50mm vs 55mm cam tunnel in BIG M block chevy

[rewguy]

what size lobes can you fit in either tunnel? curious. thankyou

[rewguy]

or should i say....with a std. barrel bbc cam core is a better question. not tunnel.

[Alaskaracer]

Mine is a 55mm core and I'm running .535" lobes. Plenty of room for bigger

[Alan Roehrich]

My cam guys tell me that the most cost effective is 54MM babbit bearings. We've been running that set up successfully in Stock and Super Stock for a while.

[Sweet P]

.500"-.515" is about the max lobe lift you can have on a stock BBC cam core

[CamKing]

My cam guys tell me that the most cost effective is 54MM babbit bearings. We've been running that set up successfully in Stock and Super Stock for a while.

The 54mm journal BBC cam core, is one of the hardest cores to find. Out of the 3 major cam core manufacturer, there is only one part# available for the 54mm, and it's roughed in at .500"/.500", 282/304@.050". and a 115 LSA on a 4/7 swap.

[CamKing]

what size lobes can you fit in either tunnel? curious. thankyou

With a 50mm, we max out around .510" lift. With a 55mm, we go to .550" lift.

[rewguy]

what size lobes can you fit in either tunnel? curious. thankyou

With a 50mm, we max out around .510" lift. With a 55mm, we go to .550" lift.

thankyou

[Sweet P]

From the sounds of the valve spring pressures and what NASCAR is/was doing, sounds like one should use as small of cam lobe and as large of a rocker ratio to get to the valve lift that you want.

CAMKING, would you agree?

[CamKing]

From the sounds of the valve spring pressures and what NASCAR is/was doing, sounds like one should use as small of cam lobe and as large of a rocker ratio to get to the valve lift that you want.

CAMKING, would you agree?

As long as the rocker geometry doesn't get out of whack. You don't want a rocker that's 2:1 at max lift, and 2.5:1 at .010" lift.