aNuBiS

iTrader: (25)

Correct me if Im wrong here, but I emailed march performance asking them if the alternator pulley included in their kit was overdrive, or underdrive or stock size. They couldnt give me a straight answer, so I asked them what belts were suggest for either just the crank pulley, or the crank WITH alternator pulley, and this is the answer I got.

4521 balancer only: use Dayco 5060760 alt.; 5040378 A.C.
4505 power and amp kit: Dayco 5060755 alt.; 5040378 A.C.

So as I was saying, correct me if Im wrong, but from what I understood the last two numbers in a belts part number is the size. So would I be accurate in my assumption then that the alternator pulley is underdriven because the belt suggested for the crank with alt pulley is a 55, whereas the belt suggested for just the crank and factory alt pulley is a 60.

It is pretty late, so maybe Im just burnt out, lol. Let me know

TheBlurLS1

iTrader: (8)

Where are you getting these numbers from, and what are you trying to get? Which pulley(s) do you want?

March only sells an underdrive crank pulley. Overdrive would be pointless, as would stock.

Viper

iTrader: (6)

TheBlurLS1

He said alternator pulley. Which they do sell.

http://www.thunderracing.com/catalog...1&sid=343#P432

aNuBiS

iTrader: (25)

I want an underdriven ALT pulley to go with my underdriven crank pulley.

But the guys at march werent able to clearly tell me if their alt pulley included in their kits were over or under.

and I got those numbers emailed to me directly FROM March.

From: marchperf@aol.com
Subject: Re: question

aNuBiS

iTrader: (25)

anyone else?

aNuBiS

iTrader: (25)

so nobody on here actually bought the kit with the alt pulley, and can tell if its larger or smaller than the original? Guess I'll find out myself in a week or so and let ya'll know.

Viper

iTrader: (6)

Why not call Thunder Racing and ask them? Sorry, I only bought the main pulley and belts ( gtom TR )

TheBlurLS1

iTrader: (8)

I am not seeing this kit for an f-body on thunder's site. Where exactly did you find it?

It did not seem to show the underdrive alternator pulley anywhere on there for an f-body.

Viper

iTrader: (6)

OK, I concede. I don't see it on TR's site either, sorry for trying to correct you TheBlurLS1. Anubis, where are you buying it from?

aNuBiS

iTrader: (25)

http://byunspeed.com/product_info.ph...bdc0ba08503ae8

I havent called Thunder, cause exactly, they dont carry it.

However, as stated above, I did call March themselves and I couldnt get a straight answer outta the guy.

http://www.marchperf.com/pg1.html right at the bottom #4505

Part #4505 Camaro/Firbird dampener crank pulley and power and amp alt pulley.

aNuBiS

iTrader: (25)

AHA! Summit sells them aswell, and as usual, nobody there can really tell me if its underdriven or overdriven, but from the picture if its of the actual product.... it looks pretty underdriven for an alt pulley maybe?

http://store.summitracing.com/partde...5&autoview=sku

TheBlurLS1

iTrader: (8)

A smaller alternator pulley would mean it would be OVERDRIVEN. For every inch of belt that passes over it, it would spin more times, and produce more power.