"Ran when pulled"

[T56MaxTorq]

Hmmm... looking at the 3rd pix in the original post, the piston at the far right appears to have the valve pockets rotated 90 degrees from the normal orientation. WTF is up with that? And the valve pockets in the 2nd pix are also not in the right orientation. Sorry, you gotta see what is up there; I'd look underneath and then pull them. Something is definitely not right if I am seeing these pistons correctly.

No, it is not normal at all to have different pistons in an engine. Something is up and you need to partially tear it apart. Having the stock shim gaskets is meaningless as far as being a factory engine; someone could have just thrown it back together with old, used gaskets.

Those aren't valve pockets. That's the flash from the camera off the cylinders. I know this because you can see the small dimples in the piston top that face forward on every magnum engine. Magnums don't use valve relief pistons.

As for boost, myself and lots of folks have ran oem pistons to 10 lbs boost as long as the ring gaps are wide, like .030" wide, the fuel rich, and the timing low.

 

[Duece]

How much boost are you thinking of? If you are going beyond the range of around 7-8 lbs of boost, then I would be looking at a strengthened bottom end. And IMHO, stock type cast pistons are out of the question; you might get by with them for a very low boost use, but maybe not. I have run both forged and hypereutectics in rally 4 bangers with 14-15 lbs boost with no problems, but forged is the preferred type.

BTW, 318willrun's comment on the piston tops is what made me look more closely. So give him the credit. And I sure would like to know what is up with those 2 pistons, so let us know when you find out.

Wont be back in the shop for a few days but I will let you all know what I find when I start pulling it apart.

I was only thinking of running 6-8psi, nothing crazy but since I am going to be re-doing the bottom end it probably is a good idea to strengthen up the bottom end a bit. I always get a bad case of "while I am at it" and was trying to avoid it with this engine, but since I have to tear it right down I might as well do it right and build it to last.

Is there anything else I should be looking at upgrading besides the pistons on the bottom end?

 

[Duece]

Those aren't valve pockets. That's the flash from the camera off the cylinders. I know this because you can see the small dimples in the piston top that face forward on every magnum engine. Magnums don't use valve relief pistons.

As for boost, myself and lots of folks have ran oem pistons to 10 lbs boost as long as the ring gaps are wide, like .030" wide, the fuel rich, and the timing low.

Feel like this is turning into a "whats wrong with this picture" game but you are right, the dimples are all facing the same direction.

When I get some time back in the shop I need to have a very close look at this to see what is up.

Thanks for the sharp eye

 

[T56MaxTorq]

Feel like this is turning into a "whats wrong with this picture" game but you are right, the dimples are all facing the same direction.

When I get some time back in the shop I need to have a very close look at this to see what is up.

Thanks for the sharp eye

You're going to want arp rod bolts and main studs if you want to play with boost. That's about it. ***** pretty strong down there, the mains are big and it spreads the load pretty well. Turbos are a little easier on the bottom end than NA, and super chargers are the worst.

 

[318willrun]

Tearing it down and rebuilding is always the BEST route. However, I believe the guy, that it ran good when pulled. the notches on the pistons are going in the right direction for the assembly of the motor. I sticking with my guess, that those are all factory pistons. But if you are going to add boost, then I would certainly do the bottom end. I would also do it with a forged crank..... from a 273, or late 60's 318 truck motor (easiest places to find a forged crank without breaking the bank).

 

[Duece]

Tearing it down and rebuilding is always the BEST route. However, I believe the guy, that it ran good when pulled. the notches on the pistons are going in the right direction for the assembly of the motor. I sticking with my guess, that those are all factory pistons. But if you are going to add boost, then I would certainly do the bottom end. I would also do it with a forged crank..... from a 273, or late 60's 318 truck motor (easiest places to find a forged crank without breaking the bank).

This motor/tranny was supposed to be a temporary fix to get me back on the road and give me a chance to get all of the other stuff done first (wiring, suspension, rear end). I have another 318 block and a 904 core that I was going to build down the road and then transfer over the top end from this one before adding any boost. Part of this project was to play around with parts so I could learn the things I always wanted to and let my boys tinker with it too, I have embraced that this will always be a work in progress Living in Canada I will only get to drive this car 6-7months out of the year so I need something to do through the winter

If I everything looks ok with this bottom end, I still would like to drop it in with the top end refreshed and see if I cant get a summer of cruising out of it at least. The boost is long term goal, just thought that if I have to build a bottom end now then I better do it properly and plan accordingly

 

[T56MaxTorq]

Whatever you do, if you ever run boost, you MUST make sure BOTH ring gaps are nice and wide. Cannot stress the importance of this.

 

[Duece]

Whatever you do, if you ever run boost, you MUST make sure BOTH ring gaps are nice and wide. Cannot stress the importance of this.

Thanks, will definitely remember that!

Just for my own curiosity though, why is that?

 

[T56MaxTorq]

Whether it's boost, nitrous, alcohol, you are adding additional heat. This additional heat will tighten the ring gap. It could get as bad to where the ring ends butt together and the top of the piston will break right off. Happens all the time.

 

[nm9stheham]

Those aren't valve pockets. That's the flash from the camera off the cylinders. I know this because you can see the small dimples in the piston top that face forward on every magnum engine. Magnums don't use valve relief pistons.

As for boost, myself and lots of folks have ran oem pistons to 10 lbs boost as long as the ring gaps are wide, like .030" wide, the fuel rich, and the timing low.

Thanks, LOL I just could not tell. 'splains the odd angles. (Yes I know on piston top types; that it why I questioned it; some looked pocketed and the rest flat! I assumed the OP had it right in front of him.)

The eventual turbo-ing changes the long term game anyhow. OP, you can go either way: short term or long term planning. Nothing wrong with either approach; many just choose to do it once. Getting a summer of fun is a good goal, AND, if you keep it simple, it will be an easier learning experience for you.

I would look carefully at that one cylinder rust spot and see if it is etched deeply into the bore once you get the rust all off. Make sure you get ALL the rust particles off; most metal oxides are very good abrasives.....

 

[Duece]

Thanks, LOL I just could not tell. 'splains the odd angles. (Yes I know on piston top types; that it why I questioned it; some looked pocketed and the rest flat! I assumed the OP had it right in front of him.)

The eventual turbo-ing changes the long term game anyhow. OP, you can go either way: short term or long term planning. Nothing wrong with either approach; many just choose to do it once. Getting a summer of fun is a good goal, AND, if you keep it simple, it will be an easier learning experience for you.

I would look carefully at that one cylinder rust spot and see if it is etched deeply into the bore once you get the rust all off. Make sure you get ALL the rust particles off; most metal oxides are very good abrasives.....

Once I get a chance to get back into the shop, I will take a closer look at those weird pistons and see exactly what the deal is there. I will update everyone with what I find and how that cylinder cleans up

Really appreciate the keen eyes and all the help!