders and took measurements of the valve openings. Here's the scoop:

...Front:
......EX: 9/64"
......IN: 4/64"

...Rear:
......EX: 10/64"
......IN: 7/64

Do these seem too problematic? Has anyone done a flathead with hardened seats and had success?

HEre is how I took measurements

depth guage.jpg

[Chris Haynes]

I would also like to find a source for over-sized valves.

[Rollo]

Might give Paul Friebus at American Cycle Fabrication (570-752-8715) in Bloomsburg a call and see what he says. He is a pro with flattties.

To (Rollo) Hardy
AMCA #12766

[DCoul]

Pardon me ahead of time if this is a dumb idea. I thing I've heard of people grinding the valve stem shorter to retrofit valves to a motor the valve wasn't intended for. Looks doable. More of a band aid than actual fix. Would that work?
Again, sorry if this is a dumb idea. It's not my first

[17thairborne]

I spoke with Steve Lemay and he indicated that is a possibility, but you have to be careful not to shorten it too much or you grind down the outer hardened surface of the nub and potentially expose the interior portion of the valve stem that is softer metal. A valve might have a completely hardened end, or en end that is not hardened all the way through if that makes sense. If the latter, then you expose the soft metal end and it will deform by pounding on the tappet adjustment screw.

If I understand this correctly

[17thairborne]

Might give Paul Friebus at American Cycle Fabrication (570-752-8715) in Bloomsburg a call and see what he says. He is a pro with flattties.

To (Rollo) Hardy
AMCA #12766

Thanks. I will do that and report back.

[motorhead1]

I cleaned up the cylinders and took measurements of the valve openings. Here's the scoop:

...Front:
......EX: 9/64"
......IN: 4/64"

...Rear:
......EX: 10/64"
......IN: 7/64

Do these seem too problematic? Has anyone done a flathead with hardened seats and had success?

HEre is how I took measurements

[ATTACH=CONFIG]17688[/ATTACH]

In this photo it would appear that hardened seats have already been installed. Click on the attachment and look at the seats closely.

[17thairborne]

I looked it over closely, and I can see how my crappy pic looks like there are valve seats pressed in, but when I look carefully and take a shot through the exhaust port letting the sun sine on the valve opening, you can clearly see the casting on the entire inside of the valve area up to where the bevel begins. I think the cylinders are still stock.

Do the values for depth that I posted above seem too deep to grind again?


IMG_3215.JPG

[motorhead1]

The seat depths should be brought back up to a height where stock valves can be used and valve stem protrusion is within specs which will allow proper lash adjustment without shortening the valve or the tappet adjuster screw. Thermal spray is an option if seat replacement is not an option. I have a 40 WLD that I had the seat area sprayed over 12 years ago and I machined the new seat angles from there. In my case, seat replacement wouldn't work since the cylinders had to be sleeved. This link is for an outfit in S.C. They can save engine parts that most have given up on. There should be someone in your area that can do this as well.
http://www.mbicoatings.com/content.c...02/page_id/171

[17thairborne]

Dan,
Thanks for that. it provides yet another option so that I can continue to use the original cylinder.

[DCoul]

Learned something new. Thermal spraying. Never know what I'll find on this site.