Would this make much difference?

I have a '72 <a href="http://www.motorhaven.com/">351c </a>4bolt main 4bbl closed-chamber heads engine that I was thinking of changing for my '75 <a href="http://www.motorhaven.com/">351m </a>2bbl but am not sure that it would make much difference.

What do you all think?
Thanks

 

You'll notice the difference...it'll feel like you have (2) 351M's in there!

I put a 2 bbl <a href="http://www.motorhaven.com/">351c </a>in a '67 Mustang I had and was disappointed in the performance compared to a 4 bbl 289.

Later I got a 70 Mach I w/ a 4 bbl 351C. There is NO comparision. The 4 bbl <a href="http://www.motorhaven.com/">351c </a>rules!

When I rebuilt it, I ran 11:1 TRW forged pistons (stock CR), stock intake for good low-midrange torque, <a href="http://www.motorhaven.com/">Holley</a> 650 dbl pumper, TRW cam w/ about .513 lift and 310 deg. duration, 1 7/8" headers into 2.5" dual exaust w/ turbo mufflers and a cross tube just back of the headers. This probably added another 60-80 hp and was quite noticable.

With the <a href="http://www.motorhaven.com/">Holley</a>, it got 15-16MPG on the highway. When I was going a long distance though, I'd put the stock carb back on and could get about 19MPG at 75-80 MPH.

Go for it!

Tom

 

Just remember, the bellhousings are different.

 

What vehicle is this for? Any emission issues to deal with? You want torque rather than horsepower for heavy vehicles. Weight and gearing makes or breaks the <a href="http://www.motorhaven.com/">351c </a>4V performance. The easiest way to make torque is displacement and a 400 or 400 stroker is cheap and easy, you don't have to deal with different bell housings, motor mounts or exhaust manifolds. Don't worry about gas mileage, a 351 4V isn't known for it's great gas mileage.

 

The <a href="http://www.motorhaven.com/">351c </a>does rule in top end horses..But remember the mounts and the bellhousing are different than the M..And this could turn into a changeover nite mare without all the right stuff.You could spend the money on a good performance hop up on the M and be happy with less headaches.If money wasn,t an object you could put the 4vC heads on the 400 block with a speciality intake adaptor and end up with a monster with proper cammng! watch which pistons you use because those 4v heads are small chambered and raise the octane needs up there.Also the exhaust manifolds would have to be off of the 4v or special headers made up.the <a href="http://www.motorhaven.com/">351c </a>ones will not work always due to the taller deck height..If it was my choice I would save the C for some special Hi-Po project and spend the money on the M and make it a 400 too if its not.Less headaches.done Ford projects for 20 some years.the ones I liked the best were the ones that got done in timely matter because the stuff fit.

 

Hmm too long..must be a wind bag huh?:>)If you were starting with a <a href="http://www.motorhaven.com/">302 </a>or 351 windsor I would tackle it with the C.but the M makes it a harder project.Specially if its a 4wd truck.the 400 can be fun to build too,and its different..But then again..All things can be done with time and money!! And this is America!! good luck.