I have a 70 and a 71 C-50. Both have 350s in them, but I have been very
interested in the 366 and 427 engines. (Have located a junkyard 427 that I'm
going to rebuild and put in the 70.)
Both the 366 and 427 truck engines were tall deck. 0.400 taller deck. Can
use regular engine heads, I believe, but don't know if they actually came
with the same or different heads. Because of the taller deck, the intake
manifold has to be different (wider) and the distributor and pushrods
longer. Supposed to be a gear driven, reverse rotation cam too - never seen
one. May be other differences, I don't know (yet).
Presumably the taller deck was to allow a longer piston so that 4 rings
could be fitted. I am guessing it was a second oil ring - don't know. They
could have done the same with a standard block but would have required
shorter connecting rods, which is not good for torque and longevity at
sustained higher rpms.
The 366 is a smaller bore 396 just as the 427 is a larger bore 396. Just
another way to say they all use the same length (3.76) stroke. 366 was 3.935
bore, 396 was 4.096 bore, 402 was 4.125 bore and 427 was 4.250 bore. Truck
engines came with forged cranks, not cast.
The inlet on the big block truck engine water pumps is about 3 inches in
diameter. At least it looks that large - huge. Lots of water flow.
I guess the popularity of those 427 blocks with racers is due to the raised
deck. Would allow longer rods if used with a three ring piston, or more
easily accommodate a longer stroke crank.
The 454 block was never produced with a tall deck that I know of but the 502
block is available with either the normal or raised deck. Thus the continued
availability of the 427 in the large trucks instead of the 454.
I have seen quite a few 366 engines in C-60 and C-70s in the junkyards. Much
less frequently see 427s. In Minnesota I saw an extremely well preserved
C-50 grain truck (still in use on a farm) with a 396 in it (and a 396 decal
on the side of the fender. The 396 was part of the C-50 casting, so it was
clear that it was original.) Couldn't tell what year of vehicle it was (had
the 67-72 style body.) Also saw a schoolbus in a junkyard that had the same
396 insignia on it. Didn't know enough about the various big block engines
at the time to see if it was a tall deck model or standard. You can tell the
difference by the appearance of the intake manifold. There was evidence of a
cold air intake system which fed via an opening in the driver's side of the
hood. I am really curious if it was a passenger car/light truck 396 or if
there was a tall-deck 396 as well. I have seen no mention of such an engine
anywhere.
As to the 400 cu in question- Confusing thing is that the 402 block in a
pickup came with a 400 badge on the side of the fender. Never made sense to
me - they called a 307 a 307, a 350 a 350, a 396 a 396, but a 402 was called
a 400. Go figure. BTW, I have the 402 out of my 72 Cheyenne all apart for an
overhaul at the moment.
Gwyn Reedy
Brandon, Florida
mailto:mgr@mgrcorp.com
> -----Original Message-----
> From: owner-oletrucks@autox.team.net
> [mailto:owner-oletrucks@autox.team.net]On Behalf Of Kevin Lake
> Sent: Sunday, March 14, 1999 11:53 AM
> To: MarkNoakes@aol.com; oletrucks@autox.team.net
> Subject: Re: Re: [oletrucks] 366 V-8/big blocks
>
>
> There is a truck specific 427ci. The two C-70 Chevy's that I
> used to drive
> at work both had 427ci "truck blocks" (1981, 1985). The motor does have a
> taller deck height, and I have been told that they use different heads and
> intake that the standard 427ci. car motor. I don't think that a standard
> 454ci would stand up to the abuse that these motors suffer. As far as I
> know they were still using this motor in the big C-series trucks until a
> few years ago (I have seen a 1991 C-60 with this motor) and may still be.
>
> Weren't all of the 400ci motors small-blocks? I have seen a 402ci. big
> block, but I thought all of the 400ci motors were small-blocks.
>
> Where is Jim Forbes when you need him. 8^)
>
> Kevin Lake
> 56 GMC Suburban/napco
> ----------
> > From: MarkNoakes@aol.com
> > To: oletrucks@autox.team.net
> > Subject: Re: Re: [oletrucks] 366 V-8/big blocks
> > Date: Sunday, March 14, 1999 5:28 AM
> >
> > This is a question for the mythical Jim Forbes.
> >
> > Even though I've heard it called a truck block, probably from
> the earlier
> > 348/409 engines which did start out in trucks and then ended up in cars,
> the
> > 427 started out as a 396. The 427 was used mostly in 67-69? (then 454)
> > Corvettes and a very few Chevelles, Camaros, Novas, etc. A very few of
> these
> > were aluminum (ZL1). The 427 usually was not put in trucks until it
> became
> > the 454. The typical truck big block was the 396/400/402 on the 67-72
> 1/2
> > tons, but some 427's could've gotten in there somewhere. GM now has a
> bored
> > out version to 502.
> >
> > Most of the 427's had more than 390hp and the L88 Corvette, which was
> > advertised at 425hp, actually put out closer to 550hp. It could be
> bought for
> > the street if you were crazy enough, but was meant for the racetrack.
> >
> > Mark Noakes
> >
> > In a message dated 3/14/99 1:56:53 AM, you wrote:
> >
> > <<
> > The 366 is a Big Block, but of a different breed. It has a
> taller deck
> > height tha n the standar family, something in the area of .6 inches or
> so, to
> > accomadate a 4th ring and taller piston. There was also a 427 "truck"
> block.
> > It really has no advantages to any other street motor, but is sought
> after
> > block for the serious racer whos limited in cu.in class. The 427 truck
> block
> > is now a hot item too.
> >
> > I've heard that GM is making the same type blocks in larger cubes now,
> also.
> >
> > Mike>>
> >
> > oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
>
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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