Trans swap?

7

75conv

Guest
My 75 LaSabre gets about 10 mpg. Is there maybe an easy trans swap to maybe a four speed auto and a locking torque converter? It has a 455 engine and I believe it also needs some carburator work or jetting.
 
I can't answer your Tranny question but, You should probably rebuild that carb and do a full tune-up. You should get better than 10 mpg even though its a big car.
I had a '72 Electra that averaged 14 in the city and on a trip to South Dakota with the A/C on and cruising at 70+ mph I got 18 mpg out of it. The Quadra Jet carb is very economical as long as you keep your foot out of the secondaries.

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1970 Riviera
1996 LeSabre
And many Buicks in the past.

[This message has been edited by Dale (edited 01-31-2002).]
 
Have any ideas on where I can find a carb rebuilt kit and some info on rebuilding my carb?
 
Just a thought, but I have find that most people like to blame their carb for their poor milage and are usually wrong. Most of the time they need to look in their distributor. Why don't you have a look at timing an engine in the Buicks.net shop and make sure both advances are working correctly.
 
Very true Bob. You reminded me that I had spent time 'tweaking" the advance curve on that Electra. A lot of trial and error using different advance springs and weights, trying several different settings for the initial timing until it was just right.
I would bet the dual exhaust helped also.


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1970 Riviera
1996 LeSabre
And many Buicks in the past.
 
Okay, cruising anywhere say 35-55 mph and i get on it, it chokes for a second or two then picks up again. I just feel like its running way two rich, but one thing i've learned is thats its not always what i first think.
 
If the carb is stock, check your accelerator pump, if it is not, it could be other things.

If you bring in more timeing it does the same thing as leaning your carberator, only more efficiently.
 
Thanks Bob. I checked the vacum advance and its not working. I've got a new one on order.
 
I'll guess that the bog you get will still be there after the distributor fix. I hope it isn't for your sake, but if you have a GM with a bogging problem, its almost always (in fact I've never seen otherwise) the Q-jet secondaries opening too fast. They are sucked open by vacuum and the speed at which they open is determined by the pressure of a tiny spring in the air horn casting. After a few years or several thousand miles this spring relaxes, allowing the upper doors of the secondaries to snap open giving a very huge gulp of naked air. Its impossible to describe exactly where it is, but pick up a rochester Q-jet manual and just flip to that section. It will show you where and how. It involves loosening a set screw, tightening the adjustment screw and resetting it. A little bit goes a long way...try turning it 1/8 turn at a time until the problem disappears...that's if the problem is still there for you after the advance fix. All of this adjustment can be done in a very short time by just removing the air cleaner.

Good luck
Curtis
 
I've got another question. The vacum source for the advance is nill. I timed the engine with a source off the carb that had about 20 lbs at idle. Can I use this to the dist? If not what vacum pressure should I look for? When I hook up the -20 psi the engine begins to take off. Do I just need to turn down the idle? The new dist made a great difference.
 
Ignition on GMs should have a manifold vacuum source, not ported vacuum, so you're looking for the 20 inch vacuum port. The timing should be set to spec (I think 6 deg BTDC) WITHOUT the vacuum hooked up, but plug the hose so you don't have an abnormal vacuum leak. When you hook up the vacuum it should return to smooth running.

When its running fast like you said, does it just sound like fast (cold) idle or does it sound like an abnormal condition? If the distributor setting and vacuum change doesn't help, I would try backing down on the idle setting to see if its off, but it didn't do that before did it? Remember how many turns you set the idle screw (and make sure the choke is fully off) so you can go back to where you were if necessary. If you're pulling 20 inches of vacuum you can probably set idle to about 500-600 in gear and 750-850 in neutral.

Good luck
 
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