Hello. Trying to decide on what to do with the 428 SCJ engine in the '69 Cobra.
Here is what I know:
Compression is good in all cylinders except #4 which is 150. I determined it is a leaky exhaust valve.
Leak down test revealed very good results with less than 10% loss at 80PSI on all except 4 which is about 15%
Main journals .010 cut. Plastic guage says .0015 clearance. Appearance is perfect smooth and polished.
Rod journals .020 cut. A little scratched but not excessive. Journal looks perfect. Plastic gauge says .002 clearance.
Engine has been bored over .040. Has 2287P pistons.
Heads and intake are stock CJ.
The reason I dug into this is that I had no prior knowledge of the car before I bought it 2 weeks ago.
Had an intake manifold lead which leaked coolant into the oil. I checked the life on the hydraulic lifters as exactly factory CJ.
What would you do going forward? Want a dependable, good running car. More power is always good. Concerned about the .040 bore. Willing to put $ into this, but don't need a 550 HP engine. 4 Speed trans with 3:50 gears which I inted to change to 3.91.
Any thoughts are welcome.
There are a few of us who do concours or near concours builds for owners like you. I would look up Anghels Restorations and look around to see how far you are from original. If you are very close, nothing wrong with going that way, in fact, if you have all the CJ bits, especially things like fittings and PCV setup, carb, etc, you probably should restore it. If you aren't, you get to choose to try go that way or go with a slight hot rod.
As far as what you see, it would be best to have the block checked for taper and square. If it was recently rebuilt, has straight cylinders, likely a square deck, torque plate clean up, replace some push in oil plugs with NPT, and maybe get away with just a re-ring, but it depends what you find. A c-scratch block is "usually" better than others, but should sonic check, then we can get pistons at even .005 larger and just torque plate hone to save cylinder wall.
The crank should be measured more accurately than Plastigauge, but depending on taper, runout and clearance likely reusable
As far as improving, a hydraulic roller cam is always good, adds about 1500 to the build as you build the heads too, best to do some work to the heads to get a good valve spring. However, I really like NOT using aftermarket rockers on a milder one with stock valve covers. End stands, hardened shafts, good hyd rockers keep things light, roomy and last forever. FWIW last all-iron concours 428 hyd roller I did was 485 HP and pump gas / vacuum brakes, it had a little money in it, but won it's class in Lime Rock too, so it looked and acted very stock
https://www.youtube.com/watch?v=mtgO0UFeXIAIf staying flat tappet, if you can determine the cam now, some bluprinting to get things right, degreeing the cam, and a few other tricks can make them run well too.
In the end, think hard what you want the car to be, then find someone who can help you find the target. Welcome to the forum