Inliners International Forums General Discussion Engines 235 water flow path?

I'm trying to trace the history and evolution of the water system in the blocks.
The 15 bolt motors had copper nozzles in the head for exhaust cooling, and according to the factory lit this stopped with the 18 bolt (full pressure oil) motors in favor of simply using larger water passages.
A diagram of a 1953 motor shows no water holes from the block jacket to the head in the front 3 cylinders. Only #4, 5 & 6 have water through the gasket.
However: later gaskets show water transfer through the gasket at all cylinders, but I can't tell from the text or pics if the holes are all the same size?
The gasket patterns are all over the place as well.
Anyone have anything more on this?

You need to look at a block,head and gasket.....

Nobody knows.....

Maybe no one cares??? I do know that there are several patterns of holes punched in head gaskets.I ran into this 10 years ago on a 261 Chevy .I never got a straight answer on which gasket is is the correct one to use.
I have two early 70's Chevrolet factory parts manuals.Both the 235 and 261 were out of production by this time Only one head gasket part number is listed for the 235 ,#3709428. And one part number for 261,#3836963.Must be GM felt these were the gaskets to use..
So maybe you can find these gaskets on Ebay,buy them ,see how they match the head and block.

I'm not trying to locate a specific gasket, and you can see by the weirdly shaped holes that the available 18 bolt gaskets accommodate several hole patterns.
I trying to track changes in the water flow pattern as to which holes were used, how big, what results.
There is nothing in the literature.

I think we are talking about the same subject.....I'm just at the end of the coolant flow study by mentioning the last gasket used by GM.
Maybe GM never did much coolant flow work on this engine.Chevy introduced the inline 6 in the late 1920's and then it changed over the years into the 235-261 engine.If the original engine cooled ok right off the drafting table them that might have been the end of it.
216's and many other engines have cooling tubes in the head.This is expensive to manufacture compared to a hole in cast iron.Surprising that GM being as cheap as they were at times didn't get rid of the tubes form the original design.

Since the copper nozzles stopped with the 15 bolt motors, cost may be enough reason.
But... how many times did they revise how much water went where, and why between 1954 and 1963?

Hi Panic . . .

I have always been under the impression that the 'engineering' around holes between the water jacket in the head and the water jacket in the block was largely limited to the 'gross area' of the openings - not necessarily the placement. After all the water pump is pumping against a closed thermostat - so the entire water jacket in the head is filled by pressure.

I was also under the impression that the low pressure event created by the thermostat opening was always engineered to allow less flow then the holes between the block and the head - so even in this state the entire head is being filled with coolant faster then the thermostat is letting it escape.

With this design principle - I don't see how specific placement of holes could create/prevent overly hot spots in the head. Hot spots would always have been addressed by water jacket thickness not flow (given the remote placement of the thermostat). That said, I would agree that in 'general' these openings need to be spread about for an even flow - but the specific placement seems more likely a result of matching the machining to the casting decisions - then to some sort of 'flow strategy'.

Personally, I have never been able to figure out why they ever went to the trouble to press in copper tubes after machining certain holes. And like you have never found anything in the literature that discusses the thinking behind this practice.

Moreover, I am a firm believer in the male dog theory of superficial engineering change: Every mutt that is given an opportunity - will lift his leg and leave his mark on the design . . . beneficial or not.

regards,
stock49

The GMC's used copper tubes also in their heads, must have been the same corporate minds at work.

Over the years I have seen a few variations in the size and placement of these holes. However it always came down to getting the correct amount of coolant through the motor at the correct locations to get even temps from front to back. The later gaskets have this figured out as to hole location and size.
Engines with the water inlet and outlet on the same end must have staggered distribution front to back for even cooling.
When and how this was figured out I don't know, but it work good.