RPMS Posted March 26, 2001 Share Posted March 26, 2001 Well, crap. I ordered .001 tighter Clevite 77 bearings for my connecting rods and mains, and when I plastigauged them dry they spec'ed out at .0016, plus or minus .0002 across the board. Encouraged by my success so far, I scraped off the plastigauge, lubed them up and torqued them to 40 ft/lbs and found that I then couldn't turn the motor by hand. What gives? Why would they spec out correct when dry, but then not want to move when lubed? This can't be normal, can it? Scott Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 26, 2001 Share Posted March 26, 2001 Try torquing the rods on the crank, without the piston in the hole. See if it still is tight. I don't know if you know this trick, but here it is: When tightening rods, put feeler gages between the rod pairs, wo that the parting line of the cap you're tightening has a feeler gage at each parting line, making the fit of the gages tight. Use similar or same size feeler gages. to assure that the the cap and rod are aligned at each parting line. Personally, I hate plasticgage. I found a set or good 0.0001" outside micrometers and snap gages used and I much prefer them. I had too much variation in readings when I tried plasticgage. Too "funky" for me - I like direct measurement, no a smashed piece of wax to back it out from. ------------------ Pete Paraska - 73 540Z - Marathon Z Project pparaska@home.com Pete's V8 Datsun 240Z Pages Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 26, 2001 Share Posted March 26, 2001 I don't know if the Chevy is the same way, but one side of the the Ford bearings is slightly camfered more than the other. If this side of the bearing is not on the radiused (outside edge) part of the crank journal, the rod will bind when tightened. It can be swapped very easily. The cornered sides face each other, and the rounded sides face away, toward the radiused journal cut. Quote Link to comment Share on other sites More sharing options...
RPMS Posted March 26, 2001 Author Share Posted March 26, 2001 Pete, You're right - I didn't check the clearance between the rod ends. Silly of me not to think of this. It's possible that they're rubbing up against one another. I'll loosen them all, clean the bearing/journal surfaces again, and reassemble things using your feeler-gauge trick. Blueovalz, On my engine, there's one side of the cap that has 'stuck out', squared off tabs on it. I put these tabs facing the crank counterweights, with the non-tab sides facing each other. Does this sound right to you? I made sure they went on in the same order and direction they came off, but that's no guarantee that the person rebuilding it the first time put them on correctly. ------------------ Scott Ferguson 1976 260-Z, surrounded by an ever-growing cloud of V8 parts... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 27, 2001 Share Posted March 27, 2001 quote: Originally posted by RPMS: Pete, You're right - I didn't check the clearance between the rod ends. Silly of me not to think of this. It's possible that they're rubbing up against one another. I'll loosen them all, clean the bearing/journal surfaces again, and reassemble things using your feeler-gauge trick. Blueovalz, On my engine, there's one side of the cap that has 'stuck out', squared off tabs on it. I put these tabs facing the crank counterweights, with the non-tab sides facing each other. Does this sound right to you? I made sure they went on in the same order and direction they came off, but that's no guarantee that the person rebuilding it the first time put them on correctly. Hi! I'm new to this web site and I could not help but respond to your problem. I have some past experience with assembley of a s-b chevy, first, is this the engine that you got from a junk-yard (305),well the tab on the head is a over heat indicator from a reman shop. the connecting rod caps should be numberd, and the slot for the bearing tabs should be on the same side of each other(tab to tab) (numbers to numbers) I can't say if I would have put tighter bearings in, it's just that the rod journal may not be round (so to speek) and the old bearings have worn in to that form, .0025 on a rod bearing is fine. there are many other things that could be happening, hard to say if it is not in front of me, hope you make out well. Quote Link to comment Share on other sites More sharing options...
Guest RON JONES Posted March 27, 2001 Share Posted March 27, 2001 Your suppose respond Dave.If you can help ofcourse. Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted March 27, 2001 Share Posted March 27, 2001 I thought I was the only one that didnt like plasticgage(?)! I never use that stuff; Hate it, Hate it, Hate it! Even in my younger days on my first engine I didnt bother w/it. I also prefer inner/outer mic's. I've used rod's in the past that were a little tight but acceptable as the crank did turn by hand. Since then I've decided always to pay the expence of having the rod's resized; cheap insurance down the road but that & balancing an engine really make a difference. After my last rebuild on my Olds engine (Balanced, Ported & Align bored); yea it was a little more expensive than usual...but the engine runs so much smoother. You can honestly tell the engine is happier! BTW: In eng.buidling 101, if the rod's are not numbered....always take a quality steel/pointed punch & mark both the rods & the rod caps where they meet; mark 1 dot for #1piston, 2 dots for #2 piston or buy a set of numbered punches. The marking will not only insure installation of the piston facing correctly but also insure you get the rod cap on the same position as it was removed. Mark them before you pull them & always mark them in the same order/location so reassembly will be simplified. Also; if you're going to have your crank turned...make sure the machinest knows to leave a small inward radius ground into the inside of the crank weight/shoulder where it meets the main (not sure what the exact term is) but that radius is where oil will ride giving lubrication to the face of the rod. Many machinest when they grind a crank will grind that radius away which as a result will hurt lubrication of the rod at high rpms and may lead to oil starvation.....a little at a time. Just my .02c's worth. Kevin, (Yes,Still a "Hate Plasticgage" Inliner) [This message has been edited by Kevin Shasteen (edited March 26, 2001).] Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted March 27, 2001 Share Posted March 27, 2001 Radius = fillet I believe Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 27, 2001 Share Posted March 27, 2001 I thought that was a steak? Lone Quote Link to comment Share on other sites More sharing options...
RPMS Posted March 28, 2001 Author Share Posted March 28, 2001 Okay, here's the poop! Last night I sat down and carefully looked at the side clearance on the rod ends. The books (I'm looking at three different ones) all say to leave about .012 clearance between the rods. Well, when I add the rod/rod and both rod/crank clearances, I've got .015 clearance TOTAL. If I make the rod/rod clearance .012, that only leaves me .0015" of space between the rods and the crank! I made a command decision and made each clearance .005". Now the engine will turn when the caps are torqued, but I'm a little concerned about having only half the recommended clearance between rod ends. Do you think this will be a problem? Everything's steel, so I'd assume that heat expansion wouldn't be an issue, would it? Oh, David - Thanks for your response. I looked at the caps, but I couldn't see any numbers on them. I kept them in order when I disassembled them, so I'm pretty confident they went on correctly. At least, they did if the last guy who rebuilt it kept 'em in order! ------------------ Scott Ferguson 1976 260-Z, surrounded by an ever-growing cloud of V8 parts... Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 28, 2001 Share Posted March 28, 2001 How did you adjust the side clearances? Seems you need to have that done at a machine shop, or use a piece of emory cloth on a piece of glass to make the big ends of the rods thinner. You sure you don't mean the bearing to journal clearances? ------------------ Pete Paraska - 73 540Z - Marathon Z Project pparaska@home.com Pete's V8 Datsun 240Z Pages Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 29, 2001 Share Posted March 29, 2001 Scott, after your bearing clearence's are checked (plastic or dial indications, and the big end of the rod is round) once you torque the proper cap to the matching rod, you should have about .015 total side clearance, and the only way to increase that demension is to narrow the side of the big end of the rod, and if that is done you must use a high volume oil pump, because you just opened the flood gates, so to speek! If you just take your time, read a good shop manual, and get some good advice you should be in good shape. with propper bearing clearances, and propper ring tension on the cylinder walls, it should take a 1/2" drive ratchet socket combo to turn that thing over. and most important is your work area should be HOSPITAL clean! Just ask Ron about how clean his garage is. ha ha!! inside joke! good luck Dave Quote Link to comment Share on other sites More sharing options...
RPMS Posted March 29, 2001 Author Share Posted March 29, 2001 Pete, Dave, I think I understand what you're saying, and I'm pretty sure I'm just not using the correct terminology. The clearances I'm talking about are to the side of the crank/con rod interface, and between the con rods themselves. The book, as Dave indicates, specs .015 between the rod ends (or that's how I'm understanding it - am I reading it wrong?) leaving no space at all between the crank and the rod ends. Here's where I'm measuring what I'm calling the rod side/crank clearance I gave this .005, then .005 between the rods, and .005 on the other side, adding up to .015 total. Oh, by the way - sorry about getting my decimal places mixed up. Too many zeros! I'm not used to having to be this precise!!! The motor will turn by hand now, although it won't just spin friction-free in the journals like I'd fantasized it might! ------------------ Scott Ferguson 1976 260-Z, surrounded by an ever-growing cloud of V8 parts... Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 29, 2001 Share Posted March 29, 2001 Unless I'm totally out to lunch on this, I think that one acceptable way to measure side clearance is to get the rods big ends separated so that they are against the crank throw cheeks and measure the clearance between the rods. I wouldn't try to measure three clearances : crank-rod, rod-rod, rod-crank, as that's prone to error. The other way is to measure the distance on the crank that between the throw cheeks on either side of the journal surface with an inside micrometer (or snap gage and outside micrometer) and compare that to the thickness of the two rod big ends together (with an outside micrometer). Quote Link to comment Share on other sites More sharing options...
Guest RON JONES Posted March 29, 2001 Share Posted March 29, 2001 Pete Your not out to lunch.No,there is no need to measure in three places.Just measure between the rods and your all set. Quote Link to comment Share on other sites More sharing options...
RPMS Posted March 30, 2001 Author Share Posted March 30, 2001 Pete sagely says: "Unless I'm totally out to lunch on this, I think that one acceptable way to measure side clearance is to get the rods big ends separated so that they are against the crank throw cheeks and measure the clearance between the rods." And I, in befuddlement, reply: I think you're right, Pete. That's exactly the way the books say to do it. But when I did it that way, the sides of the rods interfered with the crank throw cheeks. (Thanks for supplying the correct terminology, by the way!) The con rods continued to bind until I backed them away from the crank throws just a bit. What did I do wrong??? Scott Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 30, 2001 Share Posted March 30, 2001 No idea if "Cheeks" is the right term, BTW. I pulled that one out of my arse, or maybe it's legit, but I doubt it. Umm. putting the rods against the crank throw "cheeks" is just for checking the clearance. You shouldn't be turning it with the feeler gages installed for checking. Quote Link to comment Share on other sites More sharing options...
PaulR Posted March 30, 2001 Share Posted March 30, 2001 If you try to slide the rod as close to the crank as possible is there is still a gap between the rod and crank? (is that maybe the .005 gap you were refering to?) The rod should be able to slide up tight to the crank. If it doesn't, I would bet that Terry (BlueOval) called it correctly and the rods are in backwards. The "tang" on the bearing should face outward. ie, the tang the rod for cylinder 1 would be on the same side as cylider 1 (front drivers side). Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 30, 2001 Share Posted March 30, 2001 Either that or the journals have a larger-than-stock radius. But this is a stock motor, no? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 31, 2001 Share Posted March 31, 2001 RPMS, Lets back-up a step or three, how far did you dismantle the short block? (pistons, rods, crank)If you removed the piston-rod assembly, is there a chance you put them in the wrong hole? (cylinder). If you did not remove the piston from the rod, the piston will have a mark on the top of the piston, or in front of the piston, this mark indicates front (front of motor). with the mark faceing forward on cylinders 1,3,5,7 (the drivers side or left side)the bearing tab will be down or faceing outward, on cylinders 2,4,6,8 ( the passenger side or right side) the bearing tab will be faceing down or outward. So if you hold the piston rod assy. straight up in front of you, cyl. 1,3,5,7 the front of the piston to the left, the notch for the bearing tab will be close to you. when you hold the piston rod assy. straight up for cylinders 2,4,6,8 with the front of the piston to the left the notch for the bearing tab will be away from you. If you get them mixed up the off-set of the rod could be hitting the crank counter weight (cheek). When you install the piston-rod assy. in the right way, in a stock motor, big end rod clearance is not an issue. I really would read a good overhaul manual if you are not farmiliar with the S-B Chevy. Hope this is of some help, Dave Quote Link to comment Share on other sites More sharing options...
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