Are M blocks "bad"?
 

I have the opertunity to purchase a 400 M From a guy at work.
My Boss Says don't get it because the M blocks are "junk".
Is there any truth to this? Any at all?
Thanks
Matt
1948 F-1

Are M blocks "bad"?
 

No I don't think there bad .. with a little massaging you can have yourself a great motor.And it's just a 400 no M .. the 351M has the M perfix.

Are M blocks "bad"?
 

Personally I think 400s are bad to the bone. They just have a bad rep as a smog motor.

Are M blocks "bad"?
 

I'd get the motor and a new boss. There's way too many people in this world that don't know what they are talking about. If they would shut up and listen they might learn something

Are M blocks "bad"?
 

[updated:LAST EDITED ON 06-Aug-02 AT 02:23 PM (EST)]reminds me of back in the 70's & early 80's, if you told someone you had a 351W, the usual response was "sorry to hear that - maybe you can swap it for a 351 cleveland".

NOW, if you tell someone you have a 351C, the usual response is "sorry to hear that - you really need to swap it for a 351 windsor".

so what has changed from "then" to "now"? three things:

1. aluminum 302/351W heads for around $1000
2. EFI came on the scene AFTER they quit making clevelands
3. "everybody" is into the windsors now

so basically, if:

1. you don't have $1000 to plunk down for a set of heads
2. your car is not set up for the EEC-IV EFI engine controller
3. you don't give a rat's a$$ what "everybody else" is doing

...then welcome to the 335 club!

with 4" stroke, it's hard NOT to build one with mountains of torque!

Are M blocks "bad"?
 

[updated:LAST EDITED ON 06-Aug-02 AT 07:37 PM (EST)]I have a 400 and I, well I am going to use the L word I love it I built mine this year. My truck came with a 351m so for a bolt over swap it was great. Realy like the power and torque from it, but if I was going to build another motor and it is not bolt over swap I would be lieing if I said I did not consider a 460 you can build a realy powerful 400 or build a realy awsome 460. If you already have a 351m or a 400 then deffently go with the 400.
:-fire

Are M blocks "bad"?
 

No, M blocks are definately not junk. I can take you for a ride in my 78 F150, 351M, that has half a million original miles on it. It has never had a gasket relaced, either! Only minor externals, like alternator, 1 water pump after 23 years. I can drive you anywhere in North America (if you don't mind lots of rust on a vehicle!) and not be afraid. Oil pressure is always at 3/4 scale. Motor is completely stock (never came with cats). It could always squawk the tires until the last couple years. (not bad for under 200 hp rating!) 3.00 ratio.
You tell me if that's a good motor or not!

Mark


https://www.ford-trucks.com/user_gallery/displaythumbnail.php?&photoid=5362&.jpg
Ford started it; Ford will finish it!

Are M blocks "bad"?
 

>...my 78 F150, 351M, that has half a million original
>miles on it. It has never had a gasket relaced, either! Only
>minor externals, like alternator, 1 water pump after 23
>years. I can drive you anywhere in North America (if you
>don't mind lots of rust on a vehicle!) and not be afraid.
>Oil pressure is always at 3/4 scale. Motor is completely
>stock (never came with cats). It could always squawk the
>tires until the last couple years. (not bad for under 200 hp
>rating!) 3.00 ratio.
>You tell me if that's a good motor or not!
>


:-staun ford needs to put you & your truck in a tv commercial or something!

Are M blocks "bad"?
 

Yes, and Ford should also give me a new truck for doing it! LOL
It would have to have its body replaced before they put it on tv, I think.
:)
Mark



https://www.ford-trucks.com/user_gallery/displaythumbnail.php?&photoid=5362&.jpg
Ford started it; Ford will finish it!

Are M blocks "bad"?
 

yes "M" blocks are bad, mine is so bad, its been called down right nasty.

Are M blocks "bad"?
 

400 are 'bad' compared to other Ford engines. To keep compression down they built the engines with the pistons down in the hole. That makes these engines prone to detonation. The 400 was widely available during the 70's when Detroit was de-tuning big engines to meet emissions standards. The engine controls were flaky vacuum lines, the camshaft timing was retarded to help keep combustion pressure down and prevent NOx, the distributor timing was likewise tuned for emissions. There were no 4bbl intakes for the 400, and the motor is a heavy honker. So, in its day, it was a lousy engine.

As other have already pointed out, it's pretty simple to re-tune the 400 to make power. Zero deck, aftermarket 4bbl intake, recurved distributor, new cam, etc. And the heads are Cleveland heads. Pretty decent pieces.

As the saying goes, there's no replacement for displacement.

Best regards,

Are M blocks "bad"?
 

>
>400 are 'bad' compared to other Ford engines.

I think it was just like all other engines in us cars at the time.

>they built the engines with the pistons down in the hole. That makes >these engines prone to detonation.

The head profile has a lot to do with this, as well as other issues.

>the camshaft timing was retarded to help keep combustion
>pressure down and prevent NOx.

so far evertything i have seen, retarding the cam has produced better hp numbers, its amazing, -4 deg is a good number.


>the 400 motor is a heavy honker.

yes its so heavy its only 50 pounds more that a C and yet its 135 pounds lighter that the 429-460.


>So, in its day, it was a lousy engine.

it was just as good as every other engine at the time, and maybe even better. rev daves tech newsletter
https://www.ford-trucks.com/articles/mblock.php


>As other have already pointed out, it's pretty simple to
>re-tune the 400 to make power. Zero deck, aftermarket 4bbl
>intake, recurved distributor, new cam, etc. And the heads
>are Cleveland heads. Pretty decent pieces.
>
>As the saying goes, there's no replacement for displacement.
>
>Best regards,

I guess somethings dont change.

Are M blocks "bad"?