Rod/Piston swap question
Thread Starter
Burning Brakes
Joined: Feb 2003
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From: Rolla Mo
Rod/Piston swap question
Can this be done with the motor in the car? I am going to be replacing heads soon, and if possible I would like to upgrade to forged pistons and rods while the top is already apart. I REALLY don't wanna pull the motor. I realize this may not be the "preferred" or easiest way to do it, but can it be done. I have plans for more power in the future, wanna get ready.
Thanks,
Doug
Thanks,
Doug
Large Impressive Member
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
It can be done easily enough but, what do you think the chances are that your block will meet all specs such as maximum allowable wear, out of round and taper? If you have plans to increase power, you're not going to want to compromise on such things at this point. In other words, pull it out and do it right the first time. If you're planning on big power, you'll want to machine everything necessary to optimum specs to prevent problems later.
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by Dougs 90
Block has less than 5000 miles, probably closer to 2000 actually. It is a crate motor and I regret not doing it when she went in in the first place.
Thread Starter
Burning Brakes
Joined: Feb 2003
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From: Rolla Mo
Well I am considering getting a few things from blowerworks. Since I have a head change planned I have the opportunity for a larger chamber so I can get a lower CR ratio. I figured I would go ahead and drop in a set of forged rods and pistons at the same time. The engine came with a forged crank so I was hoping to be able to just drop in a balanced set. Then I would be sitting at around 9.0-9.4 CR with a forged bottom end. I figured I would check the chambers for roundness etc when I pulled the heads and decide there if I can go forward or not. I figured since the top was already opened up, I could drop the crossmember and the oilpan and go to town, at least hopefully. Isn't it amazing how one thing just leads to another, and another.....Any tips or tricks to offer?
Thanks,
Doug
Thanks,
Doug
Large Impressive Member
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
I just had another thought though. The crank really should be rebalanced for the weights of the new rods and pistons.
Team Owner
Joined: Dec 1999
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
If you are building a competition motor or just one that will see hard use, the rod/piston assembly should be balanced to the crank especially if the motor was balanced in the first place. Some machinists will add or remove weight on the crank throws to get the balance right.You could probably match each individual new rod assembly to the weight of the one coming out for each hole but I think you would be better off in the long run to pull the crank and have the whole rotating assembly re-balanced.
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Race Director
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From: Merritt Ils Fl
I venture you are near "penny wise and pound foolish". If you have plans for this thing which will increase the overall stress it should be balanced. New pistons=new rings which will require the cylinders to be honed. If you are using molly or plasma rings the block should be set in a boring machine to insure all the holes are properly finished and round. Last, With the block undressed to the point you will have it pulling it is a simple matter. In fact it might actually be quicker.
Team Owner
Joined: Sep 2002
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From: OBAMA IS HITLER
Doug, if I were you I'd most definitely heed ALL of the previous posts together. Pull that engine! Have a machine shop work it all over, along with re-balancing everything to the crank.....and this is whether whether you're going to drive it hard or not. The extra $500-$800 in machine shop work is really mandatory with what you have planned. Small price to pay for a heap load of trouble avoided
Melting Slicks
Joined: Mar 2002
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From: The Colony Tx
It has been about 10 years since I pulled an engine, 72 Vette, so if I am wrong someone please correct me. I figure you are looking at maybe 2 hours additional labor on both ends to pull the engine. Now, ask yourself if it is worth that extra time NOT to lay over and under the car do do what you are planing to do with the engine in the car.
Yes you will need to rent an engine hoist and maybe an engine stand. But at my age I would rather spend the extra money and work standing up. It also makes it easier to insert the pistons and make sure you don't scratch the crank by accident, even using hoses on the rod bolts.
Yes you will need to rent an engine hoist and maybe an engine stand. But at my age I would rather spend the extra money and work standing up. It also makes it easier to insert the pistons and make sure you don't scratch the crank by accident, even using hoses on the rod bolts.
Thread Starter
Burning Brakes
Joined: Feb 2003
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From: Rolla Mo
Thanks, you are all very correct! Thanks for keeping me on the straight and narrow! I was thinking what a great shortcut, quick fix! Like those ever work, Do it right or don't do it at all!
Thanks everyone!
Doug
(what was I thinking?)
Thanks everyone!
Doug
(what was I thinking?)
