289 vs 302 heads

[ryoungbronco]

Can I use my 289 heads on my 302 block? Is there any difference?

 

[br0nc0xrapt0r]

I have heard it would give you a higher compression...

 

[Viperwolf1]

Yes they will bolt on. The chamber size is likely to be smaller on the 289 heads so expect a higher compression ratio.

 

[ryoungbronco]

Is a higher compression a good thing? Sorry for my ignorance, I only have limited experience with rebuilding engines. That is why its good to have a mechanic in the family.

 

[taipeichris]

Not all head is equal...

 

[El Kabong]

Higher compression helps add horsepower, but requires higher octane gas to prevent detonation. Too high is pretty hard to find fuel for anymore.

 

[Oatmeal]

What year 289 heads? Early '66 and older heads use a different pushrod/rocker set up than mid '66 and up. The early heads use non rail type rockers and close tolerance pushrod slots machined into the heads that act as guides to keep the rockers aligned on the valve stems and require hardened pushrods. However, all 289 heads have adjustable valvetrains. Just something to be aware of---------Hans

 

[ryoungbronco]

The 289 heads are from a 68 and the 302 is from a 74.

 

[Broncobowsher]

Really need casting numbers off each head you are considering. Some of the 289 heads were as small as 49cc with 1.67" intake valves. Others were twins for 302 heads.

Short answer, yes 289 heads will bolt right onto a 302 block. But what it takes to get some 289 heads to work on a 302 block and how it will run afterwards is a huge question.

 

[Broncobowsher]

OK '68 289 heads are listed at 63cc
The '74 looks like it will be 58cc heads.
So you will be dropping compression/performance/economy.
Looks like you will need the adjustable valvetrain as well,

 

[broncnaz]

If the 68 289 heads have the 63cc chambers then they probably also have non adjustable rail rockers as well. Most 289s after 66 will have rail type rockers non adjustable rockers. Usually only the HiPo engines got the adjustable rockers Also 74 302 heads can also be 63cc. As was said we need casting numbers.
Overall the newer 74 heads would be a better choice as I believe they should have hardened exhuast seats to run unleaded gas unlike 289 heads which just have standard seats. Changes in compression ratio actually result in very little HP gain. But will allow a bigger cam to be used and thats where you really gain the HP.