Lapping Valves

[triggerx]

Is it really that necessary? Im getting brand new valves from partdinosaur so Im curious to know if you guys just pop the valves in and call it a day.

 

[BurrowZ]

Yes, lap them.

It's easy and doesn't take THAT long. But does require patience.

 

[bradselph]

Yes its should be done, will it run without doing it? Sure but it will be crap.

Its not hard to lap the valves just time consuming.

You must also check stem height with the new valves.

Cylinder Head 105 - Valve Job Basics - YouTube

 

[JacksonAuto]

If the valve job is good, then lapping should take a minute or so per valve. If the angle on the valve or the seat is off by just a fraction of a degree it will take forever and it still wont come out right. If they dont come in right away, its best to use a stone or cutter to face the 45* angle on the seat and also grind the 45* angle on the valve (many times the angles on the cheap valves aren't precise). Once you've got the angles to agree with one another, lap the valve and it should come in almost immediately. Be sure to use some machinist's dye to color the seat so you can see your work and how it's coming along.

A quick note on the importance of a good valve job:
The 45* angles on the valve and seat must mate perfectly. Not only does this seal the valve from allowing gasses to escape but more importantly is provides the correct area of surface contact to allow the heat from the valve to dissipate into the head where the coolant can take it away. With not enough contact area, heat will build up in the valve and it will "burn". Lots of bad things happen here. The valve can overheat and burn, it can warp or it can seize in the guide.

 

[bastarddsm]

Too add to JAM's post, I always use some machinest dye (black sharpie ) and "paint" the seat and the valve and "lap" it in without compound. Where the dye is removed is the contact area, and this helps you ensure the contact area is good before you attempt to lap the valve. If you lap it and find the contact area sucks you have to cut the seats, and re-grind the valve too. It will be hard to find the "new" seating area, if there already is on on the valve. My method save you from re-grinding the valve.

Here is a picture to get the idea across:

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[triggerx]

Thanks a lot for the tips everyone, much appreciated.
I got the head off(ugh again after the oil pump sprocket nut ruined the job the first time).
After visually inspecting it, it only looks like 1 valve is bent. It was the only one that didnt seem to seal all the way since you could see light shining through the valve. So it looks like it was just the one intake valve, but Ill be replacing both of them in a pair.
Since Im lapping these two valves, do I also need new valve guides?

 

[NHerron]

I don't mean to be a pessimist, but it probably is not just be one bent valve.

Flip the intake ports upward and fill them with water. Let them sit for at least an hour and none should be leaking.
Do the same for the exhaust valves. Note that one exhaust runner/valve, which is located FURTHEST from the cam gears, will leak some water out. This is the for the EGR system, which runs to the intake side of the head.

(This video starts with filling the chambers/domes but just skip ahead)
Cylinder Head 102 - Hydro Test Valves - YouTube

 

[JacksonAuto]

I don't mean to be a pessimist, but it probably is not just be one bent valve.
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+1

Even if others aren't bent, they wont seal because of wear or other damage. These engines are getting up there in age and very very few are able to be rebuild by just lapping the valves and installing new seals. And 80% of the time the guides are worn which makes doing a valve job nearly impossible because the tools locate off of the guides. If the guide is sloppy then when you machine the seat it's going to be off.

 

[BogusSVO]

For turbo use I would not use the cheap replacement valves, some are a 2 piece construction and the head may pop off.

Find a set of OE "6T" valves or go stainless steel, like Engnbldr if you want an economy valve.

 

[triggerx]

For turbo use I would not use the cheap replacement valves, some are a 2 piece construction and the head may pop off.

Find a set of OE "6T" valves or go stainless steel, like Engnbldr if you want an economy valve.

I see what you're saying, and i definitely agree with quality control. The valves I ordered are from enginetech, you think those would be sufficient? Here's info regarding the product.
Enginetech Standard Valves

Something u said in an old post bogus,

they are, and probly made at the same factory too, I have lots of engnbldr parts over the years with out issues, same with engine tech parts

Hopefully that applies to their valves as well.

Also we lapped the New valves, and no leaks. Unfortunatel after testing the intake and exhaust side, some still leak a bit. So my question is, when doing these tests, how much leakage is too much? ### a few valves just barely leaked, like a drop every 2minutes or so

 

[BogusSVO]

EngineTech and Engnbldr is not the same company.. at all or in any way.

EngineTech is a rebuilder supplier, I would call and ask if the valves are a one piece or 2 piece design.

 

[triggerx]

EngineTech and Engnbldr is not the same company.. at all or in any way.

EngineTech is a rebuilder supplier, I would call and ask if the valves are a one piece or 2 piece design.

Thats what Ill do tomorrow then, Ill give em a call.
BTW Bogus, Ive read some of your posts while researching and you have some very useful posts.
Seems like you rebuild a lot.
How much dripping is too much dripping when doing the water test?

 

[JacksonAuto]

How much dripping is too much dripping when doing the water test?

Any at all is unacceptable.

 

[TalonJohn94]

Sunlight is thinner than water. Use that.

 

[JacksonAuto]

What I typically do is spray WD40 or soapy water on the chambers and blow compressed air on the back side of the valve. If you see bubbles you've got a leaky valve that needs attention. Quick, easy and accurate.

 

[triggerx]

What I typically do is spray WD40 or soapy water on the chambers and blow compressed air on the back side of the valve. If you see bubbles you've got a leaky valve that needs attention. Quick, easy and accurate.

I really need to invest in an air compressor.
What do you all suggest is the problem if an intake valve still leaks after inserting a new one in and relapping it? A spring?
The drip is very minimal, and at 170,000 miles doesnt look like this head has ever been touched to be honest

And BTW Bogus I called them, they werent very knowledgeable on their own product, I was pretty dissappointed. Guy didnt even know whether they or one piece or not. However looking at the website and the design of the valves I would say they are one piece.

BTW I appreciate all the input Ive been given, this forum has been much help towards my little rebuild. Ive replaced a majority of the seals in the car, all cooling componets, and when I did manage to run the car, it purred like a panther. Hopefully after this basic valve job the car runs even better

 

[herms99gst]

Are you sure you ground the valve enough to completlt seal it?

 

[triggerx]

Are you sure you ground the valve enough to completlt seal it?

Pretty sure I did, spent a good 10-15 minutes on the valve. But if you think about it, dont valves naturally tend to lap themselves Over time? Especially with the force that a lot of these valves will be opening and closing with, they should lap over time...
Someone correct me if im wrong, ### this is obviously my first valve job. But the way I think about it is, is that the valve is going to lap itself overtime from just the motor being on. Not only that but valves are cut with way more precision than they use to be back in the day.
Makes sense when you think about it, but at the same time with these cars everyones head Im sure is slightly different, especially the seat

 

[NHerron]

The test that Jackson Auto shared I think is a good one for the DIY'er. However, I got little tiny fizzing bubbles on every valve no matter what I did. I had the seats cut for brand new valves and lapped them in three times. They had that nice even line all the way around indicating full contact, and I also have dual springs. I wasn't sure what else to do so I just put the head back together (for the third time) and ran it. As of 3 days ago with approx. 1k miles on the engine, my leakdown results are fantastic with less than 6% leakage. -My ring end gaps are also a tad wider than most, mind you. Compression is spot on for the cams I'm running as well.

And yes valves get even better seating after being ran for a while (rapid closing of valve), that's partly what I was counting up to seal up my little leaks

On a side note, it's awesome DSM specialty places can drop by a word for the DIY'ers here. Thanks guys