I second Gordon's suggestion, keep the original family of engines. In a
DUKW, you have more room in the front.
The CCKW will give you two headaches as far as V8 replacement goes: Exhaust
manifold on drivers side interfering with the steering column (major rework)
and the fact that the shaft between the tranny and the xfer is 2 u-joints
with a slip spline. There is NO room for a longer tranny (with synchros).
The correct change is to a CIVY (not MIL) 302 engine. It has (last ones
made) 160 hp versus 104 in the original 270. That is almost a 60% increase.
On top of that, you can use DUKW wheels 11.00 x 18 versus 7.50 x 20 and you
can install a WW2 Chevy xfer that has a 1 x 1 high range instead of a 1.1 x
1 in the original CCKW. This requires one drive shaft lengthening and the
removal of the xfer control interlock block as the high/low is now reversed.
Having said all that. Remember that y ou must stop it and that will be your
biggest problem. At 60mph it will be very marginal as far as heating up and
swept area is concerned.
Steve AKA Dr Deuce (and Chevy's too)
----- Original Message -----
From: Mike D'Ambrogia <miked@tworock.com>
To: Military Vehicles List <mil-veh@skylee.com>
Sent: Saturday, June 24, 2000 3:53 PM
Subject: Re: [MV] CCKW 270 Upgrade
> > Of all the bits to change........
>
> I was waiting for that... <smile> Overall I like the idea of the
original
> engine/transmission configuration, my feeling is that the engineers who
> designed this put it together that way for a reason and used the best
> combination of reliable parts and engineering that was available back in
the
> day. But, since the motor has been sitting for over 40 years its bound to
> need some work and that will mean downtime for the truck - that and the
fact
> that highway driving (3 hours or more at a streach on CA 65 mp/h freeways)
> will be plentiful concerns me for the safe running of a 270 engine in good
> shape.
>
> >The 6 x 6 drivetrain is rather lean for the existing horsepower. My
> >experience (watching DUKWs mostly) is that either the intermediate diff
> >goes or the intermediate output from the transfer case - one takes out
the
> >other not figured out which. As a completely separate problem the pillow
> >block which takes the rear drive over the intermediate axle goes west if
> >it isn't maintained and leaves you seized by the side of the road.
>
> This is my big concern, overdriving the drivetrain with more HP than it
was
> designed for.
>
> >The only bits of the system which never cause trouble are the gearbox
> >(unkillable if unfortunate in the ratios) and the engine. My advice
would
> >be to stick to the stock engine and drivetrain, with particular attention
> >to careful maintenance of the transfer case and pillow block. One good
> >point is having a matched set of rear tyres which seems to help a lot.
>
> Ok, maybe I need to approach this from a different direction. If one
needs
> to drive the 353 at freeway speeds on a regular basis what would you
> suggest? It seems like the transmission drive ratios are the keeper of
> reduced speeds. The primary motivator for the swap is the engine, getting
> it out and taking the time to rebuild it nicely while getting the truck on
> the road quickly, and not burning it up while running on the freeway. I
> love the idea of keeping the transmission in there (i must be one of the
> sick one who smiles at the idea of double clutching and I agree, the thing
> was bullet-proof), is there a list of motors that bolt directly up, or a
> source of adapter plates?
>
> >If you must upgrade go for a newer version of the same engine. I think
> >Jack Tomlins DUKW had the 302 which had more grunt in basically the same
> >engine, and if you need to upgrade the engine figure on at least using a
> >transfer case and drive system from a newer 6 x 6.
>
> urrrghh, hoping to keep it simple by just swaping engine and trans and
> having a new driveline manufactured between trans and xfer case. what
kind
> of xfer case would you suggest/recommend? Have any mpg comparisions
between
> the older 270 and the 302 been submitted?
>
> > You can fit larger
> >diameter tyres for more road speed if you need it - several suppliers
have
> >11:00 x 18 singles which have more plies in the construction and a bigger
> >rolling radius.
>
> good point, need to dig out the tire to speed calculator...
>
> >Maybe I'm being a bit gloomy - properly serviced and used the 6 x 6 will
> >go anywhere anytime, just remember transfer cases can be noisy, and can
> >scream all day but still work properly....
>
> No, not at all - I can easily respect the purist view. The truck is going
> back into service vs. being restored so my mindset is not finely tuned to
> keeping it all original. I appreciate your thoughts.
>
> Mike
>
>
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This archive was generated by hypermail 2b29 : Sun Jul 02 2000 - 23:51:31 PDT