Valve Guides

coopa

Is it considered good practice to replace valve guides when fitting new valves (assuming the new valves have the same stem diameter as before)?

Under what circumstances, if any, is it ok to use the existing valve guides?

Thanks notsure.gif

vocky

I go by the mileage of the engine or whether there is a known problem - smokey on start up, damage to the guides etc

my z22se had only done 31k and I left the valve guides well alone

I would suggest having them replaced if you were rebuilding a head after a cam chain failure or if the head had done a high mileage - above 75k

but they should last well over 100k on a standard engine these days

coopa

Thanks Vocky, just looking at those SI valves. My engine has only done around 21K so the guides should be fine as long as the stem diameter is the same?

Working to a budget as well so didn't want to ask the engine shop to replace the guides unless necessary.

thumbup

vocky

are you getting the standard size heads notsure.gif

cheaper and probably not much difference power wise

JohnnyN

All my inlet guides were replaced after 36K. Had to have them specially made though. They were replaced when the head came off for the porting and polishing. They found the guides were heavily pitted??

what..

coopa

vocky said:
are you getting the standard size heads notsure.gif

cheaper and probably not much difference power wise

Yes, standard size.

All my inlet guides were replaced after 36K. Had to have them specially made though. They were replaced when the head came off for the porting and polishing. They found the guides were heavily pitted??

Worrying... I'm planning to strip the head before taking it to the engine machine shop so I'll be sure to check them over with my coughexpertcough eye. Why did they have to be specially made?

JohnnyN

From what I was told by the chaps at Courrtenays, the inlet guides are not available to buy from Vauxhall. I was told that you would have to buy a new head complete. The people who did the work on my head on behalf of Courtenays also do the work for Thorneys head work.

vocky

JohnnyN said:
All my inlet guides were replaced after 36K. Had to have them specially made though. They were replaced when the head came off for the porting and polishing. They found the guides were heavily pitted??

what..

very strange, mine looked as new when I checked them notsure.gif