Hello everyone!

Since I last posted, the 231's been pulled out of the red Starfire and the 231 is ready to be pulled on the silver Starfire.

With the engine on the stand, I started the autopsy. This particular engine showed #6 pumping 60 PSI (lowest), and numbers 4&5 pumping 90 PSI (highest). Once I removed the intake and heads I discovered #6 had what appeared to be part of the top of the piston (edge, ring land area) that was bent upward. Oddly enough, there didn't appear to be any scoring of the cylinder wall and in other cylinders you could see in places the faint appearance of the honing pattern. While I didn't clean the top of the cylinders yet I couldn't feel a noticeable ridge at the top.

The current cylinders have "040" on top, and the previous owner did tell me either the engine was rebuilt or a rebuilt one was installed at some point. Now keep in mind I haven't opened the bottom of the engine up yet, so this might be all for nothing, and I might find something that renders this engine to the scrap bin. However, at this point it looks like this engine could be rebuilt -- so what are people's experience with a maximum overbore on the even-fire 231? I don't intend to race this car, but I might run an occasional autocross with it. The rear gear will be a 2.29 before the car sees the road again (from a 2.92) since 95% of my driving is on the highway (40-plus miles a day during the week and one 130-mile round trip to ANG drill meetings once a month) so it's not going to run very high RPM's. But I need rock-solid reliability and good mileage, my 1970 Brand C truck's 3.73 rear gear's got the engine there eating gas almost as fast as I can pump it in :angry:

So, what's the word?

Thanks in advance, and Take Care!
SrA Snyder
Kansas City, Kansas

Ken you can go .060 oversize and not have any problems . HTH
Guyopel

Ken you can go .060 oversize and not have any problems . HTH
Guyopel

Thanks for that information -- I was concerned that with that much overbore I'd run into cooling problems. The H-body cars are known to have too little radiator and the stock fan clutch is nearly impossible to find, making overheating that much easier. On my car I've gone away from the stock fan and installed an electric fan, possibly soon I'll have the 3-row radiator core replaced with a 4-row model for enhanced cooling.

In the current car there isn't any A/C condenser to block the radiator and add to it's heat, but when I move this drivetrain to the other Starfire I will have A/C and that's when it would concern me.

Since my last post I've learned that the first 231 was already .040 over and I remembered that the second 231 was .030 over. When I opened up the second engine I found that number one cylinder had been open and enough rust had formed that it wouldn't turn over. Once I cleaned it up a little and used liberal amounts of spray lubricant I could get it to rotate, but I think it will need an additional overbore if it's used. The question now is would just overboring one cylinder be worth the cost savings over all six, and just how far will it have to go in order to make it right -- I hope to find out sometime this week.

I have more information about the oil pressure situation as well -- I'll post it in the appropriate place.

Thanks again, and Take Care
SrA Snyder

overboring one cylinder may be a good repair for a car you are going to sell, or may be considered in the case of a cylinder failure in an otherwise good engine. Few engines with a failure are in good condition. When you measure your better cylinders, you will probably find they are pushing the limits of tolerances. If you want a good dependable long milage engine, you should do them all.