Interchanging valves

**T5frankie** · Saturday 10th May 2014, 10:49

I have another head coming which is an unknown quantity, now do i get this head, skim it pressure test it and fit new seals? all of which costs money, or take the valves out of it and put them in my head of which all the above work has been done this will cost me nothing, will there be any issues to me doing this? thanks

**stribo** · Saturday 10th May 2014, 11:06

Just as you wouldn't take valves out of a head and put them back in different positions, I wouldn't think it would be a good idea to change valves over from one head to another, as they all wear differently.

**merc85** · Saturday 10th May 2014, 11:12

Keep the same valves with the same head

**artfulflounder** · Saturday 10th May 2014, 11:16

But surely you would grind valves to valve seat so it wouldn't matter ??

obviously after checking stem wear etc was within spec.

**oblark** · Saturday 10th May 2014, 11:33

I would change the valves over.

BUT

I would check every valve you fit for play in the valve guides AND I would lap the valves in.

**merc85** · Saturday 10th May 2014, 11:51

Originally Posted by artfulflounder

But surely you would grind valves to valve seat so it wouldn't matter ??

obviously after checking stem wear etc was within spec.

There were a change of valve stem diameter's at some point, id keep with the matching valves personally

**JUDGENINJA** · Saturday 10th May 2014, 12:25

Originally Posted by oblark

I would change the valves over.

BUT

I would check every valve you fit for play in the valve guides AND I would lap the valves in.

What he said.... Worked on a Merc Cosworth engine years ago for full "blue printing" (not my project, just assisted). It didn't care that the valve orientation was maintained. Just that each valve was measured/inspected and carefully re ground).

**claymore** · Saturday 10th May 2014, 15:16

Like all moving components in an engine, they wear in a different way, I wouldn't even consider using different valves unless I was changing the valve guides as well, when you take a head appart, you put all the components in line so that they can go back in the same place, why do you think we do that?

**T5frankie** · Saturday 10th May 2014, 15:29

I thought so just best to get it confirmed

**smithy** · Saturday 10th May 2014, 15:30

Just put the head on that you are getting .but first have it pressure tested and checked over and skimmed to make sure its flat .i would not change valves in the heads .things you will have to look for in the bent valve head is the the guides might be cracked too