The absolute 'MINIMUM' cylinder wall thickness....

[Jim Brierley]

Originally Posted by BRENT in 10-uh-C

Bob, I agree with you however the print shows the finished thickness size to be 0.250". It does not give a + or - tolerance with that number. Based on the sheer quantity of blocks that were cast, and based on the methods Ford used, my guess their QC was very close on these measurements.

I do have an ultrasonic tester that we use to verify wall thickness, and the tester is calibrated to be within 0.001±" of what the display screen reads.

As far as the "limiting factor between 1&2 and 3&4, the bores are siamesed in most of those areas, so generally speaking I don't think that area is affected much except the upper 2" where the temps are the hottest.

I think your logic about 0.060 makes sense. There is less than 3% difference in cubic inch displacement between a standard bore vs an 0.060" overbore, so the benefit there is negligible ...however sleeving back to 3.875" and the rigidity and/or heat transfer you would gain by properly installing sleeves would likely be huge with regard to cooling.






Hey Jim, Happy belated Birthday last week. To your point, I don't think many rebuilders have ever checked them. Many rebuilders never Magnaflux or pressure test them either simply because it is a time consuming process that most customers don't want to pay for ...unless an issue was found. I think the level of professionalism and the expectations that should be coming from a professional rebuilder in these times are much different than a decade or so ago.

As for Bonneville and a 0.125 over engine, I agree that it has been done successfully however I can refer you to an engine rebuilder whose customer has a 0.060 block that appears to have a couple areas thin enough to produce 'hot spots' for his customer. The amount of lost revenue and time this issue has caused this rebuilder dealing with this troubling.

All blocks are not the same! I have 2 diamond Model B blocks that differ quite a bit in the port area. One has very large intake valves and ports and they are just fine, the other has stock size valves and smoothed ports, not really enlarged. I ran the second one for quite a few years with no problems. I rebuilt it a few years ago and cleaned up the ports using only a sanding drum. When done I noticed a spot in the port, so I picked at it with an awl, and it went thru into water.