FJ40 Mark/Downey Header

[Fe3]

The stub we provide for make-your-own exhaust positions the O2 bung right at two inches:

 

[Fe3]

By those dimensions, the O2 sensor would be at 10 inches.

If you feel better giving the two collectors some room to merge, no problem. By that school of thought we have the O2 sensor at six inches:

We hope that helps folks who are running, or plan on running an O2 sensor with this header!

 

[rlong]

I’ll buy that location. At least it comes with one! If one questions if it’s working properly in that location for their setup, one could always weld/ clamp one on further back on their exhaust. Point being better to have one bung than none, and two don’t hurt.

 

[wngrog]

On the old style 6/1 JTO, I used to put them before the gasket on the header. I used to often eat O2 sensors. Since I started moving them downstream it's almost stopped completely.

 

[gonzopancho]

On the old style 6/1 JTO, I used to put them before the gasket on the header. I used to often eat O2 sensors. Since I started moving them downstream it's almost stopped completely.

Sounds like a leak

 

[wngrog]

Sounds like a leak

Dunno. I've learned a lot after doing about 40 Snipers. O2s used to haunt me. Now it rarely comes up.

 

[gonzopancho]

Dunno. I've learned a lot after doing about 40 Snipers. O2s used to haunt me. Now it rarely comes up.

Drum brakes next?

 

[wngrog]

Drum brakes will always haunt me

 

[cstav86]

On the old style 6/1 JTO, I used to put them before the gasket on the header. I used to often eat O2 sensors. Since I started moving them downstream it's almost stopped completely.

How far back are you putting them now?

 

[cstav86]

How do you like the white lighting coating? Mine just got back from Swain Tech but it will be another month or two before the engine rebuild is done. Does it do a good job of keeping the heat down in the engine compartment?

It's hard to say, I dont have a data point of how hot they were prior to the coating as I was running a stock manifold. I can hit it with a temperature gun and see what they run at temp.

 

[wngrog]

How far back are you putting them now?

About where it's illustrated above. 3" or so past the gasket.

 

[Bad1975]

I've got about 5000 miles on my DEI heat wrapped Trimeki header and custom exhaust setup (Wrapped all the way to about an 1" or 2" shy of the coupler) and I'm using the Trimeki supplied O2 bung, no issues with Sniper tuning or O2 Sensors going bad. I'm also running a high flow CAT behind the O2 Sensor as well.

 

[Fe3]

I've got about 5000 miles on my DEI heat wrapped Trimeki header and custom exhaust setup (Wrapped all the way to about an 1" or 2" shy of the coupler) and I'm using the Trimeki supplied O2 bung, no issues with Sniper tuning or O2 Sensors going bad. I'm also running a high flow CAT behind the O2 Sensor as well.

That is fantastic, we are glad to hear that it is all working well for you!

 

[Fe3]

Just a quick video for people wanting to hear how the header + exhaust sounds:

 

[Fe3]

If you are looking for your next header, check on this review from Nolen @wngrog

Build Post in thread 'The Green Weed - Tildabogue Service Station'

Oct 2, 2026

PowderKeg did me a solid and did the intake, valve cover and fan shroud for me for the weekend. With this in place I can get a long way towards building the motor back this weekend

So this is my first TriMeki header to install. I’ve kinda balked at the price on these at first but after laying hands on it and installing it I think it’s priced right.

TriMeki “Whole Enchilada” Header + Exhaust for 40 Series Land Cruisers with 2F/F engines

The ultimate exhaust system upgrade for your F/2F equipped 1969 - 1978 FJ40.

shop.trimeki.com

First off, it fits amazingly well. In fact in fact it will only go on if it’s perfectly...

• wngrog

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