New to the forum. any help

[venom-amx]

I own a 69 AMX with a 390cid. I just spent quite a bit on building the motor. It was bored .060 over due to rust on the walls. Everything on the top end was replaced. I retained the original crank,rods and heads, they were mildly ported. Big cam,roller tip rockers,pushrods,studs,oil pump, pickup, oil pan,intake, lifters etc....I found this forum and read about losing oil preasure when it warms up. I was told by the machine shop building the motor that the pistons were a custom order, and that all the bearings that were installed would have been a lot cheaper if the motor was a chevy. Which leads me to believe that the motor is at amc spec. What else can I do to prevent this from happening to me. Thank you all for loving the AMX!!!!!

[donsjave]

Make sure that all clearances are within AMC Specifications as outlined in the Tech Service Manuals applicable to the year of the motor. This includes the bearings with the rods and cranks, the clearances for the oil pump gears, and the installation of a new oil pump pickup tube. It has always been avisable to purchase a new timing chain cover for the motor. The timing chain cover incorpates the oil pump gears and seems that this area of the cover has wear. Not a real big issue I guess, but when I have done my motors, I have insisted upon the installation of a new timing chain cover to preclude any possibility of problem with the oil pump caviites.

[Big Bad AMX]

Just to clarify before a full reply; are you saying your freshly rebuilt engine is now losing oil pressure and you suspect the engine builder used Chevy specs on reassembly? (you wrote AMC specs).



.

[venom-amx]

Thanks for the reply. I was told that everything was for that motor. All the bearings, rebuild kit for the oil pump, new oil pick up. I was told that the pistons had to be special ordered to the new bore. The motor is not back in the car yet as I am trying to find a new converter for my m12 tranny. 2500 stall. I just dont want to have that problem with oil pressure. Since the motor has not been installed yet I was wondering if there is anything else to look out for.

[Big Bad AMX]

Ask the builder for the specs the rods and main bearings were ground to. If you want to double check then pull the pan, pull one rod cap off and one main cap and read what is stamped on the bearing. Mic the rod journal and main journal and do the math to see the clearance. Max clearance on all bearings is .0015.

It's a bit trivial and I suppose I should let it go but it's a pet peeve because I hear it too much; The comment from the builder about a Chevy being cheaper is true - a small block Chevy is the cheapest rebuild you can do. He could tell his customers who own Ford, Mopar and other GM brands the same thing - but I bet he doesn't. Cheaper to rebuild than any V-8. But so what. Cheaper isn't better. An AMC rebuild should be similar in cost to rebuilding a Pontiac V-8 or Oldsmobile big block or Buick Big Block of the same era.


.