Stock Valve Question. Please Help.

Sievers · Oct 26, 2009, 07:58 AM

Is there a difference between factory exhaust and intake valves? If so, how can one tell which are which? I have to put some in a bare head of mine and need to be sure that it is done correctly.

Sorry if this has a very obvious answer. The valves are at home and I have not had a chance to look at them.

Thanks in advance.

Ryan

tkklemann · Oct 26, 2009, 08:15 AM

Intake valves are larger than the exhaust valves.

Sievers · Oct 26, 2009, 10:56 AM

Ok thanks.

I figured as much because that is how it is on almost all vehicles.

Are there any different markings?

KenMasters · Oct 26, 2009, 05:04 PM

Exhaust valves are hollow and filled with Natrium.

HeadGames · Oct 26, 2009, 05:09 PM

well....it kinda doesn't even matter if you didn't know, because the seat is different sizes. It would be like putting a square peg in a round hole, it would be so obvious if it was wrong. Your safe!!lol

Put some oil on them or Lucas additive on the stem before you stick them in.

JohnnyTSi · Oct 26, 2009, 09:31 PM

Intake Valve head diameter should be about 34mm
Exhaust Valve head diameter should be about 30.5mm

John-

94AWDcoupe · Oct 27, 2009, 03:02 AM

Quote:

Originally Posted by HeadGames

well....it kinda doesn't even matter if you didn't know, because the seat is different sizes. It would be like putting a square peg in a round hole, it would be so obvious if it was wrong. Your safe!!lol

Put some oil on them or Lucas additive on the stem before you stick them in.

guess you never took an engine apart and found the intakes mounted where exhaust should be and visa versa. I HAVE.

the intakes are marked 6T the exhaust are marked 6N, but yes intakes are bigger and should be installed in the bigger seats.

Sievers · Oct 27, 2009, 03:57 PM

^Seriously? And it ran? If so, I have no idea how.

Headgames, I do know that there is a pretty big difference in size between intake and exhaust. The reason I was asking about any of this is because I have two full sets of valves (both intake and exhaust). Both sets have the same markings on the valves but when you take a micrometer to them there is a fairly large difference in size. I guess I should of made that more clear.

Anyways, I figured everything out last night.

HeadGames · Oct 27, 2009, 07:55 PM

Quote:

Originally Posted by 94AWDcoupe

guess you never took an engine apart and found the intakes mounted where exhaust should be and visa versa. I HAVE.

Holy crap no!lol And the guy was probably wondering why it wouldn't run...

Quote:

Originally Posted by Sievers

^
Headgames, I do know that there is a pretty big difference in size between intake and exhaust. The reason I was asking about any of this is because I have two full sets of valves (both intake and exhaust). Both sets have the same markings on the valves but when you take a micrometer to them there is a fairly large difference in size. I guess I should of made that more clear.

Anyways, I figured everything out last night.

My post was one of confidence, I thought you asked the question perfectly...People who are not afraid to ask questions usually get it right is what I have learned.

Did you use anything on the stem?Lube I mean..

Tonba · Oct 27, 2009, 08:04 PM

^ My engine builder isnt too keen on putting oversize valves into my head. He seems to think its over kill...

What do you lot think about 1mm OS valves? Worth the hassle or not?

sparky · Oct 27, 2009, 09:27 PM

Quote:

Originally Posted by Tonba

^ My engine builder isnt too keen on putting oversize valves into my head. He seems to think its over kill...What do you lot think about 1mm OS valves? Worth the hassle or not?

If I am not mistaken, 9sec9's record setting Evo has a Buschur Racing ported head with stock-sized valves. You might want to PM 9sec9.

HeadGames · Oct 27, 2009, 11:18 PM

Quote:

Originally Posted by Tonba

^ My engine builder isnt too keen on putting oversize valves into my head. He seems to think its over kill...

What do you lot think about 1mm OS valves? Worth the hassle or not?

unless your making over 1000whp it's not worth it..listen to him

Tonba · Oct 28, 2009, 02:58 AM

^ Then whats the go with all these 'race heads' by cosworth, etc running oversize valves?

HeadGames · Oct 28, 2009, 09:53 AM

what sounds better... stock or oversize?

The marketing works, everyone thinks you need it. But bigger does not always mean better, or better for you. It's just big. And to be honest, some use it to gain the flow or peak number that sells heads. The head will flow more at .500 lift, which is the number people give you when you ask how much their head flows with the oversize. We concentrate on valve job technology to combat the need to go oversize. Constantly updating and learning on the flowbench about angles and widths. We have made about 1000+whp in almost every engine combo, Honda, Toyota, Mitsu, Nissan, etc...with stock size valves, so I can't imagine why a car making half of that would need more. We have even set world records with stock size valves!

It's a up hill battle to convince people that less is more...