Some of those aftermarket distributors have a selection for 4/6/8 cyls.
How would that affect the tach reading the wrong RPM?
But for the tach to be off by double (OP estimate) would would also have to be way off on the speedometer, not just a little. If tach is saying 7k rpm, you would know what a SBC at 7k rpm sounds like versus 3500The op refers to engine speed in relation to a certain road speed to judge that the tach must be reading wrong. If the speedo gear is wrong the speedo could read optimistically or pessimisticlly , potentially making some the data op is using faulty.
Yeah, I'm not arguing, I was just laying out why I think copo asked the question. I think that there needs to be some definitive measuring done with a handheld laser tach or some other means to confirm the engine speed. Seat of the pants isn't a great way to figure this out.But for the tach to be off by double (OP estimate) would would also have to be way off on the speedometer, not just a little. If tach is saying 7k rpm, you would know what a SBC at 7k rpm sounds like versus 3500
You make a fine point about the possibility of a 6 cyl tach. I'm working right now. But when I get the chance I'll take a pic and post it.If it reads 4000 when it should be 3000 RPM (and reads 2000 @ 1500)...
Somebody swapped a 6-cylinder tach into it.
What does the face look like?
I have one that originally came in my 80 (229 V6) and the red line is different from a V8 tach.