altenator pulley ratio to crank

[rod]

try to limit the alt. rpm's to less than 20K. and then only for a very short period of time.
let's say U used a 6" crank pulley and a 3" alt. pulley. that would put the alt. turning 14K with the engine at 7K. the engine would only be at 7K at the top of some gears and for a short period of time.
now if U used a 6" and a 2" the alt would go 21K. way to much.
if you have no choice, then 1. make sure you use an alt. than can be easily [meaning not some special alt. which has to be ordered and takes three weeks to show up] and cheaply replaced or 2. have all the windings epoxy coated to keep it from flying apart.

in my case on my 265 i used a nippo denso alt from a 3 cyl chevy something. i used an old smog pump pulley [5" dia] drilled for the chevy three bolt dampner pattern and the original 2 3/4" alt pulley. that runs the alt at just a tad less than 2 to 1. my 265 hit 7K twice. and again only for a very short time.

be careful of some low mount kits on camaro's. the alt. pulley runs into the steering box. i spent 3 ours reconfiguring a friends. ugh.

rod in AZ