Re-use Solid FT lifters?

[Mwilson]

I think I can already guess the answer to this one but what the heck. My current lifters are Comp "Direct Lube" with the hole in the face to directly lube the cam lobe. They were very expensive (for me lol) and have maybe 500 miles on them, I would like to re-use them. Any thoughts? 2 locals I talked to said "No problem, I do it all the time" I personally never woulda considered it in the last few years but did it all the time years ago. New cam will be here in the next 2 days.

[old blue 75]

Mwilson I think DV has done it after a little redressing on the bottom with emery
cloth. If you have his book sbc on a budget I think it is in there. He may even chime in.

[rookie]

If ya do, it's at your own risk, and if ya do, and I think ya will, I would sand them in a figure 8 pattern on a flat surface on 600 grit sand paper to reface them, then take apart and clean very very good.

[Mwilson]

Originally Posted by rookie

then take apart and clean very very good.

There is nothin g to dissasemble on solids is there? I do have that book but its on loan to a buddy in jacksonville right now.

[FlowSpecialist]

It's considered very bad practice to use old flat tappet lifters with a new cam but it merits a proper answer. With OHC engines with bucket lifters the buckets are always hardened steel, the tops are ground dead flat as are the lobes of the cam and it's perfectly ok to reuse them as long as there is no wear and the face is still dead flat.

Pushrod engine type lifters differ significantly. Firstly they are not actually dead flat as with an OHC bucket. They have a radius on the top of about 1 metre which means a dome of about 2 to 3 thou in height. Not easily visible to the naked eye but you can feel the curvature by rocking them against a straight edge. The cam lobe with this type of tappet is also ground with a slight taper of about 2 thou variation in height across its width so it contacts the side of the dome on the tappet. This, together with the lobe being offset to one side of the tappet, causes rotation and the two surfaces bed in together.

If the cam lobe was dead flat it would only touch a new tappet in the centre leading to no rotation and a very rapid end to both components. If the tappet has already worn flat and a new cam with tapered lobes is put on it then the only point of contact will be the outside edge of the tappet. Again not good.

Furthermore the tappets are not hardened steel as in an OHC engine but chill cast iron which is fairly hard to start with but work hardens further as it beds in against the cam lobe.

Now if the old tappet has already work hardened but retained its domed shape then in theory the situation shouldn't really be that different from a case hardened OHC bucket being used with a new cam. After all both types of cam usually use the same material.

So it boils down to this. Get a dead straight edge such as the blade of a digital vernier caliper and see if you can rock it over the tops of the lifters. If so they're still domed and your chances of being able to reuse them are pretty good. If they're already flat your chances diminish and if they're already dished at all then forget it.

The official advice is of course don't do it.

FWIW I have heard from one engine builder over here that rather than buying new ones at each change of cam he regularly used to reface the tops of the rather expensive solid lifters used in some CVH engines on the grinder and although that meant they were flat rather than domed it seemed to work ok with new cams with angled lobes.

Oh, while I think of it someone is bound to ask why are there two different types of tappet and cam lobe. It's a function of tappet size. In an OHC engine the bucket can be big enough so the whole, or at least most, of the cam lobe is on one side of it which ensures rotation.

In a pushrod engine the tappet is much smaller in diameter and although the cam lobe is offset there isn't so much of a net rotation force. The initial dome and tapered lobe force the contact point to be on one side to ensure rotation until the surfaces have bedded in and hardened.

Dave

[rookie]

Originally Posted by Mwilson

There is nothin g to dissasemble on solids is there? I do have that book but its on loan to a buddy in jacksonville right now.

The ones I have can.

[Mwilson]

Originally Posted by rookie

The ones I have can.

okay maybe mine do too, one more question. If I buy new I dont really have the $150 for a set of comp "Direct Lubes" do you think new lifters without the "Direct lube" feature would be better than my used but fairly new lifters that do have this feature?

[rookie]

I have never used direct lube lifters I'm to cheap, but I do use oil or additives designed for flat tappet cams, I would not scrimp on that.,

[DavidVizard-GFN]

see my post at :Decided to swap the cam
on the re-use of typical V8 lifters.
DV

[old blue 75]

A ? for DV. David can a guy with access to a surface grinder and spin fixture
(hint hint) grind a 1 or 2 deg. angle on used lifters instead of the large rad., or will that not work.
I,m thinking of some used GM hard face hyd. lifters. Maybe do the figure 8 pattern on emery afterwords.

old blue 75