well its about time to start my engine rebuild..

was going to decoke the heads and regrind he valves into the heads, is this a good plan? anyone had experince in doing this? cheers

 

bump any advice?

 

do you mean "lapping" the valves?
Ie you add a little lapping paste and then swivel the valves back and forth withh a rubber plunger on a stick.

Have seen it done, cannot comment on the benefits though.

 

you have to re check valve clearances after doing this.

 

Only really if you want to flow the heads, More beneficial to N/A tuning so ive heard

 

Suggest you speak to someone like David at APi for some good advice on engine building, mate.

Ns04

 

ok cheery for the replys

will give an expert a phone

 

its always a good idea to re lap the valves in my opinion. Over time it is possible for carbon build up under the valves so therefore not seating correctly which could lose a bit of compression (probably nothing major). If the engine is in bits then I personally would do everything I possible could to get it in the best condition possible. Just my opinion

 

thanks for that.

thats kindo what i was thinking, is it a big job re shimming the valves after you lap them in?

 

If the original engine has done 50,000 miles or more,you will probably find pitting on the exhausts seats which in turn reduces the sealing of the valve on the seat.
A de-coke and light lapping in of the valves normally restores the contact area.
Dont forget to replace the valve stem seals while your at it.
Shimming is pretty straighforward once the heads are torqued back in place on the block.
As mentioned above - give David @ API a ring/email for advice and parts.

Mick

 

iv just done the lapping and re shiming, check my project, wrx forged rebuild,

when lapping use a coarse paste 1st and grind valve into head, then onto a fine paste, clean both arease and ul see nice shiney mating surfaces, on the vales look for ant small pit of black carbon deposits, if there are still pits in valves re go sequence. usually only need 30 seconds a valve. surprising how quick the paste cuts. a light spray of wd40 on seat help, u can feel paste grinding better.

 

Perfect thanks for that.