Tappet Clearances

Pre-XK
1

Were the tappet clearance specs of the 2-1/2 Litre engine ever .006 inches warm?

2

Is this one right for some 2-1/2 Litre cars? Side valve cars perhaps?

006%20clearances
006 clearances.jpg1461×1781 766 KB

3

Hi Rob,

You’ll see from the wheelbase this is for the coachbuilt saloons. In fact for the 1936 cars. In 1937 the clearances were increased to 12 thou.

Peter

4

The sidevalave cars weren’t called “jaguar”
And their ID plates were totally different , mounted on the engine and called Commission plates.
The steel bodied car’s plates were also different in the Lubricants section, wheelbase.

5

Oh yes!??? :astonished:

Well the sidevalve Jaguars weren’t called sidevalave but they existed just the same.

Peter

6

Ok if I understand correctly, this ID plate is good for the 1936 only 2-1/2 Litre Jaguar models which had .006" clearances, but no other years or models?

7

Hi Rob,

Yes, Just so.

Peter

8

Peter
what can I say a piece of perfect pedantry. But I was referring to the 2 1/2 litre cars in question

I shal have to go off and read Wikipedia’s entry on Jaguar again.

9

A trustworthy source (snort, guffaw, cackle), he says, having spent 2 months getting approval from the powers that be of my corrections on the Standard Motors page about the relationship between Standard and SS Cars Ltd.

Quite right, Peter, the 1608 cc flathead is the smallest engined car ever to carry the name Jaguar. Wherry incidentally thought it was OHV, but Frostick, Whyte and Crouch say L-head.

Thanks for the confirmation on the .006" clearance, a surprisingly obscure bit of information to locate. The '36 2.5 being their first OHV attempt, perhaps they needed a bit of time to work out that detail before they changed it to 012.

10

Thinking about Tappets. The sidevalve SS1s had an .004" tappet clearance. The first OHV SS Jaguar engines were OHV conversions.
The very early examples in production still kept the SS1 method of tappet adjustment , down on the cam follower itself. In hindsight the sidevalve would not need as much clearance as the OHV which had a longer train of pars to expand with heat.
So presumable the .006" setting initially was thought to be enough extra clearance. but subsequently it was decided to increase that after on the road experience.