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Discussion Starter · #1 ·
We have been freshening up a 76 2.0 litre head and after grinding we found this stem seal issue! The guides are not stock, or appear to be Centerline! They are for a 9mm stem! The boss or top is only 10MM OD. Much thinner then the 11.5 stock guides. Therefore the seal fit is loose and sloppy! I hope to post pics tomorrow! Hoping someone might recognize the guide so we can find a seal to fit! Thanks S
 

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Richard Jemison
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Guides

There are other engines makes that use 9mm valve guides, many with the same OD and length so they fit. (Mercedes for one)
Seals can be purchased by dimensions (ID/height etc)

There are different size seals mounts on Alfa guides. What you have seem fragile but they probably need changing out anyway.

I use the same short guides for everything. (4 cyl and V6) They use the "Green" viton seal (again shorter than others) that is available from Centerline.
 

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Excellent pictures! I used a teflon seal on the last refresh of my own Ferrari 275GTB heads. The engine has gradually been rejecting these over the las few years. As the engine was originally built without any seals, it just smokes some, and I know where the oil goes!
I have since gone with RJ's green viton seals on Alfa heads and had no issues.
 

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Richard Jemison
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Teflon seals

Teflon seals are taller which is a real issue with heads using higher lift cams....

Better to avoid them than have a problem or a future problem if you want to change cams....
 

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I 2nd that. I had the white bind up on one head. And I have never seen a bad green even on old heads still nice and soft. But stay away from the black they are junk and go bad in no time and become rock hard.
 

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Hope you don't mind me piggybacking on this thread. I believe I'm experiencing exactly the same problem.

85 2.0L Bosch head. I'm in the middle of a head-on valve seal replacement.
I'm using the green Viton seals.

Did 2 first on the Exhaust side, original seals were the basic blacks ones. Very hard to get off and disintegrated in the process. Replacement green ones were very tough to get on, but got there in the end after ruining a few.

Go to intake side to do 2. Basic black ones come straight off with almost no resistance. Go to put green ones one and they go on easy but popup when the valve moves, way too loose.

After seeing this thread I think the valve stems are different on the intake side. they look just like the ones above.

Questions:

1. Is it possible it came from the factory like this, I always assumed the head had never been rebuilt?
2. Gee, not sure where to go from here, I guess I need resized seal, but have no idea how to track them down.

Really appreciate any ideas.....
 

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Discussion Starter · #8 ·
How we solved it! I hope!

Indications showed this head had been worked before, The valves were stock! we never did make a positive ID on the valve guides! The old seals were destroyed black ones! We had to go by sizing! Found a Teflon that would work! Machinist said he had to machine the valve guide a little to make them work! I did not see that result! It is all back together and we hope to spark it tomorrow! If it is successful, i will ask machinist the details of the guides used!
Regards
S
 

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As has been mentioned, the intake side has negative pressure and seals are a plus. exhaust side is positive pressure and guide seals not required. In BOTH cases this assumes correct stem ti guide fit. Early Alfa's and Ferrari's (and many others) ran no seals on either side and survived just fine with only minor oil loss from this area.
 

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with regards removing the collets to remove the spring, what does the tool look like? Is it a fabricated workshop tool or a specific Alfa valve spring removal tool?

I suspect head on vs head off tool would be different also as with head off, the tool will clamp the valve in place as it levers the springs down?

With head on, how do you hold the springs up? air pressure through the spark plug hole?

Naive questions I know, but while i could work out a way to do it, I am interested in the right way..
 

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with head on, obviously air pressure is the professional way to remove a spring..........as a non professional (!), I did it on my old 101 simply by putting the cyl near TDC then feeding some nice flexible cable (houehold electric cable) in thru the sparkplug hole, winding it up the last bit to TDC to hold the valves nicely in place (bit like the old rope trick to lift off a stubborn, stuck head), then use one of those nifty collet removers as described in the tools section of BB!
for instance post 5 here:
http://www.alfabb.com/bb/forums/shop-talk/200214-valve-spring-compressor.html

sure there are better ways, but that worked for me!
 

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those tools seem to look like they will work for spring removal with head on, but assembling the spring/cap/collets system will prove much more difficult due to the control needed to depress the spring and engage the collets..

I have been thinking of a sparkplug hole mounted lever arm with a spring depressor. I haven't done the measuring yet, but i suspect due to the middle chamber plug hole, the valves will be the same distance from the plug on inlet and exhaust, so one tool will work for both sides.

Sorry for hijacking..
 

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The Alfa tool works with the head on or off with proper valve face support. That can be achieved with the rope trick very easily.
 

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Teflon seals are taller which is a real issue with heads using higher lift cams....

Better to avoid them than have a problem or a future problem if you want to change cams....
Had same issue with white seals, now I have green in there.
 

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Richard Jemison
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Valve spring compressor

The Alfa tool works with the head on or off with proper valve face support. That can be achieved with the rope trick very easily.
I have had one that has laid in the shop since the early 80` and is of later design with the pivoting mount to use on both 4 cyl and V6 engines.
I quit manual valve spring mashing with the invention of air cylinder valve spring compressors.

If someone wants an true Alfa Romeo Valve spring compressior it can be had!
 

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That is the BEST on Alfa made RJ. You even have the nice wood handle panels on yours! I'm impressed!
 
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