Hello all, i am new to this forum and was searchin around, but dont quite know where to post this. But here it goes anyways: i just purchased a '76 riviera w/a 455, and i am already in love. i am plannin on drivin this for the winter months and part of the spring months while i get some things done to my other car. the problem is that this car is lacking power, lots of power. the car has been sitting for 10 years, and im new to the whole idea of a carbeurated (sp?) car. i dont really know where to start on this whole issue? probably changin the plugs and wires to start, but is there any known problems with these cars and power loss? sorry for being random with this, im just confused on even where to start with this beast. thanks guys, eric.
Start off with a basic tune up....and the work your way up from there. Make sure all vacuum lines and fittings are leak proof and not broken/brittle. Vacuum leaks kill power.....badly. Then look as engine timing and carburetor air/fuel mixture. THese are very simple engines to work on if you're willing to be patient and ask questions!! The worst thing you can do is NOt ask questions. :TU:
Since its a '76, the first question I have, Is it a 2 barrel or a 4 barrel? You are already dealing w/ a low compression, smoged engine, being a 2 barrel would only make it much worse. If it is a 2 barrel, first I would do is get a 4 barrel intake and carb. That alone would wake it up some.
it is a 4 barrel carb, and im glad to hear these are easy to work on before diving in. thanks for your help guys
Eric, If you have a timing light, check the timing on the engine. Get all your mechanical advance in by 2500 RPM, by recurving the distributor. The stock timing curve is slow, and doesn't max out until at least 4000 RPM. This can make a world of difference in the way the car feels power wise. Buicks like 12* initial, and 30-34* total. The 76 heads had open chambers, and ultra low compression(sub 8:1). Add in EGR, and AIR and it's down on power. Bolting on some earlier heads will give you more compression. Check the catalytic converter, if it's clogged, replace it or ditch it, and put a full dual exhaust system on it.
I,m thinkin here That car is going to be a dog probly no matter what you do to it.It,s the last year for the 455 and smog control s has choked the power down to the point were it has just enough gumption to get away from a lite. If it been sitting for that many years the vaccuum canister on the distributor is more than likely shot.Pull the vaccum line from the vaccum source and suck on it.Put a finger up under the distributor at the vaccum canister and feel for the rod that goes back into the distributor.When you draw on the line this should move if it doesn't than replace it with a new one than upgrade your timing and such.A can of carb cleaner around the carb and in it wouldn't hurt either.Make sure the tires have the right air pressure in them because that car is going to take alot to get it to rolling. MY 2 cents....
along the tune up route.....replace all of the vaccum lines.this is a cheap and easy thing to do, but it can have great benifits. this is an old car, and if it has been sitting for 10 years, i would bet that the lies are old and have never been touched. even if you look closely, you may not be able to see the cracks in the lines. also if the lines are brittle, they may not make good seals. then i would give it a good tune up (plugs, wires, cap rotor) and check the timing. it should run good after that. if not then you may have other issues. but the engine is wasy to work on. also a '76 chassis manual can help you out in tuning the engine and finding solutions to problems that you are having. they are only about $20-$40. it is a wonderful investment. i can give you some places that may have them, and you can check ebay. john
thanks guys, i appreciate all the help and im sure ill have some more questions coming up. looks like i have some work to do this weekend!
One thing nobody mentioned is the secondary lock-out lever that is actuated by the choke linkage when it warms up. I've seen these freeze so the secondarys never open....o No:
Hey Eric! I always wanted a SHO, so in 1995 I bought a 1990 SHO with 40,000 miles on it. I was in heaven. All the options! Then over a 2 year period I dumped about a million dollars into the damn thing! Man, I replaced every component that was bolted around the engine. And the parts that came in were never the right ones, either. I never got around to replacing the blown out engine mounts. I dumped it. As I would drive it it would cut out, then snap back on, over and over again. With no rhyme or reason as to why. Sometimes it would die for 10 or 20 minutes at a time. We know now that it could have been the crank sensor or such, but in '97 this stuff was still all a mystery. The Mrs. fought with me about buying it because Consumer Reports raped that model, but I won out and bought it any way. Seems like in the end she was right, though. I'll tell you what, tho, a SuperChips chip REALLY woke it up! I have a pair of '71 455 heads you can have for $100 plus shipping. I suggest a quick $300 valve job before bolting them on because The engine I took them off of wasn't running when I got it and there's no telling what shape they are in. The '71 heads are similar to the '70 castings with the 10:1 compression ratio. I believe in '71 the CR was dropped with the deeper dish pistons only. Should help a LOT in your case. Mess with the timing first. Set it at 10* advanced to start and see if it pings. Then go from there.
the gen 1's are the fastest of the SHO's. gen 1's and gen 2's do 0-60 in 6.6 seconds and 0-100 in 16. they are fun to drive. im sorry to hear about the problems you had with it, but your not the only one. the damn things are unreliable. im guessin the problem you had with yours was the CPS sensor (crankshaft position sensor). those are notorious to go bad, and do what your describing which was cutting out when driving, and not starting or causing hard starting. about the heads, im not sure as of right now. im trying not to sink any money into this, its just my beater car and as soon as the weather turns nice ill pull the SHO out again (hoping for low 13's) for the later spring months and summer and so on. i did some work this weekend on it, new spark plugs, a few new vacumm lines and such. i also used near a bottle of carb cleaner. when i took it out after all of that i noticed a big difference, the beast moves not all that bad. on another topic: how much are these cars worth in decent shape, mine has a tad over 86K on it. as always thanks guys, eric
