AZ28DRIVER1

I was talking to "old timer" the other day. He said back in the day they used to run different ratio rocker arms on certain cylinders. For example the center bank of cylinders would get the same ratio 1:5 while the 4 most outer (2 at the front and 2 at the rear) would get a slightly higher ratio like 1:6 to account for the additional runner length the air/fuel had to travel. Has anyone ever tried this? What do you think of his theory about compensating for the additional runner length by adjusting the rocker ratios?

Cstraub

iTrader: (1)

Yes, we still do it, especially on BBC stuff.

Chris

J-Rod

That is why some folks grind individual lobes for each cylinder. They take the entire intake tract into consideration.

Clay Smith was the first to pioneer this. He was one of the first true visonaries who saw each cylinder as a unique engine with its own needs...

Speedfreaks101

The reason that nobody has used this on the LS1 is that the intake ports are replicated, meaning that they are all the same shape. Therefore there is no need to try and balace the intake flow.

-Joseph-

iTrader: (12)

Since the carburator was in the center of the intake the furthest cylinders away would get less of a fuel/air charge. I don't see any benefit at all on anything that has a injector per cylinder which is what almost all cars have come with for at least 10 years or more.

I think the "Chevrolet Power" book had a little on it for the BBC engines though.

nuzee

iTrader: (2)

I tried running 1.6s on the four-corner cylinder exhaust valves on a small block Chevy w/ramshorn-style exhaust manifolds. The thought was that the longer exhaust path from the corner cylinders vs. the short dump from the center cylinders preferred the additional flow. I heard that it is common for circle track guys that have to run stock manifolds to do this.