Fan blade size for a 1954 3100 - 235 engine

[J.P.]

All,

Looking for some assistance......have searched the forum and lots of places on the internet but cannot determine the exact size of the mechanical fan (that fits on the water pump) needed for my 1954 3100 - 235 engine. The fan that came with the motor is a 4 blade - 18" tip to tip with blades approximately 3 1/2" wide. The fan (before it broke) was occasionally hitting the balancer.

One vendor I found has a four blade fan that says it fits a 54 235 it looks too small - it measures 15 3/4 " tip to tip but the blades are only 2 1/4". There have been postings claiming everything from 15 3/4, to 17" to 18" tip to tip measurements so I am just not sure who to believe.

What is the correct size fan and where would be a good place to find one?

Thanks in advance for the assistance.

J.P.

 

[52Panelman]

1929 - 1954 Chevrolet Master Parts & Accessories Catalog



39-54 comm, utility (exe 261)........ 18"diam, 4 blades.......................839020

 

[J.P.]

Thank you! Any thoughts of why the fan might have been hitting the balancer? Is there perhaps a spacer that could be missing to move the fan out just a little? From the end of the water pump shaft to the radiator is only 1 1/4" so there is not much clearance. Additionally, the fan was not setting in the middle of the radiator, in fact actually the bottom of the fan may just be a fraction below the bottom of the radiator. Never had any over heating issues just the occasional clipping of the blade on the balancer. Would welcome any thoughts. Thanks JP

 

[52Panelman]

" just the occasional clipping of the blade on the balancer" was it always hitting on the same blade? I'm going to guess it was under load when it would hit? is there any up or down movement in the water pump? is the balancer tight? if none of these it could be fatigue of the metal in the fan letting it flex... I'm sure someone on here will be able to help out on the fan..

 

[Bilbo]

Hi JP. Welcome to the site. Ask these guys anything, and you'll get solid answers.
I added air conditioning to my truck, with a 235 Chevy engine. In the hot Houston summer, I was concerned about possible overheating with the A/C on and went looking for a better fan. Here's what I got; Part # DER17318

Derale Rigid Race Fans - Auto Truck Parts & Accessories


Derale Rigid Race Fans - Auto Truck Parts & Accessories


This is a 6 blade, 18 inch fan with steel blades and the correct rotation, rated 6000 RPM, (I'll never see that!) And they sell spacer kits in all sizes. It works great for me. If your fan is off, put a straight edge from the front of the water pump fan hub and extend it downward and check just how much clearance you have to the front of the harmonic balancer. Then determine how much you could space the fan forward to give clearance, without endangering the radiator. BTW, If the fan flexes under higher RPMs, it should flex forward at the blade tips, (opposite direction of air flow, but it shouldn't flex, or very little.) Hope this helps with your problem.

 

[J.P.]

All,
Thanks for the responses. Sorry I have not got back sooner - Yes the fan was sometimes hitting the balancer when it was under a load. From what little that I can tell is was likely hitting on more than one blade. It did brake off a blade which has me on the search for a new fan. There is no movement in the water pump or the balancer.

Our host doesn't carry a fan for the 54/235 so I checked with another vendor and they are telling me that their blade fits "1947-55 Fan Blade Steel 216-235" it measures is 15 3/4 with 1" pilot hole . Below are a couple of pictures of what I was sent compared to what was on my 235. The vendor said the 18" blade was for a 261 which is not what 52Panelman found. The pilot and bolt holes are the same size and location and certainly the shorter fan blade would not hit the balancer. Anyone using this smaller fan....any issues with using it??????



Bilbo - did the fan you purchased have a 1" pilot hole or did it need to be machined to fit the water pump shaft? Also, what kind of clearance do you have between the fan and he radiator? Did you use a spacer? Did you have to move the radiator forward? Any pictures you could post to show clearance?

Thanks again for the attention to this question.

 

[Thunder54]

All,
Thanks for the responses. Sorry I have not got back sooner - Yes the fan was sometimes hitting the balancer when it was under a load. From what little that I can tell is was likely hitting on more than one blade. It did brake off a blade which has me on the search for a new fan. There is no movement in the water pump or the balancer.

Our host doesn't carry a fan for the 54/235 so I checked with another vendor and they are telling me that their blade fits "1947-55 Fan Blade Steel 216-235" it measures is 15 3/4 with 1" pilot hole . Below are a couple of pictures of what I was sent compared to what was on my 235. The vendor said the 18" blade was for a 261 which is not what 52Panelman found. The pilot and bolt holes are the same size and location and certainly the shorter fan blade would not hit the balancer. Anyone using this smaller fan....any issues with using it??????

View attachment 21256 View attachment 21257

Bilbo - did the fan you purchased have a 1" pilot hole or did it need to be machined to fit the water pump shaft? Also, what kind of clearance do you have between the fan and he radiator? Did you use a spacer? Did you have to move the radiator forward? Any pictures you could post to show clearance?

Thanks again for the attention to this question.[/QUOTE

.

J.P,

I read the forum a bunch but don't log in often.

If I recall, Bilbo has a Chevrolet 235 in a GMC truck.

Because he and Zig have GMC trucks, they may hav just a bit more space between between the water pumps and radiators in the GMC trucks. GMC I6 engines are about a half inch longer than Chevy blocks. When GMC engines are installed in Chevy Trucks, the radiators have to be adjusted forward.

I have an original 4 blade 54 Chevy from my truck is you are interested.

I am running a six blade fan to support the air flow needed by AC.

My six blade tapped my harmonic balancer and I had enough space to tap the balancer just a hair to clear it. It has run with very close fan tolerance both directions for over 13 years.

good luck

Jim

 

[Bilbo]

All,
Thanks for the responses. Sorry I have not got back sooner - Yes the fan was sometimes hitting the balancer when it was under a load. From what little that I can tell is was likely hitting on more than one blade. It did brake off a blade which has me on the search for a new fan. There is no movement in the water pump or the balancer.

Our host doesn't carry a fan for the 54/235 so I checked with another vendor and they are telling me that their blade fits "1947-55 Fan Blade Steel 216-235" it measures is 15 3/4 with 1" pilot hole . Below are a couple of pictures of what I was sent compared to what was on my 235. The vendor said the 18" blade was for a 261 which is not what 52Panelman found. The pilot and bolt holes are the same size and location and certainly the shorter fan blade would not hit the balancer. Anyone using this smaller fan....any issues with using it??????

View attachment 21256 View attachment 21257

Bilbo - did the fan you purchased have a 1" pilot hole or did it need to be machined to fit the water pump shaft? Also, what kind of clearance do you have between the fan and he radiator? Did you use a spacer? Did you have to move the radiator forward? Any pictures you could post to show clearance?

Thanks again for the attention to this question.

Hey JP. The fan hub was an exact fit. I bought a 1" spacer, but didn't use it. I have 1" fan clearance to the radiator. The fan is 2 1/2" of pitch, so half of that, (1 1/4") extends forward of the mounting surface. Have a couple of pictures I'll try to add...