Throttle Linkage Information Chevrolet CMPs

Because of the right hand drive driver position there are a number of issues with fitting later 216 Cubic Inch or 235-261 Cubic Inch engines in Chevy CMPs in short the main cross over shaft for the throttle linkage was originally run under the thermostat housing behind the water pump pulley. But if you are using a later engine the stock cross over linkage just will not work. My solution was to just make a new linkage instead of modifying the original linkage. Time to make a new one is about the same amount of time necessary to modify the existing one. Building a new linkage has the advantage of saving the original part unmodified.

Note- This page is a work in progress and is being posted early in a raw form to help another CMP owner out.

Below you will see a series of photos in small size click on any of these images should get you the same photo in original size so you can explore the part in more detail.

(LARGE PHOTOS are now linked to each photo)

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11 In the photo above, right and below you can see the problem of the orginal linkage on the later style (2 hole water pump) the linkage has to be 1/2 to 3/4 of an inch further forward. There is not enough adjustment to in the linkages to allow this. I tried spacing the bracket out by using tube spacers on longer bolts but this puts much more stress on the bolts and caused a leak at the housing.	12
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Following Photos are of linkage for a Pattern 13 with a 261 one engine installed this conversion uses an adapter plate and the later style two hole 216 water pump. In this case as well fabricated a new front linkage instead of modifying the original part which I have saved.
In these fabrication photos you will note that the shafts have not been welded to the lever arms. The shafts were welded once the engine was in place and the proper position for idle and full throttle could be determined the shaft and lever arms were tacked and then removed for welding. Having the all the linkages properly set up is very important not enough travel and you will not get full throttle. To much travel and when you floor the peddle you'll break the throttle at the carburetor. There is a length explanation of how to adjust these in the Chevy CMP manual. There is a special over run throttle crank arm down on the side of the block under the manifold which converts the fore aft travel of the linkage into the up and down of the carburetor. These are often missing on conversion engines, more on making one of these later. 003	Note : The pulley has not been changed yet, this smaller pulley radically over speeded the water pump and fan. It was swapped for the original pulley. 004
018 Front Cross Linkage in this version goes behind the pulley problem with this location on the 2 hole pump is that it requires grinding away half the shaft to get the necessary rotation. Above shows the linkage before installation in the truck below left and right is how it looks installed.	This is the original linkage which is was used on 42 Pattern 13 this version works on the early style water pump but hit both the body of the pump and the back of the pulley. Note also that the original style pump uses a separate pulley. While most of the later 216 pumps the pulley and flange are a single unit. If you come across the separate pulley on an old water pump grab it. These are much easier to adapt to the newer pumps as they can be pulled off the shaft without damaging the pulley. 016
0027	0024
017	015
014	030
031 Difference between the Pat 12 and Pat 13 is the length of the throttle shaft on the Drivers Side Pat 12 is overall 20 1/4". Pat 13 is overall 12 3/8".	032
033	034
035	121