W2 408 Dyno results today !
... It took 3 trips to the parts store to get 8 good spark plugs that all tested correctly...
20 years ago when I worked in parts stores, I would never have believed that statement. With my experience buying over-the-counter autoparts the past 10 years, I'm more surprised it didn't take 5 trips!
It's almost as if the OEMs for the mfgs no longer make the parts for 'everything else' these days, and it shows.
You cant beat a gas bench for understanding what is really going on but an ignition scope will tell you plenty also.
I bought another hotrod recently. It ran great (I thought), but was nearly impossible to start. It would only fire quickly with the battery freshly topped up, or with a jump from a running vehicle. Chased down voltage drops (meter on dash showed under 10 during crank, even with a brand new optima), wiring junctions, even tightened the gap at the reluctor which seemed to help. Finally decided to swap the distributor since the one that came on the engine is no longer supported (thanks Holley). When I went to swap it, I found the distributor ground was on a loose bolt, not even clamping the wire in-place. I felt stupid.. With the bolt tight, it fires right off. Then the coil died during my test-drive. Turns out it was not rated properly for the ignition module.
Long way of saying: the right testing tools absolutely help! Had I simply hooked up my timing light and cranked it, I would have found the no-spark issue. It's no scope, but it's a tool I have which can help figure out wth is going on. With it all fixed, car runs amazing and I've not flattened the battery again since then. Turns out the voltage drop during cranking is only in the dash wiring up to the meter - real battery volts are fine.
Now that makes me think maybe
@mbaird might clamp a timing light to #7 and see if he gets regular pulsing or if it drops out at some point. Easy enough to duct tape it to the hood during a test drive to see what happens under load ;) (only half-kidding). If not, it may just be 'how it is' with that particular motor.
