Increasing CCKW Engine Power

Questions and requests about Technical Repairs of the CCKW
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Randal
Draftee
Posts: 4
Joined: Wed Jul 16, 2014 2:10 pm

Increasing CCKW Engine Power

Post by Randal »

The engine of my 1943 CCKW needs full refurbishing.
The TM 10-1563 shows horsepower SAE 34.35. I believe that is very low for a heavy truck. Any suggestion on replacing stock internals for "performance" ones? Where can I get them? Compression rating needs to be higher? Better carburetor? Other modifications? This is the moment!!! Thanks!
mudflap
First Lieutenant
First Lieutenant
Posts: 138
Joined: Sat Jul 07, 2012 12:45 am
Location: Macomb Twp, MI

Re: Increasing CCKW Engine Power

Post by mudflap »

Hi Randal,

I am also working on a 270 engine rebuild project, so I have been trying to gather information on this topic as well. I agree, that while the 270 has pretty good low end torque, a little more horse power would be nice.

In doing some research on this, I found that back in the late 40's and early 50's, the GMC inline six was actually a fairly popular choice of hot-rodders from that era. According to some of the old timers that I have talked to, it would easily hold its own against the flat head Ford V-8, which was one of the top performers of the day. All this changed, of course, when the overhead valve V-8s were introduced. And, once the small block Chevy hit the scene, interest in hot rodding inline sixes started to rapidly decline.

So, it seems like the 270 does have performance potential.

There is a book written about hot rodding these and other six cylinder engines. It was written by a guy named "California Bill". Reprints are readily available:

http://www.ebay.com/itm/NEW-Chevy-GMC-B ... SwHPlWgYyp

There is also a guy named Tom Langdon, who specializes in inline six cylinder engines (primarily Chevy's, though). His website is:

http://www.langdonsstovebolt.com/

Lastly, there is a fair amount of information on this subject right here on this website, written by Dr. Deuce, who is a frequent contributor and has a lot of experience with these engines.

http://www.cckw.org/270_to_302.htm

As for my project, I think that I am going to stick to the stock configuration. I would prefer to keep the original look of the engine - which means retaining the Zenith one barrel carb along with the stock cast iron intake and exhaust manifolds. This pretty much eliminates any performance enhancements that are related to increased engine breathing (which is like, nearly all of them). I am going to get the head and block resurfaced, which may up the compression ratio a little, but that's about it.

Please keep us informed as your project progresses. I would be interested in seeing what one of these engines could do with the right modifications.

Good luck!

Best Regards...
The Scrounger
Draftee
Posts: 4
Joined: Fri Apr 29, 2016 4:20 pm

Re: Increasing CCKW Engine Power

Post by The Scrounger »

Randall, I don't know if you have rebuilt your engine yet or not. I am new to this site but have rebuilt many 270's over the past 20 years. I would suggest cutting the head to raise the compression ratio from 6.7 to 1, to 8.0 to 1. Quite a little bit of material needs to be taken off the underside of the head, about 110 thousandths, but it is worth it. The heat developed by this modification will not cause overheating issues if you have a good clean radiator.
Also send you camshaft out to http://www.iskycams.com/ and have them re-grind it to somewhere around 440 lift and 276 duration. This is my common build and produces a very stable 195 h.p. with excellent engine life span.
Good luck and happy R.'s P.M.
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