Valve lapping.. your take?

[subarub4]

So I'm cleaning up some Subaru ej25 heads so the intake valves had a lot of carbon on them.. so I've soaked the valves one by one in some crc motor treatment (seafoam is getting $$$) anyways it cleaned them up well but I still ended up lapping the valves. So what is your take on doing this for modern engines?

 

[big_bear]

I'd have a machine shop do a valve grind.

 

[subarub4]

I'd have a machine shop do a valve grind.

Nice to be made of money.

 

[DandDMachine]

As an owner of a machine shop I like the way Big bear thinks. That being said what was the reason you took them off? Valve lapping will help minor issues with valve sealing. Anything major like pitted seats, and valves and it wont fix it. It also wont do anything if the guides and or valves are worn.

 

[Gort the giant robot]

When I was young hand lapping was my only choice due to no money. When you buy your first car for $6.00 and you have to make two payments to pay it off, read the first line again.

Gort.

 

[rharman]

If there were no obvious defects, I'd lap them and see how they turn out. If you don't get a clean lap, then you go for the grind.

 

[subarub4]

As an owner of a machine shop I like the way Big bear thinks. That being said what was the reason you took them off? Valve lapping will help minor issues with valve sealing. Anything major like pitted seats, and valves and it wont fix it. It also wont do anything if the guides and or valves are worn.

The seats are not pitted and no issues with sealing, they are heads I picked up from the yard for a build, they had more carbon build up on the intake valves then my car when it had 235K on it (265K now)

 

[subarub4]

here are some pictures After I did them

 

[subarub4]

I think you can tell which valves have been cleaned up.

 

[Skin]

Nice to be made of money.

If you already have the heads off you don't have to be "made of money" to have a machine shop check the head and do any valve work necessary. They can also do a far more thorough job of cleaning than you, and even most garages, can as well. That's not exactly the easiest flat four to pull the heads from. I usually just remove the engine for a head gasket job and yes the heads always get sent out.

 

[Gort the giant robot]

Seems to me hand lapping would provide a better gas seal. At todays labor rates grinding is faster and cheaper. Back in the early 1960s we had a mechanic at the local Richfield gas station that would come to your house and grind your valves and then lap them in. If you removed and reinstalled the head or heads for him, you would save alot money.

Gort

 

[MikeF2316]

here are some pictures After I did them

I think you'd be crazy not to lap them while you have the heads off. And you'd be crazy not to change the valve seals too! And of course, as you've done, a thorough cleaning of everything.

Obviously while you're doing that you'd make sure the valve guides aren't worn, or you're just wasting your time. From your pics it looks like you've done a successful job.

I had the head off my 4 cylinder '76 Volvo back in the day. I lapped the valves before I put it back on, I remember being thankful there were only 8 total!

 

[Gort the giant robot]

Finding a Subaru cylinder head without bent valves is the hard part. If a Subaru loses a timing belt it bends the valves.

Gort.

 

[DandDMachine]

Are you putting in new valve stem seals while you are in there? That maybe why they are so carboned up. The seats look pretty good. Those dual cam subarus with the non adjustable buckets are an expensive valve job. If You did have a valve job done you would have to either re-shim the buckets or mock up the valves and cams and adjust the clearance by grinding the valve stem end or the valve face itself. If you don't want to stick a lot of money into them just lap them as you have done poor some water or solvent into the ports, if you don't see any water seeping out after 10 seconds or so you should be good. Just be sure to clean all the lapping compound out from under the seats and especially the guide area. Valve guides get destroyed very quickly if that grit is not all cleaned out.
Might not be a bad idea also to check them with a straight edge to be sure they are not warped. We see a lot of warped Subaru heads. While resurfacing the heads may not be in the budget doing the whole job over again (including new gaskets)isn't worth the money you will save.

 

[Skin]

Finding a Subaru cylinder head without bent valves is the hard part. If a Subaru loses a timing belt it bends the valves.

Gort.

A lot of engines are interference. Nothing unique to Subaru.

 

[subarub4]

Are you putting in new valve stem seals while you are in there? That maybe why they are so carboned up. The seats look pretty good. Those dual cam subarus with the non adjustable buckets are an expensive valve job. If You did have a valve job done you would have to either re-shim the buckets or mock up the valves and cams and adjust the clearance by grinding the valve stem end or the valve face itself. If you don't want to stick a lot of money into them just lap them as you have done poor some water or solvent into the ports, if you don't see any water seeping out after 10 seconds or so you should be good. Just be sure to clean all the lapping compound out from under the seats and especially the guide area. Valve guides get destroyed very quickly if that grit is not all cleaned out.
Might not be a bad idea also to check them with a straight edge to be sure they are not warped. We see a lot of warped Subaru heads. While resurfacing the heads may not be in the budget doing the whole job over again (including new gaskets)isn't worth the money you will save.

Long story short I have the same heads on my car now, however about 2 weeks ago I had to stop quick to avoid hitting a jaywalking walking in front of a large box truck.. she and her child must of thought no traffic was coming in the other lane.. lucky for me I was moving slow as the light was red, I had no time to clutch in and i slam on the brakes.. meanwhile the light changed to green and the engine pretty much died (loss compression) as soon as I pushed it off to the side and saw the passenger side cam was 11 teeth off I knew the valves got bent.. still after lining it up it had a hard time idling, it would but you can tell I was dealing with a huge compression loss, from the look and knowing the cam profile cylinder 1 took the hit. Seems the belt stretched but it was interesting that the drivers side timing was still spot on.

2 years ago when I did the head gaskets on my car I had the heads resurfaced which was no big deal and I plan on doing it again

Finding a Subaru cylinder head without bent valves is the hard part. If a Subaru loses a timing belt it bends the valves.

Gort.

It's not that hard

I think you'd be crazy not to lap them while you have the heads off. And you'd be crazy not to change the valve seals too! And of course, as you've done, a thorough cleaning of everything.

Obviously while you're doing that you'd make sure the valve guides aren't worn, or you're just wasting your time. From your pics it looks like you've done a successful job.

I had the head off my 4 cylinder '76 Volvo back in the day. I lapped the valves before I put it back on, I remember being thankful there were only 8 total!

And yes I ordered a valve keeper tool and 16 new valve seals, it's not that common for them to leak past the seal, my car has 265K and the seal is still good.. but since I'm this far might as well do it anyways since you never know how long the heads have been sitting for.

 

[Packard V8]

We see these all the time with blown head gaskets. Don't put those heads back on without having both of them surfaced.

Back in the day, I'd never think of milling any head without pulling the valves, still won't on a real build; however some of the po'boy Subie owners up here in the piney woods and the used car lots just want it running again cheapest way. They're thrown on the mill with the valves still in place and a pair of Subie heads are in and out of the machine shop in under an hour. Even the other head which hasn't yet lost the gasket needs flattening.

I still ended up lapping the valves. So what is your take on doing this for modern engines?

Ya do what ya gotta do when going it for no bucks. On real performance builds, even when it's not about saving money, most of the guys I know with the good head shops don't hand lap valves. I've been convinced it's not necessary if everything is done right on a good machine. We always vacuum test the assembled heads and hardly ever have a leak. Interestingly, on the rare occasion when there is a low vacuum reading, a tap on the stem top with a brass hammer usually seals it. The valve just hadn't cycled enough to seat in.

jack vines

 

[andywander]

I don't think a timing belt can stretch. Is there some kind of mechanical tensioner on these that might have been out of adjustment?

 

[subarub4]

Timing belts do stretch

 

[andywander]

Timing belts do stretch

Yeah, maybe a few thousandths of an inch........

 

[big_bear]

Nice to be made of money.

I wish, I'm a poor man money wise, but a rich man in other ways.

Took me over a months pay to have my heads and short block re-built in San Bernardino, $500 for the heads, and $750 for the short block, I could have done it myself for a lot less, but these guys do this type of work EVERYDAY, they're specialists, I was going to do just the heads, but when I got ready to put those beautiful heads on that block, I couldn't bring myself to do it, bought a cherry picker from Craig's list($90), pulled that short block out and had the pros work it over. I need a 4x4 that will start and get me from A2B ANYTIME i need her.

Like I said I don't have much money, but sometimes you have to bite the bullet, and it saves you money in the long run.

 

[big_bear]

Timing belts do stretch

Oh yeah, I own a 3vze.

 

[cide1]

So common wisdom I've read is that when putting freshened heads with good valves and seats on an older engine, don't be surprised to have the better seal cause ring problems and increased oil consumption. I experienced this on a high mileage Buick 231 rebuild, and was pretty frustrated when I realized the gaskets and fluids I had put in needed to come back out and the engine needed lots more work.

 

[DandDMachine]

So common wisdom I've read is that when putting freshened heads with good valves and seats on an older engine, don't be surprised to have the better seal cause ring problems and increased oil consumption. I experienced this on a high mileage Buick 231 rebuild, and was pretty frustrated when I realized the gaskets and fluids I had put in needed to come back out and the engine needed lots more work.

This is not as big of an issue as it once was. With modern rings and fuel injection not washing the cylinder walls, you can expect much more life from them. Subaru is very picky on their piston to wall tolerances and their bottom ends are usually very good. I have rebuilt many Subaru blocks and after 250,000+ miles they still look really nice.

 

[subarub4]

This is not as big of an issue as it once was. With modern rings and fuel injection not washing the cylinder walls, you can expect much more life from them. Subaru is very picky on their piston to wall tolerances and their bottom ends are usually very good. I have rebuilt many Subaru blocks and after 250,000+ miles they still look really nice.

I still had my factory cross hatching.

 

[djjsr]

You can check how well the valves are seating by using some Prussian bluing. I recommend Dykem Hi-spot paste.

 

[theknurl]

depends what the seats were cut with....

a floppy stone

or a Mira;
http://www.miratool.ch/index.php?page_id=31

all the cuts are done at the same time to the same depth;
http://www.miratool.ch/index.php?page_id=27

so no need to lap

 

[ekeller]

I always used the compound and lapping for more of a check than anything, checking to make sure the valve and the seat were ground at the correct angle and that they had the correct, consistant pattern all the way arround both the valve and seat. This verified that the valves would seal correctly. I only laped them after the valve and seat were re ground. Lapping is not going to correct any valve/seat issues unless you are going to sit there and hand lap each one for a day or 2 lol!

 

[Rhyno]

Here's a suggestion, that I have done for 30 years.......it works.

Disassemble the heads....Clean the parts.....Check the guides and stems..... Put some grease on the stems and guides, put the valve back into the original spots......put some valve grinding compound on the seats....

and here's the magic......use an electric drill to grab the top of the valve stem.... (be careful not to mar the top of the stem).......turn the drill on, and move the valve open and closed.

Stop and evaluate the contact area.....move to the next one.....

This is a whole lot easier and faster and cheaper, (unless you have to buy a drill) THAN ALL OF THE PREVIOUS POSTS.....

Good luck....Let us know how it turns out.

 

[theknurl]

Rhyno;
but thats hard on the guides and stems

use an old Zim tool with a piece of fuel line and 2 hose clamps
http://www.ebay.com/itm/Vintage-Val..._Automotive_Tools&hash=item51ad6dd61f&vxp=mtr

 

[Skin]

Here's a suggestion, that I have done for 30 years.......it works.

Disassemble the heads....Clean the parts.....Check the guides and stems..... Put some grease on the stems and guides, put the valve back into the original spots......put some valve grinding compound on the seats....

and here's the magic......use an electric drill to grab the top of the valve stem.... (be careful not to mar the top of the stem).......turn the drill on, and move the valve open and closed.

Stop and evaluate the contact area.....move to the next one.....

This is a whole lot easier and faster and cheaper, (unless you have to buy a drill) THAN ALL OF THE PREVIOUS POSTS.....

Good luck....Let us know how it turns out.

you don't lap valves by turning them 360 degrees in one direction otherwise you create hot spots and uneven distribution of the lapping compound. Its also not suppose to be done at a rapid pace.

 

[Rhyno]

Rhyno;
but thats hard on the guides and stems

use an old Zim tool with a piece of fuel line and 2 hose clamps
http://www.ebay.com/itm/Vintage-Val..._Automotive_Tools&hash=item51ad6dd61f&vxp=mtr

If you hold the drill at an awkward angle and for a few days of constant use, than you are correct.

If you don't like it, don't do it......you won't be the first to argue with success.....

 

[Rhyno]

you don't lap valves by turning them 360 degrees in one direction otherwise you create hot spots and uneven distribution of the lapping compound. Its also not suppose to be done at a rapid pace.

I know that it's tough, but read it again......There isn't constant "Tool Pressure."

And also tell me what a "Safe" Surface Feet Per Minute is acceptable for two different hardened alloys.....

(I'll give you a hint.... IT'S A HELLoFa lot more than a hand drill can produce)

Either way.......

If you don't like it, don't do it......YOU won't be the first to argue with success, either.....

And, do you really think that a Machine shop's Valve Grinding tool doesn't rotate in a 360 degree revolution and at a high speed?

Maybe you should take a "Field Trip" to a Machine Shop, and pay attention.

Anyway....

This is about helping the OP Lap his valves, and on the cheap.

 

[subarub4]

I might be taking these heads back.. too much stuff missing, the drivers side head has all 4 buckets missing for the exhaust they list (the buckets themselves) for $27 each.. plus the cam gears are missing idiots that made the cam cap bolts tighter then 7 ft.lbs when taking the heads off.

 

[Turbo_Prop]

Maybe I am just a fanatic, but anytime I deal with engine parts that have been run, especially heads, they get taken apart and put in the hot tank, maybe even the ultrasonic and then media blasted. Just to hard to see whats going on with carboned up and greasy, dirty parts.

As for the lapping of the valves, once everything is clean, and the valves and seats do not appear to be pitted, then by all means lap them. This is simple high school shop stuff, not worthy of a big debate. Lap the valves, the line will tell you most everything you need to know. After lapping, use a flashlight on the valve and look into the port for light.

Before getting to far along in the reassembly, torque the heads down and do a leak down test.

 

[SpiderGearsMan]

I always lap em in ......you don't want a NO compression event

 

[Provincial]

I always lap em in ......you don't want a NO compression event

I always lap valves, even after both the valves and seat have been ground. I once found a full set of valve faces to be non-concentric with the stems after being ground on a NEW Sioux facing machine! It turns out it had a bad chuck.

I also once lapped some pitted valve seats in a Wisconsin VF-4 engine because I had no one who could come to the farm with a seat grinder. That took two days. I was young and more patient then!

 

[Murphy4570]

I always lap valves, even after both the valves and seat have been ground. I once found a full set of valve faces to be non-concentric with the stems after being ground on a NEW Sioux facing machine! It turns out it had a bad chuck.

This right here is the prime example of why you should hand-lap valves. It will tell you whether or not the valve and seat are A-OK or not. Hand lapping by itself usually won't fix any serious problems though.

 

[scarney1988]

I am not an engine shop employee nor a machinist, but I thought that valve lapping was used to determine if grinding is necessary. Either way, when in doubt farm it out. Better to take your time and have the heads serviced by a speciallty shop than have to redo you build.

good luck.

My EJ22 is up to 230k miles with no rebuild in sight.

Pics of your subby?

 

[justanengineer]

This right here is the prime example of why you should hand-lap valves. It will tell you whether or not the valve and seat are A-OK or not.

I disagree. Lapping doesnt really tell you diddly about the seal, all it does is polish the contact surfaces. Even when spotting them with dykem its rather difficult to really be sure it will seal simply bc its difficult to spread over the small surfaces. Dont get me wrong, it gets you close enough to work most of the time, but for a real performance build its pure hack IMO. Ive seen techs fiddly fuzz around for hours trying to lap them and in the end a quick touch up on the grinder was all that was necessary. Irregardless, the only real way to be sure of a good seal is to pressure test the assembled head.

Ya do what ya gotta do when going it for no bucks.

I think thats the crux of it. If you dont have money to spend to do heads properly, do what you gotta and lapping is a good choice simply bc its cheap and will be "good enough." If you do have the money tho, a shop with good equipment and ppl can do this work much better and faster with no need to lap the valves.