'72 240Z Rebuild

[Captain Obvious]

Here's my current collection of lapping compounds. I've got the same permatex tube that you do and I've got three other fixed grits as well. After digging these out, it reminded me about something else that I don't like about the Permatex variety... The Peramtex offering is water based while the other grits I have are oil based. I found I like the oil based way better than the water based. Here's what I have on the shelf:


The green Loctite Clover can is a double ended can that has a coarse grit on one side and a fine grit on the other. I think it's a combo of 120 (coarse) and 280 (fine). The white tub is 800 grit that I got off ebay (I think). You can only buy the finer grits in big tubs (like a pound or gallon) which is great for someone who is using lots of it, but if you only need a little, you're out of luck. So there are people on ebay who have realized this and buy the tubs and then separate it into smaller containers

Anyway, this 800 grit oil based compound was my favorite and I suspect I was trying to lap out imperfections way worse than what you are trying to do. Point being, if it worked for me on what I was trying to do, I think it would work for you. If it doesn't, then you should probably look more deeply into why the valve doesn't seal. It might be a problem that lapping won't fix.

 

I did 24 valves and you can see how much (how little?) I used. I got (what is hopefully) a lifetime supply.

[siteunseen]

Thank you, thank you!  I have read a little more into the lapping process and of course my short attention only allowed me to buy the stuff and start lapping, instructions to the wind. 

 

Now I realize I should have lapped with the straight dope first, then mixed a little water and go finer.  Amazon has those two sided cans for $12, oil based too.  I need to think of something else to buy for free shipping, that'll take about 1 minute.  

 

Thank You Captain!

 

Oh yeah, I went to Back Forty last night and had a blast.  My life's not over yet, the more I work on these cars the more I can walk away from them. 

[madkaw]

So being to lazy to look up - I ask if this lapping is instead of doing a actual valve job?

I thought lapping was for just that last bit of perfection , but not actually necessary. But not to be done instead of doing an actual valve job ( cutting)

Edited August 16, 2015 by madkaw

[siteunseen]

Yes, it's an E88 I just cleaned up and put new valve seals in. The E31 is the main head, waiting on machinist to get some basic stuff done. (You know what I mean on that)!

[Captain Obvious]

Yeah, give some of the finer grades a try and see what you think. I believe after I used the 800 grit, I never switched back to anything coarser. I may have used some of the 280 grit to start and then switched to the 800... Been about two years now and don't remember for sure.

 

I used a cordless drill for the power source and changed the rotation direction every now and then. I know you can do them by hand, but with 24 of them to do and imperfections that really should have had a valve job done, I got tired and switched to the drill. If you're just doing that one valve, I would just do it by hand.

 

I did, however, have the valve seals out at the time. If you're going to do this with the seals in place, make sure you got them lubed up good before you start rotating that valve. Don't want to wear out your brand new seals!

[siteunseen]

I've got new set of seals coming in later today. I'm going to redo the lapping on all of them because I didn't read enough. I never did the fine grit finish. Lesson learned at $20 for another set of seals. I'm learning how to use my spring compressor too, that's a plus. That thing is fantastic once it's setup for our heads.

[rossiz]

live and learn, eh? (coming from the guy that has swapped heads a few more times than necessary)

as for the leftover paste, just think how much $$ you'll be able to make when you open up a lapping service for the z community!

[240260280z]

[siteunseen]

live and learn, eh? (coming from the guy that has swapped heads a few more times than necessary)

as for the leftover paste, just think how much $$ you'll be able to make when you open up a lapping service for the z community!

I actually thought about that after I got my new spring compressor set up for our heads, it's fun.  I must admit the beers I was sucking down had me thinking about a lot of stuff.      Siteunseen's Cylinder Head Shop

             Bartering Welcome

 

I could do some lapping in that cabin with her, more like she would be making laps around that cabin to get away from me. 

Edited August 18, 2015 by siteunseen

[Captain Obvious]

Siteunseen's Head Shop

 

Got a nice ring to it but I'm not sure you'll attract the right kind of clientele.

 

[siteunseen]

Siteunseen's Head Shop

 

Got a nice ring to it but I'm not sure you'll attract the right kind of clientele.

But I'd make more money! 

[siteunseen]

Now I know why there's no acorns in my air filter housings anymore.  I think I have a new pet, hopefully it's just a black snake.  The head is small and the tip of the tail is long and pointed so I'm pretty sure it's non poisonous. 

 

I've had the cover on for so long there's no telling when it slithered out, I just pulled it back yesterday and saw the skin.  When I first bought this car I turned the blower on and pieces of a skin blew out.  So I'm thinking they like to get into there.  I'm making a lot of noise so he'll leave if he is inside.