i just bought a 72 lemans tempest, it drives ok but it sounds like the motor is too loud to be going as fast as i am like if im going 50 it sounds like im going 80 or faster, does anyone know why?

Sounds like it needs a tune up. The carb orator needs to be adjusted and the distributor needs to be cleaned and the timing needs to be checked. Is it overheating too?

some one put 4.11's in the differential, gears like that will launch you like rocket but you will getbto the max limits of the engine (rpm's) at s slower speed

i bought a grand prix that had 3,42 gears in rear, facyory was 2.41 so it was quite a difference, speedometer read 85 i was going 55

ill get a tune up this week sometime how much should it cost to get my timing checked and get my distributor cleaned? the car isnt over heating though but my speedometer is showing about 30 miles faster than i am actually going what can i do about it......... about the 4.11 differential, i dont know much about that what exactly does that mean and what can i do about it?

Check for an exhaust manifold/intake manifold leak. an exhaust manifold leak will make your car very noisey, it also will reduce back pressure on the engine which will affect the vacume of the engine. This will greatly influence performance at higher speeds. An intake manifold leak will also affect performance and also can create noise but, it will be more of a high pitched whine. First, on a cold engine. Make a spray of water and dishsoap. Start the car and work your way around the exhaust manifold. If you notice a set of larger bubbles than from just the spray alone, you have found the leak. Check all vacume lines as well. If it smooths out at any point, check the area for cracks , cracked fittings or,disconnected vacume lines which are not plugged.

You're better off learning how to fix it yourself. Not many mechanics do carborator tuning anymore so if you find one you'll probibally have to pay a lot. If you're lucky someone you know can teach you. There's not a lot you can screw up on older cars just get it taken care of as soon as possible because your gas mileage as bad as it is on a car like that gets even worse if it's not tuned up

As for the axel ratio, that will cost thousands to change because you have to replace the whole rear axel

its easy to find out jack up the rear and put a couple of jackstands under the rear axle so both tires are off the ground, with the trans in nuetral, and front tired\s chocked, put a chalk mark on the tire and turn the driveshaft counting rotations until the mark is back to home position. if you turn thr drive shafy like 3 and half rotations, you have a 3.42 rearm etc........and by all means make sure engine is in good tune with no vacuum leaks, have fun with that cruiser !!!!!

If yours is an automatic another thing to check is make sure your torque converter/ trasmission fluid is not burnt or low. If the car has been driven hard before it is possible that the torque converter is bad.

I would check axle ratio my 68 firebird caim from the factory with 4.10 12 bolt , I had a 72 luxury lemans with 3.73 they really scream going down the road.

if you want the speedometer to work properly all you have to is change the speedometer gear in the tranny where the cable goes, and you don't have to change the whole rear axle to change to gear ratio. 1st thing is find out what exactly you have as far as the tranny,if it's automatic 350 or 400 or manual , & what rear end you have & go from there.

The old car gears (about three for an automatic transmission) make the RPM gauge rev high at 3k or more. To a modern six cylinder (V6) with an average of five gears these days, the RPM gauge might be around the same 3k at 80MPH. With a 400 engine, the RPM might have to work a little harder to keep the speed at least highway limit. It is a natural thing that can't quite disappear on old automatics, as an explanation.

What? ^

you have to be a lil more specific on the engine noise . is it that you have an exhaust leak ? or is the engine knocking or ticking,there are many things that came make noise.best thing you can do if you're gonna do the work yourself is to get a repair manual from pepboys or auto zone or if you have swap meets in your area you can pick up a Motor repair manual for about $10.00 just check & make sure it covers the years & repairs you need,they are not all the same. Good Luck, nice car !

Or like my luxury lemans 72 i got lucky to have a powerglide(2 gears tranny), a 12 bolt diff. And 14 inch rims!! Imagine the noise driving that in the highway.

Your rear end gears are way too low it's probably has four 11s 456 gears in it if you had to tachometer and you do 60 it should read 4,000 RPMs with a 456 rear if it's automatic you should have a 240 or 236 rear or something like that if you have a four speed or three speed you should have at least a rear in the threes like 307 or 311 to whatever you want I forget all that but I had a 456 rear with a four-speed Muncie and I tacked four grand at 60 MPh and at six grand at the end of the quarter

Just like I think it was guru said to put it up on jack stands put the car in neutral chalk the front tires and put a chalk mark on both tires and watch the tires turn as you're turning drive shaft by hand and each revolution of your drive shaft count them to one turn of your tire and that will give you your gear ratio in the rear end if it's automatic it should turn about two and a half times