Quick rocker arm/ rod question

[86Cutlass383SR]

7.800" is the stock length pushrod for the flat tappet SBC.

The info I gathered from various engine books says that you may also gain by running 1.6 rockers on the exhaust side only, too. It all depends on head flow, both intake and exhaust. Intake manifolds, headers and mufflers, head porting if any, all affect this. Since a SBC generally flows more intake air and has a slightly poorer exhaust side and it has to flow thru those headers and full exhaust system, then a 1.6 may help the exh side more than the intake side. It all depends on what the engine needs.

I've also heard that a roller-tip rocker offers no advantage over a non-roller tip on a stamped steel rocker arm. Due to the valve spring pressure, a "roller tip" on a rocker doesn't actually roll, even on a full roller rocker arm. The *roller* tip is just an axle supporting a cylindrical tip. The advantage of a roller is in the roller fulcrum reducing friction over the ball and socket of the stamped steel rocker.

I've not observed or tested this. It was gathered in the late John Lingenfelter book. I figured he'd forgotten more engine knowledge than I'll ever know so I took his research on this. Myself, I wouldn't pay extra for a roller tip. Either go full roller or a good quality stamped steel rocker.

I'm not trying to start any arguements as I know other ideas were expressed. I will not argue this. Just stating my research.

 

[beermonkey9417]

i bought comp cams 1.6:1 roller tip rockers for my elky. i got higher compression heads, and use stock sized pushrods. it works good for my stock cam/lifter setup.

 

[patmckinneyracing]

I really don't want to spend the extra coin on roller tips and just figured on going with a summit brand stamped steel 1.6 rocker which should work fine. I'm looking to give the engine the added benefits of a larger cam without have to do a cam swap.

Here are my engine specs:

-350 standard bore 2 bolt main
-333882 iron heads, 2.02/1.60 valves, guide plates, have not been decked to the best of my knowledge
-Flat top KB pistons with valve reliefs
-Edelbrock Performer intake
-Summit 272/282, .442/.465, 112 LSA camshaft
-Flowtech full length headers, flowmaster 40's, 2.5 inch exhaust (no cats)


So is there a benefit with 1.6 rockers and this setup over 1.5? And what carb would work better, an eddy 1406 600cfm carb, or a carter competition AFB 750cfm carb? I'm looking at maintaining my torque numbers with possibly a little bit more hp.

 

[86Cutlass383SR]

Well if you like experimenting a little, I'd put the 1.6's on the intake side and drive it for a while and see how it responds. Then put them on the exhaust side only. Or just put them on both the intake and exhaust. Unless you have access to a chassis dyno then testing will be seat of the pants, 1/4 mile, or even mpg's.

For a street 350, I'd stay with the 600. It'd take some mighty small block horsepower to *need* the cfm a 750 would provide.