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I just picked up a jet boat powered by a 455 Olds with big C heads. Nice engine but the previous owner over revved her, bent some pushrods, broke some valve heads off and badly damaged one head.
I need to put in a temporary engine to use the boat while I go through the 455. I have a sweet 1990 Olds 307. In my research I see that some exhaust manifold gaskets are listed as the same and some are not. Water pump plate gasket appears to be the same. I need a definative answer from an Olds Guru .. will The Hardon exhaust manifolds and water pump plate bolt to the 307? And will the drive coupling (flexplate) bolt to the crank. The engine itself, I'm assuming, will bolt in without any modifications .. Thank you for your time ... Frank in Arizona
 

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I don't know the answer, but ..... seems like a lot of work, setting up and installing a temp engine while you work on the 455, especially since I doubt you'll be happy with the replacement. If you just concentrate on the 455 seems like you'd have it together and back in fairly quick.

Just thought I'd ask .....
 

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I just picked up a jet boat powered by a 455 Olds with big C heads. Nice engine but the previous owner over revved her, bent some pushrods, broke some valve heads off and badly damaged one head.
I need to put in a temporary engine to use the boat while I go through the 455. I have a sweet 1990 Olds 307. In my research I see that some exhaust manifold gaskets are listed as the same and some are not. Water pump plate gasket appears to be the same. I need a definative answer from an Olds Guru .. will The Hardon exhaust manifolds and water pump plate bolt to the 307? And will the drive coupling (flexplate) bolt to the crank. The engine itself, I'm assuming, will bolt in without any modifications .. Thank you for your time ... Frank in Arizona
455 to 307...exhaust it the same.....except for it is in a slightly higher position on the 455 because the block is taller , intake is NOT the same
front of the block is the same....

probably kind of a waste for a swap...you would be lucky to get a ticket on the no wake zone @wot
 

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I just picked up a jet boat powered by a 455 Olds with big C heads. Nice engine but the previous owner over revved her, bent some pushrods, broke some valve heads off and badly damaged one head.
I need to put in a temporary engine to use the boat while I go through the 455. I have a sweet 1990 Olds 307. In my research I see that some exhaust manifold gaskets are listed as the same and some are not. Water pump plate gasket appears to be the same. I need a definative answer from an Olds Guru .. will The Hardon exhaust manifolds and water pump plate bolt to the 307? And will the drive coupling (flexplate) bolt to the crank. The engine itself, I'm assuming, will bolt in without any modifications .. Thank you for your time ... Frank in Arizona
Nope!
 

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Explain..........

I just picked up a jet boat powered by a 455 Olds with big C heads. Nice engine but the previous owner over revved her, bent some pushrods, broke some valve heads off and badly damaged one head.
I need to put in a temporary engine to use the boat while I go through the 455. I have a sweet 1990 Olds 307. In my research I see that some exhaust manifold gaskets are listed as the same and some are not. Water pump plate gasket appears to be the same. I need a definative answer from an Olds Guru .. will The Hardon exhaust manifolds and water pump plate bolt to the 307? And will the drive coupling (flexplate) bolt to the crank. The engine itself, I'm assuming, will bolt in without any modifications .. Thank you for your time ... Frank in Arizona
Please explain the "big C heads" part..........Olds C heads are good heads, but they're not the big heads......Some early ones were 70cc for high comp motors, but most are 80cc chambers with 2.00 intakes...1.625 exhaust.....Explain big....Ray
 

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Opps..i forgot about that...you either have to use a flywheel or make a spacer about half inch thick or grind the the end of the crank down..the rear crank snout sticks through the flexplate so the pto won't mount flat...but jet boat should have stick shift flywheel...and it will look like the boat pattern don't match cause it only goes on one way..and all the flywheels/flex plates are external balance.... here is a page with olds info....note the 307 make 180 hp...they use to come in early 80's cadillacs and ran about as well a a 350 olds diesel


http://www.442.com/oldsfaq/ofeng.htm
 
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