Valve grinding
Valve grinding
(OP)
I'm refurbishing a 16V cylinder head and was wondering if anyone has any tips on the details of fitting / grinding the valves.
I've been advised that the optiomal sealing 'line' width (valve to seat) should be around 1.5mm - 2mm after having ground to fit.
Any tips much appreciated.
I've been advised that the optiomal sealing 'line' width (valve to seat) should be around 1.5mm - 2mm after having ground to fit.
Any tips much appreciated.
Solid Edge; I-Deas 7 to 12; NX4 & currently NX5.





RE: Valve grinding
Regards
Pat
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RE: Valve grinding
While I suggest that - I have done the same as you explain - but on very cheap engines - lawnmowers, etc. and if I screwed it up - at least it ran a few more hours before totally shot. But a 16 cylinder engine is probably worth a few bucks.
RE: Valve grinding
Seek out a competent shop with a good reputation for servicing your particular engine. Finding the shop that the fast cars are using, if you are racing, is a start.
The best way to learn is to watch an expert. It is not rocket science but it does require a level of experience and a very conscientious machinist if you are looking for perfection.
Over the last 50 years, I did all my own valves. At my age, I don't have the steadiness or eyesight to do the delicate work any longer ;o( Now I farm out the head work. Our two race cars are now running "pro" built heads. Surprisingly, they were not all that expensive, considering the performance.
Rod
RE: Valve grinding
It does take a level of experience as Evelrod pointed out as well as time and constant checking ; all of which costs money.
Good luck with the rebuild and running.
Pete.
RE: Valve grinding
My local mechanic advised to just swap out the valves as is wih no prep./grinding. Its a modern VW golf head and he said that the accuracy of the modern engines / valves and given the relatively good condition of my current head, it would not warrant the need to lap in the new valves.
As an engineer I think that's a little optimistic but he claims to have had decent results from just swapping in the past and that the engines have subsequently been running OK without issues.
This engine suffered from water pump failure which took out the timing belt and bent some of the valves. (hey VW what a great idea - lets mount the water pump on the main timing belt!)- hence the valve work now required.
Anyway, I'll probably go and get a book on the subject or speak to the VW dealer.
Solid Edge; I-Deas 7 to 12; NX4 & currently NX5.
RE: Valve grinding
Rod
RE: Valve grinding
If worried about reliability some of the ones I have done have gone on another 200k or so miles and been happy enough.
very, very rarely will a cut seat and a valve actually seal right, even with decent equipment (topline serdi etc). I get the occasional joker wantign hand radiused seats and they don't care if the seals away in a few hundred miles.
Also 16 valves aren't much to do, try doing 3 or 4 16v heads a day though!
was it the usual plastic impellar slipped/broke thus allowing the pump to pull out and mangle the valves?
RE: Valve grinding
Yes it was the plastic impeller. It disintegrated and left bits of plastic all over the place. The new OEM one has a die cast impeller. VW live & learn. Now they just need to mount the pump on an aux belt (like they used to) and we'll be all set!
Solid Edge; I-Deas 7 to 12; NX4 & currently NX5.
RE: Valve grinding
It also drives the water pump of the timing belt. It seems they built in a double jeopardy.
Regards
Pat
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RE: Valve grinding
They changed the impellar to metal a while back, common issue with them. Working on heavies you see the same thing, Volvo FH12's are notorious for the impellar spinning on the shaft but not so much dropping off funnily enough. Gear driven off the cam gear on them.
RE: Valve grinding
RE: Valve grinding
I did the work over the weekend and refitted 16 new valves, seals, new head bolts/gasket, timing & cam belts & water pump. Started first time after the work. Car now runs better than it ever did. I think a saved myself about £800 compared to getting a garage to do it.
Solid Edge; I-Deas 7 to 12; NX4 & currently NX5.
RE: Valve grinding
Good job. I'm glad to see some engineers are not afraid to try something new. Watch the slippery slope, though...LOL
Rod
RE: Valve grinding
RE: Valve grinding
Solid Edge; I-Deas 7 to 12; NX4 & currently NX5.