Drilling F-body alternator mounting boss on iron block
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Drilling F-body alternator mounting boss on iron block
What have you guys done to drill and tap the mounting boss for the F-body alternator bracket on an iron block. My 5.3L is already complete, if that makes a difference. Pic below shows which bolt (not my engine). TIA
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I did mine. Be sure to use cutting oil and a good bit while drilling in cast. That is a one shot deal! A center punch helps a bunch. A good bit with a pilot tip helps too!
Also, use a good tap and again, lots of cutting oil. "Generally" taps don't like cast iron. See what the tap in question recommends. I have a carbide/tungsten tap that recommends cutting oil while my titanium set recommends lard of all things for cast.
Also, use a good tap and again, lots of cutting oil. "Generally" taps don't like cast iron. See what the tap in question recommends. I have a carbide/tungsten tap that recommends cutting oil while my titanium set recommends lard of all things for cast.
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K, I would like some extra info on this. Like why are you doing this?? I am putting a 4.8L in an 87 442, and will be swapping to F-body accessories, will I have to do this drill and tap as well?? Is it possible to do this with the engine in the car?? How do you know where 'exactly' to drill the hole....by bolting things up the best you can and then using the bracket as a guide?? Whoa whoa whoa, I feel left in the dark on this one. Sorry guys. I need someone to shed some light on this subject.
#6
The truck bracket I had for the alt. Sat way too high and would never clear my camaro hood. The camaro has a low mount alt. bracket & matches my truck block accesories with a little shimming. I know my friends gto & my other buds
Vette alt. brackets would not work with my motor, I would have to use their entire accesory drive because theirs are closer to the block. Kind of like short and long water pumps on older sbc.
Truck motors are missing one boss by the timing cover and have one at the edge of the block but has to be drilled & tapped.
Vette alt. brackets would not work with my motor, I would have to use their entire accesory drive because theirs are closer to the block. Kind of like short and long water pumps on older sbc.
Truck motors are missing one boss by the timing cover and have one at the edge of the block but has to be drilled & tapped.
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K, I would like some extra info on this. Like why are you doing this?? I am putting a 4.8L in an 87 442, and will be swapping to F-body accessories, will I have to do this drill and tap as well?? Is it possible to do this with the engine in the car?? How do you know where 'exactly' to drill the hole....by bolting things up the best you can and then using the bracket as a guide?? Whoa whoa whoa, I feel left in the dark on this one. Sorry guys. I need someone to shed some light on this subject.
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I did it with the block installed in the car, but no radiator.
Here's the steps-
-Get the metric tap and drill bit
. It might be hard to find the pilot drill diameter but there is a inch equivalent that is very close.
-Put the bracket on the engine and find a drill bit that fits inside the bracket snugly and put a dimple on the block to mark the location of the hole
-Take a 1/8 pilot drill and using the dimple to center it, put a pilot hole in the block. A drill with a bubble level is nice to keep the bit straight.
-Using the slow speed on the drill and plenty of cutting oil, drill the hole for tapping, then tap the hole. Make sure the hole is deep enough to not bottom the bolt in the hole and do this before you tap it.
It should line up perfectly when you are done
Here's the steps-
-Get the metric tap and drill bit
. It might be hard to find the pilot drill diameter but there is a inch equivalent that is very close.
-Put the bracket on the engine and find a drill bit that fits inside the bracket snugly and put a dimple on the block to mark the location of the hole
-Take a 1/8 pilot drill and using the dimple to center it, put a pilot hole in the block. A drill with a bubble level is nice to keep the bit straight.
-Using the slow speed on the drill and plenty of cutting oil, drill the hole for tapping, then tap the hole. Make sure the hole is deep enough to not bottom the bolt in the hole and do this before you tap it.
It should line up perfectly when you are done
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I did it with the block installed in the car, but no radiator.
Here's the steps-
-Get the metric tap and drill bit
. It might be hard to find the pilot drill diameter but there is a inch equivalent that is very close.
-Put the bracket on the engine and find a drill bit that fits inside the bracket snugly and put a dimple on the block to mark the location of the hole
-Take a 1/8 pilot drill and using the dimple to center it, put a pilot hole in the block. A drill with a bubble level is nice to keep the bit straight.
-Using the slow speed on the drill and plenty of cutting oil, drill the hole for tapping, then tap the hole. Make sure the hole is deep enough to not bottom the bolt in the hole and do this before you tap it.
It should line up perfectly when you are done
Here's the steps-
-Get the metric tap and drill bit
. It might be hard to find the pilot drill diameter but there is a inch equivalent that is very close.
-Put the bracket on the engine and find a drill bit that fits inside the bracket snugly and put a dimple on the block to mark the location of the hole
-Take a 1/8 pilot drill and using the dimple to center it, put a pilot hole in the block. A drill with a bubble level is nice to keep the bit straight.
-Using the slow speed on the drill and plenty of cutting oil, drill the hole for tapping, then tap the hole. Make sure the hole is deep enough to not bottom the bolt in the hole and do this before you tap it.
It should line up perfectly when you are done
Good info, thanks for the tips, these will really help.
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trying to find a press big enough to fit the block into is a challenge for most. I used a regular drill, steady hand (no booze guys!! ) and a good bit.
Yes you can do it in the car but the engine on a stand is easier. Bolt the front bracket and rear bracket to the alternator and dimple the block in the center of the blank by putting the bit thru the through-bolt of the alternator.
Is it possible to do this with the engine in the car?? How do you know where 'exactly' to drill the hole....by bolting things up the best you can and then using the bracket as a guide??
#17
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I drilled that hole once on one of my buddy's cars. We were dropping a 6L from a van into an 04 GTO that was ProCharged at that time, so the block was missing the hole. Of course, nobody noticed the hole was missing until the engine was in the car. I drilled the hole using a handheld drill and tapped it, and it was a bit off the mark. It worked well enough, though.
The suggestion I would add is, if you're going to do it by hand, a spotter would be a smart idea, as it's tough to tell if you're drilling straight when you're holding the drill.
The suggestion I would add is, if you're going to do it by hand, a spotter would be a smart idea, as it's tough to tell if you're drilling straight when you're holding the drill.
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By the way the tap you'll need is a 1.5mm 10, Hanson part number 8340
I used a 11/32" cobalt drill for the tap hole and an electric drill with one of those bubble things to tell you if you are drilling straight.
I used a 11/32" cobalt drill for the tap hole and an electric drill with one of those bubble things to tell you if you are drilling straight.