idler pulley question - why not on 305's?

[87R10]

So I'm going through the LMC cat and I see an idler pulley meant for 350 and 454 models, but not 305 equipped. I just dropped a 350 in with the 305 accessories...which does not include an idler.

Anyone know the purpose of this?

 

[bucket]

Without knowing exactly what you are asking about, the idler pulley you saw is likely for a different model year.

 

[87R10]

I'm referring to an idler tension pulley on the waterpump/alt drive belt. LMC's book only lists them for the 1987 model year, which mine is, but does not have because it was a 305. It says for 350's & 454's only.

Just wondering why the 305's don't use them

 

[bucket]

They must have the wrong application listed, because an '87 350 did not have an idler pulley anywhere.

 

[bobkyle2]

Aren't some of those years engines have a reverse waterpump or something? I don't really know off the top of my head.

 

[bucket]

'89 and later Burbs, K5's, and Crew Cabs had a serpentine belt setup that required an idler/tensioner pulley. Because of the serpentine belt, the water pump has to spin backwards, which is the reason for the reverse rotation water pump.