Botched head job and burnt ground down valves

heapy

Member
Hello, i have just recently purchased a Mk1 2000sc auto 1970. I knew it needed engine work but have seemed to have opened up a can of worms.
I was told that "the previous owner" (that old chestnut) had put in hardened unleaded seats in/ on a car that had only done 35k from new. (this bit is genuine at least) If it ain't broke don't fix it !!
Anyway, the job was botched to say the least. the rocker cover had been thrown in and was leaking oil everywhere, it had indeed been opened up as the head gasket was new. the exhaust valve seats were a shiny different colour than the inlets and are made of stainless steel i have now found. Does this mean they are hardened? or were they SS from the factory?? they also look like they have been replaced by a proper workshop.
The valves had never been lapped in either (presumably when he got it back) ... 2 of the exhaust valves were cracked and melted but luckily the seats are all fine so we have been cleaning up and lapping everything. however on receipt of 2 new exhaust valves i noticed they were both one millimetre taller!! Wondering if they were wrongly supplied i paired them up to the old ones, to see that every valve has been ground down on a bench grinder by 1mm!! assuming to avoid shimming ?? In the buckets there is only 1 shim in each and all the same size.
So my question is now, not having the manual to hand, is this disaster? Does every valve have the same tappet clearance ? ie inlet to outlet, if not what should they be? i have also looked at the link in a previous thread for shim calculation but its for a 2200.
Can i get away with the valves seeing as they've already been done or do i have to buy the blummin lot again plus shims now? bearing in mind the re seating will have probably thrown off the original gaps too. the valves are all 120.00 mm long now.. :/ :/
Many thanks.
 
Last edited:
I think the valve clearances are the same for all 4 cylinder engines. Inlet 0.008" - 0.010" Exhaust 0.013" - 0.015" If that helps.

Cheers,

Steven
 
I had the same problem with my 1976 Kawasaki engine. Someone had ground the valves down as the shims were at their thinnest, and couldn't go any further.

I had to remove the head and get a new set of valve seats fitted, then a new set of valves. Mine were however ground down too far and the inside of the bucket was actually hitting the collar instead of the top of the valve. How on earth the collets didn't shake loose, I'll never know.

The engine shop has seen this valve grinding before and it seems that it was common practice. As long as your shims/buckets are hitting the valve itself, and you can set the clearances, then there shouldn't be a problem with the shortened valves.

Personally, I like things right, so went ahead and put the whole job back to standard, as I really don't want to be taking the motor apart again any time soon.

Hope this helps

Richard
 
Back
Top