Brass Valve Seats & Lapping

[heyitsrama]

Howdy Yall,

 

Finished my summer course yesterday, got back into the garage to get some stuff sorted out with the Z.

 

So I cleaned out the head with my soda blaster, went through washed it up several times, cleaned oil passages, and the top of the combustion chamber.

I also cleaned the valve face, and above the seat up to the stem. Soda blasted the intake ones really well, for the exhaust i used a red scotchbride, with some WD40 in a drill to get the same area clean.

 

I started lapping cylinder one, the exhaust side was fine, makes good contact now, but what i realized after i finished the intake was that it appears that the brass was slightly removed from the seating. I mean this makes sense because thats what lapping is doing, but is this going to harm the seat? 

 

Pic related, its the intake valve | the lapped valve seat | the non-lapped seat. 

 

 

 

 

[siteunseen]

They look beat down. You should have them cut out and replaced with steel seats. I think I paid around $100 for my e31. What head is that? No protruding plug mound. Is it an n42?

[siteunseen]

1 hour ago, heyitsrama said:

Howdy Yall,

 

Finished my summer course yesterday, got back into the garage to get some stuff sorted out with the Z.

 

So I cleaned out the head with my soda blaster, went through washed it up several times, cleaned oil passages, and the top of the combustion chamber.

I also cleaned the valve face, and above the seat up to the stem. Soda blasted the intake ones really well, for the exhaust i used a red scotchbride, with some WD40 in a drill to get the same area clean.

 

I started lapping cylinder one, the exhaust side was fine, makes good contact now, but what i realized after i finished the intake was that it appears that the brass was slightly removed from the seating. I mean this makes sense because thats what lapping is doing, but is this going to harm the seat? 

 

Pic related, its the intake valve | the lapped valve seat | the non-lapped seat. 

 

 

 

 

A redneck trick I learned is put the valve in an suck on the port opening to make sure it seals. You'll have a big ole black ring around your mouth but it works. Lap them with the straight compound then add some water to it to make it finer for the final lapping. You'll hear the difference. I took the suction cup off my lapping handle and found a brass fitting for it then chucked it up in my cordless drill. Made it alot quicker to get that smooth sound you want.

[heyitsrama]

1 hour ago, siteunseen said:

They look beat down. You should have them cut out and replaced with steel seats. I think I paid around $100 for my e31. What head is that? No protruding plug mound. Is it an n42?

It's an E88 from a L26. I finished the exhaust valves pretty happy with the end results. Im slightly reluctant to do it with a cordless drill. I dont want to apply too much pressure to the seat, and in return enlarge the seat size. 

 

Rats really? i was hoping someone would say "lap that and stop being a lil baby" 

 

Hypothetically speaking, if i was to keep the brass seats i should lap them down? In my leak down test, i don't recall of them being an issue......... i need to find my notebook and double triple check. 

[Diseazd]

I'm with Cliff.....get rid of the brass....go to steel. While you're at it, get rid of that late E88 and get a better head....you have a low emission, low compression head

[heyitsrama]

18 hours ago, Diseazd said:

I'm with Cliff.....get rid of the brass....go to steel. While you're at it, get rid of that late E88 and get a better head....you have a low emission, low compression head

the struggle is real here on a student budget... dont really want to start eating to assets that I've saved up.... Ill try to shoot over to the local machineshop tomorrow and ask them how much, was ~100$ with seats you supplied? Diseazd you in  North Bay Area? You going to the carshow tomorrow morning in Danville?

http://www.ferraripacific.org/content.aspx?page_id=87&club_id=26666&item_id=276231

 

[siteunseen]

I think he used Manley seats on mine and said they are only a few dollars each. Black Dragon sales them too for around $5 per hole.

The machinist can get them cheaper than you. My guy said they're the same as a chysler hemi exhaust I think. He had boxes of them.

[gundee]

The shop I use said not to bring him the seats. He said he has a selection of over 120 different seats

that he prefers to use. He has done many Datsun heads.

[Zed Head]

Seems like you might be getting ahead of your self.  You started out simply cleaning up some valve seats now you're about to replace them.  But you haven't really inspected the rest of the parts.  Might not be worth new seats.  After you check the valve guides for wear, and the valves themselves (the stems), and the cam lobes and the rocker arms (you know which rocker arm goes to which lobe, right?, hope you didn't randomly disassemble), and add in the cost of new valve seals, you might decide that the ten thousand miles still left in those old worn seats will get you by until you have the cash to do a complete job.  

 

[siteunseen]

Zed Head speaks the truth.  I was going to run my brass/bronze E31 until someone pointed out that they were sunken in or "beat down" so I had them replaced.  It was a do it now or do it later thing for me and I'm guessing you're a whole lot younger than I am. 

If you did a leak down test and they hold a seal then use them as long as you can.  Like Dizeased said that 260 E88 isn't that good anyway.  So run it until you find something better.  The early E88s have a protruding mound around the spark plug threads, less CCs and higher compression.

Blue pointed this out for me, I had no idea.

Here's my E31 and a P79, both good heads.  See the hump where the plugs thread in, that reduces the area in the combustion chamber giving you more compression.  The E31 is the clean one with bronze seats still in it.  I finished all the grinding before I had them changed to steel.

[heyitsrama]

5 hours ago, Zed Head said:

Seems like you might be getting ahead of your self.  You started out simply cleaning up some valve seats now you're about to replace them.  But you haven't really inspected the rest of the parts.  Might not be worth new seats.  After you check the valve guides for wear, and the valves themselves (the stems), and the cam lobes and the rocker arms (you know which rocker arm goes to which lobe, right?, hope you didn't randomly disassemble), and add in the cost of new valve seals, you might decide that the ten thousand miles still left in those old worn seats will get you by until you have the cash to do a complete job.  

 

Yeah, been labelling everything // individually bagging stuff //  as things get torn down. The majority of the parts for a rebuild are here in a box, need to get a few bolts however.

 

It was not my intension to start refresh and replace the valve-train, only really whatever is necessary to get me by. If this head need seats to be healthy for the next couple of years, its worth the effort to do it now... I'll take a more detailed dive into all the work that would need to be done on this. 

It seems that I'm leaning toward getting these brass seats removed... however...

4 hours ago, siteunseen said:

Zed Head speaks the truth.  I was going to run my brass/bronze E31 until someone pointed out that they were sunken in or "beat down" so I had them replaced.  It was a do it now or do it later thing for me and I'm guessing you're a whole lot younger than I am. 

If you did a leak down test and they hold a seal then use them as long as you can.  Like Dizeased said that 260 E88 isn't that good anyway.  So run it until you find something better.  The early E88s have a protruding mound around the spark plug threads, less CCs and higher compression.

Blue pointed this out for me, I had no idea.

Here's my E31 and a P79, both good heads.  See the hump where the plugs thread in, that reduces the area in the combustion chamber giving you more compression.  The E31 is the clean one with bronze seats still in it.  I finished all the grinding before I had them changed to steel.

I dont see this notch in my e88 yet. perhaps i need to get a better glance at things, you happen to have a larger image of that? I reverse imaged searched google and did not locate anything. 

 

 

 

guess now i should consider getting a carbide bit and match the intake and exhaust ports out

[Zed Head]

18 minutes ago, heyitsrama said:

. If this head need seats to be healthy for the next couple of years, its worth the effort to do it now...

I was kind of wordy.  My basic point is "match the set of parts by quality and life expectancy".  If you install new seats to last 20,000 miles (2 years) but the guides are only good for 5,000, you're not getting what you thought you were going to get.  The way to do it, I'd say, is to inspect everything, make a list of what's needed and what gets you where, and execute a plan.

And if you have an undesirable head, you might not want to spend any money on it.  

I'm just the voice of economy.  I ran my coolant leaking N42 head for 20,000 miles on two cans of Barr's StopLeak, instead of pulling the head to replace the head gasket (when I would have also found that the head was warped).  Then replaced the whole engine when I got tired of it and was sure that my spare engine was in much better shape.  I was in your boat at the time.  Low cash flow.