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'64 260 V8 Bored to 289?

11K views 27 replies 12 participants last post by  Ivy66GT 
#1 ·
Hello,

I have a '64 260 V8 that needs to be rebuilt. I would like to bore it to a 289.

Will the cylinder walls become too thin if I were to bore it to a 289?

Thanks for the help!
 
#2 ·
The 260 is a different block than a 289, it is a different bore size and can not be bored to a 289, if you want more cubes just find a 302 engine. I think you can use some parts like the oil pan, oil pickup tube, timing cover, etc to make the change work. The 260 heads have smaller valves and ports, so you will not want to use them, use the heads that come on the 302. Watch the balance issue, 28 oz versus 50 oz. My 2 cts. Good Luck.
 
#3 ·
Thank you for that information. The main reason I was going to bore the 260 out to a 289 was part availability. Since the 260 is more rare than the 289, I am having trouble finding a major rebuild kit for the 260, which includes new pistons, rings, camshaft etc. I have found the gaskets for the 260 but not much else.

Do you know of a good resource that might have a major rebuild kit for the 260?

Thanks!
 
#6 ·
No way can you bore a 260 to be a 289. The magic of the SBF engine was a new 'thin-wall' casting technique used to make the blocks lightweight. With the max bore recommended by Ford you could make it into a 266.

A reputable machine shop can find anything you need for a 260 and probably the parts will be cheaper than any kit you might find. I have the 289 version of these pistons in 2 engines and through my machine shop they cost all of $15 each.

https://www.uempistons.com/index.ph...d=1741&zenid=0a10ac7e032303500164c624ef45c870
 
#9 ·
It's easy to calculate the cubes. Personally, would not feel comfortable with that bore. Certainly, it any mods.
 
#14 ·
The 260, assuming all performance mods are equal, will out run the 289 consistently at 0-30mph......I use to wathc my dad/mom race their two cars ....and it was always consistant......dad (after I grew up) explained in detail why this was so.....
 
#16 ·
The 260 gives up a lot of torque to a 289, let alone a 302. But they share the same stroke as a 289, and don't mind revs so with steep gears in the back you can be fast-ish? Ford used them for their indy cars and made big power back in the early 60s with some exotic parts. Keep in mind, even though you CAN rev them to 6500+, you'd need solid lifters and a cam to make that worthwhile, and it would hurt your already sad low RPM power even more.

Arlington, the bore in a 260 is 3.80, compared to a 289/302 which is 4.00 Are you telling me you bored a motor .200, and it somehow lived? Because frankly, I would have said that wasn't possible. That's not .020 over. .200 over. With sleeves, I guess it could be done, but that's pretty pricey!


And that brings everything back to the start. The 260's smaller bore makes it impossible to use big valve heads, because they'll physically run into the edges of the bore, or at least be shrouded to the point where they don't work well. So, stock 260 heads with little valves. And using the stock heads means a stock intake or crazy problems trying to neck down an intake to the tiny ports. The bellhousing pattern is 5 bolt, so most transmissions won't bolt up.

Bottom line? This is a good engineering problem for masochists with deep pockets, but not such a good motor to hotrod, compared to the good ol' 289 or 302 (which are, to all intents and purposes the same motor in most regards).

If you have one in good shape, as I did in my '64 Fairlane, it's kind of cool in a monocle wearing, tip-your-hat-to-the-neighbors as you go by on a Sunday drive sort of thing. I would definitely treasure and try to keep one in good shape if you have it. They're rare now! But if you want to go fast, you'd sure get better results and save a bundle by getting a later model motor. And if you get a twinge of guilt about it not being the original motor, put on the stock air cleaner and valve covers. Few people would ever know the difference.
 
#17 ·
it wasnt done for speed at the time it was done for need.i was taking an evening course in mechanics which lasted for the winter.it was one of those deals where you take the risk and the labour is free.a 65 fairlane came in with 289 that needed a block and we couldnt find one.we had a bar so decided to try a 260 which were plentyful.no cost to us except 5 bucks for the block.i spent 2 evenings on the bar and had a shovleful of shavings each night.the instructor came around with a wrench a tapped the walls to see if they would fall in.love this kind of stuff looking back.pronounced it good to go.we kept track of the car for 2 years.the reason i bring this up is i drived me crazy to see people on these sites telling others to throw away their 260 because its already .030.any 260 can go at least 100 over.
 
#20 ·
lol Arlington, that is nuts. Had no idea the cylinder walls were so thick on the old 260's. Thanks for sharing. =)


Edit: Did a bunch of reading tonight and research on this. Arlington, you must've had a "unicorn". Ford was really bragging about their 'thin wall casting' when the little Windsor 221 and 260's came out - and they meant it! A lot of the 260's actually have problems with overheating even a .030 overbore. The factory recommended .020, with .030 being the absolute limit. For your cylinder walls to be able to handle a .2 overbore means something crazy happened with your motor. That thing must've been HEAVY!

Anyway - the whole subject of overbores is always kind of a 'hot topic' - pun intended. What I usually see is drag racers swearing that an .080 overbore is just right and can be done on most blocks, and then you have the closet engineer crowd who cringe at the thought of going more than .010 for fear of angering the Gods of Reliability.

I suspect the factory's recommended .030 IS probably conservative, and thanks to core shift, not all blocks can even go that far. Since racers tend to have old engines lying around and are adventurous, if a big overbore blows up, it's not the end of the world anyway. With these engines becoming more and more rare, trying to be conservative with the bore so as to spare a rare old or possibly original engine makes more sense. If you have your own machine shop and it's your time and labor, I can sure see trying to take an engine farther than people would normally recommend. But I also wouldn't be surprised to see it run hot, have trouble with ring seal, and potentially have problems not too far down the road either.

So for those of you willing to buy weird piston sizes for big bores, and chance total engine destruction in the pursuit of greater horsepower glory, I salute you.

And for those of you meticulously resurrecting old iron with great care, caution, and attention to detail, using the minimalist approach to engine boring, kudos to you as well.


And as for you, Arlington, your "not a 289" 4" bore 260 is a pretty cool story.
 
#21 ·
thanks.thanks for not calling me a lyermost dont believe me.we took the car for a test drive and it wasnt hot.the car was close to where our instructor lived and he kept track of it for 2 years.i bored 6 engines that winter best time of my life.when your 22 and have a boring bar it doesnt get better.i wanted a bar for the rest of my life but more money than i had.3 years ago i got an old van norman 777 better late than never.they are showing up now as a lot of shops have closed.
 
#22 ·
IF the 260 block has THREE freeze plugs in the side and the "spread" motor mount bolt holes , the block will go to 4.000. Many blocks like this were used in Sunbeam Tigers . If you are worried , you could have the block sonic checked. I have done over TEN of them and never had a failure. It is important to remember that you are removing HALF of the total increase. People freak out after .030 over bore on original block material but STUPIDLY put eight sleeves (.250 or more bored out to do so) to go back to standard. Removing THAT much material severely weakens the block integrity. Same goes for cranks. Guys are worried about a thirty under crank , but have NO concern when it is offset ground to "standard" ( 2") small block Chevy. Then it's a stroker and all they hear is "standard despite ONE side being ground .123 "under".
 
#24 ·
A two freeze plug block "should" be sonic checked when going beyond .040 because of rust on the "back" of the cylinders . I have seen the early blocks ( back in the day) go to .060 but 50+ yeas later erosion in the water jackets "could" cause cylinder wall "thinning".
Randy
 
#25 ·
I found a 260 from a 'Fairlane in a pasture' to make the '260' on the fender of a 64.5 tell the truth - it had a worn out 289 to make it run so it could be sold to a sucker (my brother).
Anyway... I feel your pain - new over-size pistons are REALLY pricey - I got lucky and found enough in the 'aluminum dumpster' at a scrap yard to replace the cracked-skirt ones - and I imagine you aren't going to find '030 over' pistons in a salvage yard.
So... it's a tough one. Big $$ for .030 pistons and safe -or- much less $$ for 289 pistons and wondering every time you punch it if this is going to be the time when a wall blows out. I rebuilt mine with new cam/valves/etc no problem, so pistons are really the only bugger (except getting new bell housing - which you don't have to do). :) Good luck!
 
#26 ·
Maybe you are buying in the wrong places? The last set of .020" over 289 pistons I bought were $15 each from the machine shop that installed them. The .030's I bought before that were only $13. Rock Auto today sells some for less than $10. I can't call that pricey. Nothing fancy but, except for size, the same as what Ford put in the engine originally. Compared to the rest of the engine overhaul stock type pistons are fairly cheap.
 
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