I was working on another forum to fix an issue that I thought was timing (backfiring through carb and exhaust, had spark plugs with small/no gap).

Someone said that because my HEI doesn’t have a vacuum advance it won’t have mechanical advance either because it’s for computer control. I’m doubting it but wanted to double check here.

 

That looks like a pre-computer HEI and should have both vacuum and mechanical advance. Pull the cap and rotor to check and clean and lube the weights, pivots and springs.

 

As far as Oldsmobile distributors are concerned, the FACTORY HEIs without vacuum advance do not have mechanical advance either. All ignition timing advance is controlled by the computer. These computer-controlled distributors have an additional four wire connector that plugs into the CCC harness on the 1981-90 cars. It is also possible that someone removed the vacuum advance on a non-computer HEI and simply used a lock-out plate. This is sometimes done for engines with radical cams that don't generate enough vacuum to reliably operate a vacuum advance cam. The only way to know for sure is to remove the cap and rotor and see if there are advance weights under the rotor or not. Also, the computer-controlled HEI uses a seven pin ignition module, the regular HEI uses a four pin module. Chevy also used some five pin modules, but I have not seen an Olds distributor configured that way.

 

I had the cap open to look a few minutes ago. Looks like there is a spot for the vacuum advance. The rest looks screwy to me though, so I took a short video.

https://imgur.com/a/rgkidfD

 

On a side note, it looks like that cap and wires are quite old and probably need to be replaced.

 

Yeah, that distributor has been mucked with . No telling what the P.O. did to it.