Magnum swap questions

dgc333 said
Cam doesn't know whether the rockers are 1.5 or 1.6 ratio so there is no issue there. The shape of the lobe is dependant on the type/size of lifter that it acts on not the rocker ratio. One of the more popular changes on a magnum motor is to use 1.7 ratio rockers for the added lift.

One of the advantages of swapping a set of magnum heads onto an LA is the 1.6 ratio rockers and the slight increase in lift at the valve. I am taking advantage of this on my LA/magnum hybred 360.

Off the shelf magnum cams are ground with emissions in mind so may not be the best choice. I would go with the LA retro fit cam or have a custom one ground and don't worry about the oiling holes. If you go this route then you can use the LA front cover an all the accessories including a mechanical fuel pump. Also, Mancini has an adapter that allows the fuel pump eccentric to mount to the short snout magnum cam.

Also, I believe that they standardized the rear main seal area on the magnum engine to the 360 size so your 360 LA pan should work on the 318 magnum.

Of course the cam doesn't know what rocker is on the heads but the engine will know and this could be good or bad if you re-read my post. Adding lift is not necessarily a performance gain, on stock cam, most likely, but if you are already at the limit of lift and duration on you engine package adding bigger ratio rockers could lessen your performance by adding to much lift and duration. If you purchased an aftermarket cam for your package with the lift and duration based on 1.5 and you put 1.6 rockers on it you can throw out the window the cam manufacturers recommendations on power range. That is the point I was trying to make.

Chuck