Safe overbore?

[1961 Futura]

I searched and did not find an answer. How much can you overbore the 144/170 block? Would it be safe to go 0.180 to the 200-size piston and get 159/187 cubic inches?

Thanks,

Dave

 

[CoupeBoy]

now I could be wrong here, but I thought the safest overbore was .060 and for anything more than that you had to start looking into having the block sonic checked or sleeving it.

I think you will run into some very thin cylinder walls if you out that far..

From what I remember the recommended way to get 188 cubic inches is to put a 7 mainbearing 170 crank into a 200 block, not sure if there was a 4 main bearing 200, but if there was it would be easier to find a 4 main bearing 170...

-ron

 

[MustangSix]

Since the blocks are pretty much interchangeable, the most cost effective thing to do would be to just get a 200 and use it complete.

Coming up with weird permutations of bore and stroke on a 144/170 are doable, but in the end you have less than 200 cubes that cost a lot more to build.

The downside is, you lose the early casting number on the block, if that's an important consideration.

 

[chad]

I don't know bout E. MI but getting another I6 block is almost impossible in the NE, USA. They're all gone here abouts. Some gotta work w/what they have. I DID find a neutral bal. (was it 157 or) 164 T FW up there tho (not too rare considering all the apps).

 

[rbohm]

8) for the thin wall casting ford blocks, of which the small six is one, ford says the maximum overbore is .040", though most can go .060". any more than that however and you start running into the water jacket. my advice is that if you want to bore your block more than .040", have it sonic checked for cylinder wall thickness to be sure that a .060" overbore is ok. if you can find one, the four main 200 crank will fit your early block, and with a .030" overbore you end up with around 184ci. check with Performance Automotive Warehouse, they have all kinds of stuff you normally cant find. they may have the 4 main 200 crank in stock.

 

[1961 Futura]

This would be for purposes of retaining the original block (C0-coded 144). You can’t find 200-powered vehicles in junkyards around here any longer; but 200s do come up on Craigslist.

Assuming 0.060 is the biggest one can ordinarily go without sleeves, it looks like you get 154 with a 144 crank; 181 with a 170 crank; and 193 with a 200 crank.

I occasionally hear about these supposed seven-main 170 cranks, but I have never heard more than rumors. I know my 1968 170 block only has three freeze plugs, so I assume it’s still a four-main crank.

An early, four-main (1964) 200 crank would be worth acquiring if it came along at the right price.

Thanks fellas. Next up, getting the most from a small-log head!

 

[bmbm40]

That is interesting a 170/200 crank in a 144.
Including overbore 181 with 170 crank and 193 with a 200 crank, I wonder how many cubes the small log and carb could supply? You could use a 170 carb to look original. Are you upgrading the cam?

 

[powerband]

Overboard - overbore?...

I've been running (and tearing around 8) ) for @ 5 years with an over-bore 250, (C6DA) with AMC 258 Pistons. The AMC pistons provide a compression height that essentially zero-decks pistons in the block. Pistons have a@ 23cc D shaped relief that keeps the CR manageable. The AMC pistons wrist pins are a coupe of thous' smaller than the OEM Ford so easily can be adapted. The 258 pistons require an overbore of .070" .