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Is it possible to convert a 289 to a 302?

1102 Views 22 Replies 16 Participants Last post by  Woodchuck
Hey everyone, I am back and I was reading up again as I have finally gotten more time and money. This time I was thinking if I can convert my 289 to a 302. I was reading that a cam, pistons, and heads would do it but I am not sure as I still feel new to everything. I have a path in mind for my car i just ideally want a 302 since I have always wanted a variant of the 5.0. The heads I see on my rebuilt 289 are market "66" so I assume its from 1966 if that helps at all with anything. I just wanted to know what is possible since I have some guides provided to on how to build out my 289, also I was wondering if there are any kits so I don't have to pick and choose parts for the conversion or just to see the bump in power I have asked in the past. Thank once again, and I look forward to reading your answers.
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That's all I need for my 289 to be a 302? is it really that little?
Yep.
The earlier 289 heads are actually better with a smaller combustion chamber and without the Thermactor bumps inside if you have those.
 
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1965 2+2 Vintage Burgundy A-code C4
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It’s that easy, plus you need new emblems for your fenders and a sticker for your breather cover. It’s not nice to fool people….
 

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What's the fixation on the 302? The 289 is a very capable motor. A 302 is a variant of a 289! If your gonna spend money on a crank, rods and machine work. Why not just go 331 or 347?
I plan to make my original 289 into a 331 stroker one day 😄 It has never been bored over and it a ‘normal’ everyday Mustang with a matching VIN on the block (1968).
 

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302 and 289 use the exact same block, cam, pistons, valve train, tin….just crank and rods are different. You’re just not gaining much going from a 289 to 302 for the cost involved, so I don’t understand the motivation. 289, 302, 5.0 are all variants of each other.
 
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It doesn’t matter WHY the op wants to go from 289 to 302. He can if that’s his desire. Question asked and answered. Good luck with your quest!
Sure it does. It could be for all the wrongs reasons and misunderstandings of what he’d be gaining. There have been a lot of times I have ended up not doing something because my reasons for wanting to do so were wrong.
 

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289 heads have smaller combustion chambers than a 302. If you run 289 heads with 302 crank and rods you will significantly increase the static compression.
A 302 only has 4.5% more displacement. Compression would go up less than a half point.
 

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The bigger advantage of the 302 is when you get the later 302 with the roller cam, etc. Don't assume that adding a few cubes to a 289 is the same as a later 302.
 

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1964.5 Mustang I6 170 C4 Transmisson
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Discussion Starter · #18 ·
What's the fixation on the 302? The 289 is a very capable motor. A 302 is a variant of a 289! If your gonna spend money on a crank, rods and machine work. Why not just go 331 or 347?
yea thats what I am shooting for now, a 347, just trying to get a decent build from it
 

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Discussion Starter · #19 ·
302 and 289 use the exact same block, cam, pistons, valve train, tin….just crank and rods are different. You’re just not gaining much going from a 289 to 302 for the cost involved, so I don’t understand the motivation. 289, 302, 5.0 are all variants of each other.
oh ok, so better just to shoot higher. A 347 is what I have been eyeing.
 

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Discussion Starter · #20 ·
Sure it does. It could be for all the wrongs reasons and misunderstandings of what he’d be gaining. There have been a lot of times I have ended up not doing something because my reasons for wanting to do so were wrong.
I will not lie, it is because of misunderstanding, I thought I was much more limited on what I could do, but after learning I can make a 347 from it that has my attention much more.
 
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