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Late 71' Ambo

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shifty6980:
After waiting a year and a half to receive my new pistons and cylinders for my late 71' Ambassador 750, I discovered that they were for a 72' El Dorado 850.  Can I use them without changing out the block, crank, and piston connecting rods?

Antietam Classic Cycle:

--- Quote from: shifty6980 on January 20, 2015, 05:48:53 PM ---After waiting a year and a half to receive my new pistons and cylinders for my late 71' Ambassador 750, I discovered that they were for a 72' El Dorado 850.  Can I use them without changing out the block, crank, and piston connecting rods?

--- End quote ---

No. Ambassador pistons are quite different than Eldorado pistons. The diameter is the same, but the pin is 4mm closer to the crown on the Eldo pistons, not to mention the difference in the crown shape. Ambo is domed, Eldo has a low "plateau".

Did you order the wrong items or did the seller ship the wrong ones? I'm curious what your engine number is.

FWIW, you wouldn't need to change the block and connecting rods, *just* the crank.

Kiwi_Roy:
I'm sure someone here will take them off your hands.

shifty6980:
It doesn't have anything to do with the shape of the pistons, but rather the length of the stroke.  increasing the size of the piston and cylinder equates to nothing more than boring out the cylinders.  My question, which I believe you answered had more to do with the crank and the connecting rods than the actual piston or cylinder size.  Can the stroke of a 750 handle an 850 cylinder and are the connecting rods long enough to compensate for the increase in CC?

Antietam Classic Cycle:

--- Quote from: shifty6980 on January 20, 2015, 08:28:16 PM ---It doesn't have anything to do with the shape of the pistons, but rather the length of the stroke.  increasing the size of the piston and cylinder equates to nothing more than boring out the cylinders.  My question, which I believe you answered had more to do with the crank and the connecting rods than the actual piston or cylinder size.  Can the stroke of a 750 handle an 850 cylinder and are the connecting rods long enough to compensate for the increase in CC?

--- End quote ---

Both the Ambassador and Eldorado have the same exact 83 mm bore, the Ambo has a 70 mm stroke, the Eldo 78 mm. Connecting rod length is exactly the same. If you install the Eldo pistons in an Ambo with the stock 70 mm stroke crank, the pistons will be 4 mm from the top at TDC. Really low compression to say the least.

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