Bridged Rockers and Carb Spacers

[Tio Pancho]

I am rebuilding the 360 on our 1977 Chief. I am to the point of installing the rocker arms. They are stock bridged rockers. The part that seems odd to me is that there is no stud, and no bottom pivot for the rocker arms. Only a bolt that goes through the bridge and rocker into the threads on the base. This would mean that the rocker is "suspended" by the valve spring and the pushrod. Is this right?

Also, the PO had a total of 1" spacers between the manifold and the carb. Is the spacer necessary? This one broke, so not sure if I need to order one.

Thanks all in advance for your help. Have a safe and happy Thanksgiving.

[Dr.Bob]

Each pedestal for the rocker should bolt tight against the mounting surface on the head, like on an Oldsmobile V-9; it is not adjustable like a Chevy rocker system. When you tighten the rocker with the lifter on the cam's base circle, the tip of the rocker should contact the valve tip and depress the pushrod *slightly* into the lifter.

[Stuka]

For the rocker arms, you are basically correct. The pivot is on the top of the rocker. The pivot has a boss that goes through the rocker and will be tightened against the pedestal. The rocker itself should never touch the pedestal on the head. This of course all changes if you go with aftermarket rockers.

Spacers can change performance characteristics of the engine (Engine Masters has gone into this before). But really what you want is a phenolic spacers to isolate heat in the intake from the carb. But it certainly does not need to be an inch thick.

[Tio Pancho]

Thank you for the input on the rocker arms. I understand the depress slightly for the preload. The troubling part was that I could not find detailed information anywhere showing this scenario even in manuals

The heat insulation for the carb makes sense. I thought it was for some type of atomization assistance.

[Stuka]

Thank you for the input on the rocker arms. I understand the depress slightly for the preload. The troubling part was that I could not find detailed information anywhere showing this scenario even in manuals

The heat insulation for the carb makes sense. I thought it was for some type of atomization assistance.

There are different types of spacers. Open ones, and ones with an opening for each venturi in the carb. And they have different effects on performance depending on the intake used.

The show Engine Masters did dyno tests with O2 sensors for each cylinder with various setups. There difference was not huge, but they could impact drivability in some cases.

[Tio Pancho]

Thank you Stuka. I will look up Engine Masters to make my choice.