Erson solid flat tappet cam question (adv duration)

[My427stang]

I have run a cam in an EFI 489 cid port injected FE for a very long time, and have really liked the way it behaves on the street

It's a E240322, solid flat tappet, "Hi flow IM" 286/294, 242/246 @ .050, .595 lift. 110 LSA on 106. Various Erson tables/catalogs call out the advertised duration as "lash duration" and the catalog also has lash ramps listed at .015 with recommended lash being .026. I have never seen a manufacturer use those terms.

Like I said, I am very happy with it and would like to loosely compare advertised overlap to spec a similar cam in a different engine. Does anyone know how Erson measured adv duration, do those numbers tell me? Is it @ .015 based on what I wrote above? .020 like some solid cams? .026 lash? It's not critical for my cam choice on another engine, but making me wonder if the ramps are slower than the numbers would indicate

It's just bench racing mostlyl, but trying to compare an old school flat tappet to what I expect out of a "milder" hyd roller in another build with slow ramps without taking the 489 apart to degree it at the valve

I thought there was an Erson guy on here, and I have poured through a 90s catalog, but I cannot find a reference to what advertised duration is measured at on the lobe. Thanks!

[CGT]

I would guess, your lash is their listed lash duration multiplied by your rocker ratio, or close to it. Bullets lobe master catalog lists lobes in a similiar way. Not sure what a FE rocker ratio is.....

[CGT]

.

[SupStk]

I would guess, your lash is their listed lash duration multiplied by your rocker ratio, or close to it. Bullets lobe master catalog lists lobes in a similiar way. Not sure what a FE rocker ratio is.....

FE Fords are 1.73 with their hyd. rockers and 1.76 with solids.

[CGT]

FE Fords are 1.73 with their hyd. rockers and 1.76 with solids.

the catalog also has lash ramps listed at .015 with recommended lash being .026. I have never seen a manufacturer use those terms.

So....015 x 1.76 =.026
.015 x 1.73= .025

[My427stang]

So that is pretty funny, sorry guys, I should have done the math

Sounds to me then that I can consider advertised duration to be at that lash number given the fact they call it "lash duration"

The other stroker is going to likely be 291/295 adv (hyd roller at .006), 235/242 @ .050 approx .600 lift, but I am going to spread the centers to 112 LSA, and I am considering 114 based on power brakes and 462 inches. Sort of a unique build, not max effort, but will be a concours looking CJ street build with lots of fun inside.