Replacing pistons w/o pulling engine?

[jayro]

So here is what I'm thinking. I keep kicking myself for not intalling HC pistons when I built my cammed 3.2 due to the loss of cranking compression and it is now an interferance engine. If I pull the heads and oil pan couldnt I remove the piston/rods with the engine still in the car? I could then replace the stock pistons with HC ones.

As far as balancing...I know they would need to be rebalanced, but I think this can be done without the crank. Isn't the crank zero balanced and then the rods/pistons are balance seperate? If so then I should be able to have them balanced and then reinstalled with new rings.

This would also give me the ablility to send my heads to be ported.

Is my thinking correct, or am I way off?

 

[Lorenr]

Be Carefull

You can replace the pistons with other pistons providing they weigh the same. They should be within a couple of grams.

To find out, get a gram scale. Weigh your old pistons and get an average. If this number is less than the weight of your new pistons and hopefully it is, then take the new pistons to an engine shop and have them lightened to equal the weight of the old pistons.

If the new pistons weigh less, then you must remove the crank. You need pistons, pins, locks, rings, rods, rod bearings, crank, balancer and flywheel to completely balance an engine.

While nice to have the weights right on, 4 or 5 grams is not a big deal. You can also juggle weights of pistons and rods to get there.

:swing:

 

[jayro]

If the new pistons weigh less, then you must remove the crank. You need pistons, pins, locks, rings, rods, rod bearings, crank, balancer and flywheel to completely balance an engine.

While nice to have the weights right on, 4 or 5 grams is not a big deal. You can also juggle weights of pistons and rods to get there.
:swing:

Okay, so if the new pistons are heavier I can bring them in with the old ones and the machine shop can just lighten them until they are identical to the old ones?

As far as the other stuff, I had the entire assembly balanced when I did the rebuild. I guess I am mistaken then, I thought the crank was balanced independently from the rods/pistons. I know in these cars that the flywheel and crank pulley are not used to balance the rotating assembly in any way.

 

[rubydist]

the pistons only come out the top, unless in pieces. they will not go in from the bottom.

 

[yamahaSHO]

Forged pistons will be lighter.

Honestly, pull the motor.

 

[kevinspann]

Yep. You can go all full retard with it if you want, but by the time you pull the heads and oil pan, there ain't much left. At which point you could have just had it out of the car.

 

[jayro]

Yeah, I googled some stuff about balancing ect. If the forged are lighter then the whole thing is a no go. Ive pulled heads a couple of times and done rod bearing a few times. Thought it would be easier getting them out that way, plus not having to get more gaskets etc. Just brainstorming. Guess the motor is staying as is for a while. Thanks guys.