i'm taking the car in to have it aligned, and have 275/50's on the rear instead of the usual 275/60's that i run. the car sits about 3/4" lower in the back, will this affect the front end alignment? should i put the tires that i usually run on for the alignment?

I'm no expert on alignment but it will effect the caster reading somewhat. I don't think it would make much of a difference though.

In theory, yes. But the change you're talking about is so small as to be negligible.

If toe and camber are zero, ride height would have no effect. An increase in rear height would have the effect of a small decrease in positive caster, or small increase in negative caster.

If camber is slightly negative, increase in rear height would have the effect of increasing toe-in.
(Think of an extreme example of car standing on it's nose.)

Since you'll probably be going for max caster, with toe and camber to some values that you'll specify to the tech, I wouldn't worry about it.

ok, that makes sense. a 1" rise at the rear translates to very little change 10' away. if i get the chance i'll put the other rears on, but won't sweat it.

thanks!

You should align the car with the tires you plan to run AND have the alignment guy set the front end ride height with those tires before doing the alignment. Bring a FSM with you so he does it correctly. It's measured from the bottom of the LBJ and the 'blade' or pivot in the middle of the LCA.

set your weight in barbells on the pass seat & when you drive it on the rack pull em over to the dr seat b 4 you exit EDIT I would set the ride height ahead of time to the height that you prefer/looks good in the wheel wells (have car level/tires aired correct/half tank of gas and the weights in dr seat). If not, good possibility he will set it too low damhik. Jounce it after each of your adjustments & let it settle till you get it where you want it and the ride height has to b set b 4 the caster/camber and it'll function perfectly wherever YOU set it at (within reason) and inform him not to change it

the place i'm taking it to has a guy who specializes in these cars. he did my car a few years ago after i put it together, so he knows what's he's doing with these older cars.

i've got the front height set to where i want it, but i'll go ahead and put the other tires on. don't know that i can come up with 160 lbs of weight, maybe he'll let me sit in the car as he's doing it.

was spot on last time though, so i'm sure it will be again...

weight=bags of sand from Home Depot, save your reciept ;-)

I agree that small of a change wont affect it very much.As for using the factory specs unless you run bias tires toss them out the window.Radials need positive caster and about 1/2 degree camber.Rocky

For every 1 degree your frame angle goes up in the rear, you loose 1 degree of positive caster. Also the extra weight transferred to the front of the car [from the rear being lifted] will also change the camber and toe some, not a lot. As far as will it need aligned, if it handles ok, then tire wear is your only question. Most old cars, the tires rot off before they wear off. If you only put 1 or 2000 miles or so on a year, and it handles good, you can probably get by without aligning it. Most places will align for $100 or so. That is pretty affordable for most of us that have these old cars. If your rear end is high, don't expect to get any positive caster.