Cylinderhead work
Discussion
Quick query.... have had some cylinderhead work done to a spare head I picked up a little while ago. Gas flowing and Valve job.
The company informed me they checked the head and all was ok so I was able to approve the work to go ahead. (ie. the blank was serviceable and pressure tested OK.)
Got the head back and took a look at it.. would you expect it normal or appropriate to find:
a) 2 Cracks between Valve seats you had not been informed about,
b) several threads that were not really usable (1 plug and 2 exhaust studs)
c) valves that you can partially see light between them and the seats when they are in the closed position.
Now I'm worried that I've paid good money to a reputable company and am in possession of a head that's not really usable, or at least one that will need additional work (possibly re-doing work I've paid for already).
Or am I paranoid?
The company informed me they checked the head and all was ok so I was able to approve the work to go ahead. (ie. the blank was serviceable and pressure tested OK.)
Got the head back and took a look at it.. would you expect it normal or appropriate to find:
a) 2 Cracks between Valve seats you had not been informed about,
b) several threads that were not really usable (1 plug and 2 exhaust studs)
c) valves that you can partially see light between them and the seats when they are in the closed position.
Now I'm worried that I've paid good money to a reputable company and am in possession of a head that's not really usable, or at least one that will need additional work (possibly re-doing work I've paid for already).
Or am I paranoid?
stevieturbo said:
Certainly dont sound paranoid.
What is their explanation ?
Damaged threads are usually repairable, but of course whoever was working at the head sould have pointed this out before any other work commenced.
Likewise with cracks between valve seats.
These cracks are normal on Ali head with Steel inserts... will be ok.. pressure tested fine..don't worry.What is their explanation ?
Damaged threads are usually repairable, but of course whoever was working at the head sould have pointed this out before any other work commenced.
Likewise with cracks between valve seats.
Nothing about the threads..
On the valves front.. they'll hammer down when you first spin the engine over and seat down.. they use the best kit so these can't be real problems in errors in the machining.
I was expecting even with a list of fixes...
Either the head is good or shot... if good then these things need sorting...x,y,z..
Having put valves in before on normal road engines I would never expect to see a gap between the valve and the seat especially once it's been seated/hand ground.... let alone on a head that was specifically briefed to be used as a sprint/race head!!
Now it seems that I will have to take this up with the company... The cracks need welding up, 3 of the seats re-machining etc. etc... time, money and nause I just don't need!!
Edited by cerealsurfer on Tuesday 19th January 16:30
Did they install new valve seats ?
In some cases, cracks may not be worth worrying about too much. Either way, you should have been informed before any porting work was carried out.
As for hammering the valves... LOL
Im sure Pumaracing will wet himself laughing at this thread....or else blow a gasket !
This shop sound like a bunch of clowns.
In some cases, cracks may not be worth worrying about too much. Either way, you should have been informed before any porting work was carried out.
As for hammering the valves... LOL
Im sure Pumaracing will wet himself laughing at this thread....or else blow a gasket !
This shop sound like a bunch of clowns.
Yes they did fit the valve seats.
Paid deposit after head checked and gave go ahead for work and rest on completion and shipment to me.
I will do the test. . . But considering you can see light past the valve in places I can only imagine it would flood out.
Shame is this company is well known and has recommendations in magazines. This is the second engineering company that's not lived up to it's marketing in12 months!!
Paid deposit after head checked and gave go ahead for work and rest on completion and shipment to me.
I will do the test. . . But considering you can see light past the valve in places I can only imagine it would flood out.
Shame is this company is well known and has recommendations in magazines. This is the second engineering company that's not lived up to it's marketing in12 months!!
cerealsurfer said:
Quick query.... have had some cylinderhead work done to a spare head I picked up a little while ago. Gas flowing and Valve job.
The company informed me they checked the head and all was ok so I was able to approve the work to go ahead. (ie. the blank was serviceable and pressure tested OK.)
Got the head back and took a look at it.. would you expect it normal or appropriate to find:
a) 2 Cracks between Valve seats you had not been informed about,
b) several threads that were not really usable (1 plug and 2 exhaust studs)
c) valves that you can partially see light between them and the seats when they are in the closed position.
Now I'm worried that I've paid good money to a reputable company and am in possession of a head that's not really usable, or at least one that will need additional work (possibly re-doing work I've paid for already).
Or am I paranoid?
Regarding your questions as asked.The company informed me they checked the head and all was ok so I was able to approve the work to go ahead. (ie. the blank was serviceable and pressure tested OK.)
Got the head back and took a look at it.. would you expect it normal or appropriate to find:
a) 2 Cracks between Valve seats you had not been informed about,
b) several threads that were not really usable (1 plug and 2 exhaust studs)
c) valves that you can partially see light between them and the seats when they are in the closed position.
Now I'm worried that I've paid good money to a reputable company and am in possession of a head that's not really usable, or at least one that will need additional work (possibly re-doing work I've paid for already).
Or am I paranoid?
a) Sometimes these go right down to a waterway and sometimes they're cosmetic. Impossible to say without knowing what type of head and/or seeing the job. It's not a good sign though.
b) All of these are fixable by helicoiling and really should have been spotted by yourself before sending the head out to anyone although they too should have said do you want to go ahead given these faults or supply them another head. I would never do work on a customer's head without first checking for such things.
c) Sadly the state of seat cutting expertise in this country is abysmal. Even the best Serdi or other equipment doesn't guarantee concentric seats, especially if there is even a small amount of guide wear. In fact the Serdi is almost guaranteed not to cut good seats if the guides are worn whereas for example my own seat cutting system compensates for such things. If the valves don't lap in evenly with fine lapping paste after just a few seconds then it all needs redoing. They will absolutely NOT wear in or hammer in if they aren't right to start with. If you can see daylight and it isn't just because there is dust or debris that needs cleaning off first then I'm afraid it's refund or small claims court time.
I'm pretty much retired apart from work for friends but if you want an expert opinion before contacting the company again I may be able to have a look for you.
BTW, here's another good way of checking valve seat concentricity without pukka equipment. Get a valve lapping stick (bit of wood with a rubber sucker at each end type of thing) and the thinnest feeler blade you can find, usually 1.5 thou or similar. With everything spotlessly clean hold the valve in the guide with the lapping stick with the valve head just above the seat, insert the feeler blade and test whether it grips firmly or pulls out easily with just very light pressure pushing the valve head down. Try this at all four points of the compass around each valve seat. You'll soon get a feel for what it should feel like. If it grips on one side and barely touches on the opposite side you'll know the difference and the seat cutting is naff.
However a quick lap in with fine paste (or a check with engineer's blue) tells you pretty much the same story as long as you know exactly what to look for and don't use too much paste.
However a quick lap in with fine paste (or a check with engineer's blue) tells you pretty much the same story as long as you know exactly what to look for and don't use too much paste.
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