What do you think about using 1.6 roller rockers on a stock 1985 TPI 305? My car has the "good" factory cam but I'm wondering if my heads have enough flow to really take advantage of the increased lift and duration. I really don't want to change the cam. I have to replace the valve seals so I'm thinking I could install new springs and rockers while I'm at it.
thanks

 

The lift will increase by .030" (~.436"/~.446") and duration by ~2' (~208'/~216'). So long as the springs support the intended lift and will not bind, you should be fine. Don't worry about flow, the heads still have enough in them for the added .030" lift.

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George P. Lara
1994 Z28 LT1 T56
1984 Z28 High Output
Member: SCCA, SCFB, SC3GFB
Chevy Info --> MadMike's

 

85Z,

Welcome aboard!

The 1.6: rockers will have some benefit from the added lift and effective duration (at 0.050" valve lifts), and will also reduce friction and oil heating. According to Crane, the power gains can be as high as 16.6 HP and 17.4 lb/ft. That sounds a little optomistic, ubt additional power should be the end result. The stock springs should be good to about 0.480" lifts before bind is an issue, but if yours are weak or have high mileage, newer springs are a good idea. You might want to consider eliminating the exhaust valve rotators, since they are not really proven to improve valve life and only add reciprocating mass to the valve train. New Teflon seals can eliminate the need for oil shields on the springs, further reducing valve train mass. Size your springs accordingly.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
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