valve stem clearance

Hello Tom,

After reading your next question I can only tell you that you need to replace your valve guides, because you add an extra 0.05 mm clearance.

When you order the new valve guides at Superformance you can have them replaced and the exact clearance can be made to the new valves.
If you don't do it this way you will have excessive oil burning and you risk your valves getting burned.

The new valve guides from Superformance can be installed by an engine repair shop and the valve seats have to be cut again.
When this work is done your engine will run like clockwork again after adjusting the valve clearance.

Succes

 

Andrea,

What material is used for their guides?

 

The material is a special type of bronze.

 

Bronze guides have been pretty much the de facto performance guides for many years. I assume (hope), though I do not know, that a Ferrari engine would come from the factory with bronze valve guides. Bronze guides can run half the clearance of cast iron guides. So while an engine with cast guides would normally run an intake valve clearance of from .001 to .003", the bronze guide replacements could use from as low as .0005 to maybe .002" at max. We generally used clearances of .001 to .0015 for intakes and about a half a thou more for exhausts. Large clearanced engines, which some people like to build, are often referred to "loose" engines. Folks claim that they make more power out of the box that way but it's just a license to burn oil. IMHO "loose engines" is just another term for sloppy engine building. Of course the "slop" inherent in factory engine building/clearance tolerances up until fairly recently was the reason that one new engine might burn a quart of oil in 6-700 miles and another new engine burn the same amount in 2000 miles.

 

Thanks for those replies.

Would that still be manganese broze? Just curious, as a friend used to export many tonnes of the stuff every month.

 

There are a bunch of different bonze guide formulations, Phospher bronze was probably the most common and it was used a lot to "sleeve" worn iron integral valve guides. Manganese-bronze was another common bronze guide material. Manganese-silicon-aluminum- bronze guides were considered to be the best by many engine builders as of a couple of years ago. That, like everything else, may have changed.

Note, I said "was" in my reply because I know what was what with this when I was doing it but I quit in '06 and don't want to speak as if what was true then is true now - I don't know.

 

Are you dropping the valves with the shop?

I'd certainly advice to test-fit the new valves in the exisitng guides before permanently fitting it all.

 

Per what Jack said - you absolutely need to check the valve to guide clearance and further, I suggest you do NOT put new valves in old guides. I know people do it all the time but it's not the proper way to do things on an engine that isn't going to be "refreshed" regularly (like a competition engine). I don't know if you are trying to do this yourself but if so, I do not recommend it. Take the heads to a shop, have new guides installed and the valves/seats machined properly. This is a very critical area both for engine breathing and oil control. Minor flaws in setup will have a noticeable affect on potential power and oil use.

If you do this yourself - and certainly people do - unless you have the EXPENSIVE equipment necessary, you can only provide a single-angle valve seat. This is not efficient and even in the 60's a 3-angle valve job was common for performance engines being reworked. 5 angle valve jobs were common for performance engines as of a couple of years ago but the actual application for the engine will dictate the optimum type of seating. A good multi-angle valve job will essentially add several tenths of an inch of valve lift without actually changing the geometry of the valve train. This is "free" HP. It's free in the sense that no performance parts are required with associated reliability issues.

 

Reading back through one of your posts, this engine at a mere 27K miles, had low compression in one cylinder, hence the terrible idle. Although replacing the exhaust valves (worn and sodium, I presume), will solve the problem at hand, how will this fix the problem, long term?

Valve to guide clearances are typically.0009-.0019" on a 2-valve. With unknown guide clearances...and likely tapered bores, your "valve job" likely will be very short lived, as the valve is going to be flopping around inside the guide. Other the higher than normal oil consumption and accelerated valve seat wear, which will result in doing this job all over again far sooner than you really should have to, what's the "upside", other than you'll get the car back on the road sooner versus later?

I'll agree with you that practical doesn't apply to an "Fcar", but why not just spend a tiny bit of extra time and money...and do it right the first time, so that you can enjoy the car the way they were meant to be driven?

Mike996, in his earlier posts, give some great, solid advice on how to properly do this job. I don't think there's an engine builder in the world who would disagree with what he's saying!

Best,
David

 

You're welcome...and sadly, more than a few motors (that I've seen) have left the factory with "loosey-goosey" valves. Sometimes you just have to whip out the old yardstick to measure the valve slop...LOL!!!

Good luck with your car!


David

 

Isn't there a better oil seal to use, than the OEM one???

 

The seal shown by Ricambi for use on the 328 looks like a modern, good quality seal. As long as the seal is something like that - a positive seal that firmly attaches to the guide as opposed to an "umbrella seal," it is about as good as you can get. As a side note, in engines that used umbrella seals originally, the guides have to be machined to accept the positive seals.

http://www.ricambiamerica.com/product_info.php?products_id=199328

 

Yes, there is...

It may look like quality seal, but it's not!!!
This is the same old crap that has been in the engine kits for years. As I recall, it's the very old Perfect Circle T9010 seal.

The ideal seals for these cars are what's used on a BMW M5 and certain VW models, depending on if your engine uses a 7 or 8mm valve. These stem seals are made with viton, typically green in color...and do a far between job of controlling oil, particularly as the engine ages since the "sealing" part has a bit of "give" to it, versus the rigid telfon seal.

David

 

Thanks, David
That's what I was recalling, I guess, the BMW alternate...

There ya go, lostbowl, that'll help some....and use those NGK BP5ES flamethrowers....you'll be golden.

Alan

 

........and send me one of those valves you drop on the floor, JRV's not around, to school me, anymore.....

 

David, good info! I was just looking at the style of seal - a positive seal - when I made the comment. I wasn't thinking at all about the material itself.

 

Mike,

It does look like a great seal...but,

a) The fittment is way too tight on the valve stem
b) Over time, they get brittle
c) I've seen too many of them break apart and end up in the oil pan
d) As the guide wears, the seal "hole" tends to elongate...giving up oil control

The "softer", more resilient Viton seal doesn't look as purdy, but sure is more functional...

Best,
David

 

The seal info is good, but needs its' own thread. I was under the impression we were talking about exhaust valves? Wrong side of the head!

 

Probably I just mentioned it, as he is that point of disassembly and the valve guide discussion brought it to mind......