Diameter of Stock Pulleys ???

[392cobra]

I'm trying to find out what the diameters are for stock pulleys for the water pump,crank and alternator.This is for a 351w,that is now a 418w.

Looking to figure out how much the factory overdrove the water pump and alternator.

While I had the 392w cooling was never a concern with the March performance pulleys.The Spal 16" fan and Griffin 2 row,1.25" tubes radiator did a fine job.
The radiator is rated for up to 600 hp.

I now have a 602 hp 418w and in slow traffic in 80's degree the water tempts go to 200 - 210*.
I have completely gone thru the cooling system and all is operating as they should.
I called Griffin and told the tech people the story. The first question they asked is "Are you running March pulleys ?".

They said that March performance pulleys were the #1 cause of low speed cooling problems when the radiator capacity is being pushed a little.

March perf. pulleys underdrive the pump 12 %.
I have ordered their Street Rod water pump pulley.It will overdrive the pump 5 % .

Any help with the diameters of stock pulleys would be appreciated.

[CowtownCobra]

Good question Fred. I have seen exactly the same thing. I will talk to you Saturday about what you have found.

[DAVID GAGNARD]

Fred;

If my feeble memory is "on" tonight,I think the stock water pump pulley on my 351 W is about 6 3/4 inches in diameter give or take a half inch,not sure on the crank pulley,but I would guess at least 7 1/2 inches to maybe even 8 inches in diameter.......You should be o-k running the same diameter crank and water pump pulleys............On my street car,my crank pulley is exactly one inch smaller diameter than the water pump pulley,I run a Griffin radiator also and a 17" electric fan........any speed above 35 mph,I never have to use the fan,below that I run the fan and my temp stays on 180 with a 180 thermostat........My fan is on a manuel switch only,so in city driving I turn the fan on and forget about it,once I hit the highway I turn it off,if I do not,my water temp will drop to 170..........

David

[Jack21]

I have stock displacement 351W, Griffin radiator. Knowing no better, I ordered March performance pulley set from Summit. In a discussion with March regarding a power steering pulley, I learned they had two pulley ratios, a performance, and a street rod. March recommended the street rod ratio for a mostly street use car to cure the potential overheating problem described above. Only the water pump pulley is different, it's smaller.

[Rick Parker]

I'm running a 289 not a 351. The crank pulley is 6" & the water pump is 5 1/2". It sounds like you have researched potential problems areas. Let me share an experience I had. When the engine was first built I purchased a rebuilt (?) water pump at Pep Boys and used it for about a year. During that time I had very irradic water temps. As the thermostat would open the water temp would immediately drop to 140 degrees and then slowly creep backup and go past 180-190-200 spiking and then again dropping. Sometimes it would stabilize briefly and occasionally it would operate at 180 and then spike at over 200 and immediately drop to 140. I tried many things, but what solved the problem was the change from the water pump with a stamped steel impeller I was using, to a "NEW" one with a cast iron impeller bought from Ford Dealer. Never a problem again.

Rick