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70' c10 09-30-2010 06:49 PM

Roller rocker arms on a 350 chevy
 
hey guys i got a 350 with mechanical flat tappet lifters and i was wondering if roller rockers are a logical choice for a once or twice a week driver. how often am i going to have to reset valves if? also what kind of horsepower bump are they gonna give me? thanks!

techinspector1 09-30-2010 09:37 PM

Quote:

Originally Posted by 70' c10
hey guys i got a 350 with mechanical flat tappet lifters and i was wondering if roller rockers are a logical choice for a once or twice a week driver. how often am i going to have to reset valves if? also what kind of horsepower bump are they gonna give me? thanks!

Roller rockers do not in and of themselves necessitate adjusting the valves. That is a function of using solid lifters. Once you get the valves adjusted for the initial cam break-in, I might expect to set the lash every other oil change for a while. Thing is, once you get it set hot, then you let the motor cool and see where the lash is. Then, every time after that, you can check the lash cold and not have such a mess on your hands.

As far as hp increase, I have seen estimates of 20-25 hp if we are talking about the roller fulcrum/roller tip rockers. If we are talking roller tip and ball/socket fulcrum, I wouldn't walk across the street to get them if they were free.

You could try comparing roller rockers to other performance items to determine whether they are worth the bother. Let's say a cam and kit costs $200 and adds 50 hp. The cost per hp is $4.00. If you change a low-rise intake for a high-rise intake and pick up 40 hp and the cost is $150, then the cost per hp is $3.75. If you install roller rockers at a cost of $225 and they free-up 25 hp, then the cost is $9.00 per hp.

70' c10 10-01-2010 04:19 PM

right on thanks! that gives me a way better idea of what i want to do.
thanks again

oldbogie 10-01-2010 05:21 PM

Quote:

Originally Posted by 70' c10
hey guys i got a 350 with mechanical flat tappet lifters and i was wondering if roller rockers are a logical choice for a once or twice a week driver. how often am i going to have to reset valves if? also what kind of horsepower bump are they gonna give me? thanks!

I think this is something to consider as lift at the valve gets around .5 inch as they reduce the side loading on the stem and guide resulting in less wear, thus less oil going down the guide. At the trunnion, if you spend much time above 6000 RPM they reduce temperatures compared to what's going on with the ball and socket design. This reduces heat related failures in this area. But in and of themselves without an increase in ratio, they really are not power adders and to get the gifts they do give in reliability and durability under extreme conditions the trade of potentially large engine failures comes from the rollers being spilled into the engine should one of them fail. To guard against this eventuality screens need to be fitted to the oil returns at the ends of the valley. Where the smaller vents holes line the cam tunnel either standoffs have to be installed or the vents closed off. Then some powerful magnets need to be placed at the drain backs in the rocker box and in the cam/lifter valley to attract any possible wreckage before it gets to the screens, a double layer of insurance should a roller bearing come apart. It's not something that happens often, but if the engine isn't prepared to defend against that rare occurrence the result is quite horrific.

Bogie

spinn 10-01-2010 06:43 PM

Does anybody spead much time above 6ooo rpms on a hydraulic Na 350 ?


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