Has anyone built a 351m with a 400 crank and heads and run it on propane?

 

I would go with dome pistons and a good exhaust seat. compression needs to be bumped up.

 

If you use dome pistons, can you still mill the heads? With the 400 crank and heads and the right pistons, I was hoping to get at least 10:1

 

dome will get you some easy compression. need to use cleveland pistons and get your con rods resized for the different piston pin. don't need to do much machine work. Or use a cleveland flat top on 400 rod and 0 deck the block and you will have your compression also. Many different ways to make compression with 400 not hard just need to know who to talk to. Need to follow up on some details on actual compression. Need to know your cyl head CC's, volume. then calculate from their. Being your doing a propane engine need to have some compression to work.

 

Thanks for the info. Trying to get as much research done as I can. Probably going to build the motor in the spring.

 

Rebuilt mine with aussie heads, tim meyer pistons approx 9.5 to 1, and holley street dom manifold. Goes very well

 

You can get lots of info and advice on propane systems from these guys:

Alternative Fuels • Index page

 

. Yes, with the lower energy content of propane, but higher octane rating, need to go higher compression ratio to get good efficiency... saw a TV show a few days ago where propane use for truck fleets was claimed to only cost ~2/3's of using diesel fuel! Of course, these were commercial fleets buying their own propane in large bulk and operating over a certain area small enough to allow re-fueling at the home yards tanks...

. I assumed your original intent was to run 100% propane, not just use propane as an octane booster for gasoline as some on here are doing... with pure propane, prolly want 12:1 - 15:1 compression ratio and KB 351C FORGED pistons modified to work in a 400... with that compression ratio, I'd go with the bigger 400 piston pins rather than the smaller 351C pins, need all the strength and bearing surface you can get...

 

Buzz, I was going thru some old posts and just now saw yours from 2 years ago. I ended up going with 1970 351c(62cc) heads and Tim Meyer pistons. I also called Crane and had a cam shaft made for this engine along with rockers and springs. As close as I can Figure, the compression is between 11:5 to 1 or 12 to 1. Runs great but I don't have the truck far enough along to take it out on the road yet.

 

Please let us know how it performs when on the road...