What will this cam change do ?

[In-Tech]

Hiya Brian
The heads are a choke but the intake is a bigger choke. I am assuming a 4.250 stroke. With that Erson cam, put the ICL at 112. Port that tunnel with at least a 15 degree taper port matched to the 385, radius entry at the top, and with all of that it will pick up ~100hp
The new cam will make more power everywhere in your rpm band.

[skinny z]

I would have to see the advertised durations so I could calculate overlap.

Seat timing for sure. At the very least, some simulations ask for it. At least the modest few that I use do.

[blykins]

I would have to see the advertised durations so I could calculate overlap.

Seat timing for sure. At the very least, some simulations ask for it. At least the modest few that I use do.

Yes, ton of variables there. The new cam could be so aggressive that the engine would be under-sprung.

Hard for anyone to say what a cam will do without knowing all the specs.

[skinny z]

I would have to see the advertised durations so I could calculate overlap.

Seat timing for sure. At the very least, some simulations ask for it. At least the modest few that I use do.

Yes, ton of variables there. The new cam could be so aggressive that the engine would be under-sprung.

Hard for anyone to say what a cam will do without knowing all the specs.

.050" tends to be the number that's in the description the most.
A cam designer here at Speedtalk has so much as acknowledged that and typically posts the .050" only in his cam recommendations.
But further to that, he also states that are many other lift values are taken into consideration when he's designing a new specification.
Those I find are rarely discussed in threads of this nature.
Anyway, that's my two cents on it.

[Tom68]

.050" tends to be the number that's in the description the most.
A cam designer here at Speedtalk has so much as acknowledged that and typically posts the .050" only in his cam recommendations.
But further to that, he also states that are many other lift values are taken into consideration when he's designing a new specification.
Those I find are rarely discussed in threads of this nature.
Anyway, that's my two cents on it.

In fact he says the 50 thou figures are a resultant that he only shows after the lobe design is finished and even then it's only done for customers used to comparing that number.

[blykins]

When I spec cams for customers, I generally don't show the advertised durations. There's a lot of info that can be gained between the .050" and seat duration.

[skinny z]

In fact he says the 50 thou figures are a resultant that he only shows after the lobe design is finished and even then it's only done for customers used to comparing that number.

In some cases, the only figure for customers.
Something I've worked through, or believe I have, is how much of that spread between the seat and .050" (or .100", etc) will take some of the life out of the valve train at the expense of a gain in performance? Risk vs reward in other words.

[blykins]

The difference between the seat duration and .050" duration, in correlation with the .200" duration, can give you a pretty good idea if a cam will be a spring eater or not.

[prairiehotrodder]

I have the print-outs for both cams of the complete dimensions. Here is a couple numbers.

old cam : advertised duration 306 / 314
overlap 86

new cam: 316 / 322
overlap 95

I'm nowhere enough of a cam expert on these numbers. Thanks for everyones input. I believe the t-ram is ported but probably not by an expert. the heads have not been touched. The flow numbers for the heads are on the AFR website.

[canada1]

I don't think either of the Erson cams are all that aggressive.
You could certainly ask Erson - as they would know.
Anyhow, hotrodding is supposed to be fun - go out and try things (as you have done).
Sometimes the "internet experts" are wrong.

Good luck!!

[prairiehotrodder]

here is my current best and my goal :

9.16 at 148

goal 8.XX

mods for this year :

new tires (hoping to get my 60 foot to a consistent 1.30 or better (has done a 1.30 once before with less power)
ramped up vacuum from 9 to about 12 with a pulley change on my crankshaft ( hoping to gain maybe 5 - 10 hp)
cam swap ( hoping to gain 5- 10 hp)
new crank trigger distributor (hoping to create a cleaner revving engine)

i'm at the point where ET doesn't come easy and i'm not willing to spend big bucks. Just tweaking and tuning.

[blykins]

I don't think 95° of overlap would be the direction that you need to go, but it doesn't hurt to try.

FWIW, my 556ci BBF pulling truck engines make 1200 hp @ 8500-9000 with that much overlap.

[F-BIRD'88]

Its going to:
Run a lil faster

Run a lil slower

Or run the same.
The only way to know is to try it and see.

[novafornow]

I think that the 148 mph tells me it has power to run 8s. It just needs to get going quicker.

[TMSJoe]

I would think it would hurt your 60'. I would go with the old cam and 1.70 EX rockers.