Hello everyone,
My grandpa recently gave me a 68 cutlass supreme, and I’m currently deciding if I should pull the motor and send it to be rebuilt, or if I do suspension and brakes and steering and try to drive it next season.
I don’t want to hurt the motor, it’s sat for as long as I can remember, with him occasionally driving it a couple days a rear. He took meticulous records on oil changes and service.
Currently the car sits with the intake manifold removed, the car smokes white and has blow by. I noticed the manifold was leaking oil, so I’m in the process of changing the gasket. I think I have most of the vacuum figured out. The car has good oil pressure I believe. Usually about 40 psi, closer to 60 when given throttle. I guess my question is, what should I do to make sure I don’t hurt the motor? I’d really like to drive the car next season, but can’t afford to do the motor along with suspension and brakes. And I wouldn’t feel safe driving it next season without doing the later 2.
thank you,
Tony

 

Has the timing chain ever been done? Before you put on the water pump, check his records. The cam gear has nylon coated teeth. After 55 years, they break apart getting sucked into the oil pump pickup. The intake gasket could have been the white smoke. What did the coolant look like? I have seen the factory shim head gaskets get eaten out by really bad coolant. A compression test and maybe a leakdown test, will tell a lot as well. Good luck.

 

Yup, compression test and timing chain check and cam gear. Premium fuel only.

 

I put the water pump back on before pulling the intake. I imagine it’s worth it to pull the water pump and check the cam gear? The coolant that came out looked good and so did the oil. I am going to purchase a leak down and compression tester and will get back with the results. Does the oil pan need to be dropped to get to the timing?

Thanks,
Tony

 

The cam gear can be viewed through the fuel pump mounting hole with a borescope. The oil pan does not have to be removed but should be removed if the cam gear is missing teeth as the missing nylon teeth can block the oil pump intake leading to oil starvation. The most thorough "correct" way to do the timing chain is to remove the oil pan and clean the oil pump intake.

 

Be sure and tell Grandpa "Thanks!!!!" That's a mega-cool gift. Like the guys said above, use a cheap bore scope hooked to your phone (Amazon or eBay) to check the timing gear through the fuel pump hole. Don't wreck the newly installed gaskets if you don't have to - I see you had to make it custom from gasket material. They are available, but getting more scarce...

 

Thank you, sugar bear. I ordered a borescope to inspect the cam gear. I will update when I make progress.
Tony

 

Ive been updating him regularly. He bought the car brand new, for my grandma, before they got married. He began to develop some dementia, but he loves hearing about his old car, and all the work that’s being put into it. He always says, “I’m amazed how I could walk out of the store, and it’s still the best looking car in the lot.” I’ve been enjoying hearing his old stories about the cutlass, and can remember sneaking into the garage as a kid, to just look at the car.
And yes, I had to make the gasket, I could only find it in a kit that comes with 3 different gaskets, and they want $40+ for the kit.
Thanks,
Tony

 

here’s what she looks like! Repainted in the 70s, was originally sapphire blue with a blue top and blue interior. Interior is still original.

 

That was accurate back then and even more so today.

 

I completely agree. It’s amazing how many looks the car get. All sorts of people giving thumbs ups, slowing down to yell out the window, and stopping to say something at the fuel pump.

 

Right on advice, you might even be able to catch a glimpse of the gear with a light and some eye strain, not sure. A thought did occur to me, even if you installed the water pump you can likely remove the 4 heavier bolts at the water passages and remove the timing cover with the pump in place, without compromising its seal to the timing cover. I see at as a “while you’re there” thing that is important to do and will never be easier. As mentioned, drop the oil pan while you’re there, inspect/clean the oil pickup, etc and put the TIMING COVER ON FIRST when reassembling. Might want to put a new crank seal in cover while it’s off as well. One note of my personal preference, I always use Diesel (Olds 350 D, DX 78-85), oil pan gaskets, they are much more substantial and reliable in my experience.

Good luck and I hope you get lots of enjoyment out of that cool car.

​​​​​​….

 

Nice car - great advice from knowledgeable & friendly members. Enjoy hearing these type stories (e.g. Grandpa's car). You're doing some fine work. Compression &/or leak-down test(s) will provide good insight. Good Luck!

 

Pulling the timing cover with the pump on it is a great idea, thank you! Also for the gasket recommendations. Does the motor have to be out to pull the oil pan? There’s not much clearance between the pan and the crossmember. I was trying to avoid pulling the motor for as long as possible. But if it has to be done, then it has to be done.
Thanks,
Tony

 

Thank you

 

Do you have the 1968 CSM? There should be a section which describes removal of oil pan. Same section in 1971 CSM describes the method - you need to raise engine ~4" to gain clearance for oil pan removal. That is the procedure I follow. Raise engine either before or after (preferably before then make an adjustment to lift height) you place car on jack stands. You'll need jack stands to gain enough working room under the car.

 

I do have the manual, I’ll see if I can find the section tonight. The cars on jackstands right now, I imagine lifting from the top with an engine hoist after the motor mounts are loosed and potentially trans cross member.

Thanks,
Tony

 

Good you have the CSM. Yep...IIRC, CSM doesn't state to loosen trans. cross-member but I did as a safeguard. Front cross-member under oil pan does not need to be loosened. Didn't have to loosen motor mounts. Simply removed the nut & bolt securing engine motor mount to frame motor mount - probably same on 1968.

I wrapped a tie-down around the front of the engine & hoisted away.

 

It is a pain but I replaced my timing chain while the engine was still in the car. If I knew then what I do now, I would have just pulled the engine. Getting the chain cover back on and sealed correctly is extremely hard while it is in the car. When the engine is out you can replace the pan gasket, rear rope seal, motor mounts with ease along with cleaning and painting the engine and bay.

 

Tony - Good suggestion by Noel. If you have the time & intent, by all means yank the engine. By far the easiest esp. replacing the rear main rope seal. Suggest you have an engine stand to rotate the engine when wrestling w/ the rope seal, but each of those items would be far easier yanking the engine. Good Luck!

 

Hey Tony, That's a real nice looking Cutlass. I bet that your Grandfather is happy to see that you're keeping it going. I hope that the Service Manual is helping you. Thanks for posting the pictures.
-Andy

 

Thanks Andy, I got my shop manual off you right? I’m leakdown testing the car now and have a few questions. I guess I’m having a hard time finding pressure values in the manual. I’ve been looking in the v8 section, am I just missing the information?
First cylinder I got 65 psi out of 70 second cylinder I got 50 psi out of 70.

Thanks,
Tony


I found the red vacuum line at goodwill for a dollar, and it was the right size.

 

Cylinder 5 was even worse. I could crank the motor through the compression stroke with a ratchet with 70psi of air pressure in it. Do I just pull the heads? And hope it’s a head gasket, while preparing myself to pull the motor?

 

How did it run before pulling the intake?

 

It felt a bit sluggish. The car was smoking a bit, and overheated one night when I was driving it. I replaced radiator, thermostat, water pump and hoses.
The car has been running cool since and the oil looks ok. I really don’t think it’s the head gaskets, but If the rings are shot, I’ll find out along the way. I’ve done valve cover gaskets, pcv valve, rerouted pcv and vacuum lines, spark plug( which have stayed dry) coil, sea foam for 50 miles, radiator, water pump, thermostat hose. Also installed mechanical oil pressure, temp and volt gauge.
I really don’t want to hurt this motor. Thank you all for the input.
Tony

 

also the oil looked good, and the coolant was clean and didn’t smell like fuel.

 

A concern is pulling the heads to do a valve job and finding out afterwards that the rings are bad. I'd try to determine whether or not the rings are going to be replaced before pulling the heads to avoid pulling the heads twice.

One option since the motor has sat for a while is to put it back together, do a ring soak, drive it and then re-do the leak down test.

Keep in mind this is a high compression (HC ) 4 barrel carburetor engine with shallow dish pistons, if a rebuild is done using low compression pistons, performance will be lost.

How many miles on the engine?

 

The motor had 200k miles in 1984, based on my grandpas record. I think the odometer broke and he stopped driving it regularly. I remember the car in the early 90s and he might have drove it 50 miles a year after that. Is there any chance lifters could be stuck and keeping valves open? Also can I ask what I ring soak is?

Thanks,
Tony

 

also he said he was running regular fuel. Possibly the valves are burnt?

 

A ring soak is a product left filled in cylinders overnight or even for days. The engine must be cranked with the plugs out or hydro locking can occur and bend connecting rods. I used Kleenflo Combustion Chamber cleaner and gained as much as 40 psi. The motor may just be worn out. As said, if you do overhaul, no generic cast pistons. You either want the old school Speedpro 6cc or flat top forged, Mahle 10cc forged or DSS 3cc forged pistons, if a rebuild is necessary. You can also improve on the factory peanut cam, add W31 valves to heads and upgrade your converter at that point as well.

 

Grandpas_cutty, Any progress, updates or questions?

 

I’m on the search for kleenflo combustion chamber cleaner, online, and having a difficult time finding it for sale. I have seafoam at home, which I might use in the meantime. I’m guessing put it right in the plug holes? Try to blow it out of the cyclinders after soak, and change oil before firing?

Thanks for ask,
Tony

 

Yeah, Kleenflo Combustion Chamber cleaner is probably hard to find in the United States. I didn't have luck with Seafoam, you might. Marvel Mystery oil and maybe one of Berryman products, would be worth a try. We don't get a lot of products up here like Berryman's, for example.

 

Excellent for ring/piston soak.

 

Yes into the plug holes. Yes to the oil and filter change.

Crank the engine over by hand with the plugs out to get liquid out of the cylinders before using the starter.
After the hand crank disconnect the ignition coil wire, put rags near the plug holes and crank it with the starter to blow it all out. The cranking by hand reduces the mess by blowing less out when using the starter.

It's a V shaped engine so keeping the tops of the piston covered can be difficult, you will have to add the solvent periodically as it leaks past the rings. Rotate the engine once a day or so whilst soaking.

Be prepared for a lot of smoke on start up, do it outside and don't breathe that stuff.

 

Thanks guys, just got some of the b12 from a local autozone, I will be soaking the cylinders over the next few days

 

Update. This is how my grandpas 68 cutlass sits.
I am planning on sending to motor to S&j engines in Spokane Washington. It’s a 68 350 with a 5 and 6 head. It’s going to be refreshed, heads ported and polished, balanced rotating assembly and a new cam and timing.
Also planning to put an edelbrock 2711 on it with hedman king tube headers and pypes 2.5” x pipe. Im going to rebuild the Rochester 4bbl and am trying to decide on ignition. If y’all have any recommendations or advice. Planning on keeping the jetaway and open rear until I can afford th350 and posi.
I have also been trying to decide between running a 15” rim or 17” rim. I am planning on doing a 4 wheel disc conversion.
thank you for everyone’s help/input and happy new year.

 

Man, I just recently gave away a th350, two actually.

 

Shoot im a day late. If you run across anyone else giving away th350 or th400 send them my way haha!

 

Here's my '71 on 17" rims compared with 14" stock wheels. Check with your tire shop before committing...my guy commented that it was "too bad they aren't 18s, lots more selection".