Guru_4_hire

Is there a justifiable reason to get steel rockers that cost twice as much, on a street engine?

Xracer

Not unless your cam has some big lift numbers or a wild lobe design.

Guru_4_hire

its a compcams magnum 270 solid lifter cam.

It has .5 lift with 1.6 rockers and well under it with 1.5 rockers

I am also trying to decide if I want to run 1.5 or 1.6 rockers.

the cylinder heads I want to use come prepared to take .6 lift with a mechanical cam.

I was thinking about using some scorpion roller rockers.

And where in Rochester do you live, I was raised in Livonia down 390 from there, went to college at RIT


[Modified by Guru_4_hire, 5:56 PM 9/4/2003]

MotorHead

Aluminum wil be fine go with 1.6 ratio for that cam :D

Guru_4_hire

On Dyno2000 I havent figured out how to simulate 1.6 ratio rockers, cause just changing the lift to the 1.6 lift ratio doesnt ever do alot

MotorHead

Go tp the box where it says lift and manually change it to .500, it really only gives you a couple of horses but at .470 with 1.5 ratio why not give it a little help.

Harland Sharp make pretty good aluminum roller rockers and are cheaper that Crane Gold

Actually for your seat pressure and lift you will see very little gain if any with roller rockers, even on my setup they are not needed, I bought them mainly for the motor I am now building and I do like the clatter they make with a solid cam.

You might want to consider 1.6 stamped steel and spend the $250 on something that will actually make your Vette go faster. :D


[Modified by MotorHead, 7:32 PM 9/4/2003]

Guru_4_hire

Who makes 1.6 ratio stamped steel rockers that dont cost a hundred bucks?

I am looking at proline or what my cylinder head manufactuers recommend scorpion

mnow

the question I would ask you is.. how high are you going to rev the engine, and at what rpm will the engine spend the greatest portion of its time? If the engine is strictly a street daily driver, this isnt an issue, and cheaper will be fine.
However, if the engine will see 5-6000+ rpm consistantly, keeping the valvetrain as light, and strong as possible is a must. A heavy valvetrain at high rpm contributes to "valve float", in which the weight, and speed of the valvetrain overpowers the spring, and the valve goes ballistic-remaining open when the spring should be pushing it closed. This superheats and ruins the spring almost immediatly. Having an excessive rocker ratio can contribute to this as well, creating excessive valve acceleration.
So unless you plan on really pushing it, I, personally, cant justify the extra expense...
Just my $.02
~Michael

Guru_4_hire

I figure it **might** see 5 or 6K rpm on blasts or at the strip, but majority around 2-4K

mnow

If it was me, I would go with the cheaper of the two, and adhere to a realistic redline. Chances are you are well past peak torque at 6k, so the only thing you are doing is perhaps destroying what was likely a good set of valvesprings. If you get really unlucky, pistons and valves hitting, bent pushrods or worse.

Guru_4_hire

.5 lift with 1.6 ratio rockers on a .6 lift spring, is excessive? I can only spend my money once so I am over analyzing everything

the cam I want to use
Magnum 270 solid

* Advertised duration: 270 intake/270 exhaust
* Duration at .050 in.: 224 intake/224 exhaust
* Gross valve lift: .468 in. intake/.468 in. exhaust
* Lobe separation: 110 degrees
* RPM range: 1,500 to 5,500
* Noticeable idle


[Modified by Guru_4_hire, 9:14 PM 9/4/2003]


[Modified by Guru_4_hire, 9:15 PM 9/4/2003]

mnow

no, not in your case. But winding it out to 6k, in my opinion, is... unless your power curve extends that high, and your valvetrain is built to withstand it.
~Michael

Guru_4_hire

http://www.flatlanderracing.com/head...ghtalumsb.html

mnow

If you input everything into dyno2000, when does your peak torque occur? Remember... torque=acceleration

Dinner on the table, I'll check the thread later tonight.
Have a good one.

Guru_4_hire

But everything peaks before 6K and torque well before that
I am at work for awhile so it will be saturday before I can really post about it, gettin married tommorow


[Modified by Guru_4_hire, 9:38 PM 9/4/2003]

mnow

congratulations !!! :party:

Therefore, there is no reason to rev to 6k, since your curve doesnt extend that high, and no need for the steel rockers. Shifting to keep your rpms near peak torque will, in theory, provide the fastest acceleration.

Does she have a cute sister? :D


[Modified by mnow, 8:38 PM 9/4/2003]

boredsoIstrokedit

Higher ratio rockers are a crutch or a quick fix. Pick the right cam in the first place, and you won't need them or any of the problems associated with them. I am not saying that rollers are no good, they are, just that if you pick the right cam for your combo, high ratio rockers would HAVE NO POSITIVE EFFECTS, only problems. Some cams, though are designed for 1.6/1.7 like the LT4/HOT cam, or an LS1/LS6 cam. :cheers:

boredsoIstrokedit

Peak HP, NOT PEAK TORQUE will have the best acceleration.