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Discussion Starter #1
I have a valve seal that has leaked oil into the cylinder since I bought my 1600 Duetto in 2008. I replaced them when I did the head gasket earlier this year. It started leaking, and when I removed it it was oval. Assuming that it could have been an installation error I replaced it again, with same results after a couple of hundred miles. Compression is 200 PSI across all 4 cylinders, so I'm sure it's not a ring problem. The head was refurbished just before I bought the car. I'm thinking (a sure sign of trouble) that perhaps a bad guide was replaced in that cylinder with one that requires a Teflon seal. Is there a way to tell the difference between the two types of valve guides with the head on the motor?
 

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This is pretty tupical of a worn guide itself Tom. The valve is pushed open at an angle, wearing the seal and guide further, but the valve closed, sits straight on the valve seat. Unfortunately there is no easy way to check this without disassembly. If it's just one guide (probably not), you will not be using a lot of oil. Into early 1600 production there were no guide seals used.
Just my opinion as usual.
 

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Discussion Starter #3
Thanks Gordon. It's not burning much oil. The only time there's any visible exhaust smoke is after driving hard, and letting it idle. No visible smoke under normal driving, or cold start up. I'd just like to have it perfect. This is seat season, and wrench season is just a few short months away. I think I'll worry about it then, and just enjoy the ride for now.
 

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Richard Jemison
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Guide

The guide on that valve may be set too high in the springpan causing the valve keepers (collets) which hang below the spring retainer to hit the seal.
Common problem with the long guides made for teflon seals which are tall themselves.

I use short guides (from 3.0 V6 exhaust application) in every head built on intake & exhaust, using short green viton seals.

The total height of the installed guides should be 11mm total above the alum floor of the spring chamber.
Then there`s plenty of room for cam lift (with the correct springs) up to 13mm lift.
 

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I vote for the tall guide.
 

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Richard Jemison
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Guides

I vote for the tall guide.
Why? The short guides are adequate for the factory application where a rocker arm opens the valve? Lots of side loads opposed to a cam follower pushing strait down?

You can`t get clearance for any increase in valve lift with long guides.
 

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I meant that as the source of the problem. Either it has the white teflon seals that are taller than the green or stock ones or the valve guide wasn't driven deep enough or a combination of the two allowing the retainer to mash into seal. I could have been more clear.
 

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The guide on that valve may be set too high in the springpan causing the valve keepers (collets) which hang below the spring retainer to hit the seal.
.
I had evidence of this on my head. The PO installed high lift cams with out regard to the clearance.
Also not all guides were set at the same height causing damage to some but not others.
 

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That will do it!
 

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Discussion Starter #10 (Edited)
Is the 11mm from the spring pan with or without the seal? I installed the new seal with the motor in the car. The valve kept sliding towards the piston which was at TDC. I had quite a bit of leverage with the spring compression tool I was using. Could I have shoved the spring retainer onto the seal causing the damage? I haven't taken it apart yet. I replaced the head gasket last spring, and while I had the head off I lapped the valves replaced the seals, and checked the guides for looseness. The guides all seamed tight to me. When I take it apart I'll push the valve out of the seat, and see if it still feels tight. My cam is a 10548 10.1 mm lift I believe.
 

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Generally loss of one seal is not an issue. As mentioned, Alfa never used them until later 105 1600's. The Ferrari V12 single cams never used them until '68 with the Daytona. All those engines smoked some even fresh. It was expected and does no harm. The famous "Italian Tune Up" was devised to burn all the oil fouling off the plugs so these engines would idle (for a little while anyway). When we first started using these on the Ferrari's, they were teflon, and were called Raymond seals (no relation) The 12's would usually pop a few off, known politely as "seal rejection" to V12 builders. This doesn't happen anymore, but when I last rebuilt my 275 engine when I was MUCH younger, it quickly rejected 3 seals which I picked out of the oil pools in the head as I did valve adjustments. So I've only had 21 of them for the last 20 years or so, and yes, I can tell which cylinders when I check the plugs. I doesn't matter to me. It runs fine, and so do the Alfa's that lose one or two.
Come to think of it, I don't believe my GTA engine ever had any either.
 

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Richard Jemison
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Seals / guides

Is the 11mm from the spring pan with or without the seal? I installed the new seal with the motor in the car. The valve kept sliding towards the piston which was at TDC. I had quite a bit of leverage with the spring compression tool I was using. Could I have shoved the spring retainer onto the seal causing the damage?
Instalation crushing is common when the seals and guides are set tall in the pan.

Your stock cams shouldn be the issue as "stock" unmodified Alfa internals will clear 11.2mm cams.

But to be clear, the 11mm overall height from the floor is just the guide, no seal and only applies to the short guides. You cant set long guides that low.

Teflon seals are too stiff to work if not straight on the guide. As well they are easy to damage.

Since your head has had guide replacement at least once, and metal is broached out of the head as guides are removed I suggest this time you order the .002 oversize guides from Centerline which will take the short green seals,
and cut them to the length of the short V6 exh guides before installing. Otherwise you run the risk of having loose guides. Other option to insure they stay in is to knurl the short guides before installing.

FYI:
This week I was building a performance head (late `80s Bosch) and after cutting the seats open (I use the old guides for the initial enlarging then remove the guides for porting work) I removed the "Virgin head`s" guides. After finishing the port work I started to replace the guides with short ones. All were fine but one! The guide in #1 intake was .5mm (.020) larger in outside diameter than all the other "std" guides. No such replacements so I bought a stick of bronze and machined a guide the correct diameter and matching length and seal mount to the other guides.

Finding this "factory patch" was really aggravating since no replacements are available.
I have found in V6 heads several of the std oversize guides (.002 /.05mm) in them from the factory.
 
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