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Discussion Starter · #62 · (Edited)
I decided to try to salvage the welded on injector bung manifold. The real damage was in the upper ring of the objector bungs. The seat down lower is ok, so maybe the Injector o-Ring’s will be able to seal.

I could not fit my test injector in the bung, so I cleaned up the bungs (3 damaged now) with a Dremel tool and mini carbide. Once the extra metal was removed, I was able to insert and seat the test injector. I even tried to stack a bead on one bung to restore some of original wall height. I wish I could get in there to redrill / machine the holes, but the angles are prohibitive.

If I end up making a manifold from scratch, I’ll make it so the bungs are accessible to machine. So for this one I might just have to do the clean up with the dremel and mandrel sanding cartridges.

In terms of welding, I asked myself how would an aerospace TIG welder approached this. So I got the stubby gas lens out with a nice sharp tungsten, took my time and focused on getting a comfortable angle, getting good clean puddle and then moving it around. So, it is not pretty, but I made progress.
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The 1/2” steel rod in the pic above took the place of the fuel injectors and work effectively to provide alignment during welding.

With this approach, I am continuing the TIG welding and am 95% complete. Just need to finish welding the undercut and check for vacuum leaks.

Once I invest in the infrastructure support systems (in tank fuel pump, ECU, oxygen sensor, coolant temp sensor, etc), I can just try different experimental manifolds designs. That supports my fabrication hobbies and learning driven nature.
 

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Discussion Starter · #63 ·
TIG Welding of the injector bungs is now 100% complete. So, what is next? Now I need to;
  1. Do some grinding to clean up TIG welding on the intake manifold
  2. Final selection and order fuel injectors (just need to verify spray patter. The ones that I have in mind have 2 holes and might not deliver the cone pattern I had hoped for)
  3. Procure and install coolant temp sensor
  4. Procure crank position sensor (progress on that in another thread)
  5. Procure Holley terminator X ECU (might need to wait until I have crank position sensor on hand)
  6. Order stainless fuel pressure lines and tubing bender
  7. Research idle air control valves
  8. Verify my throttle position sensor is working
  9. Schedule date to remove / refurbish fuel tank and install in tank fuel pump
 

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'73 GT
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What's the bolt spacing for the throttle body? Mk3 VW either 2.0 4cyl or 2.8 VR6(bigger) throttle bodies are cable operated Bosch units with tps and stepper idle control so it would eliminate the need for a separate isv. Microsquirt needs a separate driver that's $60, but Speeduino UA4C can operate them and any big brand standalone should be able to.
 

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Discussion Starter · #66 · (Edited)
What's the bolt spacing for the throttle body?
60 mm bolt spacing center to center both horizontal and vertical. And a 60 mm throttle throat diameter. Don’t remember the original bolt size, but I drilled mine out and tapped for M8 x 1.25 mm pitch bolts.
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Mk3 VW either 2.0 4cyl or 2.8 VR6(bigger) throttle bodies are cable operated Bosch units with tps and stepper idle control.
Cool, that’s what I was hoping for when I started this project. Do you happen to have a VW throttle body handy to check the bolt pattern and throat diameter?
 

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Discussion Starter · #67 · (Edited)
So, a year ago, I never could have dreamed of attempting this, but I have been inspired by all of the fabrication work on OpelGT.com. One project for the weekend is to modify the Opel GT 1.9l thermostat housing for fuel injection.

There are two needs:
1) eliminate interference with injectors and fuel rail indicated by the circled yellow area in the picture below.
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2) add a coolant temp sensor for the EFI and maintain the usage of the in dash engine temperature gauge / sensor.

When pursuing the site, I found a picture of just what I wanted to do from another member. Thank you. I can’t remember who it was but I took a quick screen shot.
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the first thing I did was to pull the thermostat housing off of the car, scrape the gaskets, remove the sensor, and sort of hot tank it.
Asphalt Gas Auto part Pipe Plumbing fitting


here I completely cut off the heater hose connector.
Tin Gas Jewellery Cylinder Auto part

then I TIG welded the old heater water outlet shut
Tin Household hardware Nickel Composite material Cylinder

And TIG welded a piece of aluminum on the bottom to thread and tap one of the sensors.
Wood Nickel Cylinder Gas Auto part

Then, it was time to place heater outlet in its new location.
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And TIG weld it in place.
Water Wood Automotive tire Gesture Grey
 

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Some other similar ideas…
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Discussion Starter · #69 ·
A 27/64 drill bit fit the relocated heater coolant outlet port. I then drilled through the housing for a perfectly aligned hole that matched the relocated port.
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reconstruction complete

Drinkware Cup Tableware Serveware Cylinder
 

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Pedal Smasher
1973 Opel GT
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3,247 Posts
Not that long ago, you asked about a LS wiring harness and if it would have what you need. I would recommend just building your own wire harness. Buy the connectors you need and the wires you need. You’ll have exactly what you need in the harness and can make it look good. The Holley Terminator X is a pretty cool ecu.
 

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Discussion Starter · #71 ·
I really wanted to order the special drill that drills all of the fuel rails holes at the same time. But, it was just too expensive (close to $100) for a one time use. Although, that is what I would recommend if you are making your own fuel rail. So, instead, I ordered a 14mm drill bit.
I set the depth on my drill press to 10 mm.
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and drilled all of the holes to 14 mm.
Then I cleaned up the inlet edge with a 5/8 drill bit and some fine grit sandpaper.
Wood Musical instrument Gas Musical instrument accessory Flooring

Wood Natural material Household hardware Composite material Gas

I am still not happy with the wall finish. So I am 3D printing a quick (20 min) 14 mm mandrel to hold some fine grit sandpaper to smooth and polish things up a bit.
 

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I really wanted to order the special drill that drills all of the fuel rails holes at the same time. But, it was just too expensive (close to $100) for a one time use. Although, that is what I would recommend if you are making your own fuel rail. So, instead, I ordered a 14mm drill bit.
I set the depth on my drill press to 10 mm.
View attachment 445269
and drilled all of the holes to 14 mm.
Then I cleaned up the inlet edge with a 5/8 drill bit and some fine grit sandpaper.
View attachment 445270
View attachment 445271
I am still not happy with the wall finish. So I am 3D printing a quick (20 min) 14 mm mandrel to hold some fine grit sandpaper to smooth and polish things up a bit.
I bought one maybe 10 years ago, and needed it for a project 2 years back. Couldn’t find it, so I bought another.

Of course a year later I found my original….😳
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I bought one maybe 10 years ago, and needed it for a project 2 years back. Couldn’t find it, so I bought another.

Of course a year later I found my original….😳
View attachment 445274
That's the way it always happens no matter how well organized you are or think you are stuff just has away of hiding from you. Even when your staring right at it LOL
 

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Discussion Starter · #74 ·
I bought one maybe 10 years ago, and needed it for a project 2 years back. Couldn’t find it, so I bought another.

Of course a year later I found my original….😳
View attachment 445274
Wish I had that. Hopefully mine turned out alright. I will only know when I pressurize it.
if not, I will go with fuel rail charles is shipping to me. But hope the extruded fuel rail works. It sure shined up nice just a minute on the buffing wheel.
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Discussion Starter · #75 · (Edited)
I designed and 3D printed a quick little mandrel 13 mm in diameter to hold sand paper and smooth the inside of my 14 mm diameter fuel rail injector holder holes.
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I chucked it up in my 1/2 drill
Liquid Fluid Cylinder Tints and shades Rectangle

and sanded the holes with 320 grit and then 600 grit sand paper.

Pneumatic tool Handheld power drill Tool Wood Gesture


I think that left a nice finished to the fuel rail holes that should work to provide a good seal with the fuel injector o-Rings.
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Discussion Starter · #76 · (Edited)
I was excited to get my weld in 3/8 aluminum NPT bungs for the coolant temperature sensor. I think it was 2 for $8.
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Picked a spot on the thermostat housing and drilled a hole enlarging it to 7/8”.
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then dropped in the aluminum bung
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TIG welded it in place
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And now ready for install
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Just Some Dude in Jersey
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We(me and Charles Goin) had custom thermo housings made. I have THREE thermostats. I use a different heater outlet at the back of the block near the oil pressure sender(which I relocated up front near the oil pump).

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Discussion Starter · #78 · (Edited)
Wow, beautiful and functional.
What are the 3 temp sensors for?
I am planning for 2 coolant temp sensors.
1) I have the orginal still going to the dash gauge

2) new sensor going to terminator X, which will be used for injection/ timing and an output will also be used to control electric fan.
 

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Discussion Starter · #79 ·
I am a angling towards mounting the sensor for the trigger wheel at the fuel pump bolts. Sort of a fuel pump block off plate and a crank position sensor holder. The current design is about as far as I can get without removing the fuel pump (still needed to drive the car). This design puts the sensor at roughly 3:00 position.
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I guess I need to procure a crank position sensor. I have not researched them yet. Hopefully I get One that plugs right into the terminator harness. So, I may need to fork over the money and order the terminator X or at least figure out which wiring harness to get.
 

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Just Some Dude in Jersey
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Why make your own when you can just buy one that relocates the sensor to the fuel pump vicinity, as the pictures I posted show? Most of this modification stuff has already been done by many people for decades who are a lot smarter than most of us and they have been race proven to work. And, what's wrong with the oem design of the trigger wheel and stock mounted sensor below it?
 
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