Reduction Pulleys for a Bigblock- Anybody Using Them?
Thread Starter
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
Reduction Pulleys for a Bigblock- Anybody Using Them?
I was thinking of buying a set of March reduction pulleys for crank, water pump, & alternator but I just talked to March & the guy thought it would be best to stay with standard sized pulleys for the street. I'd like to free up another 15 ponies or so if it won't cause cooling or charging problems.
Is anybody out there running a reduction set on a bigblock successfully? Any feedback would be much appreciated!
Is anybody out there running a reduction set on a bigblock successfully? Any feedback would be much appreciated!
Le Mans Master
Joined: Mar 2001
Posts: 6,240
Likes: 1,013
From: Watkinsville, GA and Glen Cove, NY
Les, I asked the same question of my engine builder when I was ordering my March pulleys and he said to stay with the standard pulleys with big blocks. He had seen some problems cooling with the underdriven pulleys. I would think it would be especially true with Corvettes, that don't cool that well anyway. By the way, I love my March setup. Bill.
Team Owner
Joined: Feb 1999
Posts: 34,454
Likes: 665
From: Republic of Texas
I too have heard of cooling problems w/ the Big Blocks. Seems the engine tends to poverheat since the water pump turns slower. I do believe they offer a more expensive kit to fix this problem. We just added the march serpintine to our street rod, very impressed w/ the setup. This is an old pic, we since have installed the matching chrome air compressor.
3rd Gear
Joined: Aug 2004
Posts: 3
Likes: 0
From: MA
Hi. We went with the March underdrive pulleys on our 427 390 hp. We modified the cooling system with a Be Cool radiator and dual electric fan setup. The car runs at 180 all day long. The only issue we did have was the alternator not putting out enough at idle when the fans were on. We swapped March's standard size alternator pulley that comes in the kit with one size smaller and everything seems to be great. Made a huge differance in the driveability of the car. I don't worry if I see brake lights in front of me on the highway on a hot day anymore.
Le Mans Master
Joined: Jun 2003
Posts: 5,446
Likes: 2
From: Not Correctly Restored Stingray Fla.
Originally Posted by Kat427
Hi. We went with the March underdrive pulleys on our 427 390 hp. We modified the cooling system with a Be Cool radiator and dual electric fan setup. The car runs at 180 all day long. The only issue we did have was the alternator not putting out enough at idle when the fans were on. We swapped March's standard size alternator pulley that comes in the kit with one size smaller and everything seems to be great. Made a huge differance in the driveability of the car. I don't worry if I see brake lights in front of me on the highway on a hot day anymore.
I'm running a small block, BUT , March told me the same thing when I changed over to their surpentine set-up. They do not recomend the underdrive for the street. Meanwhile I was running their underdrive V-belt pulleys for almost 10 years without any issues. I have their underdrive serpentine (crank, w.p., alt.) with almost 525hp I'm running at 175 degrees all day long usually with only one of the two SPAL fans on in So. Fla.
A very good alum. radiator, alum.water pump, SPAL fans, and the engine tuned well you shouldn't have any problems.
Sure the temp. does rise about 10 degrees sitting at those long "big intersection" lights, so I'll click on the second fan for a moment. Both my fans are toggle swithches and not on sensors.
Another thing, I do not run a thermostat, I use a restrictor plate. Those things are always screwwing up.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
It does not make any difference BB or SB the problem is a good charging capacity is not reached with the March setup. By underdriving the alternator with the March pulleys which by the way is the desired result for using the setup as it takes the most HP to turn, cranking ability suffers at times. By placing a smaller pulley on the alternator to get the charging back up to normal defeats the whole purpose of the March set up. 
Sorry gentelman, BB engines are not prone to overheat contrary to some conversation on the forum. If any engine overheats, the combination is wrong or other problems exist. Stick to the stock stuff and you will never get stranded.
Sorry gentelman, BB engines are not prone to overheat contrary to some conversation on the forum. If any engine overheats, the combination is wrong or other problems exist. Stick to the stock stuff and you will never get stranded.
Thread Starter
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
Thanks to all for the feedback Rather than chance having problems it looks like I'll go with standard sized pulleys. The only remaining question is whether the price of the March pulleys is close enough to that of stock replacements to justify buying them. Time to do some pricing...
Rather than chance having problems it looks like I'll go with standard sized pulleys. The only remaining question is whether the price of the March pulleys is close enough to that of stock replacements to justify buying them. Time to do some pricing...
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