Valve guide seal replacement

[Kurtis]

Greetings everyone!

I haven't been on the forum in some time. I've decided to tackle the inspection/replacement of the valve guide seals on the 1275 engine in my Bugeye in hopes that it will help eliminated the blue smoke problem at idle. I'm planning to do this without removing the head and using compressed air to hold the valves in place. Anyone here done this recently who can give me some tips/advice?

Thanks!

Kurt

 

[nomad]

Has anyone used the nylon rope thru the spark plug hole trick on a BMC A serie's engine. Wondering if the head squish area design might make it unuseable.
KA

 

[nomad]

Should elaborate. Use a lenght of light nylon rope shoved in thru the spark plug hole then turn the engine over to compress it into the head. Common trick around here but if it does'nt work I'm not buying the gaskets. :laugh:
KA

 

[dklawson]

The air pressure method does not work. In theory it should, but the valve keepers are usually stuck way too tight and even with 100+ PSI in the bores you will pop the valves open.

I used cotton rope but nylon will work just as well. My friend Tod Miller has some pictures of how I did this on his Austin America web site.
https://www.austinamericausa.com/
click on "Technical Advice" down the left margin,
then click on "Engine" in the "Categories" on the page that opens.
Scroll to the bottom of the page for valve stem seal replacement.

 

[Kurtis]

Thanks Doug! This is exactly what I'm looking for.

Kurt

 

[tomshobby]

Kurt, too bad I did not know. Drove my TR6 right past Russellville last summer. Thinking back, I believe we stopped in for fuel.

 

[Hap Waldrop]

If the piston is at TDC, the valves can not fall far enough down anyway, no need for the rope, fiquire deck height on the block is somewhere between .020-.040" depending on the piston used, a .030" thick head gasket and a combustion chamber depth of say .275" on a stock head, less if it has been decked for compression and the most a valve can drop with the piston at TDC is about .350". Hope that helps.

 

[dklawson]

Hap, no argument from me. However, if your intent is to put seals on without pulling the head, it's a lot easier if the valves can't fall at all. Once they drop that .275" to .350", it will be heck getting the valves springs compressed, valves pulled up, and keepers back on.

What I found when I did this was that my valve guides were badly worn. The new seals bought me a few smoke free months but in the end I had to have the head rebuilt.

 

[Kurtis]

Thanks again everyone for the info.

I'm going to do a leak down test this weekend. Hopefully this will help confirm whether or not I have a valve issue or ring issue or other issue. After researching a little, and based on comments here, I'll probably just pull the head if I decide to replace the valve guide seals.

 

[jlaird]

And that is the real answer. Pull the head, have a machine shop work it over and reinstall.

 

[Hap Waldrop]

Hmmmmmm, me didn't think of that , I'm used to working on heads on the work bench.

Hap, no argument from me. However, if your intent is to put seals on without pulling the head, it's a lot easier if the valves can't fall at all. Once they drop that .275" to .350", it will be heck getting the valves springs compressed, valves pulled up, and keepers back on.

What I found when I did this was that my valve guides were badly worn. The new seals bought me a few smoke free months but in the end I had to have the head rebuilt.