STI3 valve inlet clearances of 4/5 thou
 

Just stripped the heads off my engine and checked the clearances prior to to removing the cams/heads.

The exhausts are pretty much all around 10/12 thou but the inlets are all below 8 thou with some at 4 or 5. So after grinding the valves in these are obviously going to be even tighter.

Is it better to buy new shims or just have the machine shop I use take the required amount off the valve stem? Or is the latter a bad idea?

Thanks for any advice,

Wayne.

Its fine to 'tip' the valve stems a couple of thou for clearance.
Clearances should be 0.006 ~0,008" on the Inlets and 0.008~0.010" on the exhausts.
I do have a fair selection of STi under bucket shims if you get stuck.

Mick

Cheers Mick!

I'm just in the process of stripping and cleaning the heads and have found the valves and seats to be in very good order. I'm wondering if they weren't set right the last time the engine was apart. I'm also wondering if this contributed to my hot start problems along with pistons that have excessive movement in the bores. I've a new forged short motor by Andy Williams to mate these heads to.

Wayne.

Usually the exhaust clearances which close up so yes, maybe they were set incorrect last time it was apart.

I'm thinking that they were.

The heads are flat so won't need a skim, just cleaning as I can't get a 2 thou gauge under my straight edge.

The valves do have some play in the guides so I'm wondering if these are diy replaceable or if they need a machine shop to sort?

Have I read somewhere about unscrewing the gallery plugs to clean the heads?

A decent machine shop will K-Line the guides back to spec and yes,remove the 5mm allen key oil gallery plugs to clean any possible bearing debris out and don't forget
to remove the oil restrictor (drift it out from the opposite end ) in each head prior to cleaning the gallery's and then refit it.

https://cimg9.ibsrv.net/gimg/www.sco...257404e894.jpg

Machine shop say they never take the oil plugs out of the heads they do and they do a lot for the local subaru specialist in my area. I've used them for nearly 30 years and never had a problem. So it's up to me to remove them, which I will do.

Guides are within tolerance according to them so they are staying as they are. I think I'm just being paranoid about what is very little movement.

They are going to clean the surfaces by 2 thou for me so happy days. I'm going to lap the valves in first and then take them out before the machine work. New valve seals to fit so might as well be after cleaning.

When I get the heads built up, should I set and check the clearances with the heads on or off the block, ie before the heads are torqued down?

I'll no doubt be in touch about the shims Mick and possibly another cam cap bolt as one is a different head size.

Anyway, it's going to be right this time ��

we always install the heads and then finalise tolerances as whilst not a major issue on std 11mm set-up its can vary massively on 14mm studs......

Cheers Alyn. I just didn't see the point in getting the clearances right just to take the cams out again 👍

Did you receive my 440cc injectors btw?

Cheers,

Wayne.