I'm thinking of building a 351W for my 66 bronco and have a chance to buy one of two 351W blocks A 69-71 C90E 6015-B The block is bored and honed .040 over
or a 1984 -1997 E3AE bored and honed .060 over . the bronco will mostly be used on road weekend coursing and some mountain roads running 3'5" lift and 33x12.50x15's NV4500 5Speed so I'm asking witch block would be better and more reliable ? any thoughts and suggestions would be greatly appreciated thanks for reading and your input

 

The early block has a little more meat in it but both are more than capable of supporting a relatively mild street motor, and since neither are setup for the factory roller cam assembly it's mostly a wash. That said I'd take the 40 over block for maximum durability unless you have a stroker planed and want the most displacement possible.

 

One thing to watch with on the '69 block - it has a shorter deck 9.48" vs. 9.503" than later blocks. Not much unless your blocks being decked for the second time which makes it tougher to find pistons. I've got one now built with the wrong pistons, they sit maybe .015" above the top of the block @TDC. It took some very expensive .062" mls head gaskets to make up the difference. Save yourself the headache and be sure you get the right pistons if you get the older block.

The older blocks theoretically (anecdotally?) have more nickel in them, fwiw.

 

I have an 82 bronco that the previous (and first) owner put a 351w out of a 93 F150. It has been swapped to a 4bbl carb (not sure where the intake came from but it is a stock cast one off of something) and it sits on the stock 93 heads with the smog pump, serp belt set up, and older points dist...I assume they did that to make wiring easier during the swap. But it runs great, Im lifting it 4 in in the next weekend or so, it has 33's already and a 4 spd, and starting in 2nd I can roast those 33's!!! The truck had sat for 9 years before I got it so it needed some major tuning and carb rebuilding but thats all ive done.

 

the early block is the way to go. altho the early heads are garbage the ports are very small