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I have an original 330CID in my 1967 Cutlass Supreme. No noises and no leaks. Runs quiet and still has power. It also has 139,000 miles on it. How long can these 330s last before they need a rebuild? It is not burning oil.
You have a great engine, one of Oldsmobile's best. Our engines are similar, but yours has better internals and a bit more power than mine. The conventional wisdom back then was the engine/car was shot by 100,000 miles... but in a well maintained car all that meant was the timing chain kit needed to be replaced. Then you can go another 100,000 miles, so forth and so on...
Yes compression will drop, but when you are starting at 320 hp there's a long way to drop till it feels tired. Recently the plugs needed to be replaced on my 350, she was missing, possibly 2 plugs with issues if not 3. She was still making noise on dry ground from a dead punch with a big tire. Mine is just over 140,000 miles and no known rebuilds. I'm sure she is not what she was when new, but she still has plenty.
Some rebuild because mileage or years or both has them thinking it's the right thing to do. But our engines are only original once, I would avoid it as long as possible.
Do a compression test, examine the timing chain and gears through the fuel pump mounting hole with a bore scope. If the timing gear is missing nylon teeth they're in the oil pump intake screen, drop the pan to clean or replace the oil pump intake. 330's are very good engines.
I guess it is the old saying: "If it ain't broke, don't fix it".
Yes sir, I have two long time mechanics one for about 30 years the other for about 15. They both share that motto.
And if you want a bit more get up and go and it's a Jetaway. Just swap it to a TH350. It will be a different animal, as if you gave the engine a mild performance build.
Potentially making her more agreeable and better suited to deal with modern traffic, etc.
When younger and raising a family, money was tight. I drove Oldsmobiles to about 200,000 miles before looking for a replacement car. The cars went to the junkyard because of rust. The only two "bad" Olds motors I know of was the "Quad 4" and "400G'.
hi 69
On a 330ci, swap the tranny would be a better deal than upgrade the engine (carb, manifold, camshaft)? I do have a 65 cutlass, low comp, long ratio rear axe, i have to confess cruising the highway is pain in the a... the engine screams, mph is low and mileage high.
hi 69
On a 330ci, swap the tranny would be a better deal than upgrade the engine (carb, manifold, camshaft)? I do have a 65 cutlass, low comp, long ratio rear axe, i have to confess cruising the highway is pain in the a... the engine screams, mph is low and mileage high.
hi 69
On a 330ci, swap the tranny would be a better deal than upgrade the engine (carb, manifold, camshaft)?
Without a doubt !
The engine upgrades will pale in comparison to having a real 1st gear at this point.
1966 442 Jetaway has similar performance to a 310hp 69 coupe with th350. While the 442 has 40 more hp and a better rear gear.
Now give that 442 a 3 speed auto and it's on a different level. Meaning if you do both directions you are considering it will be even better. But without the transmission upgrade the engine mods will be mostly wasted.
My '74 350 (basically a bored over 330, with a nodular iron crank, (not as good as your forged one), went 493000 miles before requiring a rebuild due to a weak number 7 cylinder. Never did smoke or make noise.
I'm in the same boat as the OP....67 Cutlass w/a 330 and about 130,000 miles on it - doesn't burn oil, etc. I was planning on inspecting the timing gears/chain and doing a compression check this off season. I have read in other threads that this is a good time to replace the water pump as well. It's been a great motor for the 2 years that I have owned the 67.
I'm in the same boat as the OP....67 Cutlass w/a 330 and about 130,000 miles on it - doesn't burn oil, etc. I was planning on inspecting the timing gears/chain and doing a compression check this off season. I have read in other threads that this is a good time to replace the water pump as well. It's been a great motor for the 2 years that I have owned the 67.
If you replace the timing chain and sprockets, I would also replace the water pump. It will be off anyways.
If you replace the timing chain and sprockets, I would also replace the water pump. It will be off anyways.
That's what I was thinking too. I will be pulling the engine, probably in Jan, to replace old gaskets and leaking seals and give it a fresh coat of paint while I'm at it.
Do a compression test before pulling the engine. Examine the oil pickup screen very closely into the shrouded area of the screen for nylon pieces broken off of the cam gear. If the rear main leaks it's time to address that when the motor is out, if it doesn't leak you could leave it alone.
Do a compression test before pulling the engine. Examine the oil pickup screen very closely into the shrouded area of the screen for nylon pieces broken off of the cam gear. If the rear main leaks it's time to address that when the motor is out, if it doesn't leak you could leave it alone.
Please post pics of the project if you would.
Hey Sugar Bear, that's my #1 on my "To Do" list. I am hoping to do the compression test before the end of the year.
I do have a small leak at the rear of the engine and one on the trans. I'll know more once I pull everything.
I'll definitely do that. I'll start a new thread for the whole process/project.
I don't underIstand everyone's hate for the Jetaway. It has a 1.76 to 1 first gear times a 2.45 hi stall variable pitch multiplication equals ~4.3 to 1, which is similar to 2.52 1st gear times a multiplication of 1.8 in a stock th350 (~2.5) tc. I understand that the torque multiplication factor would increase with an increase in engine torque, but the same would happen with the Jetaway.
I would like to see comparative times (both 0to60 and 1/4mi.) of a Jetaway and th350 in the same car, with the only change being the tranny swap.
Last edited by Cutlass Fan; Dec 14, 2025 at 01:40 PM.
Reason: New info
I don't understand everyone's hate for the Jetaway.
I wouldn't call it hate, it's just the TH350 and TH400 are far more superior in accessing an engines power production.
Original road tests do not tell the whole story clearly upon initial viewing...
You need to dig a little to see the truth.
The 1965 A2 442 seems close in performance to the 1967 A3 442. Till you factor in weight and traction issues.
Both A2 and A3 ran a 15.5 et . But the 67 weighed 400 lbs more . The 67 hit 91 mph to the 65s 89 mph. That's a 38 hp difference in performance. Meanwhile the cars were rated 345 hp for the 65 and 350 hp for the 67. Now match the 67s weight to the 65. The 65 gets destroyed.
Swapping a 3 speed auto into the 65 makes it much quicker, it's not close.
All the SP does is maximize a 2 speeds capability, in effect turning it into a 2.5 gear.
But it's still missing the effect of the other half of a gear. And the performance says as much. And once you compensate true stall for the switch pitches effective stall it's a wrap. By 1968 it served no purpose on stock Oldsmobile's.
Motor Trend June 1968.
Switch Pitch vs non switch pitch.
320hp vs 310hp. Pic has all the details and it's not close. The 320hp SP loses across the board. The non switch pitch Jetaway shows a 15 net hp improvement in performance.
Yes the switch pitch is better than non switch pitch with same base fixed stall. But never as good as a th350, etc.
Where the 2 speed shows it's excellence is in the extreme end of drag racing. When it's fully built, in a purpose built vehicle. And can be shifted at 7000 rpm with ridiculous amounts of power going through it. And the reason it excels in this situation is because it's saving time and effort with one less shift. Shifts equal losses on the extreme end of performance. (Top fuel dragsters don't shift gears at all...)
Powerglide shifting at 7000. ET and MPH at bottom of post #5.
Yes at that level its the way to go. But on stockish original muscle era, forget it. 3 and 4 speed automatics are ideal for original muscle era cars and the like. In order to show an engines true potential.
P.S. in case the turnpike cruisers don't paint a clear enough picture I posted a dedicated thread to the 1965 A2 442 vs the 1967 A3 442. Here is the link.
