John-T-53 Posted July 20, 2009 Report Share Posted July 20, 2009 Well, after 4 months, I finally got my block and other engine parts back from the machine shop. They ground the mains .040" under and supplied me with matching bearing shells. I used the plastigage method to check the clearance, and they all measure .001", right in the middle of the specs (.0005" - .0015"). When the caps are bolted on snug, not even torqued down, turning the crank in the block is very difficult. I have to put a pipe wrench on the front snout bolt and use a 4' long cheater bar to get it to turn (with one foot on the engine stand). Even with this effort, its only a few degrees at a time. With the caps torqued it's pretty much impossible. The addition of rods and pistons won't help, either. I'm worried if I continue with assembly and get the engine back in the truck, then try to start it, it won't turn over. Should I take the crank back to the shop or count on my 6 volt starter to wind up this baby? Quote Link to comment Share on other sites More sharing options...
Tony WestOZ Posted July 20, 2009 Report Share Posted July 20, 2009 Something is wrong there. A crank torqued down with the right clerances should spin easly by hand. If the pistons and rods are fitted there will be some increaced resistance but it should turn easly with a wrench on the crank end. Are all the crank bearing caps in the right order and around the right way? Remove all the bearing caps then re-install one at a time and see which one (or more) causes a problem. Quote Link to comment Share on other sites More sharing options...
Shovelhead Dave Posted July 20, 2009 Report Share Posted July 20, 2009 Sounds like the block may need to be align bored, classic symptom of the mains being non-aligned or a bent crank. Good luck. Quote Link to comment Share on other sites More sharing options...
Young Ed Posted July 20, 2009 Report Share Posted July 20, 2009 Dads one engine we did was like that. A call to the shop told us to "set" the crank by knocking it back and forth in the block. I believe we used a hunk of 4x4 on the crank with a BFH Quote Link to comment Share on other sites More sharing options...
Mike@DRH Posted July 20, 2009 Report Share Posted July 20, 2009 You should try putting the crank in the block and torque it down without the seal in the rear cap. Some of those get pretty tight when new. Quote Link to comment Share on other sites More sharing options...
John-T-53 Posted July 21, 2009 Author Report Share Posted July 21, 2009 I've taken everything apart again, checked the clearance, cleaned the caps, removed the rear main seal and still the same. I even gave the end a few blows with a chunk of wood and a BFH, and no relief. I think somethings up with the bearings...they might have not been resized correctly. I'm taking the crank back to the shop first thing tomorrow! Quote Link to comment Share on other sites More sharing options...
bkahler Posted July 21, 2009 Report Share Posted July 21, 2009 John, After the crank was installed in my 218 I could turn it with almost no effort. For some reason the spec's you provided .0005 to .0015 sure seems awfully tight to me. Then again I didn't do the assembly of my engine so I can't say if its right or not. Bottom line is you've got a problem and you're doing the smart thing by taking it back to the machine shop. Good luck! Brad Quote Link to comment Share on other sites More sharing options...
grey beard Posted July 21, 2009 Report Share Posted July 21, 2009 Something's unhappy here. I strongly urge you to find the problem before you continue assembly. First off, were I with you, we would make sure to put Plastigauge the full width of each bearing shell. This extra width will not only give us the true clearance, but also let us know if the crank is bent - one end will show more clearance than the other. Next step in finding the culprit is to remove one main bearing top insert at a time and try the crank in place with all the rest. You may find which insert is causing the bind - or if the shaft is not true, which journal. When everything is happy and the mains have assembly lube on them, you should be able to turn the crank with one hand on a counterweight without undue effort. Were you to continue assembly at this point, once the ring load and piston drag are added, she would be nigh unto locked up. JMHO Good Luck. Let us know what you find. Quote Link to comment Share on other sites More sharing options...
Mike@DRH Posted July 21, 2009 Report Share Posted July 21, 2009 Even plasti-gauge won't tell you everything you need to know. If the crank bore is out of round (or many other possible causes) it is possible that the plasti-gauge would lay in a spot on the crank where all appears to be the correct clearance. The only way to know for sure is to check crank journals with a standard mic, check bearings with a ball mic and check crank bore with dial bore gauge. Most people don't have these tools at home so I would agree with the others and say take it to someone who does. Usually when they are this far off to a point where you need a six foot cheater pipe it almost always has to do with caps on backwards or not in the right spot. Mike Quote Link to comment Share on other sites More sharing options...
John-T-53 Posted July 21, 2009 Author Report Share Posted July 21, 2009 Well, it turns out the main bearings are the wrong size. Originally, the crank was to be ground .040" under, but it ended up .030" under. The bearings they gave me were resized to 040. Thus, there's an extra hundredth of an inch in there that accounts for the crank binding up. So much for getting my truck running this week... Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted July 21, 2009 Report Share Posted July 21, 2009 Hey......Glad you found the problem before trying to fire it up! Quote Link to comment Share on other sites More sharing options...
dmulhall Posted July 22, 2009 Report Share Posted July 22, 2009 when I was in the engine shop, some kid in the back told me you can put 010 over main bearings on a stock crank, just to tighten it up...I just igorned him and moved on...make any sense? Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted July 22, 2009 Report Share Posted July 22, 2009 Well, it turns out the main bearings are the wrong size. Originally, the crank was to be ground .040" under, but it ended up .030" under. The bearings they gave me were resized to 040. Thus, there's an extra hundredth of an inch in there that accounts for the crank binding up. So much for getting my truck running this week... You might ask the machine shop about the main caps possibly being distorted when you were trying to tighten then down with .040" bearings installed. Possibly could be an issue. Crankshaft/rod bearing bore's are critical in that they need to be round to within a few ten thousanths. Bob Quote Link to comment Share on other sites More sharing options...
Mike@DRH Posted July 22, 2009 Report Share Posted July 22, 2009 when I was in the engine shop, some kid in the back told me you can put 010 over main bearings on a stock crank, just to tighten it up...I just igorned him and moved on...make any sense? No way you can put anything but stock bearings on a stock crank. You did the right thing by ignoring him and moving on. You said you used plasti-gauge on original installation and it never showed you were to tight? I never was a big fan of plasti-gauge but I didn't know it would be that far off. A whole .010 off and it never showed? Mike Quote Link to comment Share on other sites More sharing options...
John-T-53 Posted July 22, 2009 Author Report Share Posted July 22, 2009 The plastigage was showing a little under .001". This is the minimum measurement for plastigage, so anything less than that is out of reach in terms of knowing what it really is. The plastigage actually dented the bearings slightly on a couple of them, and didn't leave a clean profile on the rest - its surface broke apart. I guess when plastigage does this, it means the clearance is 0. I should have new bearings today or tomorrow. Quote Link to comment Share on other sites More sharing options...
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