Hi all, I have a 1966 289 and a 1972 302. I'm trying to decide which one would be better to rebuild. What, exactly is the difference between the two? If I put the 302 heads on the 289, do I now have a 302?

Thanks in advance.

 

The main difference is in the crank and rods. The 289 has a 2.87 stroke compared to 3.00 for the 302. The rods are different lengths also. 5.155 for the 289 vs. 5.090 for the 302. They use the same pistons. Using the '72 302 heads on the 289 would be a downgrade, since they are lower compression and I believe would have the bump in the exhaust port for the thermactor system ( air pump ).

 

The 302 has a longer stroke than the 289. Both had 4 inch pistons. The 289 generally had a better reputation because it had a higher compression ratio. But if you put flat-top pistons in the 302, it will perform just as well.

 

Awesome, thanks. I won't bother dressing up these heads then. What I'll do is pick up a set of 351W heads. What are your thoughts on that? I also need to machine my crank but maybe I should use the 302 crank instead. (if I have the clearance)

 

Just so you know, heads don't change the engine size, only the bore and stroke do.


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Use the 302 crank in the 302 block. The 302 block has longer skirts in the bottom of the bores for better piston control with the longer stroke. You can use the 351w heads with special head bolts. 351w's have bigger valves if they are 77 or earlier, but bigger chambers also which will lower compression a little.

 

Ummm... guys you are forgeting that using the 289 heads on the 302 will improve the compression ratio. They have (I believe) 58 cc chambers vise 64 cc. Also a little port work (gasket matching only) and installing new larger vavles will blow away the 351W heads. Another added bonus is that you wont have to buy the adapter washers to install the 351W heads on the 302. Just my thoughts.

 

[updated:LAST EDITED ON 17-Oct-02 AT 01:12 AM (EST)]Good advice regarding the heads, Mark. Actually, the C6AE heads have 54cc combustion chambers! They have broached push-rod holes, so he'll need to use his 289 pushrods, too. Otherwise, he's good to go. The 302 heads are lo-po.

These 289 heads really respond to some mild porting, too. Summing up; use the 289 heads and pushrods on your 302 shortblock.

Edit: These heads are the Ricardo quench design heads. Zero-deck the pistons in the block and use head gaskets in the .038-.045" range. IIRC, these heads had decent swirl in addition to the huge quench area. (I have a pair of these heads in storage ).

 

Actually, I don't have 289 heads. All I have are the 302, which I take from all your advice, that I will scrap. I also am tempted to plug the oil drain holes at the top of the block under the Intake. Has anyone attempted this? Was there any improvement? Will the cam get enough oil that way?

Thanks.