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Proud owner of 72 cutlass supreme convertible, of which I’ve donated a fair amount of time and dough. It is yellow - which wasn’t my first choice - but, it also is clean, straight and strong (and all-original minus the paint) Drives like a car 30 years younger - cruises at 85mph like it were 50. 350 rocket, 2bbl, dual exhaust with 442 bumper (technically last two both not original as well, I realize). Split bench seat with fold down armrest. Cold A/C… I’m not selling - at least not yet - just prefacing the post below.
I just bought a 68 cutlass s convertible, and, unlike the 72, I know very little about this car. Also has a 350 rocket 2bbl, but, with bucket seats/console shift. Body/paint shows nice, but lower front quarters both have blistering and some rust; overall not bad. Paint has spidering, but shines. Interior is close to pristine, some discoloration. Single exhaust. came with protect-o-plate. Here’s some things I’d like to know. I’ve included pics (some of the 72 too):
1. Is it common or even sensible to change to dual exhaust?
2. Engine needs tuning, but as is, it feels nothing like my 72. None of the ‘get up and go’, idles gently and quietly. is there any significant difference between these engines (also has ac, but needs charge at the very least, I hope). Could it be the timing/plugs/wires/compression (in short, a serious tune-up) that makes it seem so much more meek?
3. It has a lower exhaust manifold gasket, which my 72 did not, until put one in. Is that likely not stock?
4. Is it bad manners to ask what y’all what you think is fair market value, for either, sight unseen? I’ve seen similar - and lesser - 72s going for close to $30K, across the country,
5. Most importantly, what else might I need to know about the 68 s?
as a long time 68 owner I think you found a great car and I will try to help ,yes it is common and beneficial to install dual exhaust ,not only does it sound better but it will breath and run better and yes I would check timing and tune it for sure and it should run as good or better than your 72. there were no exhaust manifold gaskets from the factory ,either from manifold to the head or manifold to exhaust head pipe. I can't tell you what your cars are worth but as far as what to know about 68's ,many 68 parts are now reproduced making it easier to keep them together and on the road but being a one year design many 68 only parts are still difficult to find. give it a good inspection,keep your hood hinges lubed and watch your head ,maintain regularly and drive and enjoy.
as a long time 68 owner I think you found a great car and I will try to help ,yes it is common and beneficial to install dual exhaust ,not only does it sound better but it will breath and run better and yes I would check timing and tune it for sure and it should run as good or better than your 72. there were no exhaust manifold gaskets from the factory ,either from manifold to the head or manifold to exhaust head pipe. I can't tell you what your cars are worth but as far as what to know about 68's ,many 68 parts are now reproduced making it easier to keep them together and on the road but being a one year design many 68 only parts are still difficult to find. give it a good inspection,keep your hood hinges lubed and watch your head ,maintain regularly and drive and enjoy.
thanks MI68442W30 for the reply. I'm going to take your advice and convert to dual exhaust. The cosmetic stuff can wait, but, when I get there I'll be in need of a good source for parts. OPGI has been okay and Summit as well, but some of their stuff is cheap – especially the cosmetic stuff!
I wouldn't buy anything from OPGI,or Summit for that matter ,best to stay with an Oldsmobile only supplier if possible ,Fusicks is best ,Supercars Unlimited are also Oldsmobile only and The Parts Place is also a good source for some things ,there are a couple others but customer service is lacking ,just do a little research to determine the best place to get the parts you need . if you need any help with anything ,ask away. good luck
Congratulations on the new convertible! Both of your cars look great.
I have now owned an identically equipped '68 Cutlass S convertible for a little over a year. It ran very poorly when I got it, but now it runs great. I tried to make all of my improvements one at a time so that I could see what kind of difference they made.
As for your questions:
1) As soon as I got mine running well, I converted from single to dual exhaust. My "seat of the pants dyno" told me that it made a small performance improvement, but this could be psychological. I did it mostly for the sound.
2) If your engine is stock and if there are no obvious issues with the engine (during oil, lots of blow-by, lifter noise, etc.) you likely have a very nice engine on your hands. My understanding is that the 2bbl 350 in 1968 had the same cam as the 4bbl 350 and that the only differences were with the compression, intake / carb and dual exhaust. For reference, the 2bbl was rated at 250HP and the 4bbl at 300HP. I may be wrong, though.
3-4) I think 3 has been answered, and I am no expert on the car values.
5) You likely have the "O" type rear end (12 bolt cover, 10 bolt ring gear.) If you intend to make any changes, you need to read up on this.
The 350 does not have a lot of torque, and you likely have the 2 speed Jetaway transmission. When you can, ditch the 2 speed for either a TH350 or better yet a 200R4 which bolt bolt right in. There are a lot of great posts on here, so I would suggest you read up on these. I went with the TH350, and this made the biggest difference in fun and performance on mine. In retrospect, I should have held out for a 200R4, but I may make the switch someday.
My recommendation:
1) Change the plugs, spark plug wires, cap, rotor and points. You can do all of this yourself for less than $200.
2) Set the timing to 12 degrees BDTC and adjust up or down as needed from there. It will likely want more, but this really helped mine.
3) Clean up or rebuild your carb. I have to admit that I am no good with carbs that don't say "Holley" on the side, so I paid a local "expert" to rebuild my 2bbl, and it still ran poorly afterwards.
If you do these along with dual exhaust, and you are not pleased with the performance, switch to a 4bbl Edelbrock intake. I went with the Performer 2711, which is more or less an aluminum version of the factory 4bbl intake. Again, in retrospect, I probably should have gone with the Performer RPM 7111 which makes more power particularly at higher RPMs.
As for 4bbl carbs, you will hear a lot of people here advocate for a Quadrajet, and it will bolt right to the Edelbrock intake. I have no issue with the Quadrajet, but since I did not own one, I just bought a cheap Holley that I knew how to tune and rebuild. Mine was great right out of the box except for the vacuum secondary spring. The intake and carb made a HUGE difference for me in drivability and throttle response.
Lastly, although there is nothing wrong with the factory points style ignition, there are a lot of HEI options available to you. Even though I had completely refreshed by ignition system, I still had rough idle issues which I could see by the timing mark jumping around. I switched out my ignition to an MSD Ready-to-Run unit, and it smoothed out the idle. Perhaps the gears on my distributor were worn out, but the MSD also really made a difference for me. My car nows starts up in a blink of the eye, runs very smoothly, has great throttle response and pulls pretty hard under WOT. It is by no means a drag race car, but it checks all of the boxes on fun and spirited driving.
Great information and thank you NTXOlds! Particularly regarding the transmission. I'll investigate that more closely. All of the other updates, regarding the intake, carb and ignition are TBD. As you point out, one step at a time with this so I can determine the progress. Looks like I'll start with the easy stuff, plug, wires, cap, etc. and exhaust. Stay tuned!
