1970vette

justr got new heads and am going to bolt them onto my new engine. I was wondering if you can use stock rockers with these heads, instructions say you can if you don't have more that .480" lift. My cam is a comp cams magnum 280 which has .480" lift do you think i'll be safe with stock rockers? anyone car to share their experience with their engine setup that is similar to mine it would be appreciated. How much HP can i expect?
355ci 4bolt
Comp cams 280 magnum
Speed pro hyperutectic pistons (flattop)
Edelbrock performer RPM heads 64cc = 9.7:1 comp (i think)
edelbrock performer rpm manifold.

Maurice

I had the RPM heads / intake / cam and I used stock rockers, but I had to use .1 longer pushrods. That was per the edelbrock help line, but I don't recall the specs of my cam to compare it with yours. Hope that helped.

TravMsns

RPM cam lift is .488 intake and .510 exhaust

Jester69Stingray

DD shows 389hp @ 5500 and 398 tq @ 4500 for that combo. Cant help you with the rocker arm question though. I would call Edelbrock and see what they say.

Scott78

Call the manufacture, but I think you need "long slot" rockers so they don't bind on the studs because of the extra pivot angle from the higher lift from the cam.

Scott

Fevre

Do you follow the speed limit? Remember there is a safety margin built into it so you may be ok with having a higher lift as long as you are not getting any interference or binding.

Todbo

DUDE as everyone else has said call edelbrock here van's email address: Mattiza, Van
E-mail Address(es):
VMattiza@edelbrock.com

:crazy:

Fevre

Is he going to give you the real scoop or tell you that you can't do it because it won't work when in truth it will but since it is outside the manufacture specs he can't? If the cam is higher in lift on either the int or exh he will say you can't unless he doesn't care about product liablilty. Call but I will be amazed if they tell you you can run a cam above the stated lift without voiding their warranty and removing themselves of any liabilty.

SteveG75

Just looked at my RPM heads instructions.

Valve springs are good to .600 lift. Edelbrock suggests checking valve to pistion clearance above .450 lift. The instructions state that "long slot stamped or roller rocker arms will be required if your camshaft has more that .480" lift." This is due to the fact that the stock rocker arms will bind at .480 lift due to the short slot.

Basically, heads are good to .600 lift, just check piston clearance and buy new rockers. :smash:

1970vette

my delema is that my cam has .480" lift so i don't no if i sould risk stock rockers or if i should get new ones. I know it says stock rocker you can use them for lift no more than .480" , WHat if my lift is .480"?!?! :confused:

Fevre

You can get long slot 1.5 :

http://store.summitracing.com/partdetail.asp?part=6434

or 1.6 ratio:

http://store.summitracing.com/partdetail.asp?part=6436

I would intall you current ones and check for binding and interference.

But if you are unsure, they are under $100 so why take a chance?


[Modified by Fevre, 12:28 PM 8/30/2002]

nunus79

If those stock rockers that you are planning to use are off of your old heads, DO NOT USE THEM. Used rocker arms develop a wear pattern on the tips, pivot and push rod pockets unique to the particular head it is installed on. By reusing them on a new head, you will be opening up yourself to a lot of hard to diagnose problems that can be related to the use of the old rockers, i.e. accelerated valve tip or pushrod tip wear, unusual valve guide wear, squeeking, binding, busting, bending, etc.....

Rocker arms are relatively cheap. Good heads deserve good rockers. The quality rockers aren't that much more than the cheapos. It will be money well spent, IMHO.

mrvette

I agree with nunus, a nice set of roller tips 1.5 in order here....

I run mine with 48x-520 lifts, no problems roller tips....

GENE

Maurice

OH YEAH.....You need the long slot rockers, mine were not as stock as I thought they were. They were 1.5 but they were a roller type with the longer slot, sorry if I threw you off earlier. You should be able to call the manufacturer or your cam and ask them exactly what you need.