ZCar Forum banner
Status
Not open for further replies.
1 - 2 of 2 Posts

·
Registered
Joined
·
107,695 Posts
Discussion Starter · #1 ·
Hi all, my '73 is finally back on the road after a head transplant and it's running very well. My question is that my tach & speedo don't SEEM accurate. Although the car rev's fine, it sounds like it is about as far as I should prudently rev it at about 5000 RPM. There's a lot of space on the tach between 5000 and 6500 RPM, but it sounds like the engines really revved up at about 5000. Is it me or could the tach be out of wack? The speedo too seems to be inaccurate. It seems to read about 10MPH high (it feels like 40mph when the speedo says 50MPH). I know tire size etc. affects the speedo, but I never thought it would be very much and i couldn't tell any difference on previous cars. Am I way off base or could these gauges be wrong, and how do I check them???
Thanks, Bill
 

·
Registered
Joined
·
107,695 Posts
Discussion Starter · #2 ·
> Hi all, my '73 is finally back on the road
> after a head transplant and it's running
> very well. My question is that my tach &
> speedo don't SEEM accurate. Although the car
> rev's fine, it sounds like it is about as
> far as I should prudently rev it at about
> 5000 RPM. There's a lot of space on the tach
> between 5000 and 6500 RPM, but it sounds
> like the engines really revved up at about
> 5000. Is it me or could the tach be out of
> wack? The speedo too seems to be inaccurate.
> It seems to read about 10MPH high (it feels
> like 40mph when the speedo says 50MPH). I
> know tire size etc. affects the speedo, but
> I never thought it would be very much and i
> couldn't tell any difference on previous
> cars. Am I way off base or could these
> gauges be wrong, and how do I check them???
> Thanks, Bill

Your right tires shouldn't affect the speedo that much unless you get a much larger tire, so your speedometer shouldn't have been affected unless you changed the rear end. A real easy way to check it is to find a stretch of highway with mile markers and check your odometer with the mile markers. If your odometer counts the exact same amount of miles as you count markers your speedo should be correct since the speed is just the derivitive of the distance traveled. Or you can always time it and do the math. A less recomended method is to speed past a cop and when he pulls you over ask him how fast you were going. :) As for the tach, I know I've seen hand held tachs that have an induction pick up off the spark plug wires.
Jared
 
1 - 2 of 2 Posts
Status
Not open for further replies.
Top