Ok here is a question for ya. I'm checking clearances with plastigauge and now I'm removing the plastigauge from the inserts and journals. So I'm busy scraping with my fingernail just like I always have and it occures to me that there has got to be a better/different way to do this. So how do you fellas get the plastigauge off after you squeeze the devil out of it and it sticks?
The last one I did it to I started picking it off with my thumb nail..than i tried my bic lighter..came right off..guess just like "Badfun" said
Ive heard its like a wax? Some one told me once that you just leave it in there. Is that possible? Ive never done it i always picked it out of there. Just wondering? The flame is new! i'll remember that! Good info
I think I read somewhere that plastigauge is designed to be left in place, apparently it will just disolve into the oil. Although I may have read that, I still remove it ... never used anything but a fingernail up to this point though.
Straight off the Plastigage website...isn't Google awesome....haha "Ideally you should remove the PLASTIGAUGE stripe with a clean oily cloth or industrial de-greasing solvent, but users may be assured that any PLASTIGAUGE left behind is oil soluble and cannot harm the engine in any way".
I always use my mics and bore gages to check for clearances... And double check with the plasti gage.. I just leave it on there and let it disolve with the oil... No harm done!! Just change the oil and filter when the motor is broken in...
Never bothered to clean it off to any great extent, as soon as you start your engine it melts and dissipates in with the oil. FWIW, I think plastigauge is made from paraffin wax which is also found in many oils. No harm no foul. .
What I have noticed when you leave it on there is that it makes the engine real hard to turn over. I always use it as part of the process of checking tolerances not as the entire process. I have never had much luck with acetone and have always ended up scrapeing it off with a findernail. I just wondered what everyone else did. Sorry just cusious by nature I guess, that is probably what keeps me interested in hot rods.
Careful measuring can tell you more than Plastigage, but Plastigage is way better than nothing. And as you are using it, it's a way to confirm the measurements weren't misread or there wasn't a math error in calculating the clearances. As has been said, it slowly melts when exposed to oil. And as has been said, both carb and brake cleaner dissolves it immediately. Lacquer thinner also works well.
i admitt i am not a scrapper,,(brake cleaner) .. but while we are on the subject of "Plastigauge" i was once told by this really old... old... old...guy I mean he was older than dirt,,,, dont waste your money on that new stuff (plastic-gauge) I always took out my pocket knife and peeled off a thin piece of body lead.. and used that......ever hear of that?
And then what, measure the lead thickness with a micrometer? I almost think lead would indent the bearing a bit and give a false reading. Bearings are soft, and intentionally so, in order to allow hard particles to embed rather than stay on the surface and grind a groove in your crankshaft.
and yes that is what he said,,,, put it in tightened it up and then he mic it thats why I asked.....?
I have never heard of that but I wouldn't do it unless I was stranded somewhere and didn't have a netter alternative. I have seen Plastigage dent soft poured babit bearings. Lead would do that even more. Even on modern insert bearings I would expect some denting of the bearing. Damage of the bearing aside, any denting of the bearing, or any deformation of the housing bore caused by the lead not fully "smashing", would effect the accuracy of the reading.
I'm with everyone else on the lead. Plastigauge is just a way to double check your measurments, its hard to guess down to the nats patoot with it. I use it a lot when I'm pulling one down for inspection to give me a heads up as to what to look for. But I do things a little different than most I suppose.
I usually just hit the journals with a little 80-grit to get the last bit of plastigauge off...... that's a joke. By the way, I had a 347 stroker with a new block new rods and a freshly machine block (purchased it as a machined block). Everything checked out with plastigauge, but when the mains were torqued, it locked it up. I tried .001 under bearings, same thing and the plastigauge measured the same. I got out the mics and dial-bore gauge, the crank was spot on, but the mains, which were supposed to be line honed, were spot on for size, but the line was zig-zagged, my machine shop had to take around almost a 1/8" off the bottom of the caps to get it straight. Plastigauge and even gauges don't always show everything.
There is nothing to overcome bad machining. Sometimes a good machinist can if your lucky. I actually have started polishing my cranks with 60 grit because I read on the internet that the grooves make a place for the oil to be.
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