[DeTomaso] c & m blocks

Steve Hawkins shawkins777 at comcast.net
Tue Aug 10 18:05:40 EDT 2010


This not accurate information.  Almost everything on a 351C will swap over
to a 400 except the crank, rods, push rods and motor mounts.  You will need
adaptor plates if using Cleveland heads and intake though.  A 400 with
aluminum heads weighs about what a 351c does with iron heads, much less than
a 460.  All performance parts for a 351c will fit a 400 so I don't know what
Jack is referring to.  If a 351c stroked to 408 will make power then so will
a 400 with the same performance parts.  I just happen to have Dan Jones
400fmx block ready to go into my Pantera with A3 heads, a roller cam and a
Weber intake with individual runner EFI.  It's bored 40 over was sonic
checked with plenty of meat on all cylinders and I'm expecting 550-600HP at
the flywheel.

Steve

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of JDeRyke at aol.com
Sent: Tuesday, August 10, 2010 2:53 PM
To: Thomas.Tornblom at hax.se; detomaso at realbig.com
Subject: Re: [DeTomaso] c & m blocks


In a message dated 8/9/10 12:21:04 PM, Thomas.Tornblom at hax.se writes:

> Aren't the engine mounts different?
> Most 400 blocks, and I guess the 351M, require a different 
> bellhousing,
> same as the big blocks.
> 
Absolutely correct, Thomas. I had one around for a few weeks out of a 
motorhome, with a split cylinder (separated an intake valve going up a hill;

stock are the infamous 2 piece valves). The engine mounts in the 'M's are 
"unique"- different from all small, mediium and big blocks. The bellhousing
has a 
big-block pattern except for the rare 400M with a dual bellhousing bolt 
pattern (I've only seen photos from Dan Jones' collection). The blocks are
1" 
taller on each side than a 351C, and use very long con-rods as a result. The

higher block pushes the heads and headers up so the left one hits the
Pantera 
fuel tank and both hit the rear springs so custom headers are needed. There 
are other detail differences, too. But the biggest obstacle is the cracking 
often found in the lifter galley in seasoned blocks: it will be a 
horizontal crack above the lifer bores, about 4"-6" long thru into the water
jackets 
and unrepairable; the result of an entirely new core shift during casting. 
This was finally corrected in the mid-'70s but beware of early blocks. And 
none were thick-wall cylinders either so they still need sonic testing for 
cylinder core shift.   
A buildup can certainly be done- several have been in motorhead magazines 
recently but you will replace everything in & on the engine: as-stock 400 
cubic inches that put out 175 bhp w/2V-type open chamber heads, junk valves,
2 
bbl iron intake, unbaffled oil pans and no specific speed parts available 
(some 351C parts swap in). Found in low-revving station wagons, vans, 
motorhomes and the cheaper heavy trucks. FWIW they simply are not worth the
effort 
when 460s are cheaper, stronger, easier to build to higher performance and 
easier to find a good one. 400Ms are cheap to buy 'cause no one wants them. 
Think of an ox rather than a racehorse....My 2¢- J DeRyke
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