Once in high school I had my mom’s 66 Comet Cyclone up to what I think was about 140.
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NOT BELIEVABLE ,
Just a Mustang with weaker engines and more frontal area...
115 MAYBE
I had a 1970 Cougar with a Cleveland that couldn’t break 120 until I put a 385 series (429/460) distributor in it (351C distributors broke up at 5500 ,, 460 distributors remained stable to 7000).. and yes at high speeds my speedo read high...
My brother had a 1970 Cougar that he souped up because it would “only” run about 110, after he souped it up real good he ran it through a guard rail, as in the guard rail cut it in half between the driver’s seat and passenger seat. He and an Army buddy that was with him both survived by some miracle. My dad asked him later how fast he was going but he didn’t answer that question. He drag raced all through high school- souped up a lot of cars, pickups and even a grain truck. When he souped up the Cougar he hadn’t been back from Vietnam too long but as far as I know it was the last one he souped up.
So how would you interpret it if the needle was a dozen ticks or so past 120? It was a 390 mill!