I have a 330 / 320 HP engine in my 67 Cutlass convertible.
The 330 is a little tired it runs good burns no oil but the vacuum is low so I would suspect worn or sticky valves and at times hard to start when warmed up.
Are there any issues like cost of a 330 rebuild compared to a 350?
Are parts available for the 330?
Not looking for more HP just stock, I use the car as a cruiser not racing.
The car has a 200 4R trans and a 3:08 peg leg
Rebuild or replace is the question

 

I vote for doing a leakdown test to see how much cylinder leakage exists and where it is and go from there. The 330's had steel cranks, the 320HP will be high compression and is the correct vintage for the car. It may just need a good refresh e.g., chain, gears, gaskets, seals and possibly a valve job.

To answer the question, since your not looking for more performance, I'd try a thorough repair/refresh first, rebuild if necessary second and replace it last.

 

I'm with sugar bear. Do some initial troubleshooting to see why you have low vacuum. Bad timing set and/ or poorly tuned will cause low vacuum among other things.

 

The 330's don't get near enough Love. I had a 67 4 speed Supreme that was bad-***.
It was also the 320 horse unit. I vote for your original engine. Punch it out if needed and be prepared to be wowed as long as you do some work to the heads too. Good luck with your decision, the rebuild cost will be about the same as a 350 and you will retain originality with the engine at least.

 

Egge will have the 330 pistons. You won't find them at summit or anywhere else- though folks say that the 330 block is thick enough to safely be bored out to accept stock bore 350 pistons... I'd leave that to a machinist to tell you for sure before you order anything.

Otherwise nothing special or out of the ordinary from what is needed in any other SBO motor.
Its a 67 so it has the standard cam bank angle so off the shelf olds cams will work (64/65/66 has a different angle and needs a special cam made to use that).

The flywheel/flex plate may be specific to the 330 crank, so hopefully yours is good and can be re-used. Not sure if anyone makes though, but good used ones are out there if you have to replace.

I'd rebuild the 330 before I'd go after another block.

I kept the high comp 330 out of my '66 when I sold it... it will eventually find its way between the fenders of another 64-67, and will likely get freshened up along the way.

 

Thanks for the advise. Makes sense to Keep the 330 all the A/C, alternator, power steering brackets, exhaust, wiring would not have to be modified. Any decent reparable machine shops that know Oldsmobile engines in the Chicago area? I'm in Downers Grove IL.

 

Just rebuilt my 330 HC, so I have a lot of info to share. Building a mild 455 would have cost the same, so you should definitely think about that option. One good thing about the small block, I can safely spin to 6,000 rpm, and that's a whole lot of fun, but I'm missing that monster 455 torque in the low rpms.

I wouldn't consider a 350, the 330 is a great engine, plus it has a forged crankshaft, so compared to a 350, the 330 is a no-brainer. 330 Pistons are more expensive, that's the ONLY drawback. If you have a seasoned, working 330 engine, that's a great build platform.

I bought the Egge 330 HC pistons, and now I regret not going with a modern piston/rod combo. For the price of the Egge pistons and a little extra machining, I could have upgraded rods and pistons. No one will notice, and your engine will last 50k miles longer before the next rebuild.

Also, be really careful on cam selection. I overshot my compression at 10.4, and now I have to run super unleaded + Octane Supreme (lead). Cam choice has a huge impact on dynamic compression, and my 211/221 cam holds too much cylinder pressure. Either drop the compression a little or go with a larger cam. A larger cam comes with the need for higher stall, better gears, etc... So a little compression drop would be easier (9.75?).

Good luck, and if you need anything, don't hesitate to PM.

 

Im in elgin and i have used Opel engineering in streamwood il. and borowski race engines in rockdale . You could have your block checked and see it it will accept a standard bore forged piston. if not a 350 block can be found pretty easy. I would go that route to be honest.