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Author Topic: Engine tough to turn when case halves bolted together...  (Read 3764 times)
bugnut68
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« on: June 07, 2010, 18:55:30 pm »

Just curious as to what to look for besides pinched main bearings.  I can say with near certainty my mains are indexed on the dowel pins, but when I snugged up the perimeter case bolts/nuts, the crank didn't want to turn.  I hadn't torqued it down yet, and hadn't even snugged up the main bearing studs yet... just brainstorming during the work day Grin  Will work on it more tonight.  Crank fit in the case like a glove, thanks to VW Paradise!
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Jim Ratto
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« Reply #1 on: June 07, 2010, 19:54:13 pm »

1. are you checking with crank only (meaning no cam, no cam or distributor gears, distributor, oil pump)? Nothing but crank and mains?
2. has the case ever been welded on? (how was oil pickup tube for deep sump attached, if it's on?), welded @ # 3?, or has it been shuffle pinned?
3. have you miked all the main for spec? Are radius cut very wide? (you might see shiny streaks on outer edges of bearing if they are)
4. You sure your bearings fit your crank/case? (no matter what part number on box is)
5. Can you see "witness marks" on mains from where the "high spot(s)" is/are? This is a good way to find the culprit.

If you are trying to check with cam in place, be aware, you almost ALWAYS have to hand fit the thrust bearings to the cam, they are almost ALWAYS tight. With case toqued and cam in place the end play should be .002-.003". If you find the crank is hard to turn, check brass gear to dist pinion too. Check if oil pump is interfering with cam gear bolts. See if oil pump gear is not driven on shaft far enough "in" and is dragging on pump cover. Seen all these happen one time or another, can drive you nuts, but YOU HAVE TO FIND THE ERROR AND CORRECT IT.

Good luck
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bugnut68
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« Reply #2 on: June 07, 2010, 20:04:49 pm »

1. are you checking with crank only (meaning no cam, no cam or distributor gears, distributor, oil pump)? Nothing but crank and mains?
2. has the case ever been welded on? (how was oil pickup tube for deep sump attached, if it's on?), welded @ # 3?, or has it been shuffle pinned?
3. have you miked all the main for spec? Are radius cut very wide? (you might see shiny streaks on outer edges of bearing if they are)
4. You sure your bearings fit your crank/case? (no matter what part number on box is)
5. Can you see "witness marks" on mains from where the "high spot(s)" is/are? This is a good way to find the culprit.

If you are trying to check with cam in place, be aware, you almost ALWAYS have to hand fit the thrust bearings to the cam, they are almost ALWAYS tight. With case toqued and cam in place the end play should be .002-.003". If you find the crank is hard to turn, check brass gear to dist pinion too. Check if oil pump is interfering with cam gear bolts. See if oil pump gear is not driven on shaft far enough "in" and is dragging on pump cover. Seen all these happen one time or another, can drive you nuts, but YOU HAVE TO FIND THE ERROR AND CORRECT IT.

Good luck

Just the crank was installed, no cam, oil pump, distributor drive, etc... will take a look at the main bearings and saddles when I get home tonight.  Thrust bearing was , I believe custom trimmed by VW Paradise for this case.  I trial fitted the bearings before bringing the crank in, everything seemed to fit just fine.  Will go through all you suggested once I'm home!
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Jim Ratto
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Posts: 7121



« Reply #3 on: June 07, 2010, 20:09:55 pm »

1. are you checking with crank only (meaning no cam, no cam or distributor gears, distributor, oil pump)? Nothing but crank and mains?
2. has the case ever been welded on? (how was oil pickup tube for deep sump attached, if it's on?), welded @ # 3?, or has it been shuffle pinned?
3. have you miked all the main for spec? Are radius cut very wide? (you might see shiny streaks on outer edges of bearing if they are)
4. You sure your bearings fit your crank/case? (no matter what part number on box is)
5. Can you see "witness marks" on mains from where the "high spot(s)" is/are? This is a good way to find the culprit.

If you are trying to check with cam in place, be aware, you almost ALWAYS have to hand fit the thrust bearings to the cam, they are almost ALWAYS tight. With case toqued and cam in place the end play should be .002-.003". If you find the crank is hard to turn, check brass gear to dist pinion too. Check if oil pump is interfering with cam gear bolts. See if oil pump gear is not driven on shaft far enough "in" and is dragging on pump cover. Seen all these happen one time or another, can drive you nuts, but YOU HAVE TO FIND THE ERROR AND CORRECT IT.

Good luck

Just the crank was installed, no cam, oil pump, distributor drive, etc... will take a look at the main bearings and saddles when I get home tonight.  Thrust bearing was , I believe custom trimmed by VW Paradise for this case.  I trial fitted the bearings before bringing the crank in, everything seemed to fit just fine.  Will go through all you suggested once I'm home!
the thrust bearing shouldn't give you an issue until it comes time to install flywheel, and hopefully it doesn't then either. Was your case "thrust cut"?
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Jim Ratto
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« Reply #4 on: June 07, 2010, 20:35:54 pm »

just a note: the six 12mm mains get torqued before the 8mm perimeter bolts. Try crank fit by only snugging up on the 6 mains, go slowly, torque to 10 ft lb, check to see if cranks glides easily. Go to 15, re check, go to 20 re check, go to 25 re check. I use a power pulley on nose of crank to check, not the flywheel/big pulley, just to lessen "force" applied. The leverage is less. You get a better feel.
Don't use grease or moly paste either, use a light engine oil mixed with STP red.
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bugnut68
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« Reply #5 on: June 08, 2010, 17:09:54 pm »

Well, last night, with limited time to work on it due to an old college buddy coming over for some beers and social time, I delved back in to the motor.  Pulled everything apart (very limited task, lol), removed the crank out of the case and main bearings, cleaned everything up and then reinstalled said parts.  I used a light coating of oil on the split center main  bearing and installed the no. 1/2 case half once more.  Torqued the main nuts to 5 lbs, engine turned over fine... 10 lbs, still turned over fine.  15, 20 and 24 lbs... all good!  Not sure what happened before, but whatever the issue was, I resolved it.  The bearings weren't pinched, or anything, they were seated proper on their dowel pins.

This was just the initial trial with the crank only, so we'll see how things go once I get the cam in there and distributor drive pinion, etc.  I'm thinking I will  measure those main bearing saddles just to satisfy my curiosity, even though everything appears to be in order at this point.
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Jim Ratto
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« Reply #6 on: June 08, 2010, 18:55:35 pm »

case probably wasn't indexed, since you only snugged 8mm studs (meaning bearings were more riding crank, instead of being locked into place by case crush and torque of 12mm studs. Good to hear it is ok. Make sure you check for interference at each assembly step, so you don't get ahead of yourself and have to un-do 6 or 7 steps, instead of just one. Meaning.... check cam end play, make sure crank turns with cam installed. Check that off. Check back of oil pump for interference with cam gear bolts. If they clear, check that off. Bolt oil pump cover on, make sure all is still free, if so, check that off. Then after all that you can move to geometry and valve to piston clearance and valve full lift vs. spring bind. THEN you can start to assemble motor.
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bugnut68
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Posts: 1751


« Reply #7 on: June 08, 2010, 19:12:19 pm »

case probably wasn't indexed, since you only snugged 8mm studs (meaning bearings were more riding crank, instead of being locked into place by case crush and torque of 12mm studs. Good to hear it is ok. Make sure you check for interference at each assembly step, so you don't get ahead of yourself and have to un-do 6 or 7 steps, instead of just one. Meaning.... check cam end play, make sure crank turns with cam installed. Check that off. Check back of oil pump for interference with cam gear bolts. If they clear, check that off. Bolt oil pump cover on, make sure all is still free, if so, check that off. Then after all that you can move to geometry and valve to piston clearance and valve full lift vs. spring bind. THEN you can start to assemble motor.

Oh, yeah, no questions about all that... I learned my lesson hard on the 1776 I built last...last.  Got the case halves sealed up and everything assembled only to find out the case cylinder spigots hadn't been bored deep enough for the 90.5mm pistons...lol.  Since that time, I work very slow and deliberate, as one can't be too attentive. Grin
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bugnut68
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« Reply #8 on: June 09, 2010, 16:43:31 pm »

With cam installed and distributor drive gear, all is still good.  Next step will be to install lifters and check clearance there.  A little bummed as I found the lightened flywheel I got in a package deal with some parts from a sandrail guy a couple autumns ago seems to have a couple of gnarled up dowel pin holes.  I'd really rather not have my new DPR crank drilled for 11/32 pins, so I guess I'll have to shop out another flywheel.
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bugnut68
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« Reply #9 on: June 10, 2010, 16:35:07 pm »

Just confirmed it: lifter bores need to be milled, as there's no clearance between the lobe and the lifter.  shoulda had that checked when I sent the case off to be clearanced for the crank!
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