Home-Made Cutouts

Here’s a pair of cutouts a little different from the usual two and three bolts you see on some cars.

Five bolts to follow a theme I use on both roadsters.

I’m fortunate to own a dividing head so that makes life easy.
Even so, there are ways to lay out bolt circles and patterns without a dividing head or rotary table and obtain a fair degree of accuracy.

Cutting out the 1/4" cold rolled flange, cap and gasket is easy on the lathe.
Make the steel flange first.

As noted, this design or a slightly different one can be done sans lathe and like always a little more work is involved.

Aside from the savings in work time, with the dividing head and lathe all parts are interchangeable.
If you’re laying out everything by hand etc., drill one flange and use it for a master to make the other components.
It will probably come out accurate enough to swap parts from side to side if you’re careful.
Transfer punches and transfer screws work well here.


The cutout on it’s 2 ½" piece of exhaust tubing.



A view from the side.


The flange will be TIG’d on the inside.
If you’re careful you can keep the bead small and not much filing will be required to end up with a flat plate.

Tack in three places and do short runs so you don’t tweak the flange out of shape.
A little care here will pay off in way less work when you’re ready to ***emble with gasket etc.


Here’s a view of the individual component pieces.
The cap is 1/4" 6061 T6 aluminum and the gasket is .025 - 24 gage I believe - soft aluminum sheet.


The sheet aluminum for the gasket can be purchased at Ace or True Value.
It seems to be pretty soft and should work well as an exhaust gasket.

Exhaust heat shouldn’t hurt the cap.
We used to run 3/8" thick commercially made - with fins - cutout caps back in the day and I never heard of one getting burned through nor compromised by the heat.
These were fairly short tubed cutouts as well.

Pure aluminum melts at 1100* F if I remember right and alloys take it even higher.

The cap and gasket are easily made using the steel flange as a jig.
The flange gets pattern drilled with a #7 drill for the 1/4-20 stainless allen screws.
The aluminum in roughed out shape is clamped to the steel flange and the aluminum through drilled with the #7 drill.
Tap the steel flange 1/4-20.
Drill the aluminum cap to 1/4".
This makes the clamp setup for the next hole to be drilled and tapped.

Repeat until all ten holes are drilled in the cap and tapped in the flange.
Add bolts as you go.
My machinist pal recommends very highly to use a 2-flute US made tap on smaller sizes.
There’s a lot of stress on the usual hardware store 4-flute taps.
Not to mention the best tap I could find locally was a Chinese made 4-flute and Tin coated.
The Tin is a metal lubricant and you still need tapping fluid, even so, it was a nail-biter getting all ten holes tapped without breaking a tap.
I like to use a new tap on important jobs.
Seems like the smaller sizes go dull in no time.

Bolt flange and cap together and trim the aluminum cap to round and to size in the lathe.
A disc sander should work well in lieu of a lathe.

No names, but one of our carries sheet metal, but is a different type business shop quoted me $1450. for a 1' x 2' piece of thin perforated sheet metal.
I balked a little bit, she re-calculated and came up with $74.
We talked a little bit and she stood her ground.
I dunno if she can add or not, but she sure as hell couldn’t use a calculator.

I gave up and went to the steel supply outfit down the street and bought a whole sheet of the stuff for $26.
Expensive for what little I needed, but it’ll get used when I make a screen door for the shop.

The gasket - shown at an angle to show how thin it is - is shown in this pic.
I would have used thicker, but this is about as thick as you can buy sheet aluminum locally unless you go to a sheet metal shop.


Note also, the cap holes are countersunk with a regular drill (3/8") so the standard head allen bolts can sink in a bit - about 1/16".
This does two things.
Appearance imo is a little better.
And you won’t end up with aluminum mushroomed out after several install and remove cycles.

The gasket is easy to make.
Use the flange as a template, transfer punch hole locations and drill to size.
Leave it a bit large so you can clamp it without damaging the area where it has to seal.

Clamp the whole magilla together and trim the gasket to round and to size.
In fact this is a good time to cut perhaps .005 off all three pieces so that everything is the exact same size

Now that they’re done, not sure if I’m going to use them or not.

Thinking was that they would be convenient to use at the street drags next weekend.
Already tech’d and numbered as you can see.


The problem I ran into at last November’s Airport drags was that I couldn’t pull the collector bolts and swing the exhaust to the side due to lack of room and ground clearance if I hung them low due to the H-pipe.
So I pulled the whole exhaust system off the car.
Easy to do, the removal of 10 bolts does it.

I have to pull the whole exhaust system whether I install the cutouts or not.
Thinking I’ll probably cut the H-pipe in the middle and install a couple of three bolt flanges.
The exhaust pipes would swing to the side and get re-bolted ok if done one at a time.

If you do a cutout, no matter what flange you use, be sure and cut the cutouts exhaust tubing on the curve so you get a streamlined transition as well as better performance.
Plugging the cutout into the exhaust tube at a 90 degree angle doesn’t help all that much.

The roadster gets trailered to the races - 4 miles away.
Not to inclined to drive an open-headered car across town and if it breaks we’re set to take it home the easy way.
Not to mention with the Soccer Mom van seat - looks like a short couch - in the trailer and a potty room for the girls we got er made.
Anyway, fun project.

Nuff for now, gotta get out there and do some more stuff for the upcoming drags.

 

Very nice! If you're not gonna use them, I'll be glad to properly dispose of them for you.

 

you get realy realy bored dont you?

lol.

i like em though.

 

- Great job..!

 

nice work

 

Not really.

Stuff like this keeps me busy, but these were one of those side jobs where you do a little bit every day.

Hot Rods are supposed to be fun.
Driving and building.



Thanks for the nice words.

 

Nice work

 

My favorite is in the California Bill book, he used gas filler necks and caps

 

Nice work Jay!

 

I saw a few of those done back in the day, but they usually leaked due to the gasket couldn't handle the heat.

Most cutouts I saw - that weren't hidden under the car - were two bolt diamond shaped caps.
A common muffler shop item.

The cops would usually overlook a closed cutout, but if you got stopped for some other reason, the cutouts would be on the ticket.

 

Thanks Kerry.

Gettin' a little bit done every day.
Tryin' to get the roadster and trailer ready for the races.
Gotta unload a bunch of carport corrugated roof stuff and air up the tires on the trailer and it's done.

And my neighbor - really nice guy - chose this week to give me a big stack of grey cement blocks.
Free blocks, whatta deal . . . gonna use em to enlarge the veggie garden.
Be nibbling away at that for a few days.
Not gonna kill myself trying to do it all in one day.

Saw your new car.
Gonna be a totally *****in' tow rig and dragster combo slidin down the highway.

Somebody's going to see that and think they slipped back in time.

I'm just about to the point where I can pull the 31 body off the frame for plumbing.

Gonna put the junkyard T-400 in place of the broken case mockup T-400, get a flex plate and starter and fire up what was the mockup engine that looking a little closer seems to be in pretty good shape.

Even if it runs pretty good it'll still get some 'good' stuff.

Somewhere in between the initial fire-up and doing the engine I'll get the car licensed and registered.
So far, it looks like it will be easier to do here in Arizona than it was in California and Sunny Cal wasn't all that bad.
Just gotta learn what ropes to jump through.

Not sure about paint.
I may run it in flat black for a while.
CKs 29 roadster looked pretty good that way.
In fact, the new owner is still driving it with the old paint.

Got any more dragster updates?

 

You're making good progress Jay. And getting honey do projects done to boot. Very good! When are the races? Wish I could make that!

No real digger progress. I did finally get all the bearings, axles, and stuff to put the rear end together. I did some trueing up on the housing with heat and it's ready to go. I'm really waiting for the rear and top hoops. Should have them soon.

Tonight I got the brakes bled on the Plymouth. I could drive her if I took her off of the trailer but I'm going to leave her loaded and do a few other things. I've got a hitch receiver to modify and put on. It's at a nice height to work on.

 

The races are this weekend.

They start opening up Friday night, but just to tech and probably last minute setting up the dragstrip stuff.

Actual racing starts Saturday morning.

The track is not too long at 1/16th of a mile, low and most of 2nd for me.

The 1/8th mile at the airport drags last November went by pretty quick.
Even quicker at the street drags here, but it duplicates to an extent the stoplight Gran Prix from days gone by.

Course, the losers on the street always figured they coulda caught the other car on a full 1/4 mile.
Unofficial testing on empty late night country roads disproved that.

There will be some fast cars there.
More than a few 7 second door slammers as well as one rear engine dragster and an altered roadster.
I think both of these run on alky.

Something to do for everyone.
Races for the guys and for the gals who don't drive or crew, old downtown is loaded with some great antique and specialty stores.
Couple of great pawn shops as well with lots of tools and stuff.

Looks to be a fun weekend....