I'm really confused about tappet clearance. There seems to be conflicting specs in various sources. The Jaguar "Repair Operations Manual" on Page 05-4 shows the clearance as .0073 - .0087. Yet the Haynes Manual says .012 - .014. My engine number is 8L 40403L and I believe I have the "later" style head/cam shafts as the cam shafts have the four bolts at the front end of the cam shaft. and no oil holes in the bottoms of the lobes. Upon reassembly of my exhaust cam side (with new valves lapped in and using the previous shims ranging from .092 - .096) I am getting .006 - .010 tappet clearance. So... can anyone shed some light on my proper clearance? And if there's more info you need, please ask.

Many thanks, Bill


Haynes Manual

Jaguar Repair Operations Manual

 

All mine since the MK VII have been 0.012" Inlet and 0.014" Exhaust COLD.

That also applied to the V12 engines.

I have read heaps over the years, and never varied my spec, and never had issues.

 

Hi Bill,

Glad to hear you are getting to the end of your top-end rebuild!

The tappet clearances should be 0.012 - 0.014" as perHaynes. This is also in the Jaguar manual you posted: you are looking at the wrong part of the specs. On the left side of the page under Valves and Valve Springs, the specs are given under Inlet Valve Clearance and Exhaust Valve Clearance as 12 to 14 thou' as well. highlighted in green now:

 

Yahoo! Thank You! That REALLY clears it up!!

 

The clearance that you had highlighted in yellow in the Jaguar manual was referring to the clearance between the tappet and the bore it sits in