472 Engine - what to do with it before installation

Lennon_68

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What vehicle(s) do you drive?
1968 Deville rag top
Hi All!

I've never been a 'car guy' but this summer I bought a 1968 Caddy DeVille. I later found out that it has a 384 from 1980 in it rather than the original 472 (and that 384 would need a rebuild which isn't worthwhile). I picked up a running 472 out of a 1970 (along with a transmission) about a month ago. I got it up on the engine stand and am looking for advice on what I should do with it before installing it in the Caddy. So far I stripped off all the accessories. I know I'll be pulling the oil pan off and checking the bearings out. I *think* I should do a "valve job" (still don't really know what that is... I think replacing the valve seals). I also think I'm supposed to "remove the smog pump" (again not sure what that means).

LMK what you'd recommend. I'm willing to put a few bucks into this but definitely don't want to go crazy. The engine was running when pulled and still turns over - I have no doubts it will run in its' current state.
 

Caddylackn

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This is what would be on my list:

1. Replace the front timing set with a true roller timing set, pull the oil pan off, cleanout all the pieces of nylon gear tips from the old timing set and valve stem seals out of the oil pan, clean the pick up screen, new oil pan gasket, new front main seal gasket. I'd replace the rear main seal if it looks like it has been leaking. If not, I'd leave it.

2. New valve stem seals, the stock ones are brittle nylon and may be already gone and in the bottom of your oil pan. You can do the rope trick and change the valve stem seals without pulling the heads. Just stick in a piece of limp cotton rope into the spark plug hole with the piston up about halfway to TDC then rotate the engine up towards TDC until it gets snug and the piston mashes the rope against both the valves to hold them from falling in, when the valve retainers are removed. I would consider a mild hp valve spring replacement, since you are here and the stock ones are junk.

3. I'd clean the block best you can with spray on cleaner without pressure spraying it with water. Then rattle can the long block the proper new dark Caddy Blue. I'd paint the pulleys a semi-gloss black.

4. I'd swap in an HEI distributor. I think your 1980 368 motor one will work, but the advance curve will be messed up due to emissions. I would recurve the distributor with one of those Crane distributor advance kits Crane Advance kit. Or just add a pointless ignition kit (Petronix) to your 1970 distributor.

5. Rebuild the stock Quadrajet with a good year specific rebuild kit. Check out Cliff's https://cliffshighperformance.com/ . Buy his book, it will save you tons of trouble How to Rebuild & Modify Quadrajets

6. The smog pump doesn't really rob any horsepower, and I would just keep it in, or swap out all the pulleys from your 368, it should not have had a smog pump on it. But check to make sure you have true 0 deg TDC on the 368 crank pulley, it could be keyed different than your 472.

Now this is a bit of work, but not anything a weekend home mechanic can't handle. #2, and #4 - #6 can be done after the motor is installed. There are tons of forums and youtube videos on how to do all of the above. With the oil pan off, you should also check on the bearing oil clearances on the crank and rods, but since this is more experienced level work, I'd pass for now. If you have a buddy that knows how to do this, I would bring him over when the oil pan is off.
 

DaveM

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I have a set of new stainless steel valves that a got years ago and never used . They are for your heads. I would be willing to sell them to you at half of what others are asking for them.
 

Caddylackn

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Oh and another thing, this really should have been #1. Verify that the motor is good with a compression test before wasting any time or money on it.

With the motor on the stand, hook up the starter, a battery, and a remote start, pull the plugs and read them, look for oil, carbon, what is the color, rust, damage. Make notes. Then compression test the motor with a compression gauge. Test all eight at the same time then write the cylinder pressures down. Then add a squirt of oil in each cylinder then compression test them again and write those down. You pretty much have to do this in one sitting with the motor the same temp. If the cylinder pressures are all within 5 -10% of each other without the oil, that is good. If they are only within 10% of each other after the oil was added, you need new rings and should consider doing that with the motor out now.

If there is one or two cylinders that are much lower than the others or won't build pressure. Then you should trouble shoot what is the problem. Add one of those air attachments that go to the sparkplug hole and add compressed air when the cylinder is at TDC (remove the valve cover and verify both valves are closed). Now listen to where the air comes out. Out the intake, then the intake valve is bad and it needs a valve job or intake valve. Out the exhaust, then its the exhaust valve that is burnt and needs an exhaust valve and a valve job. Out the crankcase (listen to where you put in oil at the valve cover), then its a bad piston, broken ring, or piston land. If it sounds like it is coming out the radiator, or between the head and the block, then its head gasket or cracked head.

If all of this is more than you want to tackle, and if the motor was running when you bought it and didn't smoke like hell or overheat, its probably good to run for awhile. Install it.

At the very least of all 7 of these, cleaning the oil pan and pick up screen of debris is probably the most important. So I would at least do that, since it is a very difficult job with the motor in the car.
 
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