Leaking valves, Ahrghhh! Options

[doory100]

My efing valves are leaking! I lapped them down to the right height as suggested by delta cams. Now after installing the valve springs I poured some paint thinner in the ports to do a leak test and the thinner is coming out through the valves and into the combustion chamber. Any thoughts?? What did I do wrong?

[Bitter]

Well valves don't seal 100% when they're freshly lapped I think. I always thought they had to be run some like rings seating in the cylinder?

[doory100]

that's what I thought. are you sure?

[Smaay]

what did you set the valve clearance too?

[Bitter]

I'm assuming you have a nice even gray band all the way around and cleaned up all the compound before checking? Any compound left over will cause more leaking than normal. How much leaking are we talking about?

[doory100]

what did you set the valve clearance too?

the valve clearance is 0.006" on the intake and 0.008" on the exhaust.

I'm assuming you have a nice even gray band all the way around and cleaned up all the compound before checking? Any compound left over will cause more leaking than normal. How much leaking are we talking about?

Yes there was a grey band around the valves. I wiped up the compound with a clean rag when I was done lapping each valve. It is leaking slightly not pouring out but leaking.

[Bitter]

Might need more than a wipe with a rag, try a spray down with brake cleaner and a blast of shop air at 100+ PSI.

[doory100]

Ok but should they be water tight or do they need to be run a bit first?

[Bitter]

I think they need to run a bit first, you've got two porous surfaces.

[Box]

Like already mentioned make sure all of the compound has been removed. I'd also double check and make sure the springs and retainers are all kosher.

Another way of testing is using a pencil and marking the seat with straight lines every 1/16 of an inch apart, then rotate the valve back and forth no more than a 1/4" and if the lines smear evenly you're good to go. Of course that's before doing springs and etc...

[enderswift]

the pressure of compression and combustion helps seal the valves onto the seats

[RocketScott]

They should seal, there isn't a break in with valves like there is rings.

It takes a lot of elbow grease to lap the valves by hand. What I do is chuck a bolt in a hand drill with a rubber bumper on the end and let that spin the valve. Not so fast that it slings the compound off and not so much pressure that the compound gets oozed out. I usually check it with brake parts cleaner and it will hold that.

Did you get the valve seats refaced or are you just lapping in new valves?

[doory100]

I lapped in new valves with a drill. The drill had a rubber hose attached to a drill bit and the other end was attached to the valve stem. I would spin the valve and keep letting it up and down to lap it into the valve seat. I saw it on a you tube video. I had to lapp them pretty deep like .020" or so so they would be .008" EX and .006" IN. I am thinking I should go over them with the had lapping tool one more time.

once I get one out Ill take a picture and post it.

[TerryE]

You might want to take your head in and have it done by a shop that specializes in head rebuilds/valve grinding etc. before you end up buying a new head, new valves, new seats, etc. But it's your dollar. You do know that the valve seats have 2 angles on them? i hope you used proper lapping compound-Clover brand is the preferred type. There is a very expensive machine made by Serdi that is used for valve seats. P.S. you don't lap in valves with a drill-ever. You either do it by hand or with the afore mentioned Serdi, there's another brand too. Our machine shop did heads for customers, only two people were qualified to do the job. You are using "bluing"dye to check the fit? when you're done lapping the valve seat should be just as shiny as the rest of the seat.

This post has been edited by TerryE: Jun 2, 2015 - 1:41 AM

[TerryE]

P.S. Don't watch Youtube so much.

[doory100]

the only reason for the drill was that I had to set them in .02" or so in order for them to be .006 IN and .008 EX. I'd be there for a week If I did it by hand!! what will happen if there leaking and I install my head like this?

[doory100]

Here are some pictures of the valve stem seats.




bad pictures sorry

[Smaay]

what valves are those? they are NOT OEM

[doory100]

no there not oem. Why are you jealous?

Got them to stop leaking. Turns out they were dirty!