Finally.....The Correct Size Alternator Pulley

[Dynomite]

The Correct Size Alternator Pulley is about 2.75 inch OD on the face....This ALL Aluminum Pulley is very light and just a tad larger yet very close to 2.75 inches diameter. It is a little Pricey from Summit Racing. The Installation is very easy with my 15/16 inch modified Open End Wrench and 5/16 Allen Wrench.

The Stock Alternator Pulley is the Black Pulley on TOP and the Black Pulley to the Left (in right photo).
The MCH-208 is the same Diameter as the Stock Pulley.........The MCH-208 has identical Offset as the Stock Pulley.
Actually the MCH-208 is just a tad larger diameter................The Stock Pulley uses a separate thick offset washer.

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/992f36c2-d357-4f2c-9918-b3ac31b4ab6b.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/e46c590e-d00e-4741-a26c-7e801ba3feb6.jpg

This Pulley can be installed without removing anything including the Serpentine Belt (except the Original Alternator Pulley).
Look for MCH 208 on Summit Racing MCH-208 (https://www.summitracing.com/parts/mch-208) or Ebay MCH-208 (http://www.ebay.com/itm/March-Performance-Billet-Aluminum-Serpentine-Alternator-Pulley-208-/191407701716?hash=item2c90c9bed4:g:QJgAAOSwPYZVAEt M&vxp=mtr)

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/ff38332f-db3b-470c-badc-a0a14de41c4b.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/226cd3ef-e2bf-4c9c-8cb4-a195b58bac99.jpg

Oh.....by the way.....I just invented a New Way to install the Serpentine Belt......Remove the Alternator Pulley (takes 1 minute) and position NEW Alternator Pulley inside Serpentine Belt and lift up the Alternator Pulley and Serpentine Belt with Belt Tensioner compressed (Keep Serpentine Belt aligned with Belt Tensioner Pulley). Now just slip the Alternator Pulley onto the shaft (very easy to do and plenty of play) and tighten up the 15/16 inch Alternator Pulley Nut. :D

Lastly......install the Aluminum Alternator Pulley Cap with the three Allen Head Bolts provided with just a little torque as they are threaded into Aluminum.

If you look closely, you will notice also my ALL Aluminum Belt Tensioner Pulley.

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/d8a219b2-f604-4653-9c28-360157f1027b.jpg

See All Aluminum Alternator Pulley (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-13.html#post1592505495)

[secondchance]

How about that! I had to have the back machined for correct offset. Seems you found one with correct offset. Congrats!
http://i658.photobucket.com/albums/uu303/byongyun/Mobile%20Uploads/image_zps539zluqp.jpeg (http://s658.photobucket.com/user/byongyun/media/Mobile%20Uploads/image_zps539zluqp.jpeg.html)

[Dynomite]

Great Minds Think Alike :handshak:

Yes......just checked the offset of the MCH-208 and appears perfect.
It sure ran nice and smooth ;)

How about that! I had to have the back machined for correct offset. Seems you found one with correct offset. Congrats!
http://i658.photobucket.com/albums/uu303/byongyun/Mobile%20Uploads/image_zps539zluqp.jpeg (http://s658.photobucket.com/user/byongyun/media/Mobile%20Uploads/image_zps539zluqp.jpeg.html)

[Roadster]

Received my spare 200A alternator yesterday. Pulley may be a tad small with my unscientific measurements...lol I am guessing it is between 60-62mm. If and when it needs replacement, can always swap out the original pulley if needed.

http://i127.photobucket.com/albums/p138/SSROADSTER/94%20ZR-1/20161018_224233.jpg (http://s127.photobucket.com/user/SSROADSTER/media/94%20ZR-1/20161018_224233.jpg.html)
http://i127.photobucket.com/albums/p138/SSROADSTER/94%20ZR-1/20161018_224616.jpg (http://s127.photobucket.com/user/SSROADSTER/media/94%20ZR-1/20161018_224616.jpg.html)

[Dynomite]

Actually you can run an under drive or over drive pulley with the right length serpentine belt. But I am finding 2.75 inch (as you measure on the face of the pulley) is correct diameter and 2-7/8 even a tad better as it opens the tensioner just a tad more. I have some more of the MCH-208 on the way and will provide more photos in original post using my modified 15/16 inch Box Wrench and 5/16 inch Allen Wrench shortly.

Your pulley looks more like 2-3/8 inch diameter on the face of the pulley.

Received my spare 200A alternator yesterday. Pulley may be a tad small with my unscientific measurements...lol I am guessing it is between 60-62mm. If and when it needs replacement, can always swap out the original pulley if needed.

http://i127.photobucket.com/albums/p138/SSROADSTER/94%20ZR-1/20161018_224233.jpg (http://s127.photobucket.com/user/SSROADSTER/media/94%20ZR-1/20161018_224233.jpg.html)
http://i127.photobucket.com/albums/p138/SSROADSTER/94%20ZR-1/20161018_224616.jpg (http://s127.photobucket.com/user/SSROADSTER/media/94%20ZR-1/20161018_224616.jpg.html)

[Roadster]

Actually you can run an under drive or over drive pulley with the right length serpentine belt. But I am finding 2.75 inch (as you measure on the face of the pulley) is correct length and 2-7/8 even a tad better as it opens the tensioner just a tad more.

Thanks for the pulley tip Cliff. I also do have a spare serpentine belt. But hopefully won't have to worry about that soon, as one of the PO's had that replaced back in 2010 along with getting the belt tensioner rebuilt at that time. And its only been 12,000 miles or so that have been accumulated since then. I was lucky to get about 10 pages of service records from the Chevy dealer that did all of the work on the Z.
But you never know, always better to be prepared to an extent, rather than not!!!

[Dynomite]

Thanks for the pulley tip Cliff. I also do have a spare serpentine belt. But hopefully won't have to worry about that soon, as one of the PO's had that replaced back in 2010 along with getting the belt tensioner rebuilt at that time. And its only been 12,000 miles or so that have been accumulated since then. I was lucky to get about 10 pages of service records from the Chevy dealer that did all of the work on the Z.
But you never know, always better to be prepared to an extent, rather than not!!!

Unless you want to be "cool" with a MCH-208 Pulley.....the secret of changing Alternators is to switch pulleys from existing Alternator to New Alternator when installing Alternator. That way you are sure the EXISTING Serpentine Belt will fit with proper Belt Tensioner Operation.

A Very Easy Job changing these Alternator Pulleys after installation of Alternator using my modified 15/16 inch Box Wrench and 5/16 inch Allen Wrench. You can change these Pulleys AFTER Installation of the Serpentine Belt. Matter of fact........Install the Serpentine Belt as you change Pulleys placing the new alternator pulley inside the Serpentine Belt that has been installed on all the other pulleys. With the Serpentine Belt Tensioner Compressed, lift that New Alternator Pulley inside the Serpentine Belt up on to the Alternator Input Shaft and install the Alternator Pulley Washer and Nut. Tighten the Alternator Pulley Nut and you are DONE.....Release the Serpentine Belt Tensioner.

[Roadster]

Unless you want to be "cool" with a MCH-208 Pulley.....the secret of changing Alternators is to switch pulleys from existing Alternator to New Alternator when installing Alternator. That way you are sure the EXISTING Serpentine Belt will fit with proper Belt Tensioner Operation.

A Very Easy Job changing these Alternator Pulleys after installation of Alternator using my modified 15/16 inch Box Wrench and 5/16 inch Allen Wrench. You can change these Pulleys AFTER Installation of the Serpentine Belt. Matter of fact........Install the Serpentine Belt as you change Pulleys placing the new alternator pulley inside the Serpentine Belt that has been installed on all the other pulleys. With the Serpentine Belt Tensioner Compressed, lift that New Alternator Pulley inside the Serpentine Belt up on to the Alternator Input Shaft and install the Alternator Pulley Washer and Nut. Tighten the Alternator Pulley Nut and you are DONE.....Release the Serpentine Belt Tensioner.

Think I'll stay "uncool" on this one, easier to change out the pulley when need it.....How did you modify your 15/16" box wrench? You may have already posted, and I may have missed it......

[Dynomite]

Think I'll stay "uncool" on this one, easier to change out the pulley when need it.....How did you modify your 15/16" box wrench? You may have already posted, and I may have missed it......

On the Box end I took a torch and bent a 90 deg (at the box) and within an inch another 90 deg back.

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/ff38332f-db3b-470c-badc-a0a14de41c4b.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/226cd3ef-e2bf-4c9c-8cb4-a195b58bac99.jpg

[WVZR-1]

These very early Blue-Point offsets I'd think would do quite well for the chore.

http://alloy-artifacts.org/snapon-bluepoint-tools-p4.html

[Roadster]

On the Box end I took a torch and bent a 90 deg (at the box) and within an inch another 90 deg back.

Thanks, I have some extra 15/16" wrenches, I think I can do that!!!

These very early Blue-Point offsets I'd think would do quite well for the chore.

http://alloy-artifacts.org/snapon-bluepoint-tools-p4.html

Looked up some on ebay, seemed expensive......at least the ones I saw!!!

[Dynomite]

Thanks, I have some extra 15/16" wrenches, I think I can do that!!!


I use a acetylene torch and make that first bend as close to the box as you can.....as you like....hit the outer edge of that bend with a grinder when done bending. I actually bought the 15/16 inch box wrench new for around $5-$6.

Keep the Bend RED HOT and Bend Slowly with just a little pressure (do not force it). It will bend itself :D

After modifying the 15/16 inch combination box wrench it is still very usable as a normal combination Box Wrench.

I also have 8mm combination Box Wrenchs I did a little modifying on to reach those 8mm bolts on front of oil pan without raising engine.

The normal Offset Box Wrench does not have a steep (Right angle) offset as you can achieve with an acetylene torch.

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/ff38332f-db3b-470c-badc-a0a14de41c4b.jpg

Two more MCH-208 Alternator Pulleys will be installed tomorrow for more photos ;)

Just make sure the 5/16 inch Allen is FULLY installed in the center Alternator Shaft before you start cranking on the 15/16 inch Open End combination Modified Wrench (with cheater box wrench on end). It DOES take a lot of torque to loosen that 15/16 inch Nut holding the Alternator Pulley.

[Roadster]

I use a acetylene torch and make that first bend as close to the box as you can.....as you like....hit the outer edge of that bend with a grinder when done bending. I actually bought the 15/16 inch box wrench new for around $5-$6.

Keep the Bend RED HOT and Bend Slowly with just a little pressure (do not force it). It will bend itself :D

After modifying the 15/16 inch combination box wrench it is still very usable as a normal combination Box Wrench.

I also have 8mm combination Box Wrenchs I did a little modifying on to reach those 8mm bolts on front of oil pan without raising engine.

The normal Offset Box Wrench does not have a steep (Right angle) offset as you can achieve with an acetylene torch.

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/ff38332f-db3b-470c-badc-a0a14de41c4b.jpg

Two more MCH-208 Alternator Pulleys will be installed tomorrow for more photos ;)

Just make sure the 5/16 inch Allen is FULLY installed in the center Alternator Shaft before you start cranking on the 15/16 inch Open End combination Modified Wrench (with cheater box wrench on end). It DOES take a lot of torque to loosen that 15/16 inch Nut holding the Alternator Pulley.

Appreciate the tips.....will have to wait til I get out to the 74, as that is where the torch is, and my buddy has more experience using it than I do.....

[Dynomite]

How about that! I had to have the back machined for correct offset. Seems you found one with correct offset. Congrats!
http://i658.photobucket.com/albums/uu303/byongyun/Mobile%20Uploads/image_zps539zluqp.jpeg (http://s658.photobucket.com/user/byongyun/media/Mobile%20Uploads/image_zps539zluqp.jpeg.html)

This Pulley can be installed without removing anything including the Serpentine Belt (except the Original Alternator Pulley).
Look for MCH 208 on Summit Racing MCH-208 (https://www.summitracing.com/parts/mch-208) or Ebay MCH-208 (http://www.ebay.com/itm/March-Performance-Billet-Aluminum-Serpentine-Alternator-Pulley-208-/191407701716?hash=item2c90c9bed4:g:QJgAAOSwPYZVAEt M&vxp=mtr)


The MCH-208 is the same Diameter as the Stock Pulley. Actually the MCH-208 is just a tad larger diameter.
Use a 1/2 inch Adapter on Socket Wrench to Unload the Belt Tensioner when removing/installing Pulleys.
http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/992f36c2-d357-4f2c-9918-b3ac31b4ab6b.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/67a37c9c-32a1-4b77-94b5-713abc386e8b.jpg

The Offset of the MCH-208 is identical to the Stock Pulley.
The Stock Pulley has a removable Offset Collar.
http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/e46c590e-d00e-4741-a26c-7e801ba3feb6.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/36a4d85d-9179-4855-b52d-0d4b50df52c5.jpg

See All Aluminum Alternator Pulley (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-13.html#post1592505495)

[Roadster]

I just might have to order that MCH-208 pulley after all and have it all ready for the replacement unit whenever it may be needed......:thumbsup:

[Dynomite]

I just might have to order that MCH-208 pulley after all and have it all ready for the replacement unit whenever it may be needed......:thumbsup:

Do NOT install the Pulley onto the Alternator on the Bench tightly as you want to make the final installation of that Alternator Pulley once the Alternator is Installed on the ZR-1.

This Pulley can be installed without removing anything including the Serpentine Belt (except the Original Alternator Pulley).
Remove the Alternator Pulley (takes 1 minute) and position NEW Alternator Pulley inside Serpentine Belt and lift up the Alternator Pulley and Serpentine Belt with Belt Tensioner compressed (Keep Serpentine Belt aligned with Belt Tensioner Pulley). Now just slip the Alternator Pulley onto the shaft (very easy to do and plenty of play) and tighten up the 15/16 inch Alternator Pulley Nut. :D

Lastly......install the Aluminum Alternator Pulley Cap with the three Allen Head Bolts provided with just a little torque as they are threaded into Aluminum.

The MCH-208 is the same Diameter as the Stock Pulley. Actually the MCH-208 is just a tad larger diameter.
Use a 1/2 inch Adapter on Socket Wrench to Unload the Belt Tensioner when removing/installing Pulleys.
http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/992f36c2-d357-4f2c-9918-b3ac31b4ab6b.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/67a37c9c-32a1-4b77-94b5-713abc386e8b.jpg

The Offset of the MCH-208 is identical to the Stock Pulley.
The Stock Pulley has a removable Offset Collar which is NOT used in the installation of the Aluminum Pulley.
http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/e46c590e-d00e-4741-a26c-7e801ba3feb6.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/36a4d85d-9179-4855-b52d-0d4b50df52c5.jpg

See All Aluminum Alternator Pulley (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-13.html#post1592505495)

[secondchance]

The Offset of the MCH-208 is identical to the Stock Pulley.
The Stock Pulley has a removable Offset Collar which is NOT used in the installation of the Aluminum Pulley.
http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/e46c590e-d00e-4741-a26c-7e801ba3feb6.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/36a4d85d-9179-4855-b52d-0d4b50df52c5.jpg

See All Aluminum Alternator Pulley (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-13.html#post1592505495)

This is odd/interesting. What year is the alternator for? For 94 Z OEM pulley does not have the spacer/collar you are showing. I had to have the billet pulley machined to mimic OEM pulley shown with dished back.

[Dynomite]

This is odd/interesting. What year is the alternator for? For 94 Z OEM pulley does not have the spacer/collar you are showing. I had to have the billet pulley machined to mimic OEM pulley shown with dished back.

So far I have installed this MCH-208 on 90's.......will check 91 and 95 later and appears will have to adapt as you suggest. I am not sure how the stock pulley is offset on a 95'. I am thinking the 91' is identical to the 90' in regard to the Alternator :p

I am now curious that my 200 amp Alternator on my 95' might actually be 90' compatible in regard to the Alternator Pulley.
If that be the case....I am all set with MCH-208.

The Alternator I exchanged on my 95' I think did not have the separate spacer but did have a boss as part of the Pulley. Did your 94' Alternator Pulley have a boss as part of the Pulley? Is the Alternator cooling fan recessed just a bit where the separate spacer would sit?

[GOLDCYLON]

So far I have installed this MCH-208 on 90s.......will check 91 and 95 later and appears will have to adapt as you suggest. I am not sure how the stock pulley is offset on a 95. I am thinking the 91' is identical to the 90' in regard to the Alternator :p

I am now curious that my 200 amp Alternator on my 95' might actually be 90' compatible in regard to the Alternator Pulley.
If that be the case....I am all set with MCH-208.

I like this mod. with those side on side piece Pics I now see how it all fits together. Please let us know what you find out on the different alts. GC

[Dynomite]

I like this mod. with those side on side piece Pics I now see how it all fits together. Please let us know what you find out on the different alts. GC

I just checked a rebuilt 124 amp alternator I got from O'Rielly Auto and it is identical to the 90's I just installed MCH-208 on. I think I gave them my 95' alternator in exchange. Anyway.....O'Reilly lists the same alternator for 90' and 95' ZR-1s. But I will check the 200 amp Alternator Pulleys I have on the 91' and 95' ZR-1s for which I am installing MCH-208s.

I am now thinking All ZR-1 Alternator Fans have a small recessed (about 2 inches in diameter) around the shaft for which either a separate spacer or pulley with boss will function the same. The Boss is about half as thick as the separate spacer since the separate spacer fits into a recessed stock pulley. You can see the Boss and the Separate Spacer set the Pulley (Stock with recess and spacer or MCH-208 with Boss) the same distance from the fan recess around the shaft.
http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/e46c590e-d00e-4741-a26c-7e801ba3feb6.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/36a4d85d-9179-4855-b52d-0d4b50df52c5.jpg

In both cases the inside flange of the Alternator Pulley almost touches the fan surface at the outer diameter of the Alternator Pulley.

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/fb4c9868-d37d-4f6b-acff-d7a120547e7f.jpg
http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite19/d8a219b2-f604-4653-9c28-360157f1027b.jpg

[secondchance]

Maybe spacer was stuck to the alternator fan and I assumed the pulley offset was wrong. Either way, it's working. So...