Chevrolet CMP Engine variants

[Jordan Baker]

Thanks guys.

I'd ultimately like to use the one hole 216 water pump as it gives all the room that is needed. However as I posted in the other tread I'd need to do some serious surgery to the engine block and make up an adaptor plate.

Bob, I believe I've got the correct elbow with the flat spot.

I'm just confused by all the swaping around of pumps and pulleys.

[Bob Carriere]

If you use the harmonic balancer of the 216 ( it while fit the 235) and keep the 216 water pump pulley than you have the same speed.....however, I used an alternator ( sorry I sinned) so I had to change the pulley on the alternator to match the 5/8 belts requirements of the rest.

Note some 216 had large 7/8 pulleys.

what ever you do do not remove metal from the block..... I would be concerned with creating a weak area even if the later 261 had a huge hole to allow the pump to sit inside the block.

Let me follow with some basic photos.

First just to clear up the cab 13 versus cab 11/12

The first picture shows a cab 13 set up..... the rod is shorter and is connected to another straight rod that goes to the gas pedal.


PS...... just noticed that the second and third picture show evidence that the throttle shaft was grinded above the pulley to gain clearance...... shinny area.

*****(The second set of grey engine set up shows a cab 11/12 longer arm set up.) **** WRONG it show same cab 13 set up.
There is a flat stock piece of steel that fits behind the rod.......

I will follow up with my modified set up to gain clearance.

[Jordan Baker]

Bob, in your last picture is the throttle rod ground down to provide clearance?

[Bob Carriere]

First the original set up on my cab which was equipped with a GMC 228 engine BUT I have verified with other cab 11/12 and the set up was near original.

[Bob Carriere]

Has no modification and he made it fit ...... not sure how????

[Bob Carriere]

Too many pictures gets confusing......

I think we better wait for Phil's pictures which will be far more accurate.

sorry!!!

[Jordan Baker]

My understanding is that Grant used a 261 and a home made adaptor plate to fit an early one hole 216 water pump. Using the one hole pump there if enough room to fit the throttle rod unmodified.

My engine is a late 216 that used s two hole water pump, this means I have to either modify the throttle linkage to fit or find a way to fit the early one hole pump to a two hole pump engine. I'm not sure this is possible.

[Bob Carriere]

Would it not be easier to find a rebuilt 2 hole pump????


I think I am going to bed to think about it....

Ps one holer are $200 on ebay but a rebuilt two hole is $90


Water-Pump-CHEVROLET-1942-1946-1947-1948-1949-1950-1951-1952-CORVETTE-1953-1954.............. search for this item.

[Grant Bowker]

Originally Posted by Bob Carriere

Has no modification and he made it fit ...... not sure how????

At this point I don't recall if it was careful parts selection or pure dumb luck but I think it was a close fit although I do remember it not having a lot of spare space. There are a variety of thermostat housing castings, each a bit different from the others WRT wall thickness, clearance angle at lower front and overall bulk. There are also slight manufacturing differences in the throttle linkage across the front of the engine that can help/hurt. And... there are several different casting numbers of each of the 1 and 2 hole pumps that vary slightly in shape (plus aftermarket pumps) to add or reduce clearance. I remain very nervous about the idea of modifying the 2 hole 216 block to accept a 1 hole pump. it just looks like more holes, closer together than I am comfortable with - but it might be alright in spite of my nervousness.