If you look through the posts in this forum you'll find that Badger pistons makes a flat top replacement piston that will increase the C.R. to +/- 9:1. I've also learned that one of the contributors to this forum is currently working with Badger to create some "custom" pistons for the 400 with a taller comp. height to get them to zero deck and a small dish allowing for tailoring of the C.R. up to +/- 10.5:1 with stock heads. He hopes to be able to offer these for around $250 a set.

 

Also, if you'll look at Hot Rod magazine over the past 10 years (Lord help me, I'm plugging Hot Rod!) high compression is increasingly falling out of favor. It's a cheap and easy way to gain HP, but with today's gasolines, it's a crapshoot. It's also higher polluting in that it makes lots more NOx.

There have been many impressive builds done in HR at CRs around 8.5-1. Careful selection of cam seems to be the main factor.

What I'm saying is that low compression shouldn't deter anyone from building a high performance motor. Heck, my '71 400 with the 9-1 CR was considered "low compression" in it's day, but now 9-1 looks pretty good.

These days, a zero decked block using the dished pistons and open chambered heads looks mighty good for a street motor. You'll still get around 9-1 CR, and low detonation risk. Since the 400 was always a "pinger" no matter what pistons or heads were on it, improving on this factor makes it easier to make real HP. Detonation is anti-HP, since the explosion is literally trying to drive the piston back in the wrong direction.

 

Also,
The previous Hot Rod article mentioned by Scroob, "The 400M Ford 468 Lb-Ft, 380 HP for less Than $2000", was in the September 1998 issue.
If you don't have access to the hard-copy, here's a photocopied link:
http://www.geocities.com/styleline58/400.html

Have a good day!

 

In 1979 I bought a new Bronco.. about 25,000 miles in I knew the 351 M was not going to get it.. I took a different block and had it bored 0.040 over and went after it.. I used flattops and ended up with a static compression of 9.5-1.. I used the comp cam 268 high energy.... did a little polish on the heads and went for long tube 1-3/4 headers.. Weiand intake.. over six months I tried 4 different cam and intake combos trying to see what I could come up with.. I used my car hauler as a weight to pull and used a mountain outside of town as my test bed.. I went back to the comp cam and weiand.. That 400 pulled like you wouldn't believe.. years later I read the article in The best of Hot Rod small block Ford engines.. I'm, not saying my engine put out as much as that article, but I will say it would pull.. I can only hope it did.. and would like to think it did..

 

The writer of the article said that you cannot put 400pistons in a 351m? is this true if so why do so many people put 400 pistons in the 351m saying that the pistons and the crank are interchangable? someone please clear this up thanx.

 

If that's what the article said, then it's wrong (not a first for Hot Rod!) They meant to say that you can't interchange rods between the two engines.

 

cool thanx I was alittle confused.

 

I believe the rods are common. The stroke on the 400 crank is different, and the compression height of the piston head is taller on the 400, and won't work in the 351M.(unless I have my pistons reversed). The block, heads and valve train are interchangeable as well.

 

The rods are the same between the 351M and 400. You can't put 351M pistons in a 400 unless you're fond of the sound of breaking parts because they'll hit the heads. 400 pistons in a 351M will give you about a 3:1 C.R. You have to match the pistons to the crank. Everything else interchanges.

 

Guys,
Obviously, 78 Custom took the time to read the article by David Resch, (the Guru of these motors and the first link I posted). Mr. Beyer and Bowser are 100% correct in their previous statements about the pistons NOT being interchangeable.
After the last little tiff, between myself and another as to my husband's personal preferences, I took the time to find the article referenced for Hot Rod Magazine and then added a link to this thread. If y'all ain't gonna read it before spouting off more... what the heck's the use? Just to make yourselves sound better? Come on now, there is more to life than that.
I have found this website and forums to be very helpful and that is what I try to do also with my posts. Let's try to help each other rather than get on other tangents.
We all have to deal with enough on a day to day basis!
Read those articles! They have a lot of good info!

 

I must have had my head up you know where when I made that post. I know dang well you can't interchange the pistons. Chalk it up to late nights and advancing age...

Didn't think it through. You can't put 400 pistons in a 351M unless you also put in the 400 crank.