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Flame heater delete completed with Rattlin Trucks kit

kenn

Well-known member
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Location
Texas
After reading about ToddJK's engine fire due to some remaining flame heater components, this project was at the top of my list. Note that as I work through all of the issues (there are so many, lol), I'm trying to document what I did in hopes a post or two of mine will help others that may come behind me. My ultimate goal is near complete restoration without doing a frame-off. It will take time, of course, and I may give up when I get to "good enough". Time will tell.

The flame heater was only 1/2 removed by either a motor pool (likely) or previous owner (very unlikely). I purchased a flame heater delete kit from rattlin truck as I didn't want to hunt down fittings and I like the clean look of the cnc fittings. The kit and instructions are top-notch and I highly recommend it. I took a couple of pictures near the end after realizing pictures help tremendously! I'll add those here for reference but going forward, I'll take more pictures through the process. The pictures are the plug in the IP already, the removed T-sectioned line, the replaced fuel line, the kit, and the fittings in the intake, with the brass washer and retainer nut.

Where the truck stood when I started:

A plug was already in the IP outlet that would feed the flame heater system
Flame heater fuel pump previously removed
Ignition coil for flame heater still installed, plugged in, and attached to the spark plug in the intake
Return fuel line T-fitting still installed and connected
Small fuel line from the flame heater fuel pump disconnected/hanging
Flame heater Injector fitting still in the intake with both fuel lines attached

First I removed the t-fitting from the fuel line between the two injectors and followed the directions to cut in a new line. The anti-crush fittings are a little different than the ones that were there so I'm not sure yet if I have it tight enough. It uses a brass insert in the tubing and a compression fitting. No ferrule. I've attached a pic of those below. I guess I'll find out if they work and if I have it tight enough once I start it and run it.

Once I had that fitting disconnected, I removed the fittings from the injector sticking into the intake. I couldn't rotate the fitting out of the intake because of the metal slobber tube so I removed the 4 nuts/washers at the top of the intake and loosened the clamp on the rubber tube at the bottom and pulled it away from the slobber tube about an inch to give me clearance. For whatever reason, the larger of the two brass fittings on the injector fuel line fitting was between a 7/16 and a 3/8. I've never heard of a 13/32 wrench but I suspect that's the size that would have fit. After removing the smaller fitting to the left, I was able to get a *quality* crescent on the larger and break it loose. Once those were off, I removed the fitting and set the retainer nut aside. After removing the spark plug, I discovered a brass washer so I cleaned that up and set it aside as well.

I then inserted the spark plug hole fitting with the square head and used the included blue loc-tite. I decided to re-use the copper gasket that was there though I suspect this wasn't necessary. Following that, I inserted the larger fitting where the injector fuel lines were. This hole doesn't appear to be tapered and the fitting, while very snug, will not bottom out. I chose to put the fitting in about 3/4 of the way (plenty of thread) and leave just enough to put the retainer nut on the outside and snug it down (both of these with blue loc-tite). The instructions that came with the kit don't ask you to do that but I have read in other threads where people had trouble keeping this fitting tight so I decided that overkill is underrated here.
 

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Gypsyman

Well-known member
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Quincy, FL
Thanks for the write-up kenn. Just clarification on a couple of things...

The anti-crush fittings are a little different than the ones that were there so I'm not sure yet if I have it tight enough. It uses a brass insert in the tubing and a compression fitting. No ferrule. I've attached a pic of those below. I guess I'll find out if they work and if I have it tight enough once I start it and run it.
The compression nuts are actually an exact match to the original fittings. The ferrule is attached to the nut until the fitting is tightened down. The theory is that once the ferrule on the end "bites" it snaps free of the nut and becomes the two pieces that that you see when an old fitting is removed. The anti-crush inserts that we all use as correct common practice today were actually an afterthought by the military. They are shown in the attached PS Mag article below.

Following that, I inserted the larger fitting where the injector fuel lines were. This hole doesn't appear to be tapered and the fitting, while very snug, will not bottom out. I chose to put the fitting in about 3/4 of the way (plenty of thread) and leave just enough to put the retainer nut on the outside and snug it down (both of these with blue loc-tite). The instructions that came with the kit don't ask you to do that but I have read in other threads where people had trouble keeping this fitting tight so I decided that overkill is underrated here.
You are correct that the hole is not tapered like a pipe fitting. The plug will bottom out though. The bottom of that hole has a tapered seat to match the nozzle. On this first batch I matched the length of the plug that comes in the Quick Start ether kit. This puts the plug head a bit deeper in the manifold than I would like even though there is more than enough head left protruding to properly tighten the plug. On the next batch I will add a few more MM to the length to provide more plug head protrusion. This will also provide a few more threads if one chooses to use the jam nut method. Bottomed out or using the jam nut both work equally well. =)

Snap Line.jpg ps306 p38 fuel lines.jpg IMG_7558.JPG
 

kenn

Well-known member
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513
93
Location
Texas
Thanks for the note on the plug depth! And also on the fittings! I'll check it and if it works loose, I'll bottom it out but for now I'll just leave it be. In the picture does it look like I have them tight enough? They aren't nearly as deep as the stock ones but I feel like if I go any tighter I'm going to bend/stretch/break something. Thanks again!
 

Gypsyman

Well-known member
333
738
93
Location
Quincy, FL
Ken and I are talking via email so I will post a snip of my reply here along with photos and additional information for future reference...

These factory fittings feel very strange compared to a normal compression fitting. The feel like they stop just before the ferrule snaps free (as intended) and you finish tightening them up. When the ferrule breaks free the mating face of the nut and the ferrule will flatten and you will get another 1-2 threads of nut insertion depth. Below is the current depth that Ken is at and a comparison photo of my truck after the installation.

When I was installing mine I also stopped short for fear of damaging something. I knew that these were the same fittings as the originals so I pressed on to see if the depth of the factory fittings could be matched. Once the ferrule broke free the nut continued to compress until it was at virtually the identical depth as the originals. I stopped a little short of the factory depth to leave a bit of wiggle room should a leak develop down the road. It was just an uncomfortable feeling getting them to this point.

As I mentioned to Ken, I may need to add this to the installation manual for clarity since these are such odd fittings.

IMG-0419 - Copy.jpg IMG_7559 - Copy.JPG
 
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Gypsyman

Well-known member
333
738
93
Location
Quincy, FL
Looking at your photo more closely it does look like you have a bit of twist in the line. I would finish tightening them up until the ferrules break free. Then I would loosen one side back up, allow the twist to relax, and retighten the nut. Mine didn't seem to twist at all but I was holding the line as I tightened them.

IMG_7213 (10).JPG
 

ToddJK

Well-known member
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4,464
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Location
Sparta, MI
Good write up fellas! I reused the nuts that were on the truck and new ferrules and inserts. As I tightened up the fittings, I got it pretty snug with a small wrench. As for extra insurance, I used some rectum seal as prescribed by Tactical Repair to make sure no leaks started, but also as Gypsyman stated, leaving some exposed threads. If a leaks develops, I can tighten it down. If you bottom out the threads and a leak starts, you'll never get it to stop until you replace the line and new fittings.
I would say, this is a must for any M series with a flame heater as they leak and cause other issues (🔥). Might be worth it to those in really cold climates and the flame heater along with the lines are of better quality or well maintained, but not worth it to keep it on if you don't need it.
 

kenn

Well-known member
170
513
93
Location
Texas
Just wanted to come back and update. I finally got the oil change finished and took it out for about 10 miles worth of driving and didn't have any leaks so all is good! Again, I would definitely recommend the kit. It has everything needed and the plugs give it a super-clean finish! Customer service/support is top notch. Gypsyman knows his chit.
 

ToddJK

Well-known member
1,312
4,464
113
Location
Sparta, MI
Just wanted to come back and update. I finally got the oil change finished and took it out for about 10 miles worth of driving and didn't have any leaks so all is good! Again, I would definitely recommend the kit. It has everything needed and the plugs give it a super-clean finish! Customer service/support is top notch. Gypsyman knows his chit.
I agree, Gypsy's kit is well thought out and finished, the plugs were definitely a perfect fit and looks good too!
 
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