The Service Manual states a Valve spring fitted length of 1 7/32“ and 1 5/16“ for the 3.8 engine. Section B does not mention a different value for the 4.2, so I may assume the same fitted length for the late (xj6) 4.2 engine? Come to think of it I am looking at the green E-Type Manual.
I think the valve train is identical, other than the guide seal retaining groove, keepers, retainer, etc the Pete outlined. Marvin, New springs from the usuals are downright cheap ($30-50us). If the originals are suspect give thought to replacements. Check all dimensions and spring rate like you would the used ones.
David,
Thank you.Yesterday I finished measuring the old springs, they differ a lot, not one is in spec.
It occured to me later I should not have been looking in the E-type manual at all, but in the SIII XJ manual. The springs should be the same.
I ordered a new set from SNG and will measure those, thank you for that advice. I can only assume the engine was standing a long while, #2 springs are way off.
Promptly received new springs from SNGB. Measured all 24. They come out to be a bit stiff, 10% more load at fitted length, as well as 10% more free length. At least very consistant load values across all springs. I did not order a „stronger set“, will it be ok to fit the set with the larger load?
Just FYI…be careful in “assume”…and also check for any later Factory Tech Service Bulletins (issued after the factory manuals) and supersede parts whereby part specs change, which affects related parts as well. Nick
The free length and strength are one and the same thing. Clearance is dictated by the valve seating and the cam won’t have trouble overcoming the extra strength. Maybe the old springs got a little tired too, who knows?
I’m pretty sure that the only springs offered now are the higher rate “after market” 2.8/V12 ones as OE ones are no longer available.
Over the years I have bought many hundreds of helical springs for professional purposes on machines I have designed.
There seems to be a trend by all spring vendors, including precision die spring makers, that their products are stiffer than specification.
I think this is because the last thing a spring user wants is a spring that is weaker than he expects.
Just saying.