Hydraulic tappet question.

[Keith Clements]

This came via jowett.net contact form.

Message: My Father is interested in information regarding the Jowett hydraulic lifters, when they were developed and implemented? Were Jowett the first to implement? Thank You.

I responded.

Hi Kathy and your father,

The lifters were not developed by Jowett but used in the early Javelin model until (we think) supply issues from Lockheed forced Jowett to convert to solid tappets.

Look at this .

www.mg-cars.org.uk/imgytr/pdf/lightcar6471.pdf

I think they were originally used on aircraft engines, but I do not know if any other car manufactures used them.

I have posed the question on our forum.

Does anybody have anything to add or correct?

[David Kemp]

Pretty sure Armstrong-Siddeley also used the same tappet.Which might tie up the aircraft connection.As Armstrong-Siddeley were aircraft engine makers.

[PJGD]

If you read the paper below, you will find that our hydraulic "lash adjuster" [correct terminology] was invented by Carl Voorhies of Eaton Corporation and it was referred to as a "removable" lifter because you could take it apart to clean out the carbon particles from the oil that were holding the check ball off its seat. It appears in Figures 12, 17, and in particular 18.

It was widely used in North America, and I have to assume that Lockheed were the UK licensee. Why they lost the supply contract from Eaton, I don't know.

BTW, most modern hydraulic lifters are of a slightly larger diameter, so one would have to bore out the guides in the Jowett crankcase to utilize them if one were thinking of doing so.

Philip

[BobCulver]

Ford and Holden hydr followers used to be available very cheap but as noted were oversize and may have fouled two cams. Holes may also be different. Radius faced whereas Javelin was flat (until worn concave!)
The Jav hydr cam was different, presumably with no ramps. I dunno how hydr followers would cope with typical worn Javelin cam journals.
Hydr followers were reckoned to be troublesome prior detergent oils. Was common to find them brazed up.

Bob Culver

[David Kemp]

Checked Armstrong Siddely site , Post war cars had Hydraulics till a supply problem meant they had to revert to solid lifters , just like Jowett.

[David Morris]

Hi,
I can confirm Bob Culver's point about the camshafts for the hydraulic tappets being different to the camshafts for solid tappets.
I stripped an engine that had hydraulic tappets and the camshaft utilises different cam profiles to the camshafts for solid tappets.
Is anyone using an engine with hydraulic tappets?
It is an aim of mine to get one running. We have considerable stocks of hydraulic tappets, albeit all used, but they can be stripped and it should be possible to assemble a useable set to go with the serviceable camshaft that I have in stock.
All the best,
David

[Robin Fairservice]

My Javelin's engine # 10100, and I have a spare engine which also runs hydraulic tappets.