Ive got a 351m, I want more power and Ive got low oil pressure. Im under the impresion that a 400 cam will go in smoothly without modification. Is this so? What other parts will bolt onto the 351m for more hp.s. How bout the intake manifold? Can I put a 4bbl. manifold from a 400 on a 351m without changing the heads?

 

green 78 ford,

Many components (including camshafts) interchange between all 335-series engines (i.e., all 351C and 351M/400).

Intake manifolds are specific to either the 351C or 351M/400 engine type because of the deck height difference.

The 351M and 400 are essentially the same engine, except for the crankshaft and pistons.

You can learn a little more about parts interchangeability at this URL:

http://home.earthlink.net/~bubbaf250/history/history03.html

 

what are the most common swaps made between these two engines? What kind of power increase can I expect (noticable or not noticable)?

 

The intakes are the same for the 351m and 400 so yes they will bolt on to each other. Your best bet if your wanting to make more power is to turn your 351m into a 400. This can be done easily by changing the crank and rods (or is it pistons???). Either way if you have low oil pressure the best thing to do is replace the bearings before doing much modification. Don't want to throw money away burning up parts......


79 250 Ranger Lariat 4wd 400 C6 3.55's 33x12.5 16.5's on slots

 

just change the crank & pistons - probably the cheapest stroker in the world, since there are tons of cranks in the junkyards and you need new pistons anyway if you're re-building...

 

To address your original questions, many 351Ms and 400s used the same cam, and in some cases the 351M cam was actually better. Both 351Ms and 400s used the same 2V intake manifolds, and neither engine was ever equipped with a 4V manifold from the factory.

The only worthwhile swap involving stock parts is the 400 crankshaft and pistons to convert the 351M into a 400. All other stock parts are essentially the same anyway, so there is little or nothing to be gained swapping them.

If you're going to convert the 351M into a 400, you'll have to rebuild and get new pistons anyway, and if you're going to rebuild, you may as well start looking at some additional performance enhancements available with aftermarket parts.

The bottom line is that, short of a 351-to-400 conversion rebuild, there is nothing to be gained by swapping stock parts between 351M and 400 engines.

 

Ok, this is the problem, the 351m in my 4x4 now is about to turn 130k and the performance is less than stellar. Not to mention the fading oil pressure. If I put a 4bbl. intake and carb on, will I have to change the heads too? will this give noticable performance? If I change the cam and bearing will this solve the oil pressure problem?

 

>Ok, this is the problem, the 351m in my 4x4 now is about to
>turn 130k and the performance is less than stellar. Not to
>mention the fading oil pressure. If I put a 4bbl. intake
>and carb on, will I have to change the heads too? will this
>give noticable performance? If I change the cam and bearing
>will this solve the oil pressure problem?

All of the currently available aftermarket intakes for the 351M/400 are designed to be simple "bolt-on" components so changing the heads would not be necessary. You will get some increase in performance but probably not as much as you want. I seriously doubt changing the cam and bearings will help your oil pressure problem much because it's probably an issue with the main bearings. In fact I wouldn't even recommend changing the cam bearings without tearing down the entire engine simply because it takes a special tool and procedures to remove and install the bearings. Chances are excellent that you can simply install the new cam without changing bearings and suffer no adverse effects. Be sure to install a non-retarded timing set to achieve the max. perf. with the new cam.