Straight Axle,
Well the good news is, you have a lot of work to do for free first (or maybe confirm that slow 52-53mph at another dragstrip?)

I built a Gonkulator file of your car, assuming 2980lb with you in it (have you weighed it?). I used "my" 250 engine, stock 250, offy/390, stock exhaust/muffler. Crappy traction and slow shifting Gonkulated to
Torq 219 at 3000
Powr 169 at 4300
3.14 60ft
12.41 at 60.0 1/8 mi
18.74 at 78.8 1/4 mi

To slow the car DOWN to that 52-53mph you got, I had to really cut the power back, down about 30% across the board, like pulling 2 plug wires (are you sure it isn't a 4-cyl in there?)
Torq 151 at 3000
Powr 117 at 4300
3.14
12.89 at 54.4 (about 3000 in 3rd)
20.03 at 69.1 (about 3800 in 3rd)

Never minding the times or traction, for a car to be down 6mph in the 1/8 mile is HUGE. Something is way off or very unhappy, wont matter what exhaust valve size is in there.

Good news is, you can hunt this kind of thing down and fix it nearly for free I would guess. I would check the timing curve and compression first, make sure its hitting all 6 cylinders, is there a potato or rat or bird stuck in the exhaust pipe, etc. Something major to cut it down that slow.

Check out the carb, what's in there, is it way too lean or way too rich, is the secondary opening at all, etc. Pull the head, calc your compression - are you sure its a 250 and not a 194? It's something MAJOR wrong to be way down at 53mph. I would just lap the valves, make sure they seal, leave the head stock for now til you sort it out rather than throw money at it when something else major is going on there. Are the brakes stuck on? etc!


EDIT,
Here is another real world example.
Car Life Feb.1962 tested a 194cid 62 Nova, 3spd 3.08 gears, 2 aboard.
They got
19.00 at 70mph
0-60mph 13.0
(No 60ft or 1/8 mile back then, the Beach Boys 409/409 song didn't even exist yet!)

Gonkulator gets
2.72
12.06 at 58.0
18.91 at 71.0
0-60mph 12.8
So this is a bone stock 194-1bbl turning 58mph in the 1/8 mile. For yours to turn 53mph, again something major is wrong, or the clocks at that dragstrip are really messed up. Should be fun to resolve it!

Last edited by DeuceCoupe; 03/23/15 02:07 PM.