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Rough guide for new exhaust valve
http://www.international2cvfriends.com/forum/viewtopic.php?f=4&t=4669		 Page 1 of 1
Author:  Hannahman58 [ April 7th, 2013, 8:56 pm ]
Post subject:  Rough guide for new exhaust valve
Just removed the head off my 2cv, removed the valves and found the exhaust seat badly burnt/ pitted!
Any idea what it will cost me to get them replaced with hardened ones?
Cheers
Paul
Author:  dave 411 [ April 8th, 2013, 7:19 pm ]
Post subject:  Re: Rough guide for new exhaust valve
How long is a piece of string?
If you buy the valves and do it yourself,(i shall now go to the ecas website and price the parts),about 40quid.If you take it to a garage,havent a clue.
If you do it yourself,make sure you lap the head in,very important.
Author:  toomany2cvs [ April 8th, 2013, 7:46 pm ]
Post subject:  Re: Rough guide for new exhaust valve
Hannahman58 wrote:
Just removed the head off my 2cv, removed the valves and found the exhaust seat badly burnt/ pitted!
Any idea what it will cost me to get them replaced with hardened ones?


They're already hardened. You're thinking in terms of cast iron heads, where often the seat was cut straight into the head, needing lead to stop valve seat recession - so hardened valves were needed as "unleaded conversions". Since a 2cv has ally heads, lead alone would never have been sufficient. Officially, only late 2cvs were "unleaded-safe", but they never made any changes to the engine that anybody's ever been able to point to. It seems the engine number they're officially "safe from" was just the engine they tested...

If the seat itself's that bad, it's probably down to a long-duff valve, mebbe originally because of badly adjusted tappets. The easiest solution is probably to put a better head on.

You can buy valve seats, but note the notes...
Author:  ken [ April 8th, 2013, 8:38 pm ]
Post subject:  Re: Rough guide for new exhaust valve
Paul,
if regular adjustment of the valve clearances has been neglected on one cylinder, there's a good chance the other side has suffered as well. Have you checked the other side yet?
It might be worth finding someone who can recut the existing seats, then fit new valves.

Don't forget to set the clearances slightly wider than the original recommendation, particularly for the exhausts, which will always close up faster than the inlets.
( 0.25mm 'loose' for the exhausts and 0.25mm 'sliding fit' for the inlets works OK for me.)

Last year, I recommisioned a 12,000 mile car which had been in storage for a decade or so and the exhaust valve clearances ( cold) were barely 0.05mm.
You can guarantee that would have suffered from burnt valves and seats if it not been laid up, as the main dealer in York wouldn't have checked them until 18,000 miles, or not at all if they could get away with it... :roll:

ken
Author:  Hannahman58 [ April 9th, 2013, 6:03 pm ]
Post subject:  Re: Rough guide for new exhaust valve
Thanks Ken, I've stripped the headsoffvmy other engine, and these look much better, should only need lapping in.
Bought a set of pistons and barrels too, so it should be quite smooth when its all built up!
Is there any way of cleaning up the cylinder heads to make them look more presentable?
I have a grit blasting cabinet, if I cover the working parts, do you recon it would give a decent Finnish?
Cheers
Paul
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