The Stovebolt Site Forums The Shop Area Engine Shop Fan, Water Pump and Harmonic Balancer

I had no intention of doing the plate thing. All I wanted to do is get a water pump that would allow me to put the 1956 235 in my 1950 pickup. I thought it was as easy as buying a short shaft water pump bolt it in and done. But my fan hits that darn balancer. Did the chef of 40s sell me the wrong pump? Do I need a different fan blade. I am trying to use the fan blade from the 235 that was on the original pump

Evac34, can you please say why the stock motor did not fit without changes?

Evac54, I attached a couple snips from Patrick's website that might help. www.patricksantiquecars.com. You might want to give Patrick a call. He is a wiz on these old engines, particularly conversions. He is a great guy to talk to.

It seems to me that you need a fan spacer to move the fan out a bit from the harmonic balancer. Patrick refers to a spacer in the text of one of the attached snips. Consider starting from the radiator side of the fan instead of the harmonic balancer side. The tips of your fan blade should be about 1/4" from radiator. If you can use a spacer to push the fan out to that point, would it give you enough clearance for the harmonic balancer? If so, simply find the correct size spacer. Perhaps Patrick has one. (Word of caution...if he doesn't have one in stock ready to ship, you might want to explore other vendors because it could be a long wait to get the part.) Do a search for fan spacers on eBay or vendors such as Summit Racing and you will find options.

Note in the attached snip referring to the spacer, Patrick also mentions that the fan might need to be 'untweaked' to clear the harmonic balancer. You might want to ask him what he means by that and what is the best way to 'untweak' before starting any surgery on the fan. The snip also shows a picture of a fan that is supposed to fit, but it might be what you have.

You asked if you purchased the correct water pump. Probably. You asked if you can use the later model fan that came with the 235. Based on the Patrick's info, the answer is yes with a spacer.

I hope this helps and doesn't confuse things further,

Matt

PS--Here is a little info that might help with the harmonic balancer/pulley size questions. The '53-'54 235's with the high water pump in the same location as the 216 came with a harmonic balancer with a 6" pulley for a 3/8" belt. The '55-'62 235's came with a 6 3/4" pulley and a 3/8" belt for cars and a 1/2" belt for trucks. The smaller pulley of the '53-'54 harmonic balancer will turn the water pump and the fan slower than a larger pulley. One of those would be ideal to use on one of these conversions, but they are hard to come by. As Pre68 Dave points out in his article, if you can't find one of those early 235 harmonic balancers, use a later one made for a 1/2" belt but actually install a 3/8" belt. Why? The 3/8" belt will sit deeper into the groove acting to reduce the working size of the pulley and as such will turn the water pump and the fan slower than a 3/8" pulley with a 3/8" belt. Even though both pulleys have a 6 3/4" diameter, the working diameter of the 3/8" belt recessed into the 1/2" pulley is less than a 3/8" belt in a 3/8" pulley. Would a later harmonic balancer that came off a car with a 3/8" pulley and belt fit? Sure, but it will spin the water pump and the fan faster.

bartamos,

I hesitate to continue in this discussion.

I sympathize, as you do, with posters who bought a "short shaft" 1955-1962-style water pump for use on 1955-1962 235/261 engine. This non-standard water pump is an adaptation/conversion of a normal 1955-1962 water pump.

I have never done that installation. It seems the major problem with that installation is finding the correct diameter fan blade, and/or, finding a spacer to move the fan blade outward (away from the balancer).

Dave's conversion technique is adequately/excellently documented and "published" on Dave's blog-site.

His technique uses an original older-style 37-55st water pump, relocated in a location that is higher-up on the newer-style 55-62 block (relocated partially above the block). This relocation is the normal location of water pumps on 37-55st blocks.

His technique has no fan-interference problems.

His technique has no advice on how to make a non-standard "converted" short-shaft 55-62 water pump to work properly.

The vendors that sold/sell a short-shaft 55-62 water pump should provide ALL PARTS needed to make it work on any 55-62 235/261 engine.

I'm just a bystander trying to understand. Now it seems that a person buys a short water pump for fan clearance to radiator?, and then adds a spacer to extend the fan out?
What? I suppose the answer might be they are buying the short pump to align V grooves, not for the fan. But no one has said that yet. I'm still waiting to hear why people are buying a short pump. Maybe they don't even know. But I envision a perfectly good motor with belts aligned and then someone buys a short pump and all hell breaks loose. So I assume they had a fan to rad clearance problem they thought they were fixing. I'm talking about folks that are NOT doing the adapter plate. The adapter plate is a totally separate issue, with some different goals, and can not be discussed at the same time.

Also as Jerry and others have cautioned! Do not "tweak", cut, or bend blades. This will cause vibration, out of balance, deflection and injury to parts and people.
We are talking high RPM's here. Slight modification to hub hole or mounting holes should be OK if strict care is taken to maintain concentricity and tight fit.

The Jim Carter listing listed worked exactly as described. Short shaft pump plus flat back "216 style" fan. No spacer. No belt incompatibility. Clears radiator. No muss, no fuss. 1962 engine in 1951 truck. Easy peasy.

The only remaining questions/issues I see:
* Sub-optimal fan placement for cooling. No issues for thus far for me.
* The whole car/truck balancer difference. Is that why the OP had fan clearance issues!

1. So there is the answer for full pressure truck motors into an AD without relocating pump to a higher location. From JW51. Using J. Carter's parts or equivalent. Do this and you will have no fan to rad problems and no fan to balancer problems. It may or may not be optimum for cooling your motor.

2. A full pressure motor into an AD can also be done with Pre68Dave's relocation plate and proper older style pump and balancer. If relocation is desired.
Some folks will reuse the old parts from the old motor. Some folks will have to buy them used/new. Using Dave's advice. This will also have no interference problems and will be better cooling if you need that.

I would suggest that any other way is a waste of time and money. You can see you don't need spacers or worry about groove widths with these options. It is possible that some vendors do not have a grasp of the situation or have their own ideas. I hope I have said all this correctly. I hope it finalizes this post.

J. Carter has some good info on this. Explained on the description of the pump, fan and plate. He fails to distinguish 55.1/55.2.
He does say 37-62 on the pump but I think he is saying that because it's used up to 62 with an adapter plate. Not because it is stock 62. As evidenced by the description of that short pump. When you search his 1962 water pump you get a 55-62 stock pump.

No info yet for a full pressure car motor that I see. Seems like one of the two ways above would work after swapping the necessary parts. Dave's page did not say there was interference with car motor parts, only that the "ratio" may cause over spinning. He does explain what balancers to use.

This may have been addressed in the previous 16 pages of this thread. I gave up trying to follow it all.

To boil things into simplest form:

OP bought a short shaft pump and a 235 fan. Looks like he just needs the 216 fan and things might work.

(There are some potential secondary issues with generator pulley and such, but that's all academic until you get a fan that doesn't hit stuff)

Ok I guess I am not too smart. I began this swap to a short shaft pump because I read here somewhere that is what I needed to do. My engine is still out of the truck I figured I would get this done before I put it back in so I have no idea how close to the radiator I would have been with the original water pump on the 1956. I am soooo confused now. Is someone telling me I did not have to replace the 1956 water pump

I have said it before, but it needs repeating.
The phrase "short shaft pump" is a very bad way to describe these water pumps.
A much better way is to say Modified 1955-62 pump, where "short shaft" got the name.
Or "high mount pump" (used up until 1955 1st). This pump is all to often called a short shaft pump.
This would save a lot of confusion.

For the sake of completeness, and, at the risk of adding more confusion:

"1. So there is the answer for full pressure truck motors into an AD without relocating pump to a higher location."

GM used the term "full pressure" for at least three generations of stovebolt engines (37-63).
I like to use "high pressure" to describe the 235/261 engines that have insert bearings, and no 216-style external/internal oil-distributor valve/lines.

All of the 1954 235/261 car and Advance-Design truck engines were high-pressure/full-pressure engines.
The 1953 Corvette engine (and, maybe the 1953 car engine with the Powerglide transmission option) were high-pressure/full-pressure engines.

Those engines had a high-mounted "external" water pump - same location as on low-pressure 216/235 engines.
This same style of engine/block was also used on 1955 first series truck 235/261 engines.
These engines are, therefore, another "answer for full pressure truck motors into an AD without relocating pump to a higher location."

When the truck series changed in 1955 (to 1955 second series Task Force trucks), the block casting changed to have the lower-mounted newer/later "internal" style of water pump.

I think that someone posted info that indicated the truck model/engine changed (to "second series", Task Force Trucks) around April 1955.

Apparently, all 1955 cars had the new lower/later style of water pump, because the car model/style changed for all of the 1955 cars (the new body style).

It would be nice/educational for someone to post photos of both styles of blocks with/without their respective water pumps. I'll see if I can find useful photos of complete engines.

Evac34. We will get your answer. You are the car motor guy, so no one has confirmed what to do. I assume your pump can be used. You said your truck had a 216. Maybe someone will confirm that you can use that balancer with the "modified 55-62" pump on your car motor.

1952 216 - low pressure - high water pump - top nuts on the valve cover
1953 235 - high pressure (Powerglide) - high water pump - top nuts on the valve cover
I could not find a 1953 car/truck low-pressure engine - high water pump, top nuts on valve cover
1954 235 - high pressure - high water pump - side screws on valve cover (no top nuts/bolts)
1955 235 (car) - high pressure - low water pump - side screws on valve cover
1957 235 - high pressure - low water pump - side screws on valve cover

Notice how the later 235s (1955 and later) have a wide pulley behind the fan. This style water pump locates the fan further out from the engine than the fan on earlier engines. The JC/etc "short-shaft" water pump eliminates that pulley, and it has a smaller diameter pulley, nearer to the block. Thus/therefore, the fan hits the harmonic balancer.

As long as the fan center/post hole is the correct diameter?

Without an engine in front of me, I'm struggling to imagine a fan/ balancer interference due to a larger diameter balancer and the short shaft pump (modified 55-62 235 pump). In this case I am referring to the 216 fan on said modified pump. (As my setup has)

The pump pulley is such that the groove is nearest the pump. The face of the fan hub on the pulley sits well forward of that (2 inches?). Not at all in the same plane as the balancer.

If you are not tired of reading about this topic, and you are patient, and you can orientate yourself in viewing "foreign" photos, Pre '68 Dave (it looks like Dave's classic Puget Sound lecture images) has made an excellent tutorial on old-block vs new-block castings and water pump orientations.

Photo 21 is a good one for this discussion
My guess is that many members/posters here have not had the opportunity and inclination to study the two generations of blocks.

When you look at the photos of the front of the two styles of blocks, first be sure to orientate yourself to "top" and "bottom" of the blocks (some of the photos are "sideway" images.

http://www.victorylibrary.com/graphics/235/6%2520cylinder%2520engines%2520with%2520photos.pdf


Thanks, again, Dave

So, now you can see the potential for interference with the harmonic balancer, AND, the different locations?

The minutiae got way out of hand here. I understand your confusion.

To put a 1956 engine in a 1950 truck with the radiator in stock position, yes, you had to address the pump in one way or another. Fan would not clear the radiator otherwise.

If I read your post correctly you bought a "modified" (I called it short shaft) 235 pump from
Chevy's of the 40s. Can you link to the pump you bought so we can be sure?

If so, you need the flat back 216 fan....like the one I linked to from Jim Carter. Or just take a fan off a 216 if you have on. Bolt one on and then report back. We can address belt size and all that as a separate matter.

Dave's adapter plate is just another way to skin the cat. It moves the pump to the (higher) location and uses a "216 style" pump.

the green engine is a 1954 Chevrolet 261 big truck engine
The rusty looking one is a 1956 Chevrolet 235 car engine .

Tim, pic #21 you spoke of tells a lot for this discussion, also pic # 19.
Now I remember where I got all my information to do the water pump adapter plate conversion. The previous owner of my suburban did a A1 hack job on the core support to move the radiator forward.

Thanks for the link Tim .

Tim

JW. The pump I got has a 5/8. Arbor the 216 fan blade has a 1" hole.

Suggestion regarding this situation was posted long ago in this thread.

I think that I would grit my teeth and try to drill it to the correct diameter (or, pay a machine shop to do).

That is, however, assuming that JC's hole-size is wrong (it is not listed, as I recall, but I forget the hole diameter and your needed diameter)?
I'd buy his blade, if it works; or, drill your blade if JC's will not work for you.

http://www.oldchevytrucks.com/cart/product.asp?prodid=MEE243&i=19667|||||

Gotcha. I will try to measure the fan hole on mine tonight. It was purchased from JC.

Might also take some pics to show how it all looks on the engine.

Per evac34: The fan hole is bigger than the shaft on the pump. Drilling won't make it smaller. Maybe that's too much minutiae.

I do believe we have got the basics down on motor swaps. All the terminology everybody wants to use.

All we need to do now is figure out what evac34 needs to do.

Chev's of the 40' may or may not be confusing. I do not know what each of these pumps is for and which to use, if any, to solve the issues herein.
They both say they are for the same motor and same trucks. They both say Cars and Trucks. One is called "short", the other called "conversion" ?????? One says use a certain fan they don't sell???? One of the pumps is not available but they are taking names. So sit on your hands and on your project and wait? What a goofy site IMO. If anyone ever asked me if I would buy anything from them, I would say no. There are several other vendors with this pump.

Regarding this "motor/pump swap issue" and what to do, J. Carter makes more sense to me. The Stovebolt advice makes more sense to me.

Here are the Co40's pump descriptions:

3741033 29+54
CHEVROLET Water Pump - Short Shaft W/ Cast Iron Pulley, 1955 & Later 235ci, 261ci 6 Cylinder With A 3/8 Wide Pulley ($100 Core)

This is a water pump with a short (narrow) pulley and shaft (Cast Iron). For use on 1955 & later 235ci & 261ci engines. Includes gasket. This has a 3/8" wide pulley.

For 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 Chevrolet Cars and Trucks




3741033LP 37-54
CHEVROLET Water Pump - For Conversion To 235.???? Includes Gasket For 55 & Later 235ci & 261ci 6-Cylinder (No Core Charge)

This is a water pump for conversion to 235ci.???? Includes gasket for '55 & later 235ci & 261ci 6-cylinders. *Must use a newer 235ci mechanical fan (not our part #838277 37-54&quo...

For 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 Chevrolet Cars and Trucks

Drilling won't make it smaller. Fair point.