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Sorry if this is a stupid question first time doing my own engine build but I Just got a new set of profiler heads said valve seats have bin machined 5 angle job do I need to do anything like lapping to install the new valves into the heads ? new valves and brand new heads
Again sorry if this is a no brainer question lol
I would do whatever makes you feel comfortable. Lapping wont cause any harm. With proper machining/measuring/components there is no need for it.
 

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Lapping will embed abrasive material in the valve and seat. I have never seen or heard of a higher end shop or cylinder head person(NASACAR, CFE, Ron's etc) that lapped valves in the last twenty years. If the seats are machined on good equipment by a competent machinist or even ground old school, there is no reason for them to be lapped. I f you doubt the quality of the work, check the seats with a run out gauge(Sunnen is good) or vacuum test them. If a seat fails the run out or vacuum test, it needs regrinding or recutting by a qualified person using proper equipment.
This just is not true.
Lapping is nothing more than a final finishing process to machining and provides a finish that machining can't achieve, especially machines like most seat and guide machines. If lapping was to "embed" abrasive material in the valves and seats, the same could be said for grinding. It's the same process. Lapping just finishes the surface to a finer finish and helps "mate" the two sealing surfaces. I know when I was at Dart, Rich Maskin lapped all his Pro Stock heads (with a tq plate). We lap every valve job that leaves the shop except coated Ti. I get heads back after seasons of racing and never once have seen an issue.
 

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This just is not true.
Lapping is nothing more than a final finishing process to machining and provides a finish that machining can't achieve, especially machines like most seat and guide machines. If lapping was to "embed" abrasive material in the valves and seats, the same could be said for grinding. It's the same process. Lapping just finishes the surface to a finer finish and helps "mate" the two sealing surfaces. I know when I was at Dart, Rich Maskin lapped all his Pro Stock heads (with a tq plate). We lap every valve job that leaves the shop except coated Ti. I get heads back after seasons of racing and never once have seen an issue.
Good to hear, I've read the same about trapped compound, but I like lapping to see everything is ok. Not that other methods mentioned wouldn't.
I assume you don't do the coated TI as to not damage the coating?
 

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Good to hear, I've read the same about trapped compound, but I like lapping to see everything is ok. Not that other methods mentioned wouldn't.
I assume you don't do the coated TI as to not damage the coating?
I was lapping the seats with a stainless valve on valve jobs that I was using coated valves on but I've gotten away from that. I don't have a problem lapping uncoated Ti valves.The finish on the coated valve is about as good as it's going to get and if you're not mating the two surfaces, I don't see the point of lapping a final valve job. I use a quick lap to check the size of my valve jobs when I'm setting up a cutter. I find it a lot more accurate than a sharpie.
 

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I lap the valves as a final inspection procedure, using the finest lapping compound available from Clover. No problems.
 

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My 2 cents, thoroughly cleaning the lapping compound off with something such as brake cleaner will remove virtually all traces of the compound from the seats and valves.
 

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the problem with lapping is the valve stem has too much clearance to the guide to work as a proper "pilot"
 

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I do that also, works very well. I have one cylinder head performance builder that laps every valve. His theory is that the valves seat faster making more power sooner. I guess if one were to do an interference fit valve job it might be true, but that's not a performance valve job to me.
 
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