My thoughts exactly. I saw this article before and have decided not to try it myself.
A lot of the other tools have been mass produced. For some reason this one has not.
Valve jobs
- Thread starter bmwpower
- Start date
My thoughts exactly. I saw this article before and have decided not to try it myself.
A lot of the other tools have been mass produced. For some reason this one has not.
ColdDuckTime
Well-known member
- Joined
- Jul 25, 2007
- Messages
- 384
Hmmm....sounds to me like this car needs one of them thar Chevy V8's crammed into it.
outtaplace
Active member
All,
I'm new to this forum and wasn't sure where I should post first, but this thread seems like a good one to start with because I like engines and engine-building
First off, simply lapping valves does not guarantee sealing of the valves to the seats. This is because the tolerance between the valve stem and valve guide. I tried a home valve job on my 96 mazda head, lapping all 16 valves by hand (like 4 hours-my hands were raw) until there was a nice smooth even band on both the valves and the heads.
When I brought the head to the local engine machinist to have it milled (it was slightly warped) I insisted the valves would seal with the lapping I had done. The engine machinist proved me wrong in second flat.
He told me to find the nicest looking lapped valve in install it in the head. We installed the valve into the same place is was lapped and slapped on a spring to hold it in place. We then poured some laquer thinner into the port.....leak city. It was instananeous, lol. The machinist that lapping is a waste of time. After he cut the valves and seats, we tried again is there was no leakage this time.
Both surfaces (valve face and cylinder head seat) need to be refreshed by cutting if new valves (not necessarily newly purchased, just new to that seat) are installed.
Of course, you can say that well since the engine is going to be spinning at 6500 rpm, how much time is there for the air pressure to seep past? Probably not alot, but your missing something more important.
Exhaust valves are constantly exposed to temps of 1500 deg F or more and don't have the cool air/fuel mixture flying past them that the intake valves have. Proper seat configuration of the exhaust valves is critical as about 70% of the heat transfer from the valve to the head goes through the seat.
So sure, just slapping in different valves without proper attention to detail would be fast and cheap, but your going to open yourself up to other issues down the road. I'm sure you don't want to rebuild the head again anytime soon...
Moral of the story is get it done right the first time. And if your a cheap heeb like me, you do as much of it as possble yourself...
Since rebuilding the head on the mazda, I've purchased a Van Norman valve grinder ($200 on Craigslist) and the cool Neway seat cutting tools for working on my Mopar 440 engine/heads. These tools are not difficult to use and you gain a such a better understanding of whats going on and how simple stuff actually is to do yourself.
bmwpower-if you got the head off the car yourself, I see no reason why you wouldn't be able to remove the cams and cut the seats yourself. That tech article on cam removal without the tool made it sound like a piece of cake. I don't shy away from this type of thing because I know that no one is going to take as much care in working on my car than I am, which is why like to do as much on my own as possible. Well that about sums it up. Anyone has any questions, just let me know.
rob
I'm new to this forum and wasn't sure where I should post first, but this thread seems like a good one to start with because I like engines and engine-building
First off, simply lapping valves does not guarantee sealing of the valves to the seats. This is because the tolerance between the valve stem and valve guide. I tried a home valve job on my 96 mazda head, lapping all 16 valves by hand (like 4 hours-my hands were raw) until there was a nice smooth even band on both the valves and the heads.
When I brought the head to the local engine machinist to have it milled (it was slightly warped) I insisted the valves would seal with the lapping I had done. The engine machinist proved me wrong in second flat.
He told me to find the nicest looking lapped valve in install it in the head. We installed the valve into the same place is was lapped and slapped on a spring to hold it in place. We then poured some laquer thinner into the port.....leak city. It was instananeous, lol. The machinist that lapping is a waste of time. After he cut the valves and seats, we tried again is there was no leakage this time.
Both surfaces (valve face and cylinder head seat) need to be refreshed by cutting if new valves (not necessarily newly purchased, just new to that seat) are installed.
Of course, you can say that well since the engine is going to be spinning at 6500 rpm, how much time is there for the air pressure to seep past? Probably not alot, but your missing something more important.
Exhaust valves are constantly exposed to temps of 1500 deg F or more and don't have the cool air/fuel mixture flying past them that the intake valves have. Proper seat configuration of the exhaust valves is critical as about 70% of the heat transfer from the valve to the head goes through the seat.
So sure, just slapping in different valves without proper attention to detail would be fast and cheap, but your going to open yourself up to other issues down the road. I'm sure you don't want to rebuild the head again anytime soon...
Moral of the story is get it done right the first time. And if your a cheap heeb like me, you do as much of it as possble yourself...
Since rebuilding the head on the mazda, I've purchased a Van Norman valve grinder ($200 on Craigslist) and the cool Neway seat cutting tools for working on my Mopar 440 engine/heads. These tools are not difficult to use and you gain a such a better understanding of whats going on and how simple stuff actually is to do yourself.
bmwpower-if you got the head off the car yourself, I see no reason why you wouldn't be able to remove the cams and cut the seats yourself. That tech article on cam removal without the tool made it sound like a piece of cake. I don't shy away from this type of thing because I know that no one is going to take as much care in working on my car than I am, which is why like to do as much on my own as possible. Well that about sums it up. Anyone has any questions, just let me know.
rob
sberry
Banned
dusterdoug
Well-known member
Have been in a mechanic for 25 years, including doing valve jobs and machine work on an unbelievable amount of engines/heads made. I never skimp on machine work for my car or for customers cars. In the end it will bite you.
I am questioning why the head needs 2 valves replaced? It only has 89K on it then what happened to it? Lack of Maintenance? Overheating? No Oil?
If it happened on 2 then the other 14 might have problem also. I would definately have all of them refaced and the seats checked and reground/recut. Also check all of the Valve guides, and spring pressures.
The head is aluminum therefore to ensure proper seal it needs to remachined/surfaced to eliminate warpage. Aluminum heads warp probably 90% of the time when unbolted. The trick here is to get it machined with the proper finish for the head gasket used.
Have it also pressure checked for cracks.
The cam setup on some of these heads is a lot of work. The lifters have to be individually setup for proper clearance, yes even if they are hydraulic, there is still a specification to get the clearance right so the lifter can do the job is was designed for.
Machine work is and art and like any art there are hacks in the industry and masters.
Hope this helps.
I am questioning why the head needs 2 valves replaced? It only has 89K on it then what happened to it? Lack of Maintenance? Overheating? No Oil?
If it happened on 2 then the other 14 might have problem also. I would definately have all of them refaced and the seats checked and reground/recut. Also check all of the Valve guides, and spring pressures.
The head is aluminum therefore to ensure proper seal it needs to remachined/surfaced to eliminate warpage. Aluminum heads warp probably 90% of the time when unbolted. The trick here is to get it machined with the proper finish for the head gasket used.
Have it also pressure checked for cracks.
The cam setup on some of these heads is a lot of work. The lifters have to be individually setup for proper clearance, yes even if they are hydraulic, there is still a specification to get the clearance right so the lifter can do the job is was designed for.
Machine work is and art and like any art there are hacks in the industry and masters.
Hope this helps.
outtaplace
Active member
hey sberry, those look like big block mopar heads in your second pic...
M-technik-3
Well-known member
What engine? Could be a simple adjustment to a shimming of solid lifter style head on a S14/S38/S54 heads.
Simple grind and lapping or 5 way grind and lapping.
If this is for the M20 325 just get another used head. Did the timing belt break? Many on R3Vlimited take the short cut and just plunk a valve in and used rockers when they snap.
Simple grind and lapping or 5 way grind and lapping.
If this is for the M20 325 just get another used head. Did the timing belt break? Many on R3Vlimited take the short cut and just plunk a valve in and used rockers when they snap.
Last edited:
The price seems high. I had a 6 cylinder DOHC 2.9 Volvo cylinder head redone for $450 and that included heat straightening it to get the deck straight before remilling. They also replaced all new valve seals and did a 3 angle cut of the seats and valves. Turnaround was just 3 days.
If I already had the head off the car I would definetely at least replace all the valve seals myself and as mentioned earlier you could redo the seats for the valves yourself with some lapping compound. Very easy to do.
Omer
If I already had the head off the car I would definetely at least replace all the valve seals myself and as mentioned earlier you could redo the seats for the valves yourself with some lapping compound. Very easy to do.
Omer
mtwaterguy
Well-known member
- Joined
- Nov 16, 2007
- Messages
- 3,518
outtaplace
Active member
oops...I'll be sure to check the dates next time....
rsanter
Well-known member
for one, laping valves dosent work anymore. the seats and valves are hard and on a high performance engine that would be a **** way of doing it anyway
I have a valve machine. so if I have a head apart I will spot all the valves and seats because I can and it goes quick
are you guides OK on those cylinders or do they need replaced?
bob
I have a valve machine. so if I have a head apart I will spot all the valves and seats because I can and it goes quick
are you guides OK on those cylinders or do they need replaced?
bob
darkk
Well-known member
Call every reputable shop in the book til you get a price you like. $800 is because it says *BMW* on it...
KrisKustomPaint
Well-known member
- Joined
- Sep 8, 2010
- Messages
- 99
I just saw a valve grinder on craigslist for $150
nehog
Well-known member
Why is easy, because people come back a month or two later with one of the other cylinders failing and say "You didn't do it right, you ripped me off..." and the shop gets a reputation for doing shoddy work.
TransAmConvert
Member
- Joined
- Aug 5, 2010
- Messages
- 6
You definitely want to do all of them. The car may have run fine, but it was not running optimally.
The vacuum test is when they put vacuum on the port and measure the leakage through the valve. I don't remember the units, but -7 was always the best, -6 was good and anything less than that needed work, but a car would run with as little as -4.
You can definitely save money if you strip the head yourself. It is not so hard. Take out the cams (Remember to mark the caps where they go). You can remove the springs with a homemade tool. I cut a "window" in a socket and then welded it to a welding vise clamp (a big C clamp could work too). Then compress the spring and pull the retainers out through the window, and release the pressure.
Typical cost for a 16v 4cyl head is about $500 in West PA is you do the legwork yourself.
Also, when I get a head back I always double check the work by bolting it to the block using a cheap HG without any manifolds on or cams in and using my leak down tester to put air pressure into the cylinder. Feel/listen closely for any air leakage from the valves, there should be NONE. I've had to take heads back before to be redone, and if you catch it at this stage there really is nothing they can do to dispute it.
The vacuum test is when they put vacuum on the port and measure the leakage through the valve. I don't remember the units, but -7 was always the best, -6 was good and anything less than that needed work, but a car would run with as little as -4.
You can definitely save money if you strip the head yourself. It is not so hard. Take out the cams (Remember to mark the caps where they go). You can remove the springs with a homemade tool. I cut a "window" in a socket and then welded it to a welding vise clamp (a big C clamp could work too). Then compress the spring and pull the retainers out through the window, and release the pressure.
Typical cost for a 16v 4cyl head is about $500 in West PA is you do the legwork yourself.
Also, when I get a head back I always double check the work by bolting it to the block using a cheap HG without any manifolds on or cams in and using my leak down tester to put air pressure into the cylinder. Feel/listen closely for any air leakage from the valves, there should be NONE. I've had to take heads back before to be redone, and if you catch it at this stage there really is nothing they can do to dispute it.
