'Trust'

iTrader: (24)

I know on at least Texas Speeds website they say that "Due to the high ramp rate of this cam, 1.8 rockers are not recommended" for almost all of their cams, i dont really know anything about ramp rate, but why should 1.8 rockers not be used on say a TR 224 112LSA? Will it hurt performance, or just cause excessive drivetrain wear? I honestly have no clue, thanks for any input.

BlackHawk T/A

iTrader: (3)

It will turn your .563" lift cam setup into .596" for one.

MNR-0

Providing you have the valvetrain and springs to handle the accelerated ramp rates and lift the 1.8RRs provide, there will be no problem. I run a 0.560 high lift comp cam with 1.8RRs yielding approx. 0.600 lift with comp 918s and stock valves and its quieter than stock at idle and has no valve bounce in the upper RPMs. I'll jyst need to keep an eye on the springs every 6 months.

An added bonus if the extra lift performs like a larger valve but with the better flow velocity. All this equals insane mid-range torque - so much so my 3000 stall now flashes to 4000RPM. I want a smaller converter!

'Trust'

iTrader: (24)

I knew that, thats not really a downside though

So on a TR224 if i have crane duals it should be fine? Do i need to upgrade anything else?

SouthFL.02.SS

Valve float at high rpm and lifter wear would be concerns.

Nasty N8

iTrader: (33)

If doing a cam always build the lift into the cam not rocker ratio. You do not want the added strain on the valve train. Stick with 1.7 and get a bigger cam. Like said it can cause too much wear on other things like springs lifters... Unless the cam was designed at a 1.8 ratio or you just wanted that added umph from a stock setup it is not a good Idea. Besides it is only worth about 8-10hp over a set of 1.7 roller rockers.

Nate

Nate

mrr23

iTrader: (3)

how is it added stress on the valve train using 1.8 rockers versus building it into the cam? the way i see it, you are only accelerating the valve by using the 1.8 rockers. by building it into the cam, you have now sped up the lifters, pushrods, and rockers. now, the valve springs have to control the accelerated movement of all the parts. not just the valve.

P Mack

iTrader: (6)

Depends if you want your lifters and pushrods moving fast or being squeezed hard. If they are moving faster with 1.7's, they are also under less compressive force because there is less leverage pushing back on their side of the rocker arm. It's all the same to the valvespring, either it has to handle the higher momentum of the lifters with more leverage, or less momentum with less leverage. The valvespring will never know the difference as long as the valve events are the same.

mrr23

iTrader: (3)

another viewpoint. with the sudden acceleration of the lifter due to a more agressive ramp rate be effectively the same pressure exerted on the lifter as using a higher ratio rocker? i know that by using a higher ratio rocker, you will end up needing less closed seat pressure due to the leverage created.

also, the increased speed of the lifter would need more spring pressure to control it. the whole F=MA thing. for instance, how much force would it take to stop a 10lb object dead in it tracks and go the same speed in reverse accelerating at 60 feet per second as opposed to 50 feet per second. and accomplish that a tenth of a second. i'm sure it would take alot more force to do that.

we all talk about weight of rockers over the valve. but i don't see people thinking about the velocity of the rest of the valve train.

mrr23

iTrader: (3)

for someone looking to extract as much as possible, it might be worth it to them. in the case of the vinci/crane rocker kit, the 1.8 is the same price as the 1.7. so, that would be a net cost of FREE for 7-10hp.

P Mack

iTrader: (6)

If you're using a lever to stop the object, and if you're stopping the faster object with 6/5 the leverage as before, it would take exactly the same amount of force to stop it in the same amount of time.

Seems to me if the valve events (valve acceleration specifically) are the same then the required seat pressure would be the same regardless of ratio. The change in leverage would negate the change in lifter/pushrod acceleration rate exactly.

vettenuts

iTrader: (4)

Actually, I think it is the other way around. The higher ratio would give you more leverage from the spring whereas the lower ratio would give you less.

mrr23

iTrader: (3)

i don't see it that way. i'll use stopping a car with brakes as an example. and this might be where my thinking is off. by what i just read of yours, it will take the same amount of force to stop a car going 60 mph as it would going 50 mph in the exact same amount of distance?

i'll have to dig up some of mark campbell's posts on when using higher ratio rockers you end up needing less seat pressure to accomplish the same thing.

P Mack

iTrader: (6)

The comparison should be stopping the car in the same time, not distance.

But it doesn't matter, i was thinking about the leverage thing backwards. Now it makes sense why it takes less spring pressure to control the mass of the lifters with a higher ratio. Sorry for being dumb.