Camshaft lifters
- Thread starter jrfjr
- Start date
JoeWay
Well-known member
Self-locking (single-nut) lifters are said to be prone to coming out of adjustment, though I have not had that problem with mine.
"Double-nut" lifters (which actually have only one nut--the lifter itself is the second "nut") are more positive if tightened correctly.
Neither style can be adjusted when the target valve is closed. Some people cut down the boss. I prefer to use the adjustment procedure described periodically on the forum in which the gap is measured through the sequence, then adjusted in a second run through the sequence, then re-checked. The thread pitch is usually 20 to the inch or 0.050" per turn of the adjuster, and one quickly gets a feel for how much to turn the adjuster.
Without question it takes longer--3 or 4 times longer--to adjust with the uncut lifter boss, but I prefer to keep the full bearing surface for the lifter. It only takes maybe 15-20 minutes to go through the valves once you get the hang of it.
Joe
"Double-nut" lifters (which actually have only one nut--the lifter itself is the second "nut") are more positive if tightened correctly.
Neither style can be adjusted when the target valve is closed. Some people cut down the boss. I prefer to use the adjustment procedure described periodically on the forum in which the gap is measured through the sequence, then adjusted in a second run through the sequence, then re-checked. The thread pitch is usually 20 to the inch or 0.050" per turn of the adjuster, and one quickly gets a feel for how much to turn the adjuster.
Without question it takes longer--3 or 4 times longer--to adjust with the uncut lifter boss, but I prefer to keep the full bearing surface for the lifter. It only takes maybe 15-20 minutes to go through the valves once you get the hang of it.
Joe
just plain bill
Senior Member
Most of the double nut type that I have seen have a smaller diameter base than the self locking.
Bruce of MN
Well-known member
I have the double nut kind and it wasn't too bad adjusting them with the engine out of the car. I did have to grind my wrenches thinner though. I am dreading doing it with the engine in the car with the manifolds in the way. But, you gotta do it to make sure everything is OK.
pat in Santa Cruz
Well-known member
As mentioned, the double nut type have a smaller foot, which will reduce your duration a bit. I would not cut the bosses either. I have one engine that was done on, and I can hear the lifters rattling because the bosses do not hold them steady as well when shortened. Re-ground cams will require the adjusting nut be pretty high up, which I have worried could weaken a single lock's grip, although I have not had a problem with one yet.
Another thing I found is that some manufacturers deck the lifter top and others do not, leaving an uneven contact surface which makes adjusting it accurately very difficult as well as resulting in a noisy valve due to a small contact point instead of the full contact. Ask your supplier if the tops of the lifters have been decked before you buy. Lately it seems there are more around that have been done right than there were a few years ago.
. I finally bit the bullet and bought a new cam from Bill Stipe. I'll never regret it. Its a great cam and the joy of such good performance overrode the pain of the price almost immediately after I started driving it.
Another thing I found is that some manufacturers deck the lifter top and others do not, leaving an uneven contact surface which makes adjusting it accurately very difficult as well as resulting in a noisy valve due to a small contact point instead of the full contact. Ask your supplier if the tops of the lifters have been decked before you buy. Lately it seems there are more around that have been done right than there were a few years ago.
. I finally bit the bullet and bought a new cam from Bill Stipe. I'll never regret it. Its a great cam and the joy of such good performance overrode the pain of the price almost immediately after I started driving it.
Bubby Sharp in KY
Member
Caution People! The Lifters I bought from a vendor at the MARC national meet are too short! The lifters are about 1/4 in shorter than they need to be . I have a new set on order. The lifter cannot be adjusted by turning the cam to highest position , it will not expose the flats on the lifter at all . Only way to adjust is to remove valve and pull lifter up with magnet, adjust, then reassemble and check clearance . This is with a new high lift cam. This is the first time I have had this happen . I have adjusted three sets of valves in the last few months and this is the only set to give me this trouble. Moral of story, check heighth before assembly. Bubby Sharp in KY
Jim Brierley
Well-known member
A reground cam will not have a "very small" base circle unless it was ground on a badly worn core. In 50 years I have only seen one single nut lifter loosen, that was on a flathead V8 with a brand X cam installed. I agree, don't cut the lifter bosses down.
TinCup
Well-known member
I thought these pictures from my engine refresh were relevant to this topic. These lifters were installed in the mid 70's and were most likely from Argentina. I was constantly having to gap the lifters and so when we tore it down to put in a clutch and new flywheel valves and lifters were added to the job. What's that saying? "A picture says a thousand words".
