Measuring Rod Journals - 1974 850 4cyl

[MercMark]

I'm just about to buy pistons to have my block bored after damage to cyl. 2.<br /><br />I'm told that I need to check the journals on the crankshaft for round. I'm also told if it's out by more than half a thousandth that I should consider the scrapping the project. I'm a little concerned because my cylinders were worn tapered; hence the boring, it's an old engine.<br /><br />I did get contacted in a previous thread by someone who machines cranks and matches oversize needles, but the cost might put the project over the top.<br /><br />What I want to know is:<br />Is a dial vernier caliper good enough to measure the journals, or should I buy a micrometer. A 2" micrometer isn't all that expensive but I'd like to save where I can, especially if I have to buy the tool to learn I should scrap the project. I found a 1" for about $30 canadian that was precise enough (lee valley tools) but I think my journals are over 1". I still have to get out to the garage to check (with my vernier)<br /><br />Also any thoughts on max tolerence out of round for the connecting rod journals. So far it looks like anything at all out of round will jeaprodize my investement in a rebuild.

 

[Dhadley]

Re: Measuring Rod Journals - 1974 850 4cyl

Heres what we found. The cranks (just like the bearings) are so hard, unlike a babbitt bearing crank, that if they look good they probably are.<br /><br />However, if the journal is highly discolored, looks like "orange peel", has a flat spot, is rusted or otherwise visably damaged -- then it is damaged.

 

[Ben Konopacky]

Re: Measuring Rod Journals - 1974 850 4cyl

mercmarc; go to a local machine shop ask them to measure and if its true, how much could they charge? give it a try.<br /><br /> good luck Ben

 

[MercMark]

Re: Measuring Rod Journals - 1974 850 4cyl

Thanks, Ben<br /><br />Actually I did this with my block to measure the cylinders. It's impossible to find an inside micrometer where I am. Unless you want a very large and professional set, in which cast they're like $500. I found a guy who measured them and cleaned up the top of the cylinder that the rings broke in.<br /><br />Actually, I believe I will end up measuring them myself with a new 2" micrometer. The cost of the new micrometer will be about the same as having someone measure them (min one hour charge at 50 - 80 dollars per hour). Add in the pain in the *** of trying to drop my crankshaft off at a shop during my lunch hour and going hungry the rest of the day. The cost of the micrometer look better and better.

 

[Hooty]

Re: Measuring Rod Journals - 1974 850 4cyl

Read Dhadley's post again. If it looks allright, it's good to go.<br /><br />c/6<br />Hooty

 

[MercMark]

Re: Measuring Rod Journals - 1974 850 4cyl

What about the connecting rods?<br /><br />They look not so good. Kind of foggy and stained at the top of the wrist pin journal and I may have nicked the edge of one while tapping out the wrist pin.

 

[Reel Precision]

Re: Measuring Rod Journals - 1974 850 4cyl

You can use a telescoping gauge to measure the cylinder bore. Then measure the telescoping gauge with a micrometer. The telescoping gauges are not that bad in price you can buy set for @100$