V11 Rebuild and customisation

[kglm]

..Heads.. and loose exhaust guide

 

-KG-

[gelos]

Hey does anyone know if its normal for the heads to show discoloration like that? Valve guides worn? Im replacing the valve stem seals , just wondering if thats normal though ..

My engine - heads were the same looks,exhaust valves and stems worn explicit to replace, any seals and gaskets, another parts keep in. IMO all V11 have not valve stem seals. You can use head gasket from Breva 1.serie Nr.GU03022055 is 0,80mm thinner, compr.ratio goes to 10:1.

[knumbnutz]

Yep, valves and guides are worn, no seals. So... Time to find out how much

 

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[Lucky Phil]

When I pulled the barrels off I thoughts, mmm thats odd, the ring gapss werent in perfect alignment but they certainly were closer than 1/3 of the circumference around from each other, maybe 20-30 deg.

But then the bore and pistons werent showing any signs aparts from the tiny bit you see inside the piston. No wear at all, bores, bearings - all good.

As a matter of course, i'll reseat the valves and check guides and replace seals.

The head discoloration is pretty typical from what I've seen, as for the ring gaps well the rings rotate in operation so they may end up anywhere. Aligning the ring gaps at 30deg intervals is all well and good when fitting but in practice they dont stay that way.

In some race engines the rings rotate so dramatically they wear the piston lands significantly.

Best idea is to K-line the guides. Of course if you have a loose guide then that needs repalcement. Have you physically checked its loose? 

 

Ciao 

[knumbnutz]

Yes, last night I took the valve springs off and checked guide wear. The valves stems have .5mm wear at the top and the guides, especially the exhaust, are very worn

 

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[docc]

Yes, last night I took the valve springs off and checked guide wear. The valves stems have .5mm wear at the top and the guides, especially the exhaust, are very worn

 

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How many km/miles on this '02 motor?

 

(And, wow, gelos:  +0,5 on the compression ratio from a gasket change? Sounds like either free horsepower or a formula for difficulties?)

[JRD]

Congrats docc- I was wondering who was going to be the first to perk up when they heard the compression ratio bump just by changing head gaskets.

 

Gelos- Just trying to confirm that there is enough clearance between the valves and pistons if we use the Breva head gaskets.  No other modifications necessary?

 

Thanks for the info

 

 

 

Jerry 

[Lucky Phil]

Yes, last night I took the valve springs off and checked guide wear. The valves stems have .5mm wear at the top and the guides, especially the exhaust, are very worn

 

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Loose valve guide means the guide is loose in the head as opposed to the valve being loose in the guide. As i mentioned earlier I would K-line it. K-line guide sleeves are superior material and will last a lot longer, interupted spiral grooved for oil retention and lubrication and the best part is you can avoid using the seat cutter. When you replace guides they never go back in parrallel to the guide bore as the one that came out so there will be valve seat cutting to do with a cutter. With the K-lines you dont have this issue so you can just lap them in and save seat material.

I've seen them used in street and race engines.

 

Ciao 

[JesterGrin_1]

 Since you have the valves out I will tell you an easy way to improve flow and reduce hot spots that will help reduce chances of pre ignition (PING).

 

 Chuck the intake valve into a drill press or if one must you can mount a 3/8ths drill that will enable you to spin the valve. Take  a fine file and file the back side of the valve head to a smooth transition to close to the seating area of the valve. If this is hard to see just simply go by an automotive parts store and purchase some fine valve lapping compound and I forget what it is called but it is a stick with a rubber suction cup on the end. Place the valve in the guide with some motor oil on the stem and put some valve lapping compound on the face of the valve that meets the seat and put some pressure on it and spin it back and forth and you will get a bright ring all the way around the valve and the seat. Or you should if everything is correct.

 

Okay for the Heat Riser parts round off the corners of the face of the head of the valves outer perimeter . A nice smooth round off. Do this for both the intake valve and the exhaust valve.

 

And before you ask it is not needed to do the back side of the exhaust valve but if you like you can do so. But the main advantage is flow into the combustion chamber through the intake valve. While the rounded off of the corners of the face of the valve reduce sharp areas that may become overheated to the point that they could cause pre Ignition. As for the face of the exhaust valve it will help the exhaust gases to go around the exhaust valve and exit

 

 As for valve guide seals many will recommend PC seals for the intakes and stock seals for the exhaust. The reason for this is the PC Seal will seal better for the intake valve thus keeping the fuel charge as pure as possible thus increasing BTU's in the combustion process. The stock exhaust valve seal is so it will allow a bit of more oil allowed to the stem of the exhaust valve to help aid in cooling of the exhaust valve.

 

 I could go into further aspects of porting heads but doing this can get someone into trouble real fast lol. But I will state that if you are bored you can smooth out the exhaust passage as smooth as possible as this will help increase exhaust speed thus help increase exhaust scavenging as much as possible. Do not re-contour anything. As it may look good but that does not mean it will flow good in the right areas lol.

 

Sorry if this was long winded.

 

 Just remember an Engine is in its simplest forms is an Air Pump. So any modifications that will help aid the engine with moving air will help the efficiency of said engine.

[kglm]

.. gap after 80 000 km , -fixed with K-line..

 

-KG-

[JesterGrin_1]

.. gap after 80 000 km , -fixed with K-line..

 

-KG-

So it looks like heads will need to be freshened up around 50,000 miles? 

[gelos]

I think valve to piston clearance with thinner gasket is okay providing stock cam. My measurement find about 6,2 mm intake, 6,6 mm exhaust side free play, valve lift on TDC is about 3,5 mm, it will run good.

 

[gelos]

K-Line guide sleeve, I've never seen this, it looks well and easy.

 

My old guides kept very tight in head, wear was on inner diameter especially on exhaust side.

My new intake guides are now 3mm shorter in port and conical form for better air flowing.

[Lucky Phil]

I think valve to piston clearance with thinner gasket is okay providing stock cam. My measurement find about 6,2 mm intake, 6,6 mm exhaust side free play, valve lift on TDC is about 3,5 mm, it will run good.

Whats the squish clearance with the Breva gaskets?

Ciao

[gelos]

The squish is 1,8mm, almost optimal value.