Any tips on drilling into the frame?

[vandelay industries]

i have to drill 3 holes on each side/both left and right frame rails because my truck doesn't have the holes for the engine perches.

i'm going from v-8 to v-6. As you probably know, they didn't offer this engine until 85 and my truck is an 83---thus no holes. The position for the v-6 perches is different from the 8---as you may know the 4.3 is a shorter small block--and the engine mount point is 4.4 inches further back compared to the v-8.

These pictures should better illustrate where i need to drill:

You may notice that the rearmost holes on the crossmember DO exist and line up for the v-6 perches. So i have those plus i've connected the transmission the engine so i have those to work with to get everything centered which is more or less is. All i need to do now is drill.

Are there any tips? Should i drill a smaller hole, then slightly larger, and then larger and so forth?

 

[Mastiff]

Someone with more experience will chime in, but I generally center punch the spot, use a smallish bit first, then jump up to full size. I use WD-40 as cutting fluid, spraying frequently. Make sure the bit is sharp because it makes a huge difference.

 

[ktmoutfront]

Just step up sizes like he said. The frame is not hardened or tempered. Just mild steel.

 

[Stomis]

Drilling the frame? Honestly mild steel is not difficult to drill at all with mediocre drill bits. A fresh irwin, dewalt, milwaukee, or any other non sub par brand name bit from the local home improvement box store will go right through it. Im assuming we're talking in the realm of 3/8th bolts here so cutting fluid really isnt necessary since the frame is only about 1/8 thick. Drill a 1/8th or 3/16ths pilot so it doesnt walk on you and just give it good pressure.

Unless you're doing some ridiculous angle or difficult to position spot (which it doesnt seem like) I bet you'll be shocked to see how easy steel is to drill.


Now when you need to drill 316L stainless come back and we'll talk about difficult lol.

 

[Mastiff]

I didn't mean cutting fluid is required, I just feel like it goes faster and easier and keeps the bit cooler.

 

[Stomis]

I didn't mean cutting fluid is required, I just feel like it goes faster and easier and keeps the bit cooler.

I got ya. I draw a line when it comes to cutting fluid. If the amount of time it takes to drill the hole is so short that the bit doesnt even have a chance to get hot then I dont bother.

 

[4X4HIGH]

The 4.3 is the same as a SBC from the bellhousing to the motor mount holes unless you know something I don't. The 4.3 is basically a 350 but missing the front 2 cylinders.

 

[rjfguitar]

It's pretty simple.

Start with a 3/8" bit. Just drill the very center for a couple seconds. This will center up the whole properly. Switch to an 1/8" bit and put it in the small starter hole you just made with the 3/8" bit, drill through. Put your 3/8" bit back in and punch the hole. You don't need fluid, this is simple easy drilling.

Do NOT try and "step up" through a bunch of bits. That is a waste of time, and hard on the corners of each bit. 1/8", then the 3/8" bit. I mean really, if you have a good bit you don't even need a pilot hole for 3/8" anyway.

I use the Dewalt pilot point bits, skips the pilot drilling part all together.

 

[badmix]

Ive drilled the frame, its pretty easy. Personally, id hit up Harbor Freight and buy one of those step bits. Drill your first hole with a smaller bit and then use the step bit.

Itll go a lot quicker.

 

[rjfguitar]

Ive drilled the frame, its pretty easy. Personally, id hit up Harbor Freight and buy one of those step bits. Drill your first hole with a smaller bit and then use the step bit.

Itll go a lot quicker.

Junk. It'll be burned up after hole 1. I was riding with someone once and they said "hey lets run over to Harbor Freight real quick." I said just pull over and let me out here. This is simple stuff. Drill the hole with a good 3/8" bit, done.

 

[vandelay industries]

The 4.3 is the same as a SBC from the bellhousing to the motor mount holes unless you know something I don't. The 4.3 is basically a 350 but missing the front 2 cylinders.

i wish it were that way, but the 4.3 is the same as a SBC from block front face to engine mount holes, not from bellhousing.

And the v-6 block is 4.4" shorter than the v-8, thus mounts are further back on the frame.

 

[paratrooper307]

Just out of curiosity, any particular reason for going to a V-6 from a V-8? In these trucks dealing with a V-6 is going to be more trouble and more money to get less power.

 

[vandelay industries]

Just out of curiosity, any particular reason for going to a V-6 from a V-8? In these trucks dealing with a V-6 is going to be more trouble and more money to get less power.

i'll comment in more detail tomorrow as i'm getting ready to go to sleep, but a large reason is i like the engine and i think v-8's are unnecessary and don't make any sense---for me.

 

[Stomis]

The 4.3 is a really good motor and.would honestly suit a lot of people in a half ton truck if we weren't sold the v8 koolaid as american truck consumers.

 

[paratrooper307]

The 4.3 is a really good motor and.would honestly suit a lot of people in a half ton truck if we weren't sold the v8 koolaid as american truck consumers.

Agreed. Depending on what one is using the truck for, a V6 might be ideal. A parts truck, for instance, or daily driver. Maybe an expedition rig where the extra economy and space under the hood might be beneficial. It's kind of like everyone that thinks they need a big block, they usually don't. Since in this particular example, an SBC is typically going to be easier to find, cheaper, and fit without modification, I was curious as to the OP's motivation for the swap.

 

[Deuling]

Junk. It'll be burned up after hole 1. I was riding with someone once and they said "hey lets run over to Harbor Freight real quick." I said just pull over and let me out here. This is simple stuff. Drill the hole with a good 3/8" bit, done.

Actually I bought a few of those and they work great and have drilled alot of holes

I drilled 16 3/8" holes with one today in some 1/8" or so steel.

 

[tRustyK5]

Drill speed is everything...too much rpm will dull a good bit before you finish the first hole. Those step bits work good, but same deal. Gotta keep the RPM's low.

 

[jekquistk5]

Drill speed is everything...too much rpm will dull a good bit before you finish the first hole. Those step bits work good, but same deal. Gotta keep the RPM's low.

Was just gonna say that. I've seen a few people run full blast on the drill and go through about 3 bits trying to drill one hole. Slow down kemosabi.

Also WD 40 is a horrible lubricant, it is a water displacer. Use oil or cutting fluid if you are going to use fluid.

 

[blazinzuk]

My tips for drilling into the frame. Sharp bit. That's about it. Just metal nothing special at all.

 

[skunked]

Drill speed is everything...too much rpm will dull a good bit before you finish the first hole. Those step bits work good, but same deal. Gotta keep the RPM's low.

FWIW I've been using the dewalt stepped bits and they seem to be pretty durable.