Reply to "spark timing"

The 351c likes the high initial advance. 16. You can run that with a Mallory without the vacuum advance.

The vacuum advance is for part throttle economy.

With todays pump fuels even all in by 2800 might make the engine ping? Maybe yes. Maybe no.

The engine itself will really come alive all in by something like 22 or 2300 but no way you can run it. It will detonate pretty badly.

Just for comparison if you were racing you would want a faster curve all in by 2,000 to 2,200 rpm.

Right there is why you would need 106 racing gas.

The Cleveland really shows it's potential under those conditions but on the street you need to compromise for pump gas.

Even the ported vacuum set up can give too much part throttle advance.

You have to experiment with it and with the gas you are going to regularly use.

I like the high initial and the 13L set up with the stiff advance springs. It works best for me. Seems a little contradictory I know, but does exhibit any issues at WOT even with that much total advance. I'm sure it has to do with my specific combination which is not typical at all of an iron Cleveland.

I do have the vinyl sleeve on the advance arm. That does take out a couple of degrees of total advance right there.

I'm running my 302 based 347 there also. Virtually the identical set up. No issues so far. Well almost identical. About 12 degrees initial on that one. Otherwise it idles too high.



I don't have any port vacuum to tap into with IDA carbs. Even getting manifold vacuum with them is a big deal and does have issues.

You are creating a small vacuum leak in order to get it on all 8 cylinders and the engine can be touchy on whether it likes, dislikes or tolerates that.

Race setups with IR manifolds are not going to be set up for intake manifold monitoring. They are run mostly a WOT anyway. The vacuum gauge at idle would just be used for diagnostic reasons of the engines state of health.