'72 240Z Rebuild

[madkaw]

I would think you would want to look straight down from the top of the valve stem and look for distortion that way. any buldging will probably be no good as it will cause gaps around the valve stem.

Get a bright light and cheaters and maybe a magnifying glass too!

[Captain Obvious]

I've read through the threads where people are using these seals on the L engines and it's clear they weren't designed for the application. I understand the advantage, but the whole thing makes me a little uncomfortable. You have to get them on straight and there's no registration surface to ensure that happens. You have to get them on the right depth and there's no positive stop when pressing them on. Just wasn't designed for the application.

 

I've never used those seals, but I'd try something like this... Use a feeler gauge to measure the width of the gap at the bottom of the ones you've pressed on and then find (or make) a flat washer of that same thickness (maybe a couple thousandths thicker). Cut a slot in the washer to convert it from a donut shape into a "C" shape. The slot width should be just wide enough to fit around the width of the valve guide.

 

Then you can put this washer in place around the guide BEFORE you press the seal on. The washer should help provide not only a stop for depth, but it could also act as the perpendicular registration surface to help get the seal pressed on straight. Once the seal is in place, pull the washer out from the side?

[Zed Head]

Cut a slot in the washer to convert it from a donut shape into a "C" shape. The slot width should be just wide enough to fit around the width of the valve guide.

That sounds like a typical body shim.  

[siteunseen]

Great!  I love this forum.

 

I actually thought about cutting a couple of flat washers last night.  I can call some body shops and see if I can get one, or maybe the chain stores may have them?

 

Thank you both!  I'll get on this as soon as I can calm myself down enough.  That's about the most nerve racking thing I've done in awhile.  This is an educational endeavor for me, the E31 is next. 

 

EDIT: Hooray, the chain stores do have them.  I would probably loose some blood if I tried to make my own.

 

Edited August 14, 2015 by siteunseen

[siteunseen]

Well I have a benchmark now, I read all the other pages of the thread on hybridz about those seals.  I don't have an attention span. 

 

"I installed so the top of the steel barrel was about .550" above the height of the naked outer spring perch.

This seems to leave plenty of room inside."

[siteunseen]

Measure twice, cut once.

That was so easy after I did some measuring. They look great and all drop at about the same rate, not staying up like the first two, too tight of a seal. .080" all the way around the seal bases and the inner spring seat.

Thanks for the feedback, it gives me confidence. 8^)

Edited August 14, 2015 by siteunseen

[Captain Obvious]

What do you mean by "drop"? Are you saying that the weight of the valve itself is enough to pull it down against the friction of the seal? If it weren't for the seal getting hung up on the keeper groove, the valve would fall completely out of the head?

 

I've never tried that, but I always assumed the valve seals were tighter than that. Not the case?
 

[madkaw]

I know I will be making myself some kind of fixture to install my seals--ONCE I figure how to install them. I think the little margin for error warrants the effort to make a fixture .

Edited August 15, 2015 by madkaw

[siteunseen]

It's one of those things you just have to do to know what I mean. 

 

When I sat a new valve seal next to a bare valve guide I could judge where it should end up on the guide.  Then using that other guys measurement of .550" from the top of the metal "barrel" base of the seals to the outer spring landing I had another reference point on the valve guides.  The neat thing is both of those measurements hit at the bottom edge of the locking groove in the guides.

So after lubing EVERYTHING, I pushed the valve through then put a cut in half "condom" over the valve tip.  Put the lubed up seal over the end, holding pressure with my finger against the seal and valve tip I barely twisted the valve and it popped right through the rubber hole of the seal.  Twisted it down onto the guide with my fingers as much as I could then with a 12mm deep well, I used a 13 the first time but the 12 was perfect, I started tapping until it covered the locking groove on the guide.

 

Then went around the gap between the bottom of the barrel and the inner spring seat with angled feeler gauges, 026, 025, 020, 019 for 090" total.

They are perfect I must say.  They will stay up by themselves but if you tap the 2 that are next to each other on each cylinder they will do a slow motion styled fall until the valves hit the cardboard the head is sitting on.  It's really easy once you get your feet wet. 

[siteunseen]

They all sealed up tight except #2 intake leaks a little. I'm about to do something stupid I know. I'm going to lap it without pulling it back through the valve seal. Q tips and patience hopefully will work.

[Captain Obvious]

I'm no engine builder, but I've lapped a couple valves and about the only advice I can offer is... To start, use a finer grade of lapping compound than you think you need. You can always move to a more aggressive grit later if the fine stuff doesn't do what you need. And if you're not trying to get rid of large imperfections, you want a fine grit.

 

And I don't recommend this stuff... They call it a "multi-grade" compound where there is a mix of different sized particles in the base slurry and as you use it, the larger particles move out of the way letting the smaller ones make contact:

 

Unfortunately, I think that's the only stuff you can walk into your parts store and buy off the shelf. I've got a couple fixed grades that are much fine than this. I think I have a lifetime supply and would be happy to send you some of what I have.

[siteunseen]

Thank you for the offer, I'll keep that in mind because that's exactly what I bought ("Obviously")! 

 

I need to think more about my problem.  I haven't tried any type of liquid yet, just the old mouth over hole redneck check.  All of them, but that intake, I can suck until my eyes get blurry.  That one, not as tight.  I'll figure out how to measure the straightness of the valve first.

 

Thank you.