Brass Valve Seats & Lapping

[heyitsrama]

3 hours ago, Zed Head said:

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.

 

I got out the calipers and measured the stem diameter. They seem like they are within the upperbound (not super worn out) for what is allowed per the service manual.

There was very little runout throughout the multiple measurements that i took along the length of the stem, because of this i would believe that the tapering within the guide would also be at a minimum. However guessing is bad, and ill need to locate a tiny bore measuring tool...  this is getting kinda fun 

 

[siteunseen]

Your valve seats should "mate" to the valves, like staking ice cream cones.

Comparing your intake seats to the exhaust seats you can see the "steps" in the soft bronze the valves have caused over the years, it's a lot softer than steel.  I don't think you'll get them out hand lapping them.  If you could take the head and a valve to a machinist and let them at least look they might could face them $50?  You've already taken everything off.

  

[heyitsrama]

8 hours ago, siteunseen said:

Your valve seats should "mate" to the valves, like staking ice cream cones.

Comparing your intake seats to the exhaust seats you can see the "steps" in the soft bronze the valves have caused over the years, it's a lot softer than steel.  I don't think you'll get them out hand lapping them.  If you could take the head and a valve to a machinist and let them at least look they might could face them $50?  You've already taken everything off.

 

I took them to my local shop, he was asking $375 for getting new seats,  replacing seats, and cutting them. He was saying that the exhaust valve seat is going to get distorted when the new ones are placed in, so they also need to be cut 

My buddy took his CRX block and head to get worked on in the southbay, however if im spending the cash on something like that, i would much rather do it to a different head... 

 

Does the price seem steep? I mean if it was 80-100 bucks it would be at the shop right now i guess... 

[Zed Head]

You live in a very very expensive region of the country.  If you really want to get it done, you might see about driving a few miles out of the area.  I live in the Portland OR metro area and I've found that I could save a lot of money for machine work (driveshaft shortening, for example) by driving up the Columbia River gorge about 30 miles.  City living is expensive.

Definitely seems like a lot for a head you don't really want.  You could buy a complete L28 for that money around here.

[heyitsrama]

28 minutes ago, Zed Head said:

You live in a very very expensive region of the country.  If you really want to get it done, you might see about driving a few miles out of the area.  I live in the Portland OR metro area and I've found that I could save a lot of money for machine work (driveshaft shortening, for example) by driving up the Columbia River gorge about 30 miles.  City living is expensive.

Definitely seems like a lot for a head you don't really want.  You could buy a complete L28 for that money around here.

Yeah, its still something that i want to consider doing to the car, I found another shop in the area I'll look into, otherwise im pretty sure i would still save money driving out 45+ miles and getting it worked on.

Oregon is gorgeous you guys get some nice air quality out there. 

I just wanna drive this thing. School starting soon too  

[siteunseen]

My machinist cut out the bronze intakes and pressed in the new steel seats then faced them to match the valves that I carried him.  I'm almost positive he charged me $70 or $75 and I gave him $100, he always says he hasn't worked on an L head in 20 years but that he had done as many of them as anything back in their day.  Onery acting older guy but really just playing around.  He has a lot of money making stuff to do and works on mine when he has extra time.

I don't understand how it could distort the exhaust seats, that's news to me.  I know there is a way to heat the head up in an old oven and they'll pop out but that's not something a machine shop would do, that's something my my tight wad Dad would try. 

I wouldn't spend $375 on that head.  You can search car-part.com and get a Maxima head for $100 to $150.  MN47, but it has round exhaust ports.  You'd have to search and make sure it will work with your motor.  Or if you get lucky a P90 head would be the best.

Or put it all back together and drive the tires off, it'll run good enough until you get something better like a junkyard ZX motor like Zed Head said.

[Zed Head]

I don't know the L24 and L26 world well but the engine calculator I use suggests that an E31 should swap right over with just a small bump n compression ratio.  8.3 to 8.5.  Same valve sizes.  Here's one in San Jose.  still has the brass seats and might have other problems.  Just in case you find a major problem with the E88.

http://sfbay.craigslist.org/sby/pts/5721622083.html

http://www.ozdat.com/ozdatonline/enginedesign/

This is how we end up with a car we can't drive in the garage and a less full wallet.

[Zed Head]

I think that just replacing a few valve seats can distort the others because the seats are cut to fit the valves after they're all installed.  The seats are an interference fit so they distort the aluminum around them.  One thing leads to another...

[heyitsrama]

51 minutes ago, Zed Head said:

I don't know the L24 and L26 world well but the engine calculator I use suggests that an E31 should swap right over with just a small bump n compression ratio.  8.3 to 8.5.  Same valve sizes.  Here's one in San Jose.  still has the brass seats and might have other problems.  Just in case you find a major problem with the E88.

http://sfbay.craigslist.org/sby/pts/5721622083.html

http://www.ozdat.com/ozdatonline/enginedesign/

This is how we end up with a car we can't drive in the garage and a less full wallet.

Yeah I emailed that guy 2 days ago, i think when this thread started, no response yet, but it would be a nice head to have and work on in the intermediate time. 

I've been reading around, apparently its possible to find early e88 heads that have e31 chambers? However they also have larger valves which is a plus.....