SB

iTrader: (1)

Rocker ratio also effects the psi from the spring back thru the pushrod, to the lifter, and to the cam lobe. It also effects how fast the spring compresses / decompresses.

450lb open x 1.7 = 765 lbs pushing the pushrod and lifter, into cam lobe.
450lb open x 1.8 = 810 lbs

500lb open x 1.7 = 850 lbs
500lb open x 1,8 = 900 lbs

That's static force only.

With modern cams, it is an awful lot to ask of the lifter and spring, but they are doing fine with modern good quality components. The 1.8s can push the fuss points into your rpm range,,,,is it worth it to chase that last 5-10hp ? I say no for the reduced valvetrain life and possible issues.

If you can raise the max rpm of your engine 100rpm, you will find that same 10hp.

Again, I have seen the assed ratio with hyd lifters lower the fuss point (instability) 400rpm or so....so....I'll make engine go 100rpm higher with 300rpm to spare .

Again, as I noted before, I have not used the newer short travel hydraulics, so I can't answer for them.

There are plus's and minus's to increased rocker ratio...a ton of them.....but I feel that most hyd BBC engines getting close to 6k rpm is not a place to use higher ratio rockers unless using some old antiquated cam that ill make far less hp than a modern one that is still stable. That 10hp will be still far from hat the modern can with 1.7's will make.

1,7 is a lot of ratio, to begin with. Add in very heavy BBC valves, valvesprings, retainers, pushrods at an angle...and. well,,,,,

Lastly, we do not need to go over .700 lift to get to 700+hp anymore,,,so, why try to get there if it makes unneeded stress.

I am not , by any means saying I have the correct 100% answer above, it is strictly what I believe and I have experienced and have seen.......again without using the latest greatest supposed high tech $$$ stuff. I am one that want's 200+hr maintenance schedules. Not less, Would rather more.

Valvetrain always has and always be a tough part of the BBC engine, in endurance app's seeking as much hp as they can.

Rookie

iTrader: (4)

Thanks SB! I understand all of that. I'm just to lazy to write all of that down. I'm glad it's here now.

sutphen 30

I'll tell my engines that those 1.8's have to go.

abones

what lifters are you running?

Rookie

iTrader: (4)

They are. Going to order new rockers next week.

SB

iTrader: (1)

They don't listen to you.

The more you treat them like schit, the more they try to despise you and they keep running.

The more you treat them nice, the more they try to despise you and they kick you in the ballz.

Kinda like some women we all have met at one time or another. Doh !

MILD THUNDER

iTrader: (3)

Wonder what kind of forces, the cam/lifter/pushrod/rocker sees, when its trying to open the exhaust valve, on an engine making 2hp per cubic inch worth of cylinder pressure?

Back when I was on the phone with the guys at Trend performance, ordering pushrods, I asked him "Do guys ever order/run heavier wall or larger diameter pushrods on the exhaust side only?"

His answer was "Yes, in some applications".

Maybe a N/A engine making 1.3hp per ci, wont need the same things as a forced induction engine making close to 2hp per ci.

For the most part, thats one of my reasons I am a fan of superchargers on boats. You don't need to get crazy with lift, aggressive with lobes, high rocker ratios,, turn tons of rpm, have custom crazy cylinder heads, and custom ported intakes, and custom tuned exhausts, and custom carburetors, to make 700, 750, 800 reliable horsepower, than in most cases, will live a heck of a lot longer between teardowns, than a N/A making 750-800hp.

sutphen 30

2004 isky red zones.got them at a bargain compared to today.

getrdunn

iTrader: (7)

Exactly!

MILD THUNDER

iTrader: (3)

Yea no kidding. The price of good hyd roller lifters, is getting crazy.