need advise on valves please
Turbo Mini Forums

hello peeps i need some advise on valves, i am in the process of building up a turbo engine, i started digging out the head but need to decide on valves before i go any further, i got hold of some big valves out a old Slark race head, they are stainless and in good condition 37.88 inlet and 31 exhaust, now the problem is that they touch when put in a head with standard size guides , so i either need to use offset guides or turn down the inlet valve a mm or so for the clearance. i bored the engine +0.20 and using the omega cast pistons and a mg metro cam. if i use offset guides i am not sure if i will have the clearance in the top of the cylinder. how should i proceed cheers in advance guys

Attachments:

72.7kb

71.51kb

80.84kb

You'll be fine offsetting a 31mm ex valve. The inlet wants reducing to about 36mm to leave some decent material between the valves. This will also give a better size ratio for a Turbo motor.
Has somebody been running sandpaper around the stems of the big inlets ? They look very rough.

Phil.

Edited by Turbo Phil on 23rd Jan, 2014.

WWW.TURBO-MINI.COM

the comination of 38's and 31's are probably going to lead to cracking between the valve seats,

36 & 31 would be the biggest I would go

cheers for the advise, are 36 inlets what are in big valve metro heads as might have a set knocking about, and not to sure about the stems on the big inlets will have to inspect them, so offset the exhaust valve guide and use the 31mm exhaust valve, and source a set of 36 mm inlets cut the new seats and jobs a fish :), any advise on valve guides i presume bronze, also are the standard metro double valve springs ok they have shrunk abit from whats stated in the haynes , as theirs a set of doubles which came with the slark valves which i believe are kent. cheers again guys

big valve metro's are about 35mm

Regarding the springs, if you're using much over standard lift & 6,000rpm then the stock springs are no use. I wouldn't use them anyway due to their age.
The big valve MG valves are 35.6mm {commonly reffered to as 36mm} so will be spot on. Use bronze guides.
The Slark springs may be OTT if they have been used in a high RPM NA engine.

Phil.

WWW.TURBO-MINI.COM

36 and 31 - i totally agree with Joe C. Good quality new valves/bronze guides or kliners are relatively cheap and a good investment in my opinion. good luck with the build

Cheers Paul, where can i get 4 offset guides from cheers

I don't think there are any offset valves available off the shelf. I make all my own for my heads.

Phil.

WWW.TURBO-MINI.COM

Fancy selling four ? how do you make them on a lathe as getting my hands on one soon and would be a nice project cheers man

Yes, on a lathe mate.

Phil.

WWW.TURBO-MINI.COM

will i have to worry about the valve spring not being 100% straight ? sorry for all the questions just trying to get my head round it lol

The head needs machining to, to allow the spring to move accross.

Phil.

WWW.TURBO-MINI.COM