Alright so I got an 87 GT with an 88 engine, the engine was seized when I got it due to stuck rings. I had some time so I re-honed all the cylinders, put fresh standard rings on, new standard bearings, and lubed the crap out of all of them. I just finished re-torquing the Main Caps to 70 Ft. Lbs. and torqued 4 of the Con Rod caps to 40 Ft. Lbs. When I went to spin the motor to torque the remaining 2 caps, it won't exactly budge... I'm using a 1/2 about 24" Breaker bar... The heads are off too... I can turn it but it will definitely take around 130 Ft. Lbs. to budge it. Is this right?? The heads are completely off, everything lubed and oiled.
even with everything torqued down, you should be able to move the crank by just grabbing a counter weight on the crank, and pushing sounds like somewhere, there is at least one oversized bearing.
There's something seriously wrong someplace. Did you Plastigauge the bearings? Do you perhaps have a connecting rod in backwards? Did you perhaps mix up the rod caps ... i.e. mismatch a rod with the cap from a different rod? Are all the main caps in the right location and oriented correctly? Is the crankshaft thrust bearing installed correctly? Are the bearing inserts all installed correctly ... i.e. locating tabs oriented properly?
I would probably start by backing off all the rod caps and see if the crankshaft turns freely. If it does, then re-tighten the rod caps one by one.
I did not Plastigauge them, but suppose it can't hurt. Pretty sure I got them straight but will check again. Chance they got mixed up. For the record I did not drop the crank or do the upper main bearings, and I'm also doing this in the car. I know I'm not doing it the complete right way, but I have to get it finished. Thanks for those tips, I will do that. Just didn't know where to start myself. -Ian
As for the bearings the indents in the caps install opposite each other right? Learning as I go. Thanks, just there was about a month or two between when I stripped it down, till now when I finally got the chance to put it back together.
I can't recall whether the bearing tangs go on the same side or on opposite sides, but the turning friction of the crank once all the pistons are in place should be about 25 lbft.
Edit to add: with the heads and valve train installed but no spark plugs.
[This message has been edited by Bloozberry (edited 07-25-2013).]
their on the same side but opposite each other. i always use a saying when putting a motor together. (bearing lock to bearing lock) and on the rods (bearing locks to inside or bearing locks to outside)
[This message has been edited by dematrix86gt (edited 07-24-2013).]
You should really put in both halves of the mains. You just put a little cotter key with a flattened eye in the oil hole of the crank and turn the crank and roll out the top bearing. Do it one main at a time, it is dead easy. Roll it out lock end first and put it back the other way. The tabs go on the same side, so if you have them opposite you are wrong. If you have turned it at all you will see the results on the bearings that are in wrong. Larry
It sounds like the crank was turning to allow you to put the first 3 piston/rods back in. No. 4 was the deal breaker. It is possible and not all that uncommon to nick the crank with the rod bolt when you push the piston down the bore. Working under the car makes it all that much easier to do. Take off the last rod cap you installed and see if the crank turns again. Look at the crank/bearing insert for damage. Doesn't take much to cause lots of problems. You only have a couple thou clearance at most. Hope this helps
It "sounds" exactly like you mixed up bearing " caps". Are you SURE the main caps are in the right place ? (if you "mixed up the order of the Caps, that will for sure "lock it up". "Tangs" both on the same side ? Did the Crank turn with" little to no effort" BEFORE you started bolting "Rods" to it ? Back off the rod bolts 1 turn and see if it turns. Did You NUMBER all the caps Before you took them off ?
One thing I learned a long time ago is to measure the bearings inside diameter before installing them. The reason is that in one of my first rebuilds I bought standard size mains but what was in the box were 10 overs. Needless to say that it wouldn't turn worth a darn. Breaker bar or not.
you must mean, it takes 140 pounds to turn it over with the Heads ON and spring pressure against it, and spark plugs in. If it's just the crank, you should be able to grab the crank snout and turn it with your hand, with fresh hone and new rings, No Heads, about 10 pounds ( I just went out and checked my 3800 with a torque wrench)
It takes more then 10 ft pounds just to turn the cam. With a fresh hone and new rings it will be quite a bit higher even with no spark plugs in the holes. Larry
Well just pulled the Rod Caps, spins by hand (no wrench) even with the pistons moving still... So I guess the Mains are good. The Mains are also in the correct order and direction. The Rod caps were in the right direction ie. bearing tang on same side. And in the right order as far as I can tell. (Didn't mark em, stupid me). However with better light it looks like there might have been a couple rust particles trapped between the bearings and the crank. Guess I didn't polish it as well as I thought... Would this be enough to lock it up? Some rust particles? I know I'm doing this the "shade tree way" but it's a very very tough situation and I have to finish this, so instead of pulling the crank can I just get like a strip of 2000 grit and go to town?
So spins with the Mains torqued but the rod caps off, so either they sent me the wrong size bearings, or those rust particles caused enough friction not to spin it? And I will pick up a plasti gauge tomorrow to, thanks for the help guys.
[This message has been edited by IanT720 (edited 07-24-2013).]
You shouldn't have rust particles in the bearings, if you want the engine to last awhile you need to clean them off and apply a thin coat of oil on the bearings. Do this in a clean environment. Also use a zinc additive in the engine oil to seat new rings.
The back of the bearing shell will be stamped with the size. Ones you took out should say std also, when you have the rod cap torqued down you should easily be able to slide the rod back and forth a few thousanths easily by hand. Larry
I "think" he meant rust in the pores of the cylinders
Actually I did mean between the bearings and the crank :/ of course I know that's horrible. I just thought I cleaned it well enough but apparently I did not. My question was would those particles create enough friction to lock up the engine?
They are bad, but unless you had a lot of them I doubt it would lock up the engine. I more suspect you have mixed up the rod caps or that you have them on backwards. are the pistons installed in the right direction? Larry
You guys seem to be underestimating the force it takes to slide a piston with new rings on a fresh cylinder. You need a rubber mallet to tap them back and forth in there when you attach them to the crank. Now times that by 6... If you can turn the crank over with ONLY the pistons (no springs or camshaft etc) easily then the rings are too small or the cylinders are worn out.
EDIT: However to confirm that the rod caps are fine do what the other guy said, you should be able to slide the rod and its cap on the crankshaft journal back and forth a few thousands relatively easily. If you can then the rod bearings and caps are fine. If one of them are not moving then plastigauge it and go from there. It is recommended that you plastigauge all the main crank bearings and rod bearings when you are assembling it anyways.
[This message has been edited by DaytonTD (edited 07-24-2013).]
It takes more then 10 ft pounds just to turn the cam. With a fresh hone and new rings it will be quite a bit higher even with no spark plugs in the holes. Larry
The 3800 I recently rebuilt took 9 ft/lbs to turn rotating assembly,and 12 ft/lbsto turn with timing chain/cam (14lbs breakaway torque). Measured using a Kent Moore digital torque meter.
If you have RUST between the Crank and the Bearings, the minute you start it up the bearings will be torn up. they have to be perfectly clean, Preferably NO LINT !
Originally posted by Lou6t4gto: If you have RUST between the Crank and the Bearings, the minute you start it up the bearings will be torn up. they have to be perfectly clean, Preferably NO LINT !
yes - the no lint is a good point. if you use rags to wipe things, the sharp edges of the castings may snap some material. Use paper towels. they will dissolve.
All the rod and main caps have to be put on in the same order and same direction as they were originally. Any mix-up is trouble. Also, the pistons must be put in as they were originally. Usually, the pins on a piston are slightly offset from center, to compensate for compression wear. Therefore, each piston has a "front" that must face the front (pulley end) of the engine.
Lou,I should mention that the engine had a ceramic dry film lubricant coated cam,timing gears,crank,cam/rod/main bearings as well as cylinder walls. BUT,I did verify my readings with a local engine builder (who holds NHRA records) and his engines are actually a ft/lb or two less than mine without all the coatings so they aren't out of line. That is also without a balance shaft. Engine runs great!
Mine are all coated with assembly lube. The only way I can see a fresh engine being so tight is : The front and rear seals are dry, almost no tolerances/clearances or the cylinders were honed with much Too Rough A Grit.
I didn't mean assembly lube though I did use comp cams assembly lube. I meant actual baked-on ceramic coating (so were the pistons,heads,valves,springs etc.. ) Except the cylinder walls,that was a pressure bond? Coating for ring seal.
Well I learned some things from your tips guys... For one my old bearings say GM A-200. Does that mean .20 underside? And also one piston was very rusty and I mangled the connecting rod pretty bad with an air hammer, so I bought a replacement... I just measured it with a micrometer and it's slightly smaller then the others, so definitely part of the problem.
The last rebuilt engine I had, I had the problem of it being way too stiff to turn. Long story short? It's now at the metal recyclers and I have a different engine. Word to the wise, dump it while you are ahead.
I agree, just get another engine. FREE ADVICE- if you want to "Learn HOW to Rebuild Engines", do what they do in most schools. Get an old engine, really doesn't matter what make or how many cylinders. Clean the outside( nicer to work on), then take off the Pan, NUMBER the Main and Rod CAPS, on the rods, stamp the # starting #1 "from front to back", on the SIDE of the rods (put a number on BOTH the rod side AND Cap side( so you can't mix them up after they are apart and out.) Then take Everything apart and CLEAN it ALL. (Take everything apart whether you will ever replace it or not, that way you KNOW for the future). This is a "Learning experience", you don't need to Buy ANY PARTS. After everything is cleaned, Put it all back together and take it apart, put back together, "a few times". After you are confident that it was all done right, "fitting, measuring, torqueing", CHECK Everything. THEN "you are ready" to rebuild an engine that you will Actually USE.
Do you mean you put it back in that way? Bad start.
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... I mangled the connecting rod pretty bad with an air hammer ...
What the hell were you doing that you thought you needed to use an air hammer for?
At this point I can't stop thinking: "Do it right, or do it over." You really need to approach an engine rebuild more like a watchmaker than a blacksmith.
[This message has been edited by Marvin McInnis (edited 07-29-2013).]
though I did use comp cams assembly lube.
