Underdrive Cranshaft pulley 455
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Underdrive Crankshaft pulley 455
I have the 7 1/2-7 5/8 crank pulley, but was wondering if the smaller pulleys can be made to work for under driving the alternator and water pump, and which ones. Both should be fine at slower speeds with my setup. Thanks
PS. Yes, I misspelled/typed Crankshaft in the title originally. Also need to add I only use one belt.
PS. Yes, I misspelled/typed Crankshaft in the title originally. Also need to add I only use one belt.
Last edited by Firewalker; Oct 10, 2016 at 11:22 PM. Reason: Misspelling
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After reading a book on engine cooling systems, I would never underdrive the water pump. The side effects could be very bad, pre-ignition, detonation. The temperature gauge does not indicate hot spots that develop in the cooling system. Keep her cool, and she won't let you down. Good luck.
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After reading a book on engine cooling systems, I would never underdrive the water pump. The side effects could be very bad, pre-ignition, detonation. The temperature gauge does not indicate hot spots that develop in the cooling system. Keep her cool, and she won't let you down. Good luck.
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I had nothing but issues, that was stock weight car with OK gearing. I bought the under drive aluminum pulleys off Ebay and are available from different Olds vendors. I now use that tiny underdrive crank pulley as a jack extension. I picked up a used March aluminum crank pulley about the same size as the non A/C crank pulley. Cooling is not the only issue with that tiny crank pulley, make sure you have a minimum 100 amp alternator or it will never keep up due to the alternator turning slower. I had issues with both, never again!
Last edited by olds 307 and 403; Oct 11, 2016 at 01:25 PM.
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I had nothing but issues but that was stock weight car with OK gearing. I use that tiny underdrive crank pulley as a jack extension. I now use an aluminum crank pulley about the same size as the non A/C pulleys. Cooling is not the only issue, make sure you have a minimum 100 amp alternator or it will never keep up due to the alternator turning slower. I had issues with both, never again!
3.50 rear, with overdrive about 2.41 and 28-29 tires.
Not everything works out and adjustments are just part of life. I have used many things as jack extension, or for other things. A hardware store can be a candy land of cheap things, if you think different.
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Just my opinion, but if there was added performance or economy from underdriving the belt driven accessories, you can be certain GM would have done it. If this is a car you plan on street drivkng at all, keep the factory pulley diameter. The engine needs the volumn to keep water circulating at lower engine speeds.
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Just my opinion, but if there was added performance or economy from underdriving the belt driven accessories, you can be certain GM would have done it. If this is a car you plan on street drivkng at all, keep the factory pulley diameter. The engine needs the volumn to keep water circulating at lower engine speeds.
Most Olds are on the ragged edge of over heating, as it is, and one tip to cool better is to put a round plate on the water pump impellers like the factory used for diesels, except the impellers were cast that way.
So far, the BBC after market looks to be the right sizes and depth for mine. The mounting holes are wrong, but should be fixable.
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And how do you know that "most Olds are on the ragged edge of over heating"?
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I guess you aren't aware that Olds used closed cast impellers on all of their engines, not just diesels, and the water pump rebuilders reused the closed cast impellers as well until the original supplies disappeared and it was cheaper to make stamped steel impellers for reman water pumps.
Nope, only seen those closed cast impellers on certain rebuilt impellers, but not all.
And then the fighting of over heating problems over years I have had, and the many threads on it I also have seen. Look at how this idea of slowing the pumps down any gets you, no it will overheat.
And how do you know that "most Olds are on the ragged edge of over heating"?
Nope, only seen those closed cast impellers on certain rebuilt impellers, but not all.
And then the fighting of over heating problems over years I have had, and the many threads on it I also have seen. Look at how this idea of slowing the pumps down any gets you, no it will overheat.
And how do you know that "most Olds are on the ragged edge of over heating"?
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On a 260, 307 or 350, underdrive pulleys should be passable. A 403 or 455 are more challenged with cooling. I ran them on my Olds 350, got to 210 idiling in traffic in warm weather. A non A/C 330 bottom pulley brought it down to 185. My 403 was never where I wanted it with that pulley.
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On a 260, 307 or 350, underdrive pulleys should be passable. A 403 or 455 are more challenged with cooling. I ran them on my Olds 350, got to 210 idiling in traffic in warm weather. A non A/C 330 bottom pulley brought it down to 185. My 403 was never where I wanted it with that pulley.
The thing is not everything works out, in life or hot rods or ideas, and I would just change it back if didn't work out. I also look for cheap cheap ways to do things and run my little experiments.
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Go for it, just don't plan a long trip without testing it first. My 88 seems to be more cooling challenge. The same rad that kept my 403 between 195 and 210, even 190 with the 350 never topped 185 when swapped in the Olds powered 4x4 with equal pulleys. I plan on gutting the interior for weight in my 88 Cutlass and cutting the rad support to fit a big A body radiator, so it can cool like it should for racing.
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Go for it, just don't plan a long trip without testing it first. My 88 seems to be more cooling challenge. The same rad that kept my 403 between 195 and 210, even 190 with the 350 never topped 185 when swapped in the Olds powered 4x4 with equal pulleys. I plan on gutting the interior for weight in my 88 Cutlass and cutting the rad support to fit a big A body radiator, so it can cool like it should for racing.
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