DIY Explorer 302 Headers | Page 12 | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

DIY Explorer 302 Headers

Good luck!

Make sure the places you want that’s tiff to stick too is clean! Quick steel stuff is pretty thick not sure how it will react to some vacuum

Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

Thanks! Yes, it was not the consistency I expected, much more grainy. I wire brushed everything, cleaned with acetone, then applied the thermosteel around/on each weld. It stuck great and hardened up like metal, had to use a die grinder to remove excess afterwards.

I'm not sure how well it actually sealed, I'm going to try the vacuum again when I coat the headers. Hopefully the fine silica in the ceramic coating works it's way into any pinholes. Don't love the idea of relying on paint for sealing, but if it fills the holes and cures into a hard coating, I think it could work.

I also cut apart my driver's side TMH and it's pretty badly blown out in two primaries despite still having the merge spike.

Were TMH coated internally? This black stuff looked like carbon buildup at first glance, but the way it's chipping, it almost looks like some kind of coating

Will definitely need sandblasting before any welding. I need to call the fab shop today and see if they attempted repair on the passenger side.

i am going to say that might be scale with carbon heated onto it? i know at times my truck would have moisture coming out of the tips. i know that is the original header i had on when i did my swap, but i cant remember when i replaced it.

Got the passenger side primed tonight, but ran out one coat into the driver's side.

Hope I can find an excuse to make the 50 min round trip to O'Reilly's this weekend, otherwise I'm on hold till I drive back that way on Monday.

I'll be painting these with flat black ceramic. I'm hoping to find a way to cure the coating in some ovens at work because I'd like for it to be full strength before exhaust comes blasting into the headers. I'm not about to cook them in my food oven haha. Even if I wasn't worried about fumes, the instructions say to take them up to 600 deg F and my oven tops out at 500.

Do you have wood stove? Propane shop heater?

I have a curing / drying rack built over my shops wood stove

Looking awesome! I have gone further for less!! 50 Minutes pffft I’ll go hours just to get a part if needed

I have a propane shop heater. I was thinking about blasting it into a dog kennel boxed in with aluminum foil over plywood and making a "cure oven" that way. I could at least get through the first cure cycle (250 for 30 min) and maybe even the second (400 for 30 min). I have an old laser thermometer someone gave me, I just need to get a battery for it.

My technique for applying primer was turn on the vacuum and spray the welds pretty good. I just did a light coat everywhere else. I don't care about the runs, I just want to fill any holes. Plus they'll get wrapped anyway.

Scour FB and craigslist for an oven with non working stove. Often free.
If you do score, self clean cycle does 600 plus. You'll need to modify the lock interlock door though for monitoring temp.
Which coating brand are you using?

Good idea!

I'm using the VHT "Flame Proof" primer and paint specifically for headers.

I finally got all the ceramic paint on last night and took my headers into work for curing today. Ran everything according to the directions on the can using calibrated cure ovens we have for curing coating on big diesel intake manifolds. Sadly, the VHT ceramic stated flaking everywhere after the final cure.

Additionally, some of the thermosteel "inflated" during the final cure and is very porous now. I was tempted to run the headers anyway and just let them rust, so I ran another leak test -- they still leak at almost every port.

So that's that. I'm officially throwing in the towel on this. Good thing I learned a lot or else I'd be even more disappointed in the dozens of hours and hundreds of dollars spent. Maybe someday with a TIG setup I can do better, but for now I've been beaten.

I don’t see it this way
I mean sure you don’t have headers
But you have learned so much!

Go ask any header builders if their first set turned out

I’m still proud!
I would cut off the flanges
Take some time away from it
Tack up another set
Get them tig and learn to tig at same time

You are still thinking about them, so, not beaten. Schooled and better.

Have a Merry Christmas with your family. Back at this later.

To be clear, I am very glad about how much I've learned and I do want to try this again someday. The main thing that stinks is I don't have a path forward to getting my Mounty running again as the TMH repair isn't going as planned and my stock passenger side manifold is pretty far gone.

I definitely won't start buying material again until I can TIG weld though. Between the used mustang headers, flanges, tubing, sealant, and coating this experiment set me back about $600 so I'm in no rush to dive back in prematurely. I will keep my diy headers and hopefully use them as a template in the future. Finding good primary routing was not easy and although these headers won't work, a set like them (built by someone with the right skills and tools) would.

I could cut off the ball flanges to reuse, and maybe someday I will, but knowing what I do now, I'd probably avoid them altogether and go with V-band joints -- if you're going to the point of welding headers, it'd be worth it to go ahead and make new downpipes too.

Blamo! Exactly my thoughts
Custom Downpipes a part of the new header system removed many of the constraints you are trying to work around

You can do what I did and just throw a factory manifold on one side while you get things worked out. With my 3 inch body lift swapping out the driver's side manifold is about a 1.5 hour job total and I'm slow. you just have to unbolt the brake booster and steering shaft to get a header in and out, and only have to unbolt steering shaft for a stock manifold.
I will get my TM header repaired eventually too.

Brake booster!!! Even With the body lift? I have never had to do this For tmh!!

Yeah, I never removed my brake booster either, just undid the accessory bracket and pulled the PS pump and ac compressor to the side I fed the header up through the wheel well, then forward, then against the block, then back and into the final position.

Your thread has helped me and others I am sure.!

I am thinking 2-1/2" downs and want to do something with the 2 1/4" restriction at the TMH ball joints. It would be a bunch of work to cut the ball joints off the TMH's and go with V-band clamps.

I am wondering if one could grind-out/open-up the The TMH balls closer to 2-1/2"???

I found some 2-1/2" intermediate pipes for Fox Body Mustang, with smaller flares. I wonder/think they would fit the TMH ball???:


I opened up the ID of the ball flanges on my diy headers to about 2-1/4" because I had 2-1/2" OD tubing (2-3/8" ID) from the collector to the flange and the ball ID was only about 2-1/8" originally. However, TMH collectors neck down to 2-1/4" OD (2-1/8" ID), so the flanges themselves aren't any more of a restriction than the tubing leading to them.

I will say cutting off the flanges shouldn't be bad at all, I removed my TMH collectors with a hacksaw and everything came out clean. It shouldn't be any harder to re-weld the collectors than butt welding tubing would be. I'm having a coworker TIG that for me once I get the holes filled.

Long story short, converting TMH to a different flange style would be pretty reasonable, but making them bigger wouldn't be as straightforward. You'd probably have to splice in a different collector that doesn't neck down for 2-1/4" tubing. That sounds complicated, but wouldn't be impossible by any means. Just cut the original collector off like I did, use it as a template to mark a new one, cut, re-weld. Good excuse to go with larger diameter downs and v bands all at once.

At some point though, the primaries will become the restriction. I'm not sure, but it would seem to me that 2-1/4" collectors might already be appropriately sized for TMH 1-1/2" primaries. If you upgrade to 2-1/2" or 3" downs, you might not see gains without also going up to 1-5/8" or larger primaries. From what I've read, you don't want the downstream exhaust to be oversized compared to the beginning as the increase in volume will lead to slower exhaust flow which can reduce efficiency of the system overall. That may not be as true for a boosted application though, definitely worth further research.

My research and using this calculator: Primary Header Tube Length and Diameter Calculator

For best scavenging and flow the header primaries should be much longer. The primary header size with the stock cam and around 350HP, 6lbs boost in my build with VE of 130 is 1.5". The primary header size with the stock cam and around 400HP VE 155 is 1.58". Collectors would be 2.60' and 2.74"

The ideal exhaust is hard to achieve in these. The TMH headers flow well enough to benefit from larger downs for flow and acting as collectors, but only at higher horsepower, guessing 325 to a max of about 400. The 2-1/4" downs are good only to 370HP, 2-1/2" to 460HP, for flow and as collectors, is not ideal but better than stock.

Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

I picked up my passenger side header today. Good news is the fab shop only charged me for an hour of labor. Bad news is it still leaks. I don't feel as bad about my welding skills now, clearly collectors are very challenging. For the record, I don't mean that as a dig at the fab guys -- this is not their typical job and they were very pleasant about it and willing work with me.

I guess I'll wait and see if my coworker does a better job on the driver's side. If he does, I'll be cutting the passenger side back apart and having him redo the fab shop's work too. If not, maybe I'll just run leaky headers or maybe I'll order the Dorman replacement cast manifolds. I'm pretty much out of ideas and just want to have a running Mountaineer again.