I have a 1969 Chevelle that, ever since I switched from the 396 to a new GM Crate 502, has required the driver to correct the steering wheel up to 1/4 turn under hard acceleration.

Rear end bushings are all new, lower control arms are Hotchkis, same with rear sway bar. I've had it on the hoist many times and do not see any stress lines, cracks, or lines in the frame at any points. Nothing is up against steering components or would torque into them. I've had the car looked at and driven by the best alignment shop in the area and the owner of the shop, in business for 25+ years, could not figure it out.

Any ideas? Thanks in advance

Some stuff I'd be looking at if it was me:

1. Rotted FRONT control arm bushings. Acceleration forces cause the control arm to move; screws up the camber and toe causing steering forces.

2. Worn ball joints; (including tie rod ends, idler arm, and drag link/center link) Acceleration forces cause uneven toe, creating steering force.

3. Wiped body bushings allowing massive frame flex under load.

4. Faulty front end alignment; including too much toe, and/or camber angles when combined with frame flex. One front wheel is carrying more weight than the other wheel when accelerating; and that wheel is toed or cambered to produce a steering force opposite of the steering wheel direction.

You have an open dif or a loose posi?I think drag racers run a spool to help stay straight among other reasons.

Did the alignment shop check the thrust angle of the rear axle?

Don't forget to check for equal tire circumfrence also. Had it happen to a customer when I ran alignment shop..Posi trac diff. She had bought some used tires for rear, and they were different sizes.

different tire size and different tire pressure will cause those symptoms.