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#1
12-24-2007, 02:37 PM
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how do you dial indicate....
the face of the thrust bearing? my engine is being gone through right now, and i want to know how you can check the trueness/squareness of the number 4 main cap.
i had a very irregular wear pattern on my forward thrust bearing that gave out on the dyno,(no tranny load..) it looks as if the cap is leaning torwards the front a bit, causing wear on the bottom half of the shell only. there is next to no contact on the upper/block forward half, but the lower/cap half is worn down over .002 or more. the endplay was at .008 at the rebuild, and was over .012 at teardown. the backside of the lower/cap half has almost no contact either...... anyway, he is going over the engine now, but i want to know how others check the squareness, so i have some comparison of knowledge when we talk about it. also, if the cap is leaning, do you cut it and reline hone? i am not well versed in machining, so thanks for the patience...... any info or help on this issue would be greatly appreciated, i really want this to be the last time i deal with this engine not cooperating..... thanks folks!!!! davey
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1968 Lemans/GTO clone, 6-71 blown 474ci 1969 Ram air III, Hardtop (sold it to my dad!! still care taking for it) |
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#2
12-24-2007, 02:49 PM
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I had exactly that problem with an Olds 455; the cap wasn't cut square when the block was line honed.
I discovered this with feeler gauges; I could get an .008 between cap and crank on the front, but not between block and crank. Knocking the crank to the rear, I could get the feeler gauge between the block and crank, but not the cap and crank. Therefore the cap had to be at an angle. I filed the parting line of one of the bearing shells--just a touch, and only from oil groove to the rear thrust surface--so as to supply a little more oil to the rear thrust face. I ran the engine about 35 minutes on a test stand then tore it down for other reasons. It's a classic "long story" that involved a defective lifter and also the garage burning down while the intake manifold was off--and in the end I chose to use another block. The entire rotating assembly went from the first block into the second block; and the thrust bearing looked beautiful. Perhaps that was because there was only 35 minutes running time on it; perhaps it's because it never saw any real load--the test stand doesn't have a pressure plate or torque converter on it to push the crank forward. If you still have the block apart, I don't know why you couldn't verify the straightness of the cap with a square or straight edge firmly placed against the main web of the block, and then using a feeler gauge. Similar to checking for head warpage with a straight edge and feelers. |
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#3
12-24-2007, 05:03 PM
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Quote:
There are many times machinists overlook this when line boring/honing mains. Often when the sides of the thrust cap is ground they aren't perpendicular with the parting line hence the cap is crooked on the block. If that the case you need to determine how far out the runout is on the thrust flange and angle cut the cap to correct. The block will have to be realign honed. If you need further information on set up and checking proceedures, I'd be glad to pass on some info. |
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