Drilling Fuel Injector Holes?

tjh566 · Apr 9, 2007

Ok, with my eaton set-up I just ordered a carb intake that said it could be drilled for fuel injectors, Now looking at my intake it appears to be a 3/8" hole straight thru with a 1/2" hole a little ways in for the injector to sit in. Now my question is, And I think I can, just drill them in very carefully with a drill?

My dad says they's have to be machined in at a shop but it doesnt appear to be THAT precise of a deal to me? In the intakes Ive put injectors in they werent really as sealed as I thought they should, they just kinda sat in the hole, but still held the seal fine.

What are your guys opinions on this?

I think im gonna try to drill them in my self, just sart with a small pilot hole and get the angle correct then slowly set up the sizes and drill slow to get a nice smooth hole. Then once I get to the 1/2" step compare to my old intake, mark the bit and drill that in slowly.

Thanks In advance!

final5-0 · Apr 9, 2007

Not saying you couldn't do it

Some of my concerns would be

Correct location to drill
Correct angle of hole
Correct size of each dimension
Correct depth of each dimension
Ensuring a smooth surface for a no leak O-Ring condition

This is one of those kind of things that could cause your Stang to burn
down to the ground in a hurry

I see this project as having N O margin of room for error

Grady

The Green GT · Apr 9, 2007

Machine Shop.

Unless you REALLY know what you are doing.

tjh566 · Apr 9, 2007

final5-0 said:
Not saying you couldn't do it

Some of my concerns would be

Correct location to drill
Correct angle of hole
Correct size of each dimension
Correct depth of each dimension
Ensuring a smooth surface for a no leak O-Ring condition

This is one of those kind of things that could cause your Stang to burn
down to the ground in a hurry

I see this project as having N O margin of room for error

Grady

-Correct Location ill just center punch the bosses on the manifold (see pic at bottom)
-Correct angle ill level out witht he tops of the bosses
-Dimension is 27/64" for the small hole and 17/32" for the larger one
-The depth one goes all the way thru, the other goes paritally down, can measure and mark the bit (have an old intake layin in the garage)
-Smoothness and can dremel down the very top edge of the hole slightly rounded

Just curious on how an error would cause the stang to burn down??

bill302 · Apr 9, 2007

tjh566 said:
-Correct Location ill just center punch the bosses on the manifold (see pic at bottom)
-Correct angle ill level out witht he tops of the bosses
-Dimension is 27/64" for the small hole and 17/32" for the larger one
-The depth one goes all the way thru, the other goes paritally down, can measure and mark the bit (have an old intake layin in the garage)
-Smoothness and can dremel down the very top edge of the hole slightly rounded

Just curious on how an error would cause the stang to burn down??

Just curious on how an error would cause the stang to burn down??
if the hole drilled is not precise angle and size the o-rings will not seal causing a fuel leak and then a fire...take my/our advise take it to a machine shop or learn from experience.....your choice. thats intake looks to good to mess up.

94CobraPace · Apr 9, 2007

I would not try if with a hand drill, posssible a drill press at a min. Then make sure the intake is at a 90 degree angle. Most drill presses have a scale on the handle for depth. Then I would not do it on a new intake, possible a older cheaper one. Getting 8 all the same angle and depth would be too hard with a hand drill.

tjh566 · Apr 9, 2007

yeah, i was gonna use a drill press and set the bench angle and not change it throughout the process.

Level out the tops of the bosses with the bench and make sure the bit/press is plumb and go at it. I think if I take my time I can get it damn close.

tjh566 · Apr 9, 2007

theres a specific drill bit made just for this but its $130 I just can see spending that much on something I'll only use this one time, plus i dont really have $130 to throw around.

final5-0 · Apr 10, 2007

The pic is very insightful if you ask me

If I'm looking at it correctly

It seems like you would end up with 3 different diameters

A really difficult task to do with just a hand drill and 3 bits

Pretty good little chore ...
even with a drill press and 3 bits I'd say

I can see ... maybe ... doing it with that special drill bit and a press

I'd wanna know the difference in cost of the bit and Pro Labor

Good Luck which ever way you go

Grady

BlackVert · Apr 10, 2007

i would worry about making sure they were spaced apart correctly so that the fuel rails would fit correctly on the tops of the injectors.

i wonder if someone might make screw in injector bosses ... you know what i mean ... where you would just drill and tap and then screw these in, and the injector sits in that? something like that would make life easier ...

tjh566 · Apr 10, 2007

there are injector bosses made, they are about $100 for a set of 8, but they have to be welded in which is an option also.

And the 3 different Diameters your seeing the largest one is just for the top of the hole to give the edge sotra sloped back a little.

95Mustang302 · Apr 10, 2007

just take it to a machine shop, do it once and do it RIGHT

tjh566 · Apr 10, 2007

Ok figured out what Im gonna go, found some fuel injector bungs on ebay for a reasonable price and got them, gonna drill the holes and weld em in.

BlackVert · Apr 10, 2007

that is the kind of thing i was thinking about ...

94-302-vert · Apr 11, 2007

Did you ever find out how much a machine shop would charge?

divit250r · Apr 11, 2007

tjh566 said:
Ok figured out what Im gonna go, found some fuel injector bungs on ebay for a reasonable price and got them, gonna drill the holes and weld em in.

It sure looks like this is gonna raise the height of the injectors and change the spray path / pattern down into the intake port.

I tend to agree with the take it to a shop idea, but doing something on your own is a very rewarding thing too. :SNSign:

Good luck!
Scott

tjh566 · Apr 11, 2007

they are trim to fit, you cut the bottoms for your specific intake.

divit250r · Apr 12, 2007

tjh566 said:
they are trim to fit, you cut the bottoms for your specific intake.

I figured that, but you'll still need to drill two sizes of hole in each port to seat the bung, and for the fuel to pass through. One other little comment is that it sure looks like a specially cut endmill to me, not just a simple twist drill. You have access to a drill press, but I would use a mill myself. Much more of a repeatable process that way, since you're drilling at least 8, possibly 16 holes. Again, good luck!

Scott

tjh566 · Apr 12, 2007

you drill one hole all the way through, the size of the bung, and thats it.

2muchtime · Apr 12, 2007

what the hell are you asking questions for if all you do is answer them yourself..
go ahead if your so confident your not going to make one mistake..
btw 1` mistake = 1` intake. but it sounds as if you have done some homework.
in any case if someone is asking questions why they shouldnt do something
that tells me about their confidence...good luck..
basically if you knew what you were doing you wouldnt be asking would you?

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