Minimum cylinder wall thickness on a 289?

sstcobra_old · May 31, 2007 at 3:16 AM

A few weeks ago, I had my newly rebuilt '66 motor fail about 30 minutes after firing it up. Upon inspection, there are 2 cracks in the #1 cylinder wall. I plan on having the walls thickness tested tomorrow. Can someone tell me the minimum acceptable wall thickness for a 289? The block was 40 over bored, so I know this was close. But nothing speaks like data.......I wish to be able to compare the actual measures to the recommended minumum thickness.

64.5 07K_old · June 2, 2007 at 12:24 PM

Real sorry about your failure! The way Ford engine

parts are going for now, it's not going to be cheap

to get it going again....

I don't have any data but, I had my 5-bolt 289 K

rebuilt with the bores +.030 and once the outside

temp was 95+, cooling was barely marginal. Had to

use a 3-core high efficiency radiator which should

be run with the hotter running 302/5.0 retrofit

engines. Still runs a bit warmer than normal but,

cooling is better. My thots are one or more of the

bores has spots approaching min thickness and the

water jacket is super heating, steaming at that point.

Those spots would be the best place where cracks, fails

originate. That doesn't totally negate the fact that

it might have been unrelated to bore thickness, just

a metal failure.

Beagle1_old · June 2, 2007 at 2:04 PM

I doubt you will be able to find data for thickness, but most likely you can for Maximum Overbore. Moneymaker would probably have the most knowledge on this. I'm willing to bet even the service manual does.

Mine had to have 8 sleeves put in because it sat outside uncovered for 10 years and some cylinders were filled with water.

3 years now and it's been fine. Took a while for the rings to seat due to the hardness of the sleeves.

My Dad has had many a flathead break through at .060" OVERBORE and some go .120" no problem. Could be you had a thin casting?

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