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Are 68 vintage 289 and 302 heads/manifolds interchangeable?
My latest cougar, a 68 standard, vin lists as having a 289. The heads and manifold are stamped as being from a 289. I pulled them to have them rebuilt (ends up not being worth it) and the block is stamped with 302 between the valve lifters. Date code on the block is from 68
 

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Yep. 289 and 302 parts are all interchangable. The 289 has a different front cover, balancer, etc but all will bolt to the 302 block. The only real difference is the connecting rods. If you swap them (you CANNOT mix them!) you will change dispacement.
 

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Ehm, Bob. How can you change the displacement by swapping the connecting rods? I thought displacement was dictated by the crank? I can see why you would be changing the compression ratio by using different length connecting rods, but the displacement would still be the same right?
Just curious.

@mbdundee, you might want to mesure the difference between TDW and LDC to find out if you've got a 289 or a 302.
289 should have a stroke of 2.870"
302 should have 3.000" stroke.
Good luck on the rebuild, I'm currently doing one myself.

Cheers!
Matthijs
 

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In 1968 they used 302 castings to make 289's. So most, if not all 1968 289's say 302 on the block. You have to measure the stroke to really be sure.

Heads and intakes will swap with no problems.
 

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Ok, so how do you go about measuring the stroke. I am thinking removing a spark plug, finding TDC, then inserting a small rod and hand turning the engine until it gets to the bottom of the stroke. Then I could measure the distance travelled on the rod. Will that do?
 

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That works, a piece of coat hanger wire does nicely.
 

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Isn't it possible to put 302 heads on a 289 and basically change it to a 296?
John B/
 

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No, that would not change the displacement. The bore and stroke are all that control the displacement. The cylinder head has a combustion chamber that may affect compression ratio if it is a different size but that is not the same as a displacement increase.
 

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Gulf00 said:
Ehm, Bob. How can you change the displacement by swapping the connecting rods? I thought displacement was dictated by the crank? I can see why you would be changing the compression ratio by using different length connecting rods, but the displacement would still be the same right?
Just curious.

@mbdundee, you might want to mesure the difference between TDW and LDC to find out if you've got a 289 or a 302.
289 should have a stroke of 2.870"
302 should have 3.000" stroke.
Good luck on the rebuild, I'm currently doing one myself.

Cheers!
Matthijs
Ooops. Guess I should read before I post. I was so focused on the rods not being the same (the 302 are slightly shorter) that I completely left out the crank. :eek:
Matthijs is correct, the crank is the big displacement changer, but the rods will physically fit although they are not the same, so don't mix them up. Keep 221/260/289 rods on a 289 crank. And 302 rods on the 302 crank.
:)
 
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