LS1-->408ci, alternator bracket doesnt match?
02-25-2007, 08:00 PM
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LS1-->408ci, alternator bracket doesnt match? mounting my alternator onto the 6.0 block and the block is missing 2 out of the 3 holes the bracket uses to mount to the block. as of now i could bolt the Alt to the upper bracket behind it, and the lower bracket hole. would those 2 points be enough? or should i look into an alternate bracket of some sorts? pics to follow...
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02-26-2007, 07:20 PM
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here's a little step by step i did on a 6.0L block recently.
Problem with the 6.0L block when using it in a F-body is there is only one hole for the alternator bracket that is held to the block with three bolts. So, the block needs to be drilled for the other two holes. (pic below).
Problem is the block only has one other spot that can be drilled. Not a big deal, as the third hole is only to support the bracket itself. The two long bolts that go through the alternator to the block will still be used. The arrow show the third hole that will not be used.
What I did was bolt the alternator bracket to the block and use the hole as a guide to make a mark on the block where it will need to be drilled. I used a 3/8" drill bit to make my mark.
Now, remove the bracket and you will see the mark made by the drill bit. From here, I now use a small drill bit (7/64") to make my pilot hole. You need to take your time and make sure you remain straight and perpendicular to the block facing.
I 'stepped' the hole by using 3 drill bit sizes, 5/32", 5/16" and 11/32" ending at the 11/32" as it's the size just under the thread pitch of 10mm x 1.5" that you'll need to tap it with. You'll notice a square protrusion just behind where the hole is being drilled. I drilled the hole until I was to that point, which is about 3/4" deep.
The next thing to do is use a 3/8" drill bit and drill into the hole about 1/8" deep. This chamfers the hole, for two reasons. First one is when it comes time to put the bolt in, you have a guide to insert the bolt into, rather than having the threaded hole flush with the block. Second, it will be easier to tap the hole because you have a slight recess to guide you on the initial start.
Tap all the way until it bottoms out. Again, take your time as you do not want to break the tap. Turn inward about one turn, then back out. Repeat until done. In the picture, you'll see the recess and then the threads start just after that. All done.
Problem with the 6.0L block when using it in a F-body is there is only one hole for the alternator bracket that is held to the block with three bolts. So, the block needs to be drilled for the other two holes. (pic below).
Problem is the block only has one other spot that can be drilled. Not a big deal, as the third hole is only to support the bracket itself. The two long bolts that go through the alternator to the block will still be used. The arrow show the third hole that will not be used.
What I did was bolt the alternator bracket to the block and use the hole as a guide to make a mark on the block where it will need to be drilled. I used a 3/8" drill bit to make my mark.
Now, remove the bracket and you will see the mark made by the drill bit. From here, I now use a small drill bit (7/64") to make my pilot hole. You need to take your time and make sure you remain straight and perpendicular to the block facing.
I 'stepped' the hole by using 3 drill bit sizes, 5/32", 5/16" and 11/32" ending at the 11/32" as it's the size just under the thread pitch of 10mm x 1.5" that you'll need to tap it with. You'll notice a square protrusion just behind where the hole is being drilled. I drilled the hole until I was to that point, which is about 3/4" deep.
The next thing to do is use a 3/8" drill bit and drill into the hole about 1/8" deep. This chamfers the hole, for two reasons. First one is when it comes time to put the bolt in, you have a guide to insert the bolt into, rather than having the threaded hole flush with the block. Second, it will be easier to tap the hole because you have a slight recess to guide you on the initial start.
Tap all the way until it bottoms out. Again, take your time as you do not want to break the tap. Turn inward about one turn, then back out. Repeat until done. In the picture, you'll see the recess and then the threads start just after that. All done.
02-26-2007, 08:57 PM
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no possible way to have 3 bolts holding the alt on a LQ4/9 block. you just have to deal with the 2 holding it on. none in the middle.
drill and tap the top boss for the hole and thats what you gotta live with unless you wanted to make some sort of custom braket
drill and tap the top boss for the hole and thats what you gotta live with unless you wanted to make some sort of custom braket
