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Username Post: long water pump vs short pump        (Topic#187693)
Posts: 200

Loc: Tonawanda, NY
Reg: 09-16-02
04-19-08 09:16 PM - Post#1415297    

I have a 1972 350 in my 55 210. It has a long water pump. I want to add some sort of cooling fan in place of the original fan but don't have the clearance between the water pump and the radiator. Can i switch to a short water pump without causing problems?


Posts: 348
Loc: S. E. Ks.
Reg: 08-26-05
04-19-08 09:46 PM - Post#1415314    
    In response to gkif68

The pump will fit fine but the pulley needs to be changed also . Not sure about the alternator mount but it might be alright . It has been a while but I'm sure you'll need to change the water pump pulley for sure .Just check out everything else with a straight edge.

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Very Senior Member
Posts: 2690
Loc: Minneapolis,MN
Reg: 01-29-03
04-19-08 10:07 PM - Post#1415325    
    In response to Datguy57

You will need to change the Crank pully, allternator pully, Alternator bracket, PS if you have it, also AC. Possibly your fuel line from the pump to carb if you have a mechanical pump. I am finishing up a 350 with a short pump right now Ill try to get you some pictures. Also your heater hoses will need to be re-routed depending on the brand of pump. How much room do you need you will gain some but not tons with the short pump. I went to a short on my 36 for the same reason you are thinking and it's good now.

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Very Senior Member
Posts: 2946
Reg: 06-20-01
04-21-08 03:43 AM - Post#1416174    
    In response to gkif68

If you already have the motor ready, or in the car, why not use a radiator in the "6" position?

S.Pollard 57 Belair sport coupe 69 C/10 stepside (wife's) 84 Monte Carlo SS

Senior Member
Posts: 8486

Loc: Mustang, OK, USA
Reg: 12-25-99
04-21-08 04:58 AM - Post#1416218    
    In response to gkif68

Just for additional information on long vs short water pumps, when it happened, and what parts were affected.
The short pump, same as what was introduced in 55, was in use up through 68. YES, YES, YES, I know, someone is going to jump in and mention Vettes and trucks, but for this question, I'm directing this information strictly to pass cars (full size, Chevelles, Novas, Camaros, etc).
Then in 69, EVERYTHING changed. The long pump was introduced, the alternator moved over to the RIGHT side and the AC compressor moved over to the left side (MAJOR MISTAKE by Chevy). With the change to the long pump in 69, ALLLLLLLLLLLLL of the pulleys also changed. Up through 68, the generator/alternator was mounted on the left exhaust manifold, thus, all 55-68 left side exhaust manifolds had a bracket cast onto them for gen/alt mounting (and again, YES I KNOW, the Vette generator moved to the right side in 58). So, for the sake of bolting 55-57 parts/accessories to a later SB engine, they are all a 100% bolt-on fit, such as ex manifolds, water pump, front engine mounts (REGARDLESS of long or short pump, all blocks/pumps share the exact same bolt pattern). Let me stop right here for a moment. SOME later SBs do not have the holes drilled and tapped on the front of the block for attachment of the stock front engine mount brackets. That is TOOOOOOOOOOOOOOOO EASY to fix. All SBs have the bosses cast into the front of the block for mounts, so simply use a stock 55-7 front mount bracket as a template to drill and tap holes in the bosses. Also, intake manifolds, flywheels, bell housings, distributors from a 55-7 engine are a bolt-on fit. No modifications are necessary. About the only thing that WON'T work (it will bolt on, but won't work) for example, is a 55-6 intake manifold on later heads, such as a 350. The runners on 55-6 intake manifolds are smaller and it is very likely that a 55 manifold bolted onto 75 heads will result in a severe leak.
Above, I mentioned that flywheels will fit. This is only true for 55-85 crankshafts/flywheels. In 1986, the SB changed to the one piece style rear main seal (giant O-ring). The center hole in the flywheel as well as the bolt pattern changed for engines with a one piece rear seal, thus, a 55-85 flywheel will not work on an 86-later engine.
But if you have ANY 55-85 Chevy SB (EXCEPT SB400) that you want to put in your 55-7 Chevy and you want to retain your original 3sp or PG, it will bolt right up to any 55-85 SB. The exception for the SB400 is because those are an externally balanced engine and MUST use a special UNbalanced flywheel/harmonic balancer.
One last thing about using later SBs in a 55-7 Chevy. Many later engines, ESPECIALLY 350s, have a much larger diameter harmonic balancer than the stock 55-7 balancer. To install a later SB with the bigger balancer (such as a 350), AND, retain the stock 55-7 front engine mounts, it is necessary to slightly grind away some metal from the motor mount brackets for clearance of the bigger balancer. I have done this and seen it done many times and the mount brackets are still plenty strong enough to support the 350. Only a small amount of the bracket has to be removed.

Senior Member
Posts: 9224
Loc: So Cal
Reg: 04-14-04
04-21-08 09:42 AM - Post#1416439    
    In response to DZAUTO

Great info Tom, thanks....



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