Thread: Low alternator mount brackets

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I am hoping someone here can help me to understand what is causing my alternator brackets to not align with the water pump or balancer pulley.

I have an 89 4.3L mounted, and am using the short water pump. I have a single groove pulley for the WP, HBP, and alternator pulley. I ordered a JEGS 555-50542 Low mount alternator bracket, that is designed to mount the full-sized GM alternator like I have.

Everything bolts up exactly as intended, but the alternator pulley is 7/8" behind (towards the engine) the other 2 pulleys.

This would lead me to believe that I have wrong pulleys on my engine and water pump, but actually they came off an old 307 SBC I had around, and it had the short shaft pump on it. I did some comparing of the block mounting surface between the 4.3, and the 307, and they are identical.

Has anyone run into this? Are there different pulleys that sit further back? Looks to me like the balancer pulley is at it's farthest limit now! Are these brackets intended for a double alternator pulley perhaps? I must be missing something, and don't want to shim the brackets out 7/8". Seems it would not be nearly as strong, and I would need to purchase longer bolts. Help please...

Originally Posted by BioTex

I am hoping someone here can help me to understand what is causing my alternator brackets to not align with the water pump or balancer pulley.

I have an 89 4.3L mounted, and am using the short water pump. I have a single groove pulley for the WP, HBP, and alternator pulley. I ordered a JEGS 555-50542 Low mount alternator bracket, that is designed to mount the full-sized GM alternator like I have.

Everything bolts up exactly as intended, but the alternator pulley is 7/8" behind (towards the engine) the other 2 pulleys.

This would lead me to believe that I have wrong pulleys on my engine and water pump, but actually they came off an old 307 SBC I had around, and it had the short shaft pump on it. I did some comparing of the block mounting surface between the 4.3, and the 307, and they are identical.

Has anyone run into this? Are there different pulleys that sit further back? Looks to me like the balancer pulley is at it's farthest limit now! Are these brackets intended for a double alternator pulley perhaps? I must be missing something, and don't want to shim the brackets out 7/8". Seems it would not be nearly as strong, and I would need to purchase longer bolts. Help please...

Sometimes they forget to include the fine print. I've had two sets of $treet and Performance brackets and pulleys on 2 different SB Ford engines. Spacers both times. This last time, it was behind the now surplus a/c bracket. Bolts, even ARP's which I use are cheap in comparison to a failed POS from Lowe's, etc.

I have a set of manifold/header mount brackets, that give perfect pulley alignment for all three pulleys. The trouble is that in order to tighten the belt, the alternator hits the inner fender. I chose the lower mount thinking all would be well...

I looked into installing a double pulley on the alternator, but that gains me only 1/2" and I need 7/8". I would still need to shim it. I already cut down some shims, and will hook the brakets back up to see if it is going to be sturdy enough. I have a feeling the pulleys need to be changed out to deeper ones, but finding them will be the harder part.