HillBilt
Active member
Yes you do, I had already done the needed mods when I swapped to the Autolite carb. This is a direct replacement for one so just some minor adjustment needed.
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SnowChicken Bombi Build
- Thread starter HillBilt
- Start date
Caribou
New member
A disease for which there is no cure
HillBilt
Active member
In the exhaust, drilled and welded in a threaded bung.
Are you asking for a specific location in the exhaust?
Caribou
New member
YES, APOLOGIES... curious where in the exhaust you plan to place O2 sensor - instructions state "if you have tube headers, mount the sensor approximately 1-10" after the collector. You must have at least 18" of exhaust pipe after the sensor." When I think of tube headers, I think after-market 'headers'... and not the typical OEM exhaust manifolds that weigh a ton.
Not sure if you have the OEM exhaust manifold (collector), but in my 77' the initial exhaust pipe is clamped by two bolts with flange - off of the OEM manifold - bends down, around, and out of the engine cover and stubs pointing up where the muffler is then attached just outside the cab for total of 26"...
I was planning to place my O2 sensor at 3" from the manifold pipe attachment flange (3/4" hole on top) leaving 23" to muffler attachment. ....curious where in the exhaust you have placed or plan to place your O2 sensor along that same stretch of exhaust pipe.
Not sure if measuring 18" down from muffler is a better spot, leaving O2 sensor at 8" from collector... or does it even matter?! I can call Holley # and ask their techs if this makes any difference too.
Not sure if you have the OEM exhaust manifold (collector), but in my 77' the initial exhaust pipe is clamped by two bolts with flange - off of the OEM manifold - bends down, around, and out of the engine cover and stubs pointing up where the muffler is then attached just outside the cab for total of 26"...
I was planning to place my O2 sensor at 3" from the manifold pipe attachment flange (3/4" hole on top) leaving 23" to muffler attachment. ....curious where in the exhaust you have placed or plan to place your O2 sensor along that same stretch of exhaust pipe.
Not sure if measuring 18" down from muffler is a better spot, leaving O2 sensor at 8" from collector... or does it even matter?! I can call Holley # and ask their techs if this makes any difference too.
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HillBilt
Active member
I’ve done a couple efi swaps on different engines, and honestly it’s just a suggestion for the best possible reading. The most important thing is to make sure you have no exhaust leaks near the 02 sensor as it will not give the best readings. I’ve seen the sensors mounted in many places with good results, even one mounted in a header primary reading off one cylinder without issues. I wouldn’t stress it too much, put it in the best place you can and I’m sure it will be fine. I have just the stock manifold. Header or stock manifold it doesn’t matter it’s just referencing an area where you can gather the best reading from as many cylinders as you can. I mounted mine right before the exhaust bends up to my muffler mounted on the back of the cab.
HillBilt
Active member
Got the EFI swap completed and running, no issues so far. Need to get it out for a test run. Have a video of first fire but to large to upload. Flashed right up. Another nice feature is the touch screen interface with gauges.
The computer needs a coolant reading and there is nowhere on the engine to mount one. So I just put a T in the heater hose line that comes from the intake.
and welded in a bung for the 02 sensor in the exhaust. Was kind of a PITA to get to. I should of removed the pipe, but oh well, done now.
another item needed is an electric fuel pump with at least 60psi. I had already swapped the fuel pump last year and was the same in-line style so just swapped it out for the Hi psi unit. The throttle body has a built is pressure regulator that’s set at 58psi. I have it mounted in the belly of the machine, hard to get a good photo of it
If you scroll back a few pages on the thread you’ll see where I added a fuel return in the stock tank. That’s probably the most work to do the swap, everything else is pretty basic install.
and welded in a bung for the 02 sensor in the exhaust. Was kind of a PITA to get to. I should of removed the pipe, but oh well, done now.
another item needed is an electric fuel pump with at least 60psi. I had already swapped the fuel pump last year and was the same in-line style so just swapped it out for the Hi psi unit. The throttle body has a built is pressure regulator that’s set at 58psi. I have it mounted in the belly of the machine, hard to get a good photo of it
Caribou
New member
Hillbilt, I like your style! Would you be willing to make one of those pressure return aluminum plates to gas tank for me to buy? I’m waiting on my hi pressure fuel pump and was trying to figure out how I was going to install-what did you use as a seal / sealant, I’m a fan of your design but lacking in the scale of shop tools and a layman in snowcats!
HillBilt
Active member
Thanks, it's not that I wouldn't mind making one for you, it's the price to ship it to you from where I'm at would be most likely the same cost for you to get a custom fuel cell made....Canuck shipping is outrageous, especially when boarders are involved.
You don't need any fancy tooling, a simple hole saw for the aluminum plate and drill your mounting holes, and some pipe fittings and your good to go. I used the lathe because I have it, didn't really need to. The sealant I used is called "Right Stuff" and is an awesome product. You could make a rubber gasket that sandwiched between the plate but Im lazy lol.
Also if I were to re-do it I would mount it on top of the tank, its where it should be mounted, not where I placed it. At the time I was worried it wouldn't clear the hood, but I had already removed it to get any measurements. Now after I have it back together I'm sure it would clear. It didn't leak at all last year so fingers crossed its good, but I will be monitoring it, if it's an issue Ill relocate it to the top.
Caribou
New member
Aye, ok got it!
Caribou
New member
Love it ...Better than slip-sliding trying to get into the cab each time bust'n a shin!
Looking good! When I mounted my AFI Kit, I was told I couldn’t mount it in a “pocket” the sensor had to have water flow over it…so mine got more tricky, but I basically did the same thing! Does your display readout give u oil pressure? That’s the one thing I really wish mine did!
HillBilt
Active member
Thanks! and yes, this kit states the same, I don't think you need coolant to "flow" directly over it at all times, but I feel it refers to an area that coolant moves constantly. So for example, mounting it under the thermostat or above it where coolant sits rest are places to avoid, but I could be wrong. After running mine for a bit it seems to run great and matches temp readings to my gauge. This kit does have a option for oil pressure and numerous other gauge read outs, but you have to get another harness that plugs into this existing harness to add more gauges, I might add it later on as I plan to boost it with a small turbo eventually.
Caribou
New member
KickerM - what are the brass fitting sizes for that piece you installed for the EFI coolant sensor? Do you have the source info / where you bought it? Any other gotchas to pre-consider and how you tackled em? Looking more for additional parts required as I'm in a snowcat down situation and fewer miles snowshoed to/from means I might get to use this again before spring...
- Throttle linkage (Any adjustments / Fabrication required? HillBilt provided some details on his as well, just curious!)
- High pressure fuel pump and fuel return to tank (What HPF pump did you use and how/where did you install return?)
- O2 Sensor on Exhaust (Got this from HillBilt)
- Coolant temp sensor (Brass fitting size details?)
- Wiring seems straight forward, yes, but ...?
Attachments
HillBilt
Active member
Caribou-What EFI kit are you planning on using? They are all relatively the same but also very different. Some kits come with a high pressure "sump" that has the HP pump in it, others have a different style throttle body which would require a totally different throttle linkage setup, possibly an intake adapter and so on...
Ill let Kicker correct me but I believe he is running a AFI kit which is different from the holley unit Im using, also judging from the photo it looks like he is running a Ford 300-6? so throttle linkage and other items you asked for would be different then what is on your bombi 1.6
To answer you brass fitting question, any industrial shop or tractor supply shop with have an assortment of fittings you can choose from, and will be most likely 1/4 or 3/8 NPT
HillBilt
Active member
Yup, I took Bob's advice and went with the pertronix swap as well.
HillBilt
Active member
Come again?
HillBilt
Active member
Small report on the EFI setup….couldn’t be happier, Cat is running mint, totally new machine. It has made quite a power difference, (using all 60 Herspers now!) but I feel that is from the poorly tuned and clapped out carb that was on there before. The drivability is awesome and keeps getting better.
Sorry only photos I got last run. I was so blown away where we went, the terrain is actually quite steep, photos are coming back down the mountain, about 5’ of snow with a fresh 8-10” on top. photos do no justice.
Sorry only photos I got last run. I was so blown away where we went, the terrain is actually quite steep, photos are coming back down the mountain, about 5’ of snow with a fresh 8-10” on top. photos do no justice.
I used a Lokar Throttle Cable
The AFI kit came with it, just use a pump that puts out at least 50psi, return line is T and controlled by Vaccum pressure
AFI Kit came with it
Brass T: 1/2” MPT x 1/2” FPT x 1/2” FPT
Picked it up at Auto Value
AFI Kit comes with great manual and great Tech Support from Norm at AFI!
