18HP Briggs Opposed verticle.

[JoeMeg]

I know it's more of a lawn tractor vs aatv motor,but still wondering about something. I have one that is very "tired" and am tring to decide what to do with it. ( Brian, do you remember my admiering the horizontal in your Hustler?). Looking at rebuild kits on ebay and have not seen one that mentions valve guides or anything similar. When I turn engine over by hand and look into the exhaust port,I can see the valve stem is soaked with oil where it came "out of the guide" which leads me to thing that replacement is in order. Are there some type of bushing in there or is the valve stem just "softer" in that area? Thanks.

Joe.

[Roger S]

Joe, go to heymow.com - Lawn Mower Racing Forum - Index and read the flathead forum. They have everything from mild to wild. On the high end, I just saw a stainless steel valve set, springs, and a guide reamer, in a billet rod engine that turns 7000 rpm. If you want to build a flathead opposed, this is the place to read. They have all kinds of budget info too. Little jewels of info, like the briggs manual has the rod installation wrong, the oil holes facing the wrong direction, on the splash oil/non pressurized models.

[golpher76]

I believe those engines have a small rubber seal with a metal band around it that sits on top of the valve guide helping to keep oil out. I haven't had one apart in a long time so I'm not 100% but I just rebuilt the top end in my 4 wheeler and it had them on top of the valve guides as well.

[JoeMeg]

Thanks Roger, I've heard of that forum before,sounds more relitive to my application. I'll check them out. Would the oil hole thing be obvious by looking at it,knowing direction of rotation?

Thanks Golpher76, don't see anything like that yet,however more may be coming apart.

Joe.

[Roger S]

I'm not familiar with the flatheads.. I read but don't pay serious attention to details. But those guys know everything that's possible, stock to extreme.

[golpher76]

It may not have them but the should be located inside the valve springs on top of the valve guides. The valve slides up through the valve guide and the seal is supposed to cap the top of the valve guide so oil can't escape down the tube.

[JoeMeg]

Thanks for the tip Roger. I was able to glean the little bit of info I sought from their flathead section as you stated.I will contact the local mower/small engine shop to see if he has the tooling to service the guides in this block.Allthough most of the "special" tools required appear easy to fab/improvise, I will still feel better speaking in person to the owner.If nothing else,perhaps he can tell me which specific guides are in my model so that I may review the necessary procedure of replacement to better determine what to do about tooling.(I don't think purchasing them is a cost effective option).

Thanks also for the tip,Golpher76. Were allmost into that area.

Joe.

[Jeff t-boss]

I believe gopher is right about the seals. I would mic the valve stems and guides before I start any reaming/rework. If the seals were leaking then the stems obviuosely were getting enough lube, and there may not be enough wear to require reworking of the guides. (Valve stem -to-guide clearance shouldn't be more than .002-.003. Check with dealer for exact specs for your engine.) Also, If you are getting a Rebiuld KIT", the guide seals should be included.

[JoeMeg]

Thanks Jeff t-boss, I've been on ebay shopping for parts and have yet to see "guides" or "seals" for valves. Thinkin there are no seals and the guides may b a factory only item?This engine is of the "L" design, not OHV.

Joe.

[Jeff t-boss]

I too, have gone through my books, and cannot find anything about valve guide seals for the "L Head" engines. So you just may be looking at a rework. What about buying recon heads as opposed to time/money spent on reworks? Just a thought.

[Roger S]

After browsing heymow, I'll make an assumption of myself. The exhaust uses a replaceable guide. The intake guide is simply bored out of the alloy block. There are specialty tools to replace the guide, and a guide/liner is made for the intake, after reaming. You will spend a little $ doing this and of course it needs the valves and seats ground, and valve clearance set with the cam you're using. You should take it apart and see what things look like in there.. I didn't find anything on valve seals

[JoeMeg]

It's a "flathead" engine. The guides are in the block. So far I believe them to be the type repaired by sleeving a counterbored hole placed in the existing guide. This gets the job done but IMO leaves a little to be desired. I quess some loctite at assy wouldn't hurt though.

Joe.

[Jeff t-boss]

POP!!!! Just got my head out of my rump. Don't know what I was thinking on that last post. It's been a while since I reworked an old "L-Head". I'm stuck on the OHV's. So, I guess I was/am no help here, and apologize if I misguided anyone.