[Roadsters] Datsun-roadsters Digest, Vol 9, Issue 40

[Steve]

John ,

You are about to learn what it takes to keep a U20 Datsun 2000 engine 
alive . So

"Oh, my gosh, this head needs"_Complete Over haul_" and what parts needed to be determined after tear down.

We know that it needs at least an Exhaust valve that is burned ! It 
appears to have been very rich and burning oil.
Not knowing anything else about any possible previous work, It will need 
at least:
1. New Steel Intake seats ,2. Valve stem seals, 3. Exhaust valve 4. 
Valve job,  5. I have a suspicion this is late model as I see a smog 
check valve, so I'm guessing you had too much ignition timing because 
Distributor isn't re curved to early
Dizzy cam ,and or Valves too tight . Lower chain guild needs replacement 
,even though some will tell you to just leave it off ,
as it is unnecessary ... I have Never ever built an U20 engine unless it 
I used it . Your timing chains, tensioners, upper guide are shot. They 
are at best a 50K miles only parts .Over that and reliability of all 
components is a crap shoot, especially if the upper is too loose and the 
upper tensioner is not shimmed .

That is my over 46 years of Datsun experience opinion based on 1 pic. My 
recommendation is to turn this head over to a shop that knows the U20 
head and rebuild techniques, Not just any average engine machinist ,or 
you will be sorry . Again only one pic and I'm not entirely clued in 
,but this is the normal scenario.
Best regards,
Steve Ehlers
Rising Sun Performance Inc
The Oldest Datsun Specialty Shop in Texas and Z car Experts
est 1978

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