I'm installing a '76 455 (out of a 98) into an '89 Custom Cruiser. Before installation, I plan on changing the timing set with an adjustable set.


My question is this: what is the correct intake lobe centerline?


I'm assuming the stock set is installed retarded for emissions so between that and the wear, checking where the centerline is (or should be) before disassembly will be meaningless. Generally, on stock low compression engines, to compensate for initial stretch and boost low end torque, I install 4 degrees advanced, but I need to know where the centerline should be straight up in the firstplace.

 

Someone should be able to get the cam specs for you.
But I'm willing to bet they're not installed "straight up" to begin with. I'm taking for granted you fully understand that term. Most don't.

 

So far, the best figures I've come up with on the aftermarket cams are that the mild cams (duration @ .050 from 187 to 215 degrees) with slightly wider LSA's (109 to 112 degrees) come in at between 106 and 112 degrees for the intake centerline. My previous experience with other engines (built mild for low end torque) is that I used to set the ICL from 105 to 108 degrees.

I tend to agree with you. If the factory cam was installed retarded, then the intake centerline is also retarded, perhaps in the 113 to 115 degree area. Before I pull the stock timing set, I'll see where the ICL falls, adjusting for whatever stretch I measure in the stock set.

 

I sincerely doubt they'd install the cam on a low compression engine at a centerline that late. I'll bet it's much earlier than that.

 

Hopefully I'll be able to figure that out. I'll pass along what I come up with.