DGGM WX3

iTrader: (1)

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

RetroLSX

iTrader: (9)

I had the guys at Vengeance Racing drop a 5.3l and they were able to drill and tap the block without to much trouble.

TTLS1GP

iTrader: (10)

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.

Redrumls

Thanx for the info, I'm putting the same bracket on my 6.0 & was a little worried, LOL

cutlass_455

iTrader: (2)

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.

Redrumls

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.

cutlass_455

iTrader: (2)

Oh, ok, so if you swap the entire drive assembly, like I plan to do, you dont need to do this drill and tapping of this hole??

LS1MCSS

iTrader: (18)

If you don't drill and tap the hole, where the blue arrow is pointing, you will be missing a mounting bolt for the alternator bracket.

jomomma

iTrader: (39)

i would put the bracket in place and then use a transfer punch on the hole to be tapped. you cant go wrong this way!

cutlass_455

iTrader: (2)

OK, thanks for the info. I was unaware of this 'difference' between the truck and car blocks. Thanks again.

the_merv

iTrader: (88)

I did mine and it's a little crooked..but it works.
I wish I had a Drill Press big enough to have made it perfect but all I have is a normal Drill.

dpd069

iTrader: (1)

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

cutlass_455

iTrader: (2)

Good info, thanks for the tips, these will really help.

DGGM WX3

iTrader: (1)

Thanks for the info guys. So this is totally possible with a hand-held drill and tap? Just go slowly and try to keep the drill as straight as possible?

the_merv

iTrader: (88)

That's what I did and it got a hair crooked. If I was to do it over again I would use a Drill Press.

TTLS1GP

iTrader: (10)

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.

Chris442

iTrader: (1)

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.

dpd069

iTrader: (1)

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.

cutlass_455

iTrader: (2)

Thanks, I was just gonna ask this. You must be a prophet.

Spoolinsteve

Bringing this back from the dead, are the truck alternators compatible with the f-body bracket? If i shim the bracket enough for the pulleys to line up?