1971 DeVille Valve Job

[elanmike]

A few months ago my 71 SDV was stolen out of my garage. We found it 4 days later with an extra 500miles on the car. The car is a true survivor with 33k mile on it Unfortunately, one of the issues was the car was running poorly after it was returned. Considering it was running like a top previous to this we investigated and found that they had burned the valves among other things. So off come the heads for a valve job this winter. Is there anything that I should be looking for , tricks to these engines or modifications that should be done (other than hardening the seats)? I figure that I probably should do the timing chain  will I'm in there. Any thoughts or suggestions are greatly appreciated

["Cadillac Kid" Greg Surfas 15364]

Chances are they "floated" the valves by over-revving the motor.  When the valves float on that motor they have a good chance of hitting the pistons, so be prepared for more than just valves.
Greg Surfas

[elanmike]

Would that be evident if one were to pull a plug and look with a scope?

[The Tassie Devil(le)]

Sorry to hear about your experience.

These heads don't need replacing the valve seats, unless they are damaged, as they were designed to run Unleaded Petrol when they were new.   These Cadillac heads have a high Nickel content, and therefore will stand up to the pounding on the valves.

Using a Bore Scope to check for damage would be a good idea, especially if one wasn't intending to pull the engine to do the heads.

If your Insurance covers the vehicle being stolen, then it should also cover any damage caused as a result on the theft, and I personally would be getting the Insurance Company to pay for the repairs, and be checking EVERYTHING.

I have heard of cases where the Insurance Companies have written-off vehicles that have been recovered, simply because of the possibility of additional claims being made following the vehicle being returned to the owner, as internal damage might not immediately show up, but could after a lot of driving.   Insurance Companies don't like additional claims after signing off.

Bruce.

[TJ Hopland]

What sort of diagnostics was done to come up with burnt valves?    Even with abuse that doesn't seem that likely for one of these engines and if it was the problem due to abuse I would be concerned about what else got trashed. 

[elanmike]

We went through the diff, driveshaft and transmission. They seem to be fine (fingers crossed). The car was bottomed out and we have replaced a tire, wheel bearing and done an alignment. Probably because of this one of the motor mounts was trashed too. We will do all the mounts including transmission when we replace the the bad mount (while we are at it syndrome). We ran a leak down test because the car was running poorly after the theft. We , coincidentally, had the car dialed in because the carb had been rebuilt and we had added an electronic ignition just the month previous to the theft. I took a hit on the payout from the insurance company to not get it totaled and end up with a "Prior Salvage) title. The car is too nice for that and hopefully when done will be better than new.

[35-709]

If your car is not a daily driver, you need to talk to an insurance company that specializes in classic cars like yours.  Hagerty Insurance is one of several specializing in antique/classic car insurance.  You can get agreed value insurance where you and Hagerty agree on the car's value and you don't have to worry about an insurance company totaling your car for a minor mishap like yours or paying you less than what you should receive for your loss just to avoid totaling the car.  And you will, no doubt, pay far less.     

[elanmike]

So we scoped the pistons and all look good. Any suggestions regarding where to purchase valvetrain stuff? I am assuming they are not all created equally. Thanks

[Big Fins]

Are you getting any internal noise like maybe a collapsed lifter? Did you pull the covers and look for broken springs? Maybe even a bad spark plug is causing your issues.