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Discussion Starter · #1 ·
hello a little background here, I have a 81 motor in my 71 z the motor has very good compression and runs fine, however there seems to
be oil seeping by the seats, I notice it on my plugs(on the threads) and a puff of white smoke when I decelerate or in between shifts if driving spirited
should I have them changed or wait till I can afford to have my e 31 head done (from 71 motor) and put my momney in that
I welcome all opinions
thanks
 

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First, it seems that all spark plug threads on the Z's that I've had always have that oil on them. This is normally due to the fact that the cylinder heads are aluminum and the threaded holes in them strip out over time, leaving a place for unburned oil to seep in as the engine reciprocates. Second, valve seats by themselves do not leak oil, as the oil is sucked down the valve stem past the valve stem oil seals(in order to lubricate the valves). Third, if you were seeing blue smoke, that would indicate oil leaking past the valve stem seals or the piston rings. You would also be able to see the oil on the plugs themselves if the oil consumption was bad enough. But, you say you see white smoke. Questions I have are, are the plugs coated with little white specks of hard material and/or do you keep having to put coolant into your engine? If this is the case, your head gasket is bad, or you have a cracked cylinder head coolant passage. The only solution then is to either replace the head with your other one(which also must be pressure tested before install time), or to put on a new head gasket. To find out which color smoke that is coming out(and smell too)will be your key here. If you can't find out, have a compression and leakdown test done at your local garage($50). Have fun!
 

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Changing out the valve seats with harder ones..

This is a little off subject, but since his original post was about valve seats, here it is:
I have an N42 head I want to get worked on, but it has the original seats. I am going to put the Arizona Z valves in it, but I would like to know if I should have the valve seats changed????? The head has not been shaved yet, and is in pretty good shape. Thanks a lot guys....

Tony Lynch

> hello a little background here, I have a 81
> motor in my 71 z the motor has very good
> compression and runs fine, however there
> seems to
> be oil seeping by the seats, I notice it on
> my plugs(on the threads) and a puff of white
> smoke when I decelerate or in between shifts
> if driving spirited
> should I have them changed or wait till I
> can afford to have my e 31 head done (from
> 71 motor) and put my momney in that
> I welcome all opinions
> thanks
 
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