Sorry for posting here I seem to get the best responses here, and I troll around this forum a lot Anyway...I recently took a head to a local machine to install some valves and do some angles etc..(I have never used this local shop before but he came highly recommended so I tried him).

Call us primitive but my tuner usually pours gasoline down the valves to see if it seats, usually we expect that it would seal if no liquid would pass through. The valves all leaked, so I call the machine shop and he says that our testing techniques are outdated and the valves will set on their own. He also says he uses a 45 deg on the seat and a 44 deg on the valve and that this is the modern system.

My question is, are the valves supposed to leak gas and then seat later? I dont want to put up the head only to realise this guy is BS when I lose compression. Can anyone tell me how to simply test a well seated valve.

Thanks in Advance...

 

They shouldn't leak at all. You can test them using vacuum on the manifold side and spray some water on the valves to see if the vacuum sucks the water through. That is the way I do it and it shows me where the valve is not seated.

 

Cmon guys someone must know this answer

 

my guy always vacuum tests the ones i send him.

 

Using a 44&45 degree seat angle is old tech.It acually has a better chance of sealing a liquid that way.If it won't seal now it means the valve seat isn't concentric to the guide or the valve face isn't concentric to the stem.The standard valve jobs I do get vacuum tested and the race car stuff gets check with a concentricity gage.Its very easy to "steer" the pilot that goes in the valve guide because of the small diameter and mess up the seat.The "gas test" is still a very valid quick check.

 

it's been my experience that if it leaks with the gasoline(or some other liquid) it's not going to seal on the motor. Altough, I have seen the valve job beat itself in and seal like the shop was talking about.
I have no idea what you have available as far as parts stores in Trinidad but my suggestion would be to get a lapping stick and some lapping compound (medium grit preferred) and try lapping them in, pay attention to where and if the valve job comes in on the seat and on the valve, you should have a sixty to eighty thousandths thick line on both that is very visible and dark. if you do put it back together and try your test again.

 

Doing a valve job on a honda head is very hard not many shops have the right eqipment..

If it leaks its gona take a while too find its home and probally put puck marks on the valves

 

I would think that they should not leak any gasoline. I still use that technique for a quick check. The 45/44 degree trick I believe was used back in the days when they said the spring would pull so hard on the stem that the face of the valve would bend one degree and therefore be matched up. I would not think that would be applicable to ss valves. You might try hitting the top of the valve stem with a hammer hard enough to unseat the valve for an instant and try the gas trick again. HEADS idea on the lapping compound is a good one if you have the ability to pull the springs. Basically I think your head guy screwed up.

 

Thanks guys your the best.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by earl &raquo;</TD></TR><TR><TD CLASS="quote">. Basically I think your head guy screwed up.</TD></TR></TABLE>

Thats what I thought when I first heard it. It will be the first and last time I do any head work on this island

 

You might want to lap the valves lightly and see if that will make it seal. If that it doesn't "clean up" with a ligth lap then your valve job won't last long.

My head guys also vacuum checks for seal.