My 289 is a mildly warmed up 289 - just for street use.
I hear a lot about roller rockers, lifters, etc. and understand they do a lot to reduce friction and heat in the engine. What does the ratio on a roller rocker mean? Is one specifically for a 289, or do different apps or cams call for different ratios?
What's the cost (generally) of a quality set? Do I need 'em ?
I ask because my valve covers will be off in a few week for media blasting, and that would be an opportune time....TIA - Dickson
They certainly wouldn't hurt, especially if you like to step on the gas once and awhile. You'll need screw in studs, which would require stock heads to be machined. You could have valve cover clearance problems, depending on the roller rocker used. Roller tipped steel rockers (200?, ask Johnpro, he has 'em on his 65 I think) are an option for clearance and I think COMP CAM Pro Magnum rollers ($260, Summit) will clear stock covers as well. My Trick Flow billet rollers were $240, but I needed taller valve covers. Figure $2-300 for a good set along with the cost of studs, guidplates, and any shop work.
you will need to take off lots more then your valve covers to convert to roller lifters..you need to replace the cam as well..I have a complete article about the conversion..I can email it if you decide to go ahead with it.
If your heads are in good condition with a fairly recent rebuild, and the engine is running well, don't do it. MUCH TROUBLE COMES FROM FIXING THINGS THAT AREN'T BROKEN. If your heads are due for an overhaul(valve grind, new guides, new springs, retainers, etc.) yeah, go ahead and have them machined for studs. The old rockers probably need replaced anyway.
Likely not....I street-raced for years with stock rockers and ran in the low-14's at the track...
If you want to, if you have early heads with the slot for the pushrod, you can run some Crane Energizer's, like I use on the race car, for a cost of under 200.00...add a bit for taller valve covers if you don't have them already.
Your stockers are 1.6's and that's what I've always run on any of my W-based engines...
The ratio means the rocker multiplies the lobe lift of the cam by the ratio, in this case 1.6. So, if you have a cam with .500" lift (they're rated at the valve), the actual lobe will lift the lifter only .312"....when I degree in camshafts, I measure off the lifter (you've likely seen duration figures at .050" lifter rise)
I'd say to start thinking about roller rockers when lift is getting into the low .500's at the valve (which usually means substantially stiffer springs than OEM)
Of course a roller top end is better in any motor, the only question is can your wallet take it. Roller Cam, Lifters ,Rockers, diff. pushrods, and don't forget about the the new screw in studs your machine shop will have to put in. Also Stud-girdles and push-rod guides while you're there. This all should be done by a professional only. Don't do it yourself !!!!