Flathead exhaust valve guide seals
 

Are seals used and or needed for the exhaust valves on the 8BA engine?

Thanks

Re: Flathead exhaust valve guide seals
 

Re: Flathead exhaust valve guide seals
 

I use never seize on the exhaust and RTV on the intakes

Re: Flathead exhaust valve guide seals
 

Ol Ron,
No seals on either? John

Re: Flathead exhaust valve guide seals
 

I'm with Ron on no seals in either. I use a little hi temp RTV on the intakes.

Re: Flathead exhaust valve guide seals
 

This is a logical decision I made because the Hi Temp RTV was not available back when Hank designed the flathead. AND, that's a big and, from 32 to 48 Ford never used any seals. Now what you should be concerned with is the valve stem ti guide clearance. THIS, is where the oil is pulled under hi vacuum. I Knurl the guides and ream them for a .0005/.001 fit. The knurel will keep the guide well lubricated. AND yes Knurel the new guides you bought and ream them as well. I've done this to every engine I've build over the past 30 years.

Re: Flathead exhaust valve guide seals
 

Ol' Ron - The knurling makes sense to me but being an electrical engineer I don't know how it is done. Do you have to take the guides to a shop or can you do it yourself?

Re: Flathead exhaust valve guide seals
 

I do mine in a lathe now, however I did them in a vice with a fixture I made out of wood to hold the guide while I ran the knurling tool, and the reamer. Most auto machine shops should have the tools

Re: Flathead exhaust valve guide seals
 

BTTT: Here is how I just did it:

Here is the problem - all the guides I've ever used are fairly loose in the guide bore. This is something that I 'fix' with knurling. When Ron talks about knurling, he is talking about the traditional knurling of the valve guide bore to tighten up guide bore to valve stem clearances. I know some experienced racers that won't knurl flathead valve guides (especially the exhaust), they install bronze liners. The reason is that they want better heat transfer from the valve stem to the guide and tightly fitting bronze liners do this supposedly better than a knurled cast iron one.

Video: The problem with loose fitting guides (in the block):

https://www.youtube.com/watch?v=qZBXFMqHs-c

Here is the knurling process and final result:

Video: Knurling:

https://www.youtube.com/watch?v=UqYqBIy1BAI

Here are some final guide pictures - you can see my spring spacers for the Isky 185-G springs as well as the cut-back section I do on the top of the valve guides (so they don't obstruct the port).

Enjoy:

Attachment 226290

Attachment 226291

Re: Flathead exhaust valve guide seals
 

Knurel is a good friend of mine!

Re: Flathead exhaust valve guide seals
 

I don't bother to Knurell the outside of the guide the RTV takes up the room between the guide and block. However, doilg this will probably center the guide and grinding the seat with the knurelled guide in place will make a true seat. My valve grinding fixture locates on the guide bore.
BUT, we haven't addressed the stem to guide clearance here.

Re: Flathead exhaust valve guide seals
 

I'm still wondering what is considered proper stem to guide clearance for 8ba? Not showing up in a search.

Re: Flathead exhaust valve guide seals
 

https://www.fordbarn.com/forum/attac...0&d=1433215518

https://www.fordbarn.com/forum/attac...1&d=1433215518

Re: Flathead exhaust valve guide seals
 

On one hand knurling the outside is good because it makes the guide tight in the block so the valve seat remains solid in place but you also lose about 30% contact area which relates to a LOT of heat transfer capability.
In a street engine you may not notice the shorter life.