Updated 4:40 pm - Clarifying Question - Re: Briggs & Straton 28M707 1162-E1; L Head - valve seats and clearances

[Adevo]

Discovered that the intake valve seat was sitting wonky when I went to replace the head gasket.

Now that it's in place & I've lapped both valves it appears that the Intake Valve clearance is at .006 (upper limit is .005) and no clearance on the Exhaust Valve (lower end should be no less than .005).

This is with piston 1/4 down from TDC following compression stroke.

When I was trying to match the seating visually of the Intake to the existing seating of the Exhaust I may have seated it too well ... I can barely fit a fingernail between the meeting surface of the seat and intake valve opening.

Before I take anything off the end of the exhaust valve stem Question: should there be a "step down" from the Exhaust seat to the exhaust valve opening? It is not flush. It makes me wonder if the seat is pushed in too far.

If that is the case how do I safely unseat the Exhaust seat without damaging the surrounding aluminum?

Thoughts?

 

[Adevo]

[Sorry … the included pics with inserted text are basically useless since the quality got degraded in the upload.]

 

[Fish]

If I understand your question, the exhaust valve seat looks ok, it is the intake that is your problem.

 

[Fish]

This guy does a rough valve service, I don't know why he doesn't re-cut the seats though. Those get cocked in the bore and just lapping the valves is insufficient.

 

[StarTech]

The valve seats are recesses that have a stop lip so they can't inserted too deep. The intake seat once reseated must be staked in place.

And your valve clearance specs seems off but I don't see the engine numbers posted so I can't look them up.

But normally most L-Heads have the following valve clearances. ANd I always shoot for the larger clearance as L-Head tends to close up the gaps over time.

 

[Fish]

But your problem is the intake valve seat is not fully seated in the recess, and the ability of curing it is likely not feasible on such an old engine.

 

[Adevo]

Engine: 28M707

Let’s try this again. Clearly I confused you.

Intake Valve Clearance should be
.003 - .005 it’s at .006, if not .007

Exhaust Valve Clearance should be
.005 - .007, it’s at 0

I have reseated the Intake Seat, seems pressed in all the way.

Exhaust seat, that I haven’t touched looks like it is pressed in too far. It does not seemed to be up against a lip. When I feel it it’s not butting up against anything.

So how do I dislodge the Exhaust Seat without damaging it.

Do I? That’s what seems best.

Or do I just leave it as is, it’s been lapped & take off some from end of valve stem to create needed clearance?

 

[Adevo]

This guy does a rough valve service, I don't know why he doesn't re-cut the seats though. Those get cocked in the bore and just lapping the valves is insufficient.

Thanks for you attempt to help me ... I love this guy ... his videos have helped me a lot.

 

[StarTech]

Hmmm still not giving all the engine info but I took a look at 1 of 200+ 28M707 and here is it valve clearances for the L-head.



The valve clearances you are quoting are for an OHV engine not a L-head.

Now if can pick which of the following is your engine would help looking it up.

 

[Adevo]

Hmmm still not giving all the engine info but I took a look at 1 of 200+ 28M707 and here is it valve clearances for the L-head.

View attachment 67021

The valve clearances you are quoting are for an OHV engine not a L-head.

Now if can pick which of the following is your engine would help looking it up.
View attachment 67022

Apologies once again:
28M707-1162-E1 Code: 980325ZA