Mech. flat tappet cam; Does lash affect cam/lifter wear?

[plovett]

Question is: does running tighter or looser lash affect wear? I am talking about running lash within a "normal" range.

If you run it tighter there is less time with the lifter off of the cam and less time for oil to get into that area?

If you run it looser is there increased "pounding" at the interface. I'd guess not if it is still on the lash ramp?

thanks for any thoughts,

paulie

edit: For example, let say you have a cam where the hot lash could be varied from 0.010" to 0.030".

[Walter R. Malik]

An oil film is only a few thousandths thick at the most.
Hydraulic flat lifters, (with no gap), work quite well with enough oil sprayed entirely on the lobe to create a film...

Running lash wider than the LASH RAMP of that particular cam lobe would create excessive wear.

[pdq67]

I think that if you get right close to CC and flat ask them that their solid flat tappet HE and Magnum cams can be lashed from .015" to .030" fine.

Anyway, the CC-282S cam in my 496 is set at .015" lash cold.

pdq67

[cv67]

many of the old OE solids had a fair amount of lash lasted many thousands of miles. Perhaps less spring and slow ramps back in those days?

[plovett]

Thanks guys.

[modok]

Ideally, the lash ramp should match the actual lash+flex. It would work smoothest and quietest that way, and might last longer just from being smooth, instead of "bouncing" as it opens and closes. In real life.....it's never perfect, and, maybe does not need to be perfect, but within reason.

If you have twice the lash ramp as you need, that can't be ideal.,... at the very least, giving up some torque/stability at lower speeds and idle.

[plovett]

Ideally, the lash ramp should match the actual lash+flex. It would work smoothest and quietest that way, and might last longer just from being smooth, instead of "bouncing" as it opens and closes. In real life.....it's never perfect, and, maybe does not need to be perfect, but within reason.

If you have twice the lash ramp as you need, that can't be ideal.,... at the very least, giving up some torque/stability at lower speeds and idle.

That makes sense to me. Thanks.

paulie

[CamKing]

Tighter will not have any added wear issues.
Looser will.

[Truckedup]

Tighter will not have any added wear issues.
Looser will.

Why do some cams like the older Chevy flat tappet solids run .030 lash? Do the engine components expand so much they tighten up the clearance? I had a Lazer Cams tight lash cam in my vintage 302 GMC inline 6 engine. It was a regrind on a stock core... .005 lash cold, typical is .012-.016....Guys told me it's no good, the cam will wear out.....The cam was still fine at 60,000 miles...

[Walter R. Malik]

Tighter will not have any added wear issues.
Looser will.

Why do some cams like the older Chevy flat tappet solids run .030 lash? Do the engine components expand so much they tighten up the clearance? I had a Lazer Cams tight lash cam in my vintage 302 GMC inline 6 engine. It was a regrind on a stock core... .005 lash cold, typical is .012-.016....Guys told me it's no good, the cam will wear out.....The cam was still fine at 60,000 miles...

It is pretty simple to understand.
The GM camshaft lobe profile was DESIGNED with a long, slow lash ramp and the LAZER cam had a very short, faster lash ramp.

ALL solid lifter camshafts are not created with equal lash ramps.

[Truckedup]

Tighter will not have any added wear issues.
Looser will.

Why do some cams like the older Chevy flat tappet solids run .030 lash? Do the engine components expand so much they tighten up the clearance? I had a Lazer Cams tight lash cam in my vintage 302 GMC inline 6 engine. It was a regrind on a stock core... .005 lash cold, typical is .012-.016....Guys told me it's no good, the cam will wear out.....The cam was still fine at 60,000 miles...

It is pretty simple to understand.
The GM camshaft lobe profile was DESIGNED with a long, slow lash ramp and the LAZER cam had a very short, faster lash ramp.

ALL solid lifter camshafts are not created with equal lash ramps.

..I should have said What is the hot running lash of a cam like the 30-30 if the valves are set to .030 cold?

[PackardV8]

many of the old OE solids had a fair amount of lash lasted many thousands of miles. Perhaps less spring and slow ramps back in those days?

For true. FWIW, in a second-hand account from an unimpeachable source, Ed Winfield claimed to have designed the early SBC performance cams for Chevrolet Engineering. His explanation was Chevy didn't want to spend the money for better valve springs, so lobe lift was low and the ramps were the longest, slowest takeup and closing possible.

..I should have said What is the hot running lash of a cam like the 30-30 if the valves are set to .030 cold?

On a SBC with iron heads, stock springs, it only changes a couple thou.

[statsystems]

many of the old OE solids had a fair amount of lash lasted many thousands of miles. Perhaps less spring and slow ramps back in those days?

For true. FWIW, in a second-hand account from an unimpeachable source, Ed Winfield claimed to have designed the early SBC performance cams for Chevrolet Engineering. His explanation was Chevy didn't want to spend the money for better valve springs, so lobe lift was low and the ramps were the longest, slowest takeup and closing possible.

..I should have said What is the hot running lash of a cam like the 30-30 if the valves are set to .030 cold?

On a SBC with iron heads, stock springs, it only changes a couple thou.

The Ed Winfield story sounds like one I can believe.

[hoffman900]

many of the old OE solids had a fair amount of lash lasted many thousands of miles. Perhaps less spring and slow ramps back in those days?

For true. FWIW, in a second-hand account from an unimpeachable source, Ed Winfield claimed to have designed the early SBC performance cams for Chevrolet Engineering. His explanation was Chevy didn't want to spend the money for better valve springs, so lobe lift was low and the ramps were the longest, slowest takeup and closing possible.

..I should have said What is the hot running lash of a cam like the 30-30 if the valves are set to .030 cold?

On a SBC with iron heads, stock springs, it only changes a couple thou.

The Ed Winfield story sounds like one I can believe.

And unsurprisingly, the aftermarket camshaft manufactures likely built their master database as such. It probably wasn't until the '80s and '90s where things finally started progressing.

[Stan Weiss]

Other than the point where the lash ramp is "knotted" to the lobe lift curve. What does the lash ramp design have to do with the lobe lift design?

Stan