What size rockers?

[mobileaudio25]

Im running a .489/.476 exhaust lift on a set of dart shp heads. I have a 2300-2500 b&m stall converter with 373 gears.
http://www.jegs.com/i/Comp+Cams/249/CL12-601-4/10002/-1

This is the head i'm running :
http://www.jegs.com/i/Dart/301/127121/10002/-1 .520 max lift

Im upgrading my heads/intake/cam and i was wondering what size rockers i should use? 1.5 or 1.6? Im not running a stud girdle and a tall style valve cover. Thanks !

 

[drogg1]

More lift is pretty much always a good thing. However, upgrading up to 1.6 rockers will bump your right out of the lift range of the springs you and higher ratio rockers also lead to a more unstable valvetrain. If you were willing to swap springs also, I would recommend the 1.6s a least for the intake side. If not, you'll be fine with a good 1.5 rocker on both intake and exhaust and probably be perfectly happy with the performance.

 

[mebe007]

Also good luck running roller rockers with short valve covers. My 1.5 scorpions wouldn't fit. Now I have 1.6 scorpions with tall valve covers. I gave a lot more cam though. Is this a flat tappet or roller cam? Is it new?

 

[mobileaudio25]

I'm running a flat tappet and I'm running tall valve covers. Would you guys suggest switching to a slightly smaller cam and then running 1.6 rockers that way I can achieve almost full performance out of my heads?

 

[GhettoRacingKid]

IMO

valve list if valve lift. doesnt matter if it comes from the rocker or the cam because its always a combo of both.

Stick with what you have and if you want more then go with the 1.6 rockers.

 

[drogg1]

With that kind of cam, you'll need a much higher stall anyways. It really is probably too big for your application especially if this is for a 350. I would shoot more for a 230-240 intake 240-250 exhaust duration cam for a 350-383. As I said before, I would shoot for as much lift as you can get especially if you're trying to maximize the potential flow your heads.

Something like this:

http://www.summitracing.com/parts/CCA-12-246-3/

Would be pretty good for a 350-383.

So, using something with .490" lift, with 1.6 rockers, you'd be at 1.6(.490/1.5) ~= .523" which would be pretty good for a hydraulic flat tappet. This would probably require changing springs though.

If you were okay with the maintenance involved(checking and setting lash and valvetrain noise), I'd recommend swapping in a solid flat tappet as they generally have higher lobe lift. Or, a hydraulic roller if you can afford the cost would be nice for the street.

Or you could keep the cam you have and just use 1.6 rockers like Ghetto put above, but in my opinion, that cam is pretty big duration wise for a street driven car.

 

[mobileaudio25]

I think I'm going to have to keep the 1.5 rockers. I don't want to go through the trouble to change the valve springs and if I run the 1.6 rockets then I will have a lift of .523 which is too big for my springs. But no matter where the lift comes from whether it be cam or rockers a stall needs to math that lift amongst your weight and gears correct?