CGT Restoration - Update

Phil Waterman · #1 13-03-08, 23:38

Hi Walde

If you 216 is the original or even if it has the original accessories hold on to it or offer the bits up to us other CMPers as parts. If you have the original deep sump oil pan hold I'd be interested as some of the other will be as well.

Right now I'm looking at how to graft the deep sump onto a 235 or 261 pan and extend the pickup tube down.

Interested to hear that the 235/261 water pump adapter works well will be interested to here from some of the rest of our group that have these on trucks on the road how the actual cooling is. I have some concerns about the flow and distribution because the 261 are particularly prone to steam pockets.

Cheers Phil

Bob Carriere · #2 14-03-08, 03:53

HI Phil

I was adamant that I would not remove my original in blcok 261 water pump for a reduced size external 216 pump.....come hell or high water.

Well watewr rose too hight and I gave in........ Grant and I worked two full days trying to make the fan blade fit.... can't remember how many model we tried.... different deep shalow pulleys.... HELL you cannot fit a 261 original water pump and the original trottle in a CMP without some big shoe horn.

Even with the adapter plate it took some trick to fit the linkage for the gas to go underneath the water elbow to the block.

I am not sure yet if it will be sufficient to keep everything cool enough but if a problem arises I would be more tempted to increase the engine oil capacity and use an oil cooler than rip the tight fitting cab 11 engine bay area apart. I will be running two full size PH 8 spin on filters mounted inside the frame underneath the passenger side......

Tell us how did you manage the linkage and water pump in your cab 12..... you got a 235 in there correct... same as a 261 or did you use an early 235 with the old pump....

Grant will be facing the same issue with his 261 cab 13 arrangement.

Phil Waterman · #3 15-03-08, 00:20

Hi Bob

Just started working on the throttle linkage for the 235 and Pattern 12. I originally put a 1953 216 in the Pattern 12 and the water pump and thermostat housing were enough different that the original throttle cross over shaft would not fit period. I fabricated a totally new cross over shaft assembly.

The 235 is still running in on the test stand, I’m addressing several little issues. I’ve got 10+ hours on the clock now on this engine and just as with the one other rope rear main seal engines after running for some real time it has started to weep just a little. Just enough that with a clean piece of paper on the drip pan on the test stand I can see a fine line of oil drops after the engine has run for an hour. So I’ve got to do some real checking to see what is causing the leak, though they ground the crank and fitted all new bearings during the rebuild machine work, I forgot to tell them to grind the rear main seal surface. If that is the cause then the fix is simple speed-sleeve over the seal area. That was the fix on the 1953 216 and it has worked well. What is strange is that there is more oil on the left side of the bell housing than on the right, this might mean two things that I can think of one that the oil passage plug on that side is leaking or that the oil is leaking bye on only one side of the rear main, I can not remember if I shimmed the rear main. If the rear main surface is smooth and clean then I’ll just replace the rope and be extra careful of fitting of the seal. I really don’t think the replacement gasket is as good as the original.

I’m going to replace the exhaust valve rotators to see if I can get rid of a click. Did a compression test on the 235 this afternoon with the engine fully warmed up about 190 degrees all of the cylinders are right at 130 psi +/- 2.

I’ve got to clean the radiator on my test stand because it just can not get rid of the heat with the engine at 1500 rpm it comes up to 190 even with auxiliary cooling on the heater connections, I have to heater cores with a blower hooked up. I think my problem is that my main radiator fan just is not moving enough air. I’m getting a 15 degree drop across the main radiator and I’m getting a 20 degree across the heater cores. The 235 is running 180 thermostat.

I want to do these engine swap once each truck then I just want to drive the trucks for 30 years without touching the engines.

The reason I pick 30 years is that is how long I’ve driven my HUP without ever tearing the engine down. The 216 engine in the HUP has never been apart in all the time I’ve owned it. Engine leaks oil but it runs so nice that I hate to take it apart.

The 261 engine is just about complete, (missing of all things the oil drain plug) I’m going to run it in on the test stand with the correct 261 water pump. Then I’ll move over to the adapter type, really wish I had a flow meter that would tell us do they move the same amount of water.

Think your idea of adding an oil cooler may be a really good idea.

The guys I know who have re-engine there US military stuff with 261 have cheated and used 12 volt electric radiator fans and not bothered with all the conversion of the water pump. I’ve got to go take some pictures of how they did it.

Bob Carriere · #4 15-03-08, 03:38

Hi Phil

Yes it would be nice to compare the flow rate of the 261 original pump against the adapter 216...... but.....

One has to remember the air flow charateristics of the cab 13 and even worst the cab 11/12. At least a cab 13 can have a fan shroud which will greatly improve the air flow..... forget that idea with a cab 11/12.

According to by truck there is NO way you can fit a 261 engine pump in a cab11/12 without moving the engine back i nto the frame.... and then the fan is not centered on the rad.......

Any one can cheat with a wired in 12 volt fan mounted on the radiator...but then you would loose all the original whine of the fan when the engine is running. I remember running a M37 without a fan belt so we could listen to and adjust the valves....... 90% of the engine noise went away when the fan was not running......

Chev 6 cyl. like the Dodge flat head six were not usually known for running hot... I have driven M37 with no rad cap...... after running a branch right through the rad....... it never boiled over....... on the other hand a V8 Ford would boil over in Winter.

If we have an overheating problem with the 261.... which I don't think we will with a good recored rad..... a deeper oil sump.... extra spin on filters and as a last resort and engine oil cooler should take care of it..... short of over stressing the engine with a heavy load and trailer at low road speed in Summer..... the 261 should do us proud..... only time will tell!!!!

speaking of breaking in the engine..... are you running diesel engine oil as per the news article...??? what weight..??

Now if only the 261 heat could be used to melt the darn snow!!!!!!

Boob

Walde Libera · #5 17-03-08, 01:26

Gents!

I rebuilt my 235 a couple years ago so I don't know if there are cooling issues yet, but here is some info I had when I installed the adapter plate, I don't remember where I got it from , but assume from the supplier of the adapter plate.

Quote:

1955-62 water pump adaptation

When installing a 1955-62 235/261 full pressure engine in place of a 216 or early splash 235 engines, this one time conversion allows you to put the early style pump on the later engine.
In the past modifying the 1955-62 water pump was done but required a press to force the hub further back on the shaft, then the hardened shaft that was left protruding required being cut off. Additionally a special pulley and fan was required. After all that the pump and fan still sat 3" lower than the 216/early 235 pump that could lead to overheating and possible fan hum.
By using this adapter with a 1941-54 water pump the pump is put back in the stock location*. If you need to replace the water pump in the future you can buy an over-the-counter pump and install it without modification.

Note: I recommend using the harmonic balancer and water pump with the belt width you want from your original engine.
1941-52 ⅝" belt
1953-54 ⅜" belt
1937-40 must use one of the above

Caution: Do not use the 1955-62 balancer since the pulley is larger and will turn the pump too fast.

* Stock for 1941-54
* 1937-38 fan will be ½” back from stock.
* 1939-40 Belt and fan will be ¼” forward from stock.

Bob Carriere · #6 17-03-08, 01:48

Hi Walde.

I first tried shortening the shaft on a good 261 pump and used a shallow chromed pulley from a SB Chevy..... had to grind the body of the pump to get more clearance as the pulley was rubbing on the outlet casting. The all the fans I had.....4 blades, 5 blades and 6 blades were not fitting properly and would hit the lower pulley on the crank........or the big GM I had was hitting on the lower outlet of the rad because the fan sits so low...... besides even with the fan blade removed I still did not have sufficient rad clearance.

The other issue is that you have to discard the large elbow outlet that fits to the head of the 261....... mine was the larger model and it prevented the installation of the throttle linkage..... I reverted back to a 216 elbow from an old cab 13...... it has a special flat spot on the bottom of the elbow that is needed to fit the throttle rod behind the pump pulley.....

Reluctantly I went with the adapter and all fits well so far...... I will need to run it wirth the full engine enclosure before I know for sure if it will run hot or not!!!!!

First picture of my 261 with the original pump and 1959 GM fan......looked nice but was useless..... not enough clearance for the rad and the fan blade hit the lower outlet of the rad....

Bob Carriere · #7 17-03-08, 01:54

....after hours of fiddling with the help of Grant we finally got it to fit....

The fan blade came from a 216.....cab 13 water truck.....

Once the pump was changed I had to change the harmonic balancer ot match the pulley size and the alternator...... belt came from a tractor dealer in 7/8 size for an Allis Chalmers.......

Bob