The Stovebolt Site Forums The Shop Area Engine Shop Fan/ Harmonic balancer clerarance issue

Putting together a 61-261 that will be going in a 37 chev. I bought a short shaft water pump to eliminate the need to relocate the radiator. In dry fitting the front of the engine ie. mountiing the water pump, balancer, generator, fan & belt, I noticed that the fan blade hits the harmonic balancer by about a 1/4 inch. Tried both 4 & 5 blade chev fans to no avail. The hub that's pressed on the water pump is set right for all belt groove alignment. Has anyone run across this before and any easy ways out? As always, your comments are appreciated.

This issue has been discussed many times. I think you would find the water pump adapter and a 216 pump will solve the problem. It puts the fan and water pump exactly where it was with the original motor. However I don't think you can use the 37 pump. Pre 68 Dave, the inventor of the adapter can tell you what pump you need.

You can look at using a fan spacer, which are available at NAPA and other stores. My COE, with the later 235, already had the later water pump with narrow belt, narrow pulley on the generator and balancer. So the spacer was the easy solution for me. That does leave the fan lower down on the radiator than desirable, so the adapter may be a better solution.
Kent

Ran into the same issue on my 40. Just today I cut a section out of the fan for clearance. I would have done the adapter but I just purchased the short water pump and didn't want to pay for another pump.

I used a smaller diameter fan blade on my 1960 261 for a few years (in the 70s).

I have since used Pre '68 Dave's water pump re-locator with a 1954 fan blade.

I had a similar problem. I have a 1962 261 in my 55 1st series. I called Patrick in Arizona. Patrick had a water pump and fan blade that solved my problem. Couple hundred dollars later with the new parts installed, I had clearance. I recommend calling Patricks. Good luck.

I would caution against cutting on the fan blade. It will not be balanced and will shorten the life of your water pump, and in some cases could cause the fan to shake apart and make a big mess with pieces flying.

As above^^^. Chopping down a 60 year old steel fan blade with hard to detect stress fracutures and trying to achieve 'balance nirvana' seems like a difficult task. My solution was an aluminum flex fan with a 1/4" spacer. It's mounted with the 'short pump'. The amount of rotating mass is reduced and each of the five blades is affixed by four rivets. I've never had an overheating problem on this dd/only vehicle.

I would think the the 55 and later water pump design would do a better job of moving water through the system.

Walt Williams
La Verkin, UT

Here are the trade-offs:

Short-shaft 1955-2nd to 1963 water pump on a 1955-2nd to 1963 235/261 block in a 1947-1955 Advance-Design truck:
- might be more efficient water pump in terms of cooling (questionable)
- the fan is 3" lower relative to the radiator, resulting in less efficient cooling
- a fan blade must be found that will not interfere with the harmonic balancer
- possible fan-pulley and/or harmonica balancer and/or generator-pulley miss-match in diameter and groove widths, depending on the equipment/pulleys that will be used. This is not just a fitment consideration, there are implications related to fan RPM.

Pre-1955-2nd 216/235 water pump on a 1955-2nd to 1963 235/261 block installed in a 1947-1955 Advance-Design truck:
- might be less efficient water pump in terms of cooling (questionable)
- fan is in the correct location relative to the radiator, resulting in more efficient cooling.
- allows use of the truck's original equipment harmonic balancer, fan pulley, and generator and the original fan belt will work fine. No fitment problems and original fan RPM.

There is also the consideration of almost original appearance when using the water-pump relocation plate (made and sold by Pre '68 Dave).