Hi guys. I'm not used to posting in the tech. section since the car I usually ask about doesn't run. The new (to me) 1980 we just bought does run..pretty well at that. I have a couple of questions about the gauges. The speedometer moves, but is not even close to showing actual speed, and it seems to top out at about 45 MPH, and the tachometer also moves, but not in relation to the actual engine RPM. It shows up to 6500 RPM when I'm just cruising. What do you suggest I look into first? I was thinking of getting a new circuit board, but don't know if this is actually what's wrong. I could use some input.
Also, the oil pressure gauge doesn't work at all. It seems the needle is pegged all the way to the right, but under the actual peg. I'm guessing I need a new gauge, but wanted to ask your input.
The tires are 275 all the way around. I asked on the general forum, but thought you go-fast types may have your own take on it. The tires are new Goodyear Eagle's, so I'd hate to replace them with 255/60/15's, but I don't want any body damage either. What do you think about this one?
One more thing I could use some help with: the air cleaner wingnut is hitting the bottom of the hood...not hard, but it is making contact. What would the best solution be for this? Here's the aircleaner as I bought it.

Thanks for your help. These are great cars and great people to talk about them with.

 

Get a lower wingnut that won't hit the hood, that one is not stock

Oil pressure gauge could be bad sending unit, dead short in wire, or bad gauge. Really need to trace the wire and eliminate it as an issue. You could see if the resistance at thye sending unit changes between off and engine running. If those don't fix it, then get the gauge rebuilt.

As far as speedo, You may have the wrong driven gear in the transmission. I would get and install a new driven speedo gear based on your tires and rear end ratio.