Ford flathead adjustable mushroom lifters mystery.

[Bored&Stroked]

Originally Posted by GB SISSON

What is the benefit? More surface area on the lobes?

The wider face allows a more aggressive opening ramp that uses the additional width to open the valve faster/sooner.

[GB SISSON]

Originally Posted by Bored&Stroked

The wider face allows a more aggressive opening ramp that uses the additional width to open the valve faster/sooner.

Thanks Dale, I get how that would happen. Would these lifters be used in conjunction with a performance/high lift cam, or are they a less expensive alternative to an aftermarket cam? I hope I'm not asking dumb questions, it's just that the workings of valve trains is a really interesting subject to me.

[Bored&Stroked]

Originally Posted by GB SISSON

Thanks Dale, I get how that would happen. Would these lifters be used in conjunction with a performance/high lift cam, or are they a less expensive alternative to an aftermarket cam? I hope I'm not asking dumb questions, it's just that the workings of valve trains is a really interesting subject to me.

They are definitely something specifically designed for a cam whose lobe design needs the broader face. If you put them with a cam not designed for them, you'd achieve nothing as no part of that extra diameter would be touched/used.

Mushroom profiles were something that certain cam grinders used to create more aggressive profiles before roller-lifters became the thing. Once roller lifters took hold, my guess is that almost nobody created mushroom profiles since.

Just think about how much fun it is to install and service them! You have to pull the whole damn lower-end down (on a flathead Ford) - just to get to them.

Back in the late 30's, there were companies like Chrysler, Studebaker, Cadillac, etc - that used mushroom lifters in a lot of their engines. I've retrofitted some of these for Bonneville engines (prior to going to roller-lifters)

Radius Lifters: Some folks like Isky created radius lifters - which in a sense are kind of a baby-step towards roller lifters. The big radius on a non-rotating lifter allowed more aggressive profiles and ramp speeds to be used. The big issues there are having to index the lifters, premature wear, etc.. While we like to talk about Isky's 404A radius cam (and others - Crane, etc), the usage of these lifter designs was quite limited and not popular at all with street driven vehicles.