HEI distributor tuning problem

[JOJABOY]

Originally Posted by WadmalawJoe

I don't have a vacuum pump either. They can't be to much, I will look into getting one, but I think I can get some readings anyway with out it, just by unplugging the advance vs plugged in advance.

It's not exactly the same. When you rev your engine in park, the engine isn't under any load. So the vacuum is different. Short of hiding under your hood with a timing light while your wife takes the truck for a drive.....You can get a cheap $5 vacuum pump and pull the vac advance can in. This will simulate the intake creating different vacuum till all in.

Sure beats hanging on to the headers while straddling the fan and wife at the wheel.