22nd Jan 2009, 13:01

I have a 78 Cutlass with a 260 V8. Just put 2000 in body work and hope it's worth it. Does anyone know how to modify this engine?

19th Feb 2009, 17:44

I inhereted a 1978 Olds Cutlass Supreme. It has a 260-V8 and get this...it's a 5 speed. I have tried to find more like it, but haven't found one that runs like this. From what I understand, my dad special ordered it. Does anyone know how I can find out what it's worth. It has original paint and rims and its in great shape and runs great. Thanks, Olds Guy.

28th Apr 2009, 20:23

There was a statement that the 260 was only good for 15 mpg. Can't be true, in Colorado (high altitude), I regularly get 20 mpg in a salon 4-door with auto trans, and speeds up to 70 mph.

13th Jun 2011, 13:15

We also have a 78 Olds Cutlass Supreme with a 260- V8 and it's a 5 speed also. This one was specially ordered by my father-in-law. We have been trying to find others like it and also the value. Have you had any luck?

13th Jun 2011, 19:49

To: 22nd Jan 2009, 13:01.

The best way of modifying the 260 is to rip that pathetic excuse for an engine out & throw in at least a 350 in its place, along with at least a TH-350 trans. The only things that the 260 are good for are:

1. Boat anchor

2. Door stopper

3. Paperweight

13th Jul 2012, 20:28

Pertaining to the 260 V8 being good for nothing more than a boat anchor or paperweight, I have to disagree. It is a fantastic, reliable engine. It will also pilot an Olds -- and allow it to cruise for miles and miles to speeds (with the 231 rear gear, which was common in the late 70s) to almost 130 MPH, in stock form.

As a weekend drag racer of more than 25 years, I can say that powerful it ain't, but it's got as much oomph as a Chevy 305CID, when fitted with a free flowing exhaust. There are very few performance parts for these small V8s, but with some ingenuity (ported heads, an aftermarket intake, exhaust and a small 390CFM 4bbl), you can achieve an honest 220 HP with decent fuel consumption. They are not hot rod engines, but they are fantastic street engines, and if well cared for, there is no reason one cannot see a quarter of a million miles out of one. I saw over 200K on mine, and it was running strong when I sold it.

Overall, if you want inspiring performance, drop in a 350CID. Otherwise, the 260 is just fine -- especially with a 700R4 or 2004R tranny fitted. The fuel economy should be 20-22 MPG at 70 MPH, and with a TH350, you should get 17-18 MPG.

14th Jul 2012, 11:33

To the poster of 13th Jul 2012, 20:28:

If a 260 Cutlass could have reached 130 mph stock, I guess that would mean that the 1972 W-25 455 442 that I had years & years ago would most likely have been good for 200 mph!

19th Sep 2013, 19:55

Well he did say that with the right rear gear... Yeah, I had a 78 with that engine and mine barely pushed past 120, but the damn thing won't die; it still goes, and on the roads it will get 25 MPG.

The only issue I have is the speedo doesn't work, and neither really does the fuel gauge, so I often have to guess with the miles...

I still have the old girl, but due to money issues and gas prices, I've had to buy a small Honda for its fuel efficiency and ease of driving in the town I live in.

20th Sep 2013, 15:37

Likely your 442 Big Block would blow up. I have 411 rear and it is roaring at 70.

8th Oct 2014, 15:10

I've got a 1978 Olds Cutlass Salon 260 V8.

There is a tapping noise in the engine, ONLY DURING ACCELERATION, not during idling; it idles great. A mechanic told me it sounds like a crankshaft bearing is going, which means an engine rebuild. The car has only 30,000 k on it. Is there something else that could be making that noise? Or what?

I also heard if you use Lucas oil and 93 octane gas, that might solve the problem.

Thank you.

10th Oct 2014, 14:23

Could be a loose main bearing. Or an exhaust leak. Check the metal lines going to the smog pump if it has them. Those are notorious for leaking with age, and producing the same sound under acceleration.

30th Jan 2015, 04:01

Years ago I had a 78 Olds Cutlass Supreme with a 260 that developed an intake manifold gasket leak with the coolant. When I removed the intake manifold to repair it, I also cleaned out the crust & sludge in the engine block. Not sure what you call it, but there is a plate that has 3/8" small holes (one per cylinder), which I guess helps keep the oil in the top half of the motor & controls the flow of oil to the bottom of the block. Since the engine is tilted a little toward the firewall, the back 2 holes were blocked. Once I cleaned them out & put the engine back together, the knock went away. I always wondered if this was solution to the "Chevy Knock". Good luck - it was an 8 hour job for me (I'm not a mechanic).

My mistake was I sold it in '92 because of its age (160K miles) & it drove me nuts in stop/go traffic (it wanted to coast while the 4 cylinders didn't). That car was amazing & built like a tank - I still miss it.