Whatever the case I'm thinking that shimming the back part of the third arm mount, with a few washers, away from the frame cradle (then reset toe in) would solve the problem.

 

what is the part number on the side of the arm
Drivers side
on the crossmember

 

somethings wrong there........

 

With that thought in mind, THERE IS A DIFFERENCE between early and later steering arm BRACKETS, shown below.
BUUUUUUUUUT, I do not know exactly when the change took place (that is, between which year models).
Here is an early and later bracket (next 2 pictures). Notice the difference in the REAR portion of the bracket where it bolts to the rear of the cross member. The bracket with the thicker rear area would lower the steering arm. Again, I cannot say for sure when the change occurred, but possibly it occurred later in the 56 model year when the tapered shims were added between the cross member and frame rails.







The next 2 show the casting numbers of the 2 different brackets.







I forget what year model car I removed this bracket from, BUT, it had these 2 thick washers (shims) installed. I'm presuming this was an interim modification between the early and later brackets

 

Not sure I'd stack washers since it's such a critical component,
A pair of good fitting bushings should be ok.
if you do stack, check it, check it, check it, after you drive it.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~


Couple things I can think of for you are:
----------------------------------------------------
Incorrect 3rd arm bracket.
(2 different ones for 53-62 but I don't have measurements}
(All the 3rd arms are the same size for 1953-62)
--------------------------------------------------------
Pulley application.
(lots of stuff can be changed in 60 years)
--------------------------------------------------------
Water pump length
-------------------------------------------------------

This thread interested me because I have a very early 1958 #00026 that I bought like it is.
Engine is a 1967 327 with the original large 8" balancer.

When my car was on jackstands (under the frame not a-arms) I turned the steering wheel all the way and the dampner (not the pulley) barely touched the 3rd arm,. I've never noticed it hitting when the car is running and sitting on the ground but it's paper thin close. I thought the problem was it had the larger, later model balancer and forgot about it. Now I think it's a combination of an early 3rd arm support with a larger than stock balancer..

My crank pulley is original to the car but chromed.
(It's very flat against the balancer)
Yours is stepped out more than mine but is maybe correct for your car.
(see pulleys below)

Do you have a short water pump or long one?
A short one, the back will be almost touching the timing chain cover.
Long one has about 1/2" gap from back of pump to t/c cover.



Some photos / description from CorvetteCentral.com

Catalog says:"1953-56 3rd arm bracket"
(not part of CC description but is it for up to early1958? since the crank pulley changes for late 58?)
(original cast #3727511)






1958 Late to 1962 3rd arm bracket
(original cast #3742688)


1958 Late to 1962 crank pulley
(looks like the one on your car?)




1957-58 Early crank pulley (57 283 HP - 58 Early) #991
(Looks like the one on my car, flatter than one shown above)









See how close my lower pulley is to the balancer
(8" balancer and 6" pulley


See how close my lower pulley is to the balancer
(8" balancer and 6" pulley

 

Why don't you go measure them.
1" is thinner than they should be. Mine measure about that, but I compressed mine more than desired for hood clearance by cutting teh sleeves and making solid aluminum lower pucks.
There is supposed to be a metal sleeve over the bolt to keep them from being over compressed. If the sleeve is missing, someone could crank the snot out of the bolt and over compress them.

That all said, i still have what looks like about 1" clearance between the third arm and my 8" diameter balancer. It is possible someone shimmed the front of the third arm support down, (making it tilt up towards the rear) to align the front fiberglass from a bad repair job?? IIRC, the radiator support mounts to the third arm support, and shimming the rad support is how you get the correct front body height.
Doug

 

I just took my shroud and fan out for powder coating, and rad hose replacement, so i did some measuring.

There is right at 1.5" clearance between my 8" balancer and the third arm.

The bottoms of the motor mount cross plate are about 5" above the frame rails, at the mount towers. In case someone shortened your mount towers to put a big block in at one time.

Doug