For those who have a good knowledge of what those spacers go through, would aluminum be an acceptable material, or should I just head straight for mild steel? I've got access to a mill/drill, a lathe, and a pile of stock, and I personally think the prices on spacers are outrageous

Also, how thick? 1/2", 5/8", and 3/4" are my options. Consider it a stock motor, none of the mods are even worth mentioning in this matter. Would airflow mods change the reccomended spacer thickness? (consider this a multi-level question.. stock motor vs. open element/cat/catback vs. cam/heads/headers (the more extreme being for educational purposes only, since they would also involve a carb intake manifold with an adapter plate, thus meaning a non-fabricated spacer anyway... unless I get really bored))

 

im going to be installing a 1/2 inch spacer in a few weeks, that is the biggest i will go because of clearance issues (14x3 flat based open element) and if you go any bigger, you are going to have problems with linkage. Do a search, there are hundreds of posts about this same topic.

 

1/2 inch, no more then that.