underdrive pulley for a small block?

[V8-valiant]

just wondering if an underdrive pulley is worth the money, can you really tell any gains and what the best kind. has anyone even tried them and what are your thoughts. thanks

 

[GoodysGotaCuda]

Just becareful on the underdrive. It does slow your water pump and alternator speed down. Most of our alternators can barely keep up as it is with headlights on at idle. . .

 

[340Dart]

Just be careful on the underdrive. It does slow your water pump and alternator speed down. Most of our alternators can barely keep up as it is with headlights on at idle. . .

That's the problem I had. I bought one from Auto Specialties. Very nice piece. Powder coated, looked great. Turn signals barely worked at idle. Discharged at idle. Car ran hotter but didn't overheat. I put the stock one back on. I wouldn't recommend it.

Fred

 

[68valiant400]

i had bad experience with under pulleys car ran way to hot and aventually fried motor

 

[rumblefish360]

I didn't have a cooling problem with mine. Or charging for that matter. Idle was higher than normal. Big cams don't idle at 750 - 850 rpm.

I could not tell if there was any gain. But I did stop throwing belts with the new pulleys. That in itself was worth it for me. As you can see, it was a two for one deal.