underdrive pulleys

[XxBIGxTEXxX]

So i ordered a pair of the underdrive pulleys ffrom summit but i dont know what kind of belt to put on her because the cam shaft pulley is smaller than the stock pulley and the alternator pulley is a little bigger. Can anyone help and tell me what kind of belt i should go with if they know or had this same problem?

 

[SunlitComet]

How about before changing them leave the belt on and mark your tensioner position. If they developed a good kit the belt length may not have changed. If a new one is required the install instruction will specify it.

 

[AtomicHoe094]

i dont suggest you put the underdrive pulley on the alternator..

 

[99Yuk]

My kit also came from Summit. It came with the crank underdrive pulley and the overdrive ALT pulley. It did need a new belt. I bought a belt that fits on an 07 avalanche. The kit gives you the part number of an off brand belt. I used google to cross-reference to a Goodyear Gatorback belt. If the kit comes with the overdrive ALt pulley, go a head and instal lit. It brings the ALT almost back to stock config.

I havn't had a problem with mine at all....about 6 months so far.

 

[stuntmanray385]

What is an underdrive pulley? Ive heard of this before. And what are the benefits?

 

[99Yuk]

What is an underdrive pulley? Ive heard of this before. And what are the benefits?

Smaller/Underdrive Main Crank Pulley.
Bigger/Overdrive ALT Pulley to keep ALT at stock RPM.

Came as a kit from Summit.
Allegedly bolts on 15+HP for not much $$$. IDK, but I like it!
I think it would compliment your existing mods nicely.
Now if only I/we could get the E-waterpump mod to work in a Vortec......

EDIT: Kit didn't come with new belt.
EDIT 2: As mentioned elsewhere, the kit does slow down the OEM water pump, but I have experienced no ill effects as of yet.

 

[ezdaar]

make this simple. have friend hold tensioner while you run a string inplace of the belt. then measure the lenght of string it took to make the full pattern around pullys..
This will get you +/- 1/8" inch or so, depending how tight you pulled the string.

Better yet call summit and ask them..

 

[stuntmanray385]

Smaller/Underdrive Main Crank Pulley.
Bigger/Overdrive ALT Pulley to keep ALT at stock RPM.

Came as a kit from Summit.
Allegedly bolts on 15+HP for not much $$$. IDK, but I like it!
I think it would compliment your existing mods nicely.
Now if only I/we could get the E-waterpump mod to work in a Vortec......

EDIT: Kit didn't come with new belt.
EDIT 2: As mentioned elsewhere, the kit does slow down the OEM water pump, but I have experienced no ill effects as of yet.

so the crank pulley is smaller? will that still have a positive affect on my engine even though its a stroker? sounds great tho. whats the part number for the belt you used? my buddy had a electric waer pump on his vortec but it was customized. have you noticed the difference when u added the puilly?

---------- Post added at 08:37 AM ---------- Previous post was at 07:29 AM ----------

is this the part? it says v6

http://www.summitracing.com/parts/ASP-541001/

 

[99Yuk]

so the crank pulley is smaller? will that still have a positive affect on my engine even though its a stroker? sounds great tho. whats the part number for the belt you used? my buddy had a electric waer pump on his vortec but it was customized. have you noticed the difference when u added the puilly?

---------- Post added at 08:37 AM ---------- Previous post was at 07:29 AM ----------

is this the part? it says v6

http://www.summitracing.com/parts/ASP-541001/

Yes, the crank pulley is smaller.
Yes, it will work with your stroker.
Part Number of belt is GatorBack 144738. See THIS thread.
I'd like to know more about buddie's custom e-waterpump.
I did three upgrades at the same time so it's hard to say which mod did what for me. All I know is that I like it! BBTune, Efans and UD pulleys. Read THIS thread.
No, that's not for your 96. I Think that's for a TBI. You need THIS kit from Summit for your Vortec.

It's a relatively cheap mod and it works!


EDIT: Wait the application years on Summit's webpage I think are wrong. I know theres a kit for TBI and a kit for Vortec. Vortecs started in 96 and TBI's ended in 95. Summits years are off by one year I think. IDK, you should verify with Auto Specialties before ordering though. Maybe someone here can shed some Sunlit?

 

[SunlitComet]

Maybe someone here can shed some Sunlit?

I could get use that.

---------- Post added at 04:30 PM ---------- Previous post was at 04:24 PM ----------

According to manufacturer the 541084 is for 97-99 and below is as listed:

88-96 4.3, 305, 350, 25% Crank, 23% Alternator, full charge 950 RPM ASP541001
nitride $89.95
ASP841001
hard coat black $94.95

---------- Post added at 04:34 PM ---------- Previous post was at 04:30 PM ----------

is this the part? it says v6

http://www.summitracing.com/parts/ASP-541001/

And it actually say 350 5.7l V8

Perhaps you were looking a number of grooves.

---------- Post added at 04:36 PM ---------- Previous post was at 04:34 PM ----------

As far as belts for the '96 application:

Auto Specialties recommends these pulleys be installed by a qualified mechanic.​

​

1. Remove existing belt and pulleys. If underdrive alternator is used, remove spacer ring from behind factory pulley.​

2. Install new pulley/pulleys. Use Loctite Thread Loc #242, or equivalent, to secure bolts.​

3. Install Gates (or equivalent) belt as follows (with a/c):
541000, 841000
88-95 K060910 (optl. K060915)
88-89 w/smog pump K060990
90-95 w/smog pump K060945
96-01 K060930
​

541001, 841001
88-95 K060915
88-89 w/smog pump K060990
90-95 w/smog pump K060955
96 K060935
​

4. Insure adjustments marks on tensioner are within the limit marks.​

5. Check for proper belt alignment and that the new pulley(s) installed do not wobble.​