I was going through the summitracing website looking at goodies for my 86' L98, and I was wondering about the Roller rockers. What would be a good type for all applications? Whats the differnce between 1.5, 1.52, 1.6? What ones can be used for my Baby? Any help would be great thanks!! Ryan

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The difference in 1.5, 1.52, 1.6, etc, is the ratio of lift: the higher the number the more the valve moves cmpared to the cam lob. If for example the ratio were 2.0, the value would move .50 inch if the cam lob actually moved only .25 inch, etc.

Getting a higher lift rocker set is a "cheap" way to: 1) get more lift (going from 1.5 to 1.6 increases lift and breathing by about 6-7%) and more power at higher RPM (also, generally, reducing low end torque a bit), 2) put a lot more stress on cams, lifters, and rockers, 3) require heavier springs, 4) create the potential that you have too much lift and the valves hit the pistons.

You have to know quite a bit about clearances, etc., to pick what is best, and it has to match your cam, and the pushrods and lifters need to be appropriate for it, too. If you have everything else stock, you can sometimes just switch out to higher ratio rockers (say 1.6 instead of a stock 1.5, or whatever) replacing the springs with heavier, too, and get more power without worries. But if you do not know exactly waht cam, lifters, etc are inside your engine, be careful. I would recommend talking directly with an expert at a cam amnuifacturer or rocker rocker manufacturer/vendor to get recommendations for what fits. Usually it is best to buy the whole set: canm, lifters, springs, pushrods, rockers, etc., as a matched set tailored to your engine.

 

Wow, that was VERY imformative!! Thanks a bunch, I will contact the vendor to see what's best

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Also, one other thing, you will have to have taller valve covers and that will present a problem with exterior clearance on early TPI's. [8D]

 

You can get ratio'd rockers that are stamped steel like the factory ones that should clear factory valve covers.

 

would this mods really effect it at idle? Would buying completed "High Flow" heads come with them already?

 

I thought 1.6 were ideal for my car.(86) Thats what I was told on another forum. Does it make it idle rougher louder??? It reduces friction I know but probably not alot of horsepower gains unless you have more work done. Just making an educated guess on that though.

 

Reduces friction? How? Never heard that before.

 

That was I found on another forum that I was just looking on random threads. Like I said im just making educated guesses.

 

I have used the crane cams 1.6 roller tip rocker on other engines I have built ,although they are not a true roller rocker because the fulcrum is still the ball pivot type they are a durable cast unit and because of the roller tip design it will stop the side scrubing action on the valve tip and after years of service wear out valve guides( friction robs power ) if the fulcrum is roller bearing this also creates less friction . You will not notice a difference in power or torque because it really is a small gain , but it is a gain .

Generally one of the drawbacks of stock small block chevys is RPM . To change that you get a cam , springs and roller parts in the valve train ( along with some mild porting of the gasket areas) you can spin them up to 6000 rpm with very good power results and still be a daily driver ( don't go nuts with the cam specs.) consult with a reputable engine builder or talk to one of the crane cams hotline guys . ( no I don't work for Crane but have used their stuff )

I know drag racers that will index their spark plugs to get the most out their engine.( buy pointing the electrode down towards the piston the flash has a better shot at lighting the fuel air charge) I won't be doing this lol

I will be installing some rollers on my 86 this winter . I hope to find some true roller rockers that fit under the stock covers .