What are the chances of the crank in an old 400 being serviceable? I'm looking to do a 351m -> 400 conversion but availability of 400 cranks is limited. I see a lot of 400 motors for sale, often not much more than a crank. Of course, all say, "running when it was pulled".

My 351m is in good condition so I'm hesitant to do a full swap. I know a lot of people will recommend throwing in a 460 but I like the 335s. I don't need to build out a 400 hp monster and keeping my MPG over 10 would be nice. With the 400 and TDC timing it should do what I'm looking for.

Thanks!

 

I used a 400'crank from a Craigslist buy and Tim dynoed the engine with no problems. In other words, buy a used engine and send the crank out for machining. It will be just what you need in conjunction with Tim's pistons.

 

Chances of a 400 crank being serviceable are excellent. They are also quite tough from what I've been able to learn. A few drag racers have used the factory crank at RPM's that would make most people cringe.

 

Yup, pretty much somes its up. The stock 400 crank has been used, and shown reliable in some crazy engine builds, upwards of 500hp.

 

i bought one at rock auto years back. but i thing Tim as some now.

 

I dont see why it wouldnt be servicable, i plan on spinning mine up around 6500-7000 with a 10/10 grind and arp'd rods

 

I would stud the bottom end, polish and shot peen the rods, use full circle main bearings(pushes oil to the rods 360' vs 180') and get it all balanced. Also good dampener would go a long way.

 

Studding the bottom end for a small rpm motor is tad overkill ya? Fresh bearings and a grind (if needed) should be fine on a daily w mild cam i would think (check cam bearings too)

 

No mild cam is going to do 7k. I think you need a bit more research.

 

I did all the above and I'm running a comp cams 252h, now that's a mild cam.

 

I think you can turn rods and mains to .030 and that's plenty for most deep scratches. Just make sure they put the right radius on it.