21HP Intek Valve Guides

[jmartin99]

Does anyone know what the specs are for the valve guide clearance on the 21 HP Intek (331877 0939 B1)? It is from a Craftsman Rider about 6-7 years old. I have not put a dial indicator on them yet but they are pretty loose!! I was burning oil BAD before I decided to rebuild. I believe the head gasket was blown between the piston and pushrod chamber so this may be where the majority of the oil was getting into the combustion chamber. Do people knurl the guides to tighten them up? I know that is what we did 30 years ago in high school when rebuilding an engine.

Thanks!

Jeff

 

[bertsmobile1]

Ben a long time since you were in high school I would guess.
Knurl the piston, knurl the valve stem ( not easy ) but knurling a guide would only be done if the guide was slipping in the head.

Inteks have a fubdamental faw in the design ( copied off the Vanguard when better materials were used ) where thers is insufficient clamping pressure on the head gasket between the pot & push rod tunnel.
I have never needed to touch the valves save fitting a new seal on the inlet.
However I always have to touch up the head which you will find has gone hollow at the bridge between the pot & tunnel.
Really annoying, and extra .020" thickness on the head would have added enough stiffness to fix this but B & S ignored this problem & continue to do so.

 

[Rivets]

This manual might help you out.

https://doc-0o-5o-docs.googleuserco...253/*/0B6NaqjIxWV1ySkZjTTA5TGltZEE?e=download

 

[jmartin99]

Bertsmobile1, How do you "touch up the head"? I am almost sure my head gasket was blown there!

Jeff

 

[bertsmobile1]

Bertsmobile1, How do you "touch up the head"? I am almost sure my head gasket was blown there!

Jeff

You check it very carefullt with a strait edge .
Usually they go hollow at the bridge between the pot & tunnel so you have to lap the head to get it flat.
A couple of sheets of wet & dry on a sheet of glass wit the hose running on the water slowly to was away the cut debris.
Gentle circular motion till all the surface that the gasket sits on is the same colour.
Otherwise it will blow the new gasket in no time flat.

 

[motoman]

My 24 hp Intek . Cannot buy valve guides only complete heads. Poor man's straight edge-your table saw machined surface. Look for a "light band" or ""rocking"if the head is warped. I once levelled a set of header flanges with a long Sears file. A new sharp one is also the poor man's surface mill. Use blue marker pen accross the head surface and stroke one way. Keep cleaning the swarf (aluminum filings) from the file teeth. A .001" feeler should not fit when done. Good luck.

 

[Tinkerer200]

Wet or Dry Paper on Plate Glass is the best way to assure flat. level as said above.

Walt Conner

 

[jmartin99]

What grit sand paper do you recommend?

Thanks!

Jeff

 

[Tinkerer200]

What grit sand paper do you recommend?

Thanks!

Jeff

Start with 400 then go to 600 to polish as surface appears true.

Walt Conner

 

[motoman]

Walt, Won't such fine paper load up terribly . Also the surface finish on an aluminum head to mate to a head gasket is not polished. Sounds good for a chisel. Just sayin'...