Just finished adjusting intake to .0120 and exhaust to .0140".
Plus bunch of new seals and gaskets for oil and cooling.

 

Cool

 

I REALLY hope that is a typo Mish_Mish

 

when I changed my heads I set the clearances to 0015" as per the
information for improved mpg in experience in a book, it was too noisy for me, so I had to go through the agro of re-shimming them all back to 0012".
I hope the big gaps didn't do excessive wear
my engine plate states 0012" -0014" for 1984 HE
looking at the setting above maybe the u.s. spec is different

 

No typo, this was done per suggestion from very knowledgeable XJS racing enthusiast and I like the result.
Absolutely no extra noise, but much more agile revving up smoother engine.
.012 - inlet, .014" - exhaust.

 

then is WAS a typo, thank god...
Re-read your original post. It says .12 and .14 not .012 and .014

 

that scan is from the English jaguar workshop manual, there is only one publication. Details are given for differences in different specs, but there is only one spec for intake and exhaust clearances. Maybe the info was later changed or confused, my workshop manuals are from 1987

 

this is the plate on my radiator cross panel I was wrong about gaps, it only states 12-14 in my Haynes book, so I do tend to go with the engine plate fitted at the factory, mind you B.L. didn't know their **** from their elbow.

 

Yep, just noticed and fixed, thanks! That would make one hell of a tapper if I left 3mm clearances

 

Early HE's came with super tight clearances, like .010 and .012exh, for some emissions reason, making engine run on the verge of losing compression at full warm up, due to valve stem expansion. So if one wants a happy engine, clearances need to be 012/014. Mine runs a lot better now, noticeably more power.

 

the HE all the way up to the last 6.0 uses .010-.012 as it's valve clearances.

I'd say if .010-.012 is factory and you feel .012-.014 is better, set the thing to .012

 

Valves tent to expand on these with age, in my case I had one cylinder starting to fart into exhaust, after full warm up.

 

if you actually had an exhaust valve not sealing properly,and it was an HE, it most likely had seat regression, or valve sucking deeper into the head.(refered to as sucked a valve)

either not good, comes from high heat in the valve area only, a common HE thing.

and personally i like the loose valve clearences, even tho it is noisy! safer when/if it over heats.

 

It seems to run perfect now, so I am not sure what it was. Motor I have is very clean and does not seem to have previous overheat issues. However, since those become harder to get, look what I just got at a local junkyard

80K miles, seems to spin smooth and has most of accessories intact, $500!

 

personally i'll stick to the factory specs. .001 change in valve clearance results in 3 degrees change in duration. I'd rather have it run the way it was designed to.

not to mention the possiblity of slack resulting in less air coming in, which will get the computer to run the engine lean...causing overheating

 

PERSONALLY id use a set of PRE-HE cams in an HE engine, designed for performance !

 

I second that, and if you're going even bigger I'd give isky a call and get one of their regrinds.

I used the isky XM5 grind.
My machinest said that you're best to shim towards the larger tolerance in the valve lash specs because after a fresh valve job it's gonna get slightly closer and if you're at the minimum you'll end up under it.

 

Motor is post Leyland, '88 and seems to be in OK shape. I had to buy and weld reinforce $60 stand for it. Slowly I will break it down and build it as a perfect spare.