j16jrf

iTrader: (3)

Hi,

right got my heads back from the guy who as polishing and porting them. He was also triple angle grinding the vavle seats.

Now got it back and removed the rocker covers and the cams were tight as hell on the buckets i mean ZERO clearance. When the cam was at its lowest the valves are still slightly open.

So took them back to him today to tell him to set the valve clearances properly. His reply was that was easy he would just remove valves and grind a bit off the tail to make them clear.

Surely, me being no expert, i thought that was the whole idea of there being shimms in the buckets. you just replace them until they are at the right clearance?


Please help, is thie grinding down of the valve an acceptable answer? As obvioulsy the valve has that section at the bottom with the groove in it and taking too much off it could result in catastrophic failure.


Thanks
Jamie

wrxbart

iTrader: (5)

You should replace the shim with a thinner shim of the right thickness to give you the clearence you want,not grind the valve.

j16jrf

iTrader: (3)

thats what i thought too rob thanks.

cant wait to get this turbo bolted on

FB Tuning

iTrader: (30)

Yes, machining the valve is an acceptable answer, to a certain degree when rebuilding a head.

ONLY if the smallest available shim size is leaving you with NO CLEARANCE, then you'll eaither need to have a bit (accurately) machined off the top of the valve stem or have new seats fitted to give clearance back

If the top of the valve is to be cut down, you need to make sure that the valve stem remains higher than the retainer if using shim over bucket .
If using shim under bucket then obviously the installed shim needs to be higher than the top of the retainer

If the smallest available shim size still leaves you with no clearance, then It sounds like the seats may have been cut too heavily in the first place. - I've been there, done that, and spent a small fortune to recify

If this is the case, you might want to consider a shimless bucket conversion, as an acceptable solution to your issues.

j16jrf

iTrader: (3)

where would i get smaller shims from? and what sizes should i get?

wrxbart

iTrader: (5)

you can only find out what size you want by using a set of feeler gauges and measureing the clearance seeing what size it should be then you can calculate the thickness you want.If like you say there is no gap what so ever then you need to take 2 shims get them machined down so there is now a gap,then size all the valve clearences up using these 2 shims and calculate from there mate.You will need to know the thickness of the 2 shims when they have been machined.

FB Tuning

iTrader: (30)

...as above - feeler gauges and a micrometer required

wrxbart

iTrader: (5)

Oh i forgot about the micrometer

j16jrf

iTrader: (3)

cheers guys, have passed the info on to the engine builder and hopefully this time it is right.