Advice needed from some of you folks that build your own engines. A little background. I built a straight eight engine. Cam, Head re worked. Bored and forged pistons. Ran real well. Seemed to get better each time it was driven. Right up until the coffee colored yuck started appearing. After doing all the testing and inspection I could without tear down , decided to bite the bullet and pulled the head. #6 cyl has a crack!. OK, I pushed the limit on the bore. Without testing. Now I don't know if only one cyl had a thin spot, or if all are on the ragged edge. So need to KNOW before sinking anything into it. BUT, have found no one in the area with a sonic thickness tester. And shopping for one of my own, I find prices all over the place. $100.00 to $4000.00 +. What would you guys do in this situation? Thanks Ben
Are you just looking at automotive machine shops for the sonic testing ? You may need to find a company that does structural testing on man lifts, sky jacks, crains, hoists etc. They may not want to do it as it’s not in there wheel house but you should be able to find someone.
I have a sonic tester that I bought online. I am sure that it is made off-shore. I had reservations about the accuracy of it. I also could find no one to sonic test my engine, so I bite the bullet and bought my own. I checked this tester against known thickness's of medal, stuff that I could get a mic around and knew how think it was. I was amazed at how accurate this little hand held machine was. I think the one I bought was $139.00. The one thing I did do to it was lightly file a contour to the sensor as I also was checking cylinder bores.
The worst that could happen is that you might have to sleeve all the cylinders and bring the sleeves back to match your pistons. Buy a cheap tester and see what happens.
If there is a university around with a metals lab they may have a ultrasonic thickness tester. I did ultrasonic thickness testing for years in boilers, piping etc. It is very difficult to get a full scan and it is possible to have isolated thin spots due to pitting or casting. The UT readings will give you a good idea on the average wall thickness and may help to see if there was a casting core shift. To do proper readings the UT meter needs to be calibrated using a coupon of the same material. We had stepped gauge blocks for different alloys as the signal travels at different speeds in the metal. The device actually measures the time that it takes for the signal to reflect off the the back wall of the material to convert time to thickness. The UT probe is put on the gauge blocks at a thickness closest to the thickness to be tested and adjusted to read the measured thickness. UT testing gives a good representation of the wall thickness to see on average if there is enough metal to have a sound engine. It is impossible to read the whole cylinder walls. If your nominal thicknesses are good then the one cylinder may have had pitting that weakened the wall. That may give some comfort to sleeve the one cylinder. To do a full cylinder scan requires really sophisticated automated digital equipment where it would be less expensive to buy the french military block.
I've got one of these. http://dakotaultrasonics.com/product/racing/pr-82-sonic-tester/ I use it for cylinder head porting. Cut, check, cut, check... Also used for a few blocks to check the bore wall thickness. It comes with one transducer as I recall, I bought two more different models. After I received it, I started checking things. I first measured some cast iron with a dial caliper, then with the tester. Within .002" of each other. I've had it 6 or 7 years, still works well. And I have a "check" block that I use before every actual use to verify it isn't going haywire. Still good. Mike
The Jalopy Journal
