Technical Fuel injector Fab

For those who have made or worked on these before - what material did you make the throttle shaft out of? I was contemplating using drill rod. Worst case if I fall flat on my face trying to make one - I could buy a shaft worst case, but where's the fun in that without trying first? Besides money's a little tight as my previous employer decided that my job could be done better in China (rotsa ruck with THAT)
Drill rod is cheap - not sure what'd it cost to hard chrome it or if I really need to right away. EDIT: Or should I just stick with TGP? or?
We'll see. Thanks for everyones comments - I think I learned alot so far.!

 

I have a 4 shooter Rons fuel injection setup,for sale cheap.

 

I ordered precision ground 3/8 rod for mine. You need something that is very machinable at first and then Hard Chrome. A 1/16 thick slitting saw is your friend, be prepared to grow a set machining shafts! I've done a few sets of them, they are a treat to machine but if successful a big notch in your belt tackling that one! Even extending a slot for larger blades is a chore, you just don't want that blade to grab and bend the hell out of the shaft. I have my methods in doing it, successful so far to date.

 

On the baby bug catcher, I milled a flat on a 3/8 bronze shaft. Might have been 5/16. That was 20 years ago. Just under half way through. Bigger rod, but half of it was gone. Worked fine for the three trips to the 5 that it made

 

Careful with "Drill Rod" as its not always round but a 3 nosed cam, and will measure round. Thought I would be fancy and use 2" Drill Rod for a narrowing fixture. Measured it and bored the sleeves to match plus a couple thou. would not fit, took a scrap piece and kept machining till it fit and measured and it was way off. Returned the DR and bought some 2" TGP (cheaper to boot) and slid right in my tooling. For the limited use, I don't see the need to get it hard chromed, None of the Manuf go thru the trouble. Purchasing a throttle shaft has the ends serrated (splined) over having just a pinch clamp arm over a round shaft. FYI Hilborn FI is having some items made at Enderle FI

 

Dreracecar, I read that somewhere else too. I ordered some TGP - the spec's on it were VERY tight so we'll see.

 

Rich, I've seen that done elsewhere, but can't recall at the moment.

 

402bossman, I've been given that lots of thought - I have a couple ideas, but admit I'm no expert. I bought extra shafting incase I screw a few up!!!!

 

I saw it done on some Motocraft 4 bbl carburetor. Worked for them.Should work for me. Originally I used a choke shaft from a Holley. Had to extend the slot a little. Broke two of them on the dyno. So went to the flat side deal on a bigger shaft. And it was 5/16

 

Well slight detour, after giving it some more thought I decided to add the bronze bearings after all. I figured now was the time since it was already in the vise. I also chose a size where I can upgrade the shaft size by just swapping bearings. For now though I'm gonna try the 5/16 shaft. Figured I'd put the end bearings in first and then jig off those for the inner ones. Hopefully that will prove to be a good decision - time will tell

 

Slow, but progress.

 

Used the plug from the injector body to make the butterfly fixture. I also was a little careless trimming the sheet metal blank and went a bit too small leaving a small flat that didn't clean up during machining, but it still proved that the approach will work.

 

That's a calibrated air gap for idle!

 

Yeah that's what I'm thinking. Actually it's no problem - I'll just make more. My mistake was forgetting that the BLANK needs to be OVAL (or at least big enough for one) - I was cuttin the blank thinking I needed a useable 3" dia, but the reality is that a 3" butterfly on my angle is nearly 3-1/16 in the long direction - duh!!!

 

Power tapping the throttle shaft. Normally I wouldn't do that hang in' off the end of the vise like that but I wanted to be sure that these were all perfectly in line.

 

Slittin' time!

 

So we had a mini disaster on the throttle shaft. While machining the slot corners from the opposite side I mis-indexed the shaft in the collet indexer on the 2nd to last corner! The result was a scarfed up edge. Salvageable? Yes! Acceptable? No! So shaft attempt #2 was started. The first shaft also suffered from a slight perpendicularity issue (screws not perfect 90 derees to slots) due to my fixture - which is why I had switched to the collet indexer in the first place. So attempt #2 would include an improved fixture - no collet indexer this time. The fixture worked perfect the second time with the shaft indexing perfectly (meaning the holes are perfectly perpendicular to the slots). The only thing left to machine is to finish the c'bores for the screws (I left that for last due to my fixture redesign) and of course I still need to remove the little web on the ends of the slot due to the cutter's radius. I've got a cool idea for that which I'll try on the junk shaft first!!

 

Don't concern yourself with cutting the slot into the bushing area of the injector, as long as there is a bridge in that area, your fine, plus it holds oil.

 

Nice work!
Very ingenious.
So I take it you are going with your original vision of a blown FED. You did real well running the Hilborns. I look forward to seeing it run with the blower. Alky I presume?
You da man Jacin. Subscribed

 

Here's a little anecdote about throttle plate angle:
While working at Ford Engineering it was reported in back-to-back customer drive evaluations on us versus Chevy that those surveyed preferred the "get-up - and - go" of the Chevies. Dyno tests, etc. did not show any performance edge of their engines vs ours. It was finally determined that our carbs had a 9 degree throttle plate angle and theirs had a 14 degree throttle plate angle. It was also determined that most drivers use about 40% of the throttle travel under typical driving situations. So if a Ford driver uses 40% and a Chevy driver uses 40% of the available throttle travel the Chevy will feel stronger because more air is admitted past the throttle when the throttle plates started out at a 14 degree angle. This led to the introduction of a series of tests designed to determine the P.T.A.I. - the Part Throttle Acceleration Index - and steps were taken to eliminate that perceived advantage the Chevies had.
Just a little food for thought...

 

dreracecar, I was thinking along the same lines, but I still have to remove some of the web. When I did the bores (at the last minute) I switched the bore spacing to match a Hilborn 4 port incase I fell on my face and couldn't make the throttle shaft (my backup plan would have been to buy one), so the downside of that is that Hilborn spaces holes 1-2 and 3-4 close to one another - 1/8" separation. Not wanting to have the slots touching there leaves me with some web to deal with one way or another. This was one downside of copying their spacing. Not a big deal, but every decision has a consequence one way or another. Thanks for your comment - I appreciate the feedback!!!!

 

Thanks Greg! Yep still alky. I put a 6-71 on it last fall, haven't run it on the track yet - just a test fire in the driveway. It sounds awesome...I may be a tad biased. Even with it mild it sounds great - you know me - I've got a lot to learn so I won't be trying to set the world on fire by any means.

 

Greg, that's awesome. When Jill got her first minivan I HATED the throttle. Chrysler used/uses an asymetrical cam on the throttle body making it real touchy on the take off. Clearly some marketing trick to make you think it has more POWER than it really does. Her "new" Chrysler has the same thing - I hate it as well. I was just having this throttle plate angle discussion with someone the other day. I came to the conclusion that 14 degrees was just a way to get a head start to getting to 90 and by your description it sounds like I may have had it right - I settled on 10degree as I'm not kidding myself into thinking I'm John Force or Don Garlits!!!!
I LOVE your story though! It confirms some of my suspicions. I wonder if the Marketing teams ever consider the guys like me who HATE their tricks????

 

yup
Of course in your situation you can vary the opening rate of the plates vs the gas pedal movement by monkeying with the throttle bell crank / lever length(s).

 

So onto the fitting of the butterflies. The slots machined perfectly with the updated fixture leaving only the ends of the slot needing squared up. My first thought was to try a homemade slotting tool and just use the Bridgeport quill (manually stroking it up and down) and while that did actually work it was painfully slow . Attached is a picture of the tool I ground from an old drill bit. It probably would have worked a LOT better with a slotting attachment (which ironically I have but was too lazy to set it up). So I ended up taking a bit of a caveman approach and took a jig saw and cut the bulk of the material with that. Next I took the shaft over to my ancient Die Filer. Using the die filer and my single file that would fit the narrow slot, I cleaned out the rest of the corners. There's no magic with the die filer other than it holds the files relatively square. Couple of test fits and I was IN!!!!! A word about die filers - I bought this one about 15 or 20 years ago for 99 bucks, and I still see them pop up from time to time at the surplus machine tool place for - you guessed it - around 99 bucks - in 20 years they haven't changed in price from my limited experience.< EDIT: Curiosity got me and I just checked Ebay - seems like these filers now get 3 bills! I may have to grab the next 100 dollar one and flips it!!> It went WAY WAY faster than filing by hand although someone with more patience than me could certainly pull it off - even on the 4140 material I used. YMMV

 

I re-thought my butterfly fixture. My first one has the threaded holes (to mount the butterfly to the fixture) drilled perpendicular to the angled surface. And that's OK to make one at a time. But if you want to make several at once then the angled screws/holes will be further and further off center as you stack more plates on. Being lazy I needed a better way. So by drilling the screws to be inline to the centerline of the part you can now stack as many blanks on with no affect on hole position. Plus as an added bonus the set you make will be dead nuts identical.

 

Tried the new butterfly fixture today - it worked great! But I learned that if you're not real careful cutting the blanks you can easily bend/tweak them and not know it because when you clamp them with the fixture you don't see it. The pic with the fixture in the lathe - there's 4 butterflies being cut at once - it's a little deceiving. I've been using scrap aluminum so all of these issues are valuable lessons. Tomorrow I hope to make the real butterflies - I need a better way to blank them out - maybe a nibbler or hole saw - we'll see. As for the injector- have you ever seen a more pretty pile of scrap aluminum? I haven't! Then again I am definitely a little biased on this one!!!

 

A beaut.
Why not put a few rows of grooves down the outside with a ball mill to give it a more "racey" look?

 

Greg, I've been debating that. I was thinking I should do something to make look similar to my homemade hemi distributor. Maybe even a finned look. Whatever I do will wait until I get the nozzles in. I have so many ideas - it's hard to stay focused sometimes