Scalliwag

This kind of goes with my resurfacing rotor housing project. Does anyone here have first hand experience or knowledge of the best way to bore the approximately 2" hole in the housing. I have a mill and a lathe and the positioning of the housing is not the question. The question is more the cutter tooling used.
Since tooling for mills is expensive I would like to know what has worked for others and avoid as much trial and error as possible.

rxtasy3

iTrader: (2)

I've never done bridge porting, but I do have some machining experience, I would suggest using a boring tool in ur mill with a carbide insert.

peejay

I'm no machinist but the aluminum cuts nicely with a drill bit! One day I took a fresh battery in my cordless and chucked a big ole 1/2" bit in there and drilled a starter port. The metal shaved away nice and clean. After I did that, I was told that if I'd have used ethylene glycol coolant as a cutting fluid it would have cut even nicer.

The metal insert was a bit tougher, but it's chrome-moly steel so it kinda should be

No pics, and if I had any they'd not be worth seeing, just a 1/2" hole vaguely where an intake port should go while I finally decide on a port configuration.

Scalliwag

A 2" drill bit would not be as practical as you may think. A bi-metal holesaw may work but I have a feeling the hole may look as primitive as the tool.

rxtasy3

iTrader: (2)

A starter hole is a no brainer, he's talking bout a 2" hole. U need something that will cut a smooth, round, straight hole that size. Just like if u were making a carb adapter plate.

DaveB

You might consider a flycutter in the mill. They are not very expensive at places like Kennemetal. You might have to start with a pilot hole and make multiple cuts, but it really shouldn't take long.

Just a thought...........

db

rxtasy3

iTrader: (2)

Fly cutters r for milling the surface, not boring a hole.

Scalliwag

Actually a hole saw seems to work pretty well. The only bi-metal one I could find in my garage was just 7/8" but I was looking more for how the teeth cut the material more than the size since it is all relative.
Just in case any of you want to try this. I will not go into setting up the lathe jig so this is after the housing is mounted in position to bore.
Since the hole saw used a 1/4" pilot bit I used a bare bit and drilled a 1/4" hole the entire way through.
Most of you can figure out that if you get a hole saw on an uneven surface that it is going to try to "walk" on you and leave a pretty rough looking hole. Since the surface where the bit enters the housing is awkward this is how I kept it from walking.
I took the 1/4" drill bit out of the hole saw and put a smooth piece of 1/4" round stainless rod in its place.
This forced the saw to stay true to the pilot hole. If I would have left the drillbit in it would have had a tendency to side cut the hole. Since the side of the rod was smooth it could not cut change the shape of the original pilot hole.
I know that is a long explanation but it is real important that anyone who tries this method adhere to that step. Otherwise you might end up with a oval hole.

I am milling a set for Ken Sheepers. This port is based on what he currently uses which is very similar to factory peripheral ports as opposed to the Racing Beat that comes in at a different angle than what he is wanting. He has ran both types and prefers this from experience.
Just in case you have not looked at a housing in a while remember where I drilled this is a little below center of an existing hole. The second picture from the bottom would appear to be screwed up if you don't keep that in mind.
I will post a pic after I do an actual pport ready housing and if I run into any surprises. So far this is a pretty inexpensive way to tool up for a job

Rota_Motor

hmm interesting, Im also thinking of building up a PP for myself, so just a few quick questions

when you have the 2" hole bored, are you going to use an insert of some kind and then seal the water galleries off?

and also the final port shape on the ionside of the housing? is this just going to be a round hole, as I am thinking of stopping just short of the insert and doing final port shaping using a die grinder or something to control the port timing a bit better.

any help, thanks.

Scalliwag

Yes. The insert is actually just a tube. Since you drill through a water jacket it is at least the easiest way to accomplish this. All the pports I have seen always used an epoxy like Devcon with the exception of Jesus Padilla that uses some kind of silicone. Or at least that is what it looks and feels like.
And after I measured Ken's the tubing was 2" ID with a 2 1/4" OD. He has a huge dual 55mm throttle body fuel injection setup.
I understand why people use epoxy just to be sure they don't get any leaks but if this was mine and not Ken's here is what I would do.
I would start off with a thicker walled tube. I would prep my hole saw. If you feel the outer edge of a hole saw you will be able to feel that the teeth slightly bend outward because these are not made for precise work and it allows clearance to reduce binding. Basically I would spin the holesaw on the lathe and file the hole saw so it was true. I would bore the holes and get a precised measurement.
After I had the measurement I would put the tubes on the lathe and make them a little oversized and put a small taper at one end.
The tubes would then go into the deep freezer to shrink them as much as possible. I would put the tapered end of the tube in the bore then press fit them in.
It should work like a freeze plug. You have to make sure the the tubes are longer than neccesary since it needs to be ground to follow the curvature of the inner wall of the housing.
To bench test it I would make to block off plates. (see picture) One would be tapped for an air fitting to tap into it. Laying the housing flat with the fitting pointing up I would fill it with a flourescent liquid and hook the air compressor to it. Look and see if there are any obvious leaks and if not hit the lights and fire up the blacklight and see if there is any sign of even slight leakage.
If it passed that test I would grind it back and to a finished state and test it again.
Obviously if I did this pport setup it would be for a race motor anyway so if it had to come back out it would not be the end of the world and it could still be epoxied later.
I will conceed that is more trouble than it is worth but I just like to do things sometimes to see if it will work


This would be two plates sandwiching the housing using 3 bolts and using sheet rubber between the plates to seal.

peejay

If you were really **** retentive you'd bolt a complete "empty" engine together (just housings, no internals) with the tension bolts torqued to spec, then heat everything up to operating temp (flow hot/boiling water through it) so all the stresses are the same.

Kinda like boring cylinders with a deck plate.

Some head porters bolt deck plates on the cylinder heads and flow hot water through them before doing a valve job! Every little bit of accuracy counts

Scalliwag

Dammit Peejay why you want to get me doing something like that?!?!?! I think a hot liquid under about 180 lbs. of pressure will have to do.
Then again if I drilled and tapped the plate that is opposite of the air fitting I would put a small heating element and a temperature gauge as well as a pressure gauge to keep it from getting ridiculously hot.... dammit Peejay, see what you got started?!?!?!

peejay

At some point you have to shoot the engineers and make the damn product already!

That's why I said hell, I'll just pot the whole thing with Devcon and chew a port out of that. Not pretty, but pretty doesn't matter.

Scalliwag

No don't shoot the engineer! At least not while I'm the one wearing the hat that day!
Yes, theory can only get you so far and you have to put up or shut up eventually. You just want to do as much practical research as possible and look for any problems that may be avoidable.
My wife went to WW Grainger and picked up my holesaw and I have to run by a shop and pick up a piece of aluminum pipe after work. So by New Years day hopefully I will be doing a pport.
Right now I don't have anything to use on the tailstock of my lathe to turn the pipe on so I am trying to figure out how I am going to make due on that.

Scalliwag

Well I got home and I looked at the hole saw. Like a kid in a candy store I made a beeline for the garage! I popped another housing up on the lathe and ran the 1/4" pilot and ran the 2 1/4" hole saw. It worked great.
I can also tell looking at it without a tube epoxied in why they epoxy them. There is no place for the water to circulate past the tube.
I probably won't try to press fit it after all.
So like I mentioned earlier the only hurdle now is figuring out how to support the tailstock end of the tube on the lathe so I can turn it down to fit in the hole now.