How strong is the bottom end of the 400. What kind of RPMs can it handle. Anything out there to make it a little beefier. I'm not talking about 4 bolt mains.

thanks

 

I think it is already tough enough, but it inst a 7 grand motor i dont think.

 

>How strong is the bottom end of the 400. What kind of RPMs
>can it handle. Anything out there to make it a little
>beefier. I'm not talking about 4 bolt mains.

Ford added some metal to the main webs of the M blocks in the 77 model year. Look for blocks with the D7TE or D8 casting codes.

 

do you think it can take 6000 safe rpms

 

>do you think it can take 6000 safe rpms

This is strictly my opinion so take it FWIW but based on feedback from folks who know I'd say that with the appopriate modifications to the oiling system, i.e. HV oil pump, restrictors, external oil line, windage tray and ARP main & rod bolts/studs, the bottom end will hold up fine for 6000-6500 RPM even 7K for short bursts. If I were going to keep it there for extended periods I'd try to look into getting a stud girdle made for it as well as custom rods.

 

i think the bottom end will hold up extremely well with the mods listed. do i think you can rev it to 8k yes, do i think it will run all day there, no. but it will hold up real well. just my opinion

 

make sure you micro polish the crank and chamfer the oil holes, these two things are recommended by Roush for the 351C (in fact, I don't think he even lists any other mods, even for a NASCAR engine) and I suspect the same is true for the 400 as the cranks are of similar design. These steps were taken for the Aussie 351C engines which had to rev at 6-8k rpm for 500 miles at Bathurst.... in fact, a Ford Engineer who worked in 1969-71 on developing the cleveland engine said micro polishing the crank is about the best thing you can do to it. Apparently, if you leave the motor (cleveland) revving at 6250rpm for more than a few seconds it can shatter due to the harmonic resonance, but the M would have a different frequency so not to worry.

 

[updated:LAST EDITED ON 17-Dec-01 AT 11:40 PM (EST)]>make sure you micro polish the crank and chamfer the oil
>holes, these two things are recommended by Roush for the
>351C (in fact, I don't think he even lists any other mods,
>even for a NASCAR engine) and I suspect the same is true for
>the 400 as the cranks are of similar design. These steps
>were taken for the Aussie 351C engines which had to rev at
>6-8k rpm for 500 miles at Bathurst.... in fact, a Ford
>Engineer who worked in 1969-71 on developing the cleveland
>engine said micro polishing the crank is about the best
>thing you can do to it. Apparently, if you leave the motor
>(cleveland) revving at 6250rpm for more than a few seconds
>it can shatter due to the harmonic resonance, but the M
>would have a different frequency so not to worry.


What do you mean by, "similar design"?

The M and 400 crank have larger main journals than the C,(3" vs 2.75") which may be stronger but are not the best bet for sustained high RPM use. In fact, the NASCAR blocks use the windsor oiling path(mains first) and the 2.24" crank journal size(302 size) So they are far from 400 territory, both block and crank.

Not sure I've ever heard of the "resonance" problem you've mentioned but the C/M/400 do need attention to the oiling system to live at sustained RPM's.

 

Hey There :
For those who don't know me I have a pulling Truck called ShaZam. I run a 400 Bored and Stroked to 425 C.I. Putting Out 650+ H.P.and 600+ #T.Q.
How strong is the bottom end of a 400 is the question.
All I can say is my motor ran really good last year with almost no problems.
I only had one bad pull last year, where I hurt my motor when on a very loose track I ran my motor at 8200 RPM for 24 Sec.Pull and ran the oil pan dry. Saftey switch shut down my motor when I hit only 20 psi oil pressure, But it still smeared the bearings.

So let look at this: Stock lower 2 Bolt Mains,650+ H.P. 8200 RPM for 24 Sec.and it's still together. I run this truck at 26 pulls last season. With it's operating range at 6200 to 8200 RPM.
At the end of last years pulling season I pulled this motor and it's now my Back-up motor for next year.
I moved up in class and at this time I'm putting together another 400 Bored An Stroked to 436 C.I. with 799 H.P. and 667 #T.Q.
Only this Motor will have a little help on the bottom end with a main stud girdle. Weather it really needs it I don't Know but figure it can't hurt.
ShaZam

 

[updated:LAST EDITED ON 23-Dec-01 AT 01:01 PM (EST)]Hey Shazam, are you having the main stud girdle custom made?

 

Hey there Bill:
Well I guess I'll have to seeing as they never made one for the Cleveland. I can find windage trays but no Girdles. I'm going to try taking the 351W girdle And filling the holes and redrilling them to the Cleveland bolt pattern.Seeing as I've seen the 400 Crank turned down to be put in a 351W then the cap spacing is the same. At least I hope I'm Right
Now Bill I'm no Ford Guru on this so maybe you can help me on this.

 

After reading my post it comes off pretty snobbish I didn't mean it that way.
there should have been a Comma or a period In that first sentence....
"Well I guess I'll have to. Seeing as they never made one for the Cleveland"
Just don't what anyone to think I'm a snob.
:-staun

 

>After reading my post it comes off pretty snobbish I didn't
>mean it that way.
>there should have been a Comma or a period In that first
>sentence....
>"Well I guess I'll have to. Seeing as they never made one
>for the Cleveland"
>Just don't what anyone to think I'm a snob.

No sweat. I was just hoping maybe you'd found someone who sells them off the shelf. I have a friend who has his own race shop/fabricating business, I'm going to find out what it would take make some.

 

Hey Bill :
So am I right when I say the cap spacing is the same between the 351 W and M