| Author |
Message |
David Prall (Davidpra)
Junior Member
Username: Davidpra
Post Number: 99
Registered: 2-2001
| | Posted on Thursday, July 04, 2002 - 5:05 pm: | |
No, it's not... There are 2 ways to re-bore the crank journals. The method you guys are talking about bores to maintain the original diameters but relocates the centerline. The method I was referring to bores to a larger diameter and retains the original centerline location. Which you do is a matter of preference and whatever limitations (allowable material to remove, over-sizing limits, and piston to valve clearance limits) exist on the engine geometry. |
Ben Millermon (Brainsboy)
New member
Username: Brainsboy
Post Number: 20
Registered: 5-2001
| | Posted on Wednesday, July 03, 2002 - 2:45 pm: | |
The last post is wrong. The crankshaft does move up everytime its lined bored. How much depends on the machinest. Keep in mind the amount it moves is very little, due to the fact its usualy the caps that are ground down, causing the rebore to remove more material off the caps not the block. As far as how many times a block can be line honed would be a good question to ask. I would guess at least 5 or 6 times before any type of a problem would arise. Also check your pistons at TDC, they will measure taller. If you would like to keep the original height I might suggest honing the piston rods. Everytime you hone a rod, that rod becomes shorter, which in turn brings the piston back to its original height. As far as the gears. The best thing would be to measure the gear's prior to line boring. Then let your machin shop know the numbers. They can take care to remove as little as possible material off your linebore. |
Mitchell Minh Le (Yelcab1)
Junior Member
Username: Yelcab1
Post Number: 203
Registered: 11-2001
| | Posted on Wednesday, July 03, 2002 - 2:42 pm: | |
I have already "dropped" the #2, #3 and #4 caps by 0.020" while leaving the #1 and #5 caps alone. This, according to the machine shop, will force the boring to cut into the saddle a bit and move the center line toward the timing gear drive pulleys. That is what I am trying to avoid. Thanks for the info. |
David Prall (Davidpra)
Junior Member
Username: Davidpra
Post Number: 97
Registered: 2-2001
| | Posted on Wednesday, July 03, 2002 - 10:28 am: | |
Very unlikely that line boring will cause any shift in the original nominal centerline of the bores. If done properly, all bores are done simultaneously which corrects all to a common centerline. The only way this new, common centerline could be shifted from the original centerline is if all the bores were worn in the same radial direction (i.e., all upwards towards the heads). This is virtually impossible --- the bores tend float in different and random directions. Boring should restore the original centerline, but will increase the OD of the main bearings --- what you really should worry about is making sure you don't exceed the oversize limit of available bearings. |
Mitchell Minh Le (Yelcab1)
Junior Member
Username: Yelcab1
Post Number: 198
Registered: 11-2001
| | Posted on Tuesday, July 02, 2002 - 10:28 pm: | |
I am having my block line-bored. In this process, it is pretty much necessary to cut away at the block saddle. This has the effect of raising the center line, and therefore raising the crankshaft with respect to the rest of the engine. How much of this "raising" can I get away with before there will be interference between the timing gears, the crankshaft, and the oil pump gear, and then they don't turn anymore???
0.005", or 0.010" or ...
Thanks |
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