CAN100
First used Plastigage 50 years ago. Rebuilding the engine on my first car (a year before I could even drive it). An old time mechanic down the road had taken pity on a poor kid with zero mechanical experience. My dad was non-mechanical to say the least. Anyhow, I had purchased a 1961 Ford Falcon in 1972. Perfect body and interior, but engine had not been run for years--still only 60,000 miles. 170 ci straight six with three on the tree.
Started by pulling the head, strapping it to my bike and peddling it 2 miles to the shop. I had a lesson in patience. Instead of using that nice new Sioux valve and seat grinding equipment. I was taught to use clover compound and lap all twelve valves back into tolerance. It was a few years until I full appreciated what that taught me.
He suggested we go through the entire engine. He only had daughters and I think was sorry he had never passed on his skills to anyone else. He was to grouchy to say so, but it was his idea. Soon the engine was out and I was tearing it down. The mysteries of all the tolerances and fits were revealed to me. I was amazed at how clever the plastic gauge was. He had me measure the journals and use a telescoping gauge to measure the bearings. Time consuming and fraught with error for my unskilled hands. Then he showed me the little paper strip and did a one time demo.
I then checked all the mains and rods. Maybe only an hour or two even for a 15 year old novice. Unlike my measurements, the results of the ground journals and new bearing inserts were clear. Those green "smudges" looked like "peas in a pod". Hot dawg, time to reassemble. But no, had to remeasure until I got it right and "proved" the plastigage was telling the truth. I got there and again developed some skill.
But after teaching engines and repairing engines (gasoline and diesel) for much of my life I have always gone to Plastigage for checking running clearance-both before machining and after. It is quick and accurate. As my experience spelled out, measuring is great, but unless you are skilled, you will have questionable results. If time and/or skill is an issue you just need to buy this stuff and use it. It will get you to where you need to go quickly and with the fit required.
I see others gripe about the cost. Yeah, it seems expensive for what is in the paper tube. But what you are buying is not the physical stuff....it is the data that results from using it. There is NO cheaper, quicker way to get that info.
Plastigage was developed in England and was first used in the USA in 1948. I have used it for other "fits" as well in the machine shop, much as Prussion Blue is used for finding proper fits. One of those good, simple, should have been obvious ideas that is still the best method after 75 years of use.
| Brand | Sealed Power |
|---|---|
| Material | Plastic |
| Item dimensions L x W x H | 12.2 x 1.4 x 1 inches |
| Item Weight | 0.01 Pounds |
| UPC | 724956611850 |
| Global Trade Identification Number | 00724956611850 |
| Manufacturer | Sealed Power Corp. |
| Model | Gauge |
| Item Weight | 0.16 ounces |
| Product Dimensions | 12.2 x 1.4 x 1 inches |
| Item model number | SPG1 |
| Is Discontinued By Manufacturer | No |
| Exterior | Machined |
| Manufacturer Part Number | SPG-1 |
| OEM Part Number | SPG1 |
Brianhouse
cem
moose
Dan of all trades