FJ40 Mark/Downey Header (8 Viewers)

[martymart]

Is this a Mark’s/Downey header? Are the headers interchangeable between the F and 2F engine? I plan to install on an F engine.

 

[brian]

Looks like a marks.
Yes interchangeable...some heads just do not use the front and last most fasteners

 

[pjohnson]

It will fit. I recently did this on a 72 F motor. I had mine ceramic coated also.

To make sure it sealed properly, I replaced all the studs/bolts with 12mm in a longer length. I also used matching thick washers and flange nuts for a better clamping force.

 

[70fj40]

This is a Marks header on a 1970 F motor

 

[Downey]

Scored!!!!!

 

[NCFarmboy]

This is a Marks header on a 1970 F motor

View attachment 2818885

Can you give more info on what looks like an oil filter relocation or is that an added bypass filter?

 

[70fj40]

Relocated. Makes for easy filter change and I like the Wix filters

 

[martymart]

Bought the headers. Should I wrap them?

 

[Downey]

Bought the headers. Should I wrap them?

No, No, No, Headers literally melt inside thermal wrapping, they end up full of hair line cracks. Dragster guys wrap their Headers for 1/4 mile, then remove and rebuild engine before re-wrapping for another 1/4 mile.

 

[martymart]

Thanks for the information. I will not wrap

 

[martymart]

What size ID pipe should I install with the Downey header? I was thinking 2 1/2” or 2 1/4”.

 

[pjohnson]

I went with the same size as the collector flange to a Magnaflow 6" round muffler. It was tucked up next the frame at the front of the rear arch and an exit behind the tire. Worked very well and gave the engine a nice sound.

 

[brian]

2.5

 

[martymart]

Thanks 2.5” it is

 

[65swb45]

2.5 on a 2F; 2.25 on an F.

 

[emac]

You can wrap them and send them to me for Christmas!!

Nice score! Jim has given advice on sealing headers. Once I followed that advice (and had my headers/intake matched) no leaks.

 

[brian]

2.5 on a 2F; 2.25 on an F.

Soooooo, when are you having more made?

 

[65swb45]

Soooooo, when are you having more made?

It is not going to happen. Two factors. One, I’m not sure if I will continue to operate Mark’s Off Road long enough to sell off as many headers as it would take to get a shop to build them for me now. Two, the shop that built the last batch moved to a different location, and somewhere along the way, they lost the jig.

 

[brian]

i was actually just yanking your chain, but thats horrible news that the jig is now even lost....these were, without doubt or question the greatest headers for the F series engine.

 

[Dizzy]

Is there anyone making headers for other straight-sixes? Like is the exhaust port pattern similar enough that the mandrel bending could be done on equipment intended for a Stove-Bolt? Then making the flange specific to an F/2F, etc.

Is my Downey/Mark's Off-Road header covered by proprietary intellect, or can someone emulate it? What would be a critical roster of shop equipment needed? Were there any CAD drawings produced that detail critical dimensions, and manufacturing specifications?

Is there a shop, looking to have rapport with the Land Cruiser community, that could do a rehab on my header? The PO did what was possible with ranch tools, and, at least it needs a new flange, and corrosion protection.