351/5.8 Guru's - Need cam selection help
 

I have been financially forced to settle for a stock 94 5.8L bottom end and I have a set of Canfield heads I am going to use on it along with a Victor 5.8L intake. These Canfields have been shaved a couple times and were tested at 60cc chambers still. The block I am buying came out of a 94 F-150 or Explorer so I assume the pistons will be flat tops. Am I correct in my thinking or do these pistons have valve reliefs?

Either way, what is the biggest cam I can get away with? I'm hoping to go with something like the Comp Cams XE274HR, or maybe even a little more aggressive. I suppose if I have to cut the pistons I'll have to see what I can come up with.

The XE274HR specs are:
2200-6200rpm range
274/282 advertised duration
.555/.565 lift
112 degrees lobe seperation

Thanks.

that should be a real nice cam for your application. I'd run a bit more lift if you could while keeping the duration the same. the 351 WILL make the cam seem smaller than in a 302, but for street manners keep the duration reasonable. You didn't say what CR you would have with the milled heads...the more CR the more cam you can run too. I also like the 112 separation for a nice fat torque band.

I am not sure what the compression ratio would be. The heads have 60cc chambers so someone should be able to tell me from that with a stock 94 5.8L bottom end.

The lift and duration is what I am concerned with for piston to valve clearance issues. How big can I go with stock pistons?

your pistons probably have some sort of reliefs, but I'm almost certain you'll be notching them if you want to put any sort of cam in your motor...and with those heads it would be a waste if you don't! #1 those heads are milled so they sit closer to the block deck. You just lost valve to piston clearance! #2 canfield probably uses different valve centerlines than the stock heads. I know they use bigger valves. This means even with stock valve reliefs, the reliefs may not be where you need then to be. I get them notched and do the job right. You'll never regret it. (like you would if you ran into valve float and put valves through your pistons):)