DIY Explorer 302 Headers

[fast_dave]

Any tips for removing rusty manifold bolts/studs? I bought new studs already, but getting the old ones out might be a heck of a job...

@97Sandbox

Lots of methods, but a winner that I've witnessed is;

Concentrated Torch Heat and then either candle wax OR marvel mystery oil for the capillary effect.

HTH -

 

[410Fortune]

When we get the blue wrench out the saying goes

“It can’t be stuck if it’s liquid!”

 

[97Sandbox]

After much difficulty extracting broken exhaust manifold bolts, I'm getting close to cutting up my fox headers and starting to play around with primary routing on my Mounty.

For the driver's side, I have an idea that I think will be tidier and simpler than the TMH design. It'd have the cylinder 6 primary running around the steering shaft instead of behind it. I'll have to see if there's really a good path that doesn't get too close to the shaft or any brake lines, but I'd like to avoid the "up and behind" routing of the TMHs if possible -- we'll see.

For the passenger's side, I'm struggling to find a way to keep the collector at the exit flange. I noticed the TMHs have the collector close to the shock tower then have a single tube from the collector to exit flange.

I'm realizing Rob probably did that because if the collector is at the exit flange, the cylinder 4 primary would have to come forward more which would block the spark plug.

Unfortunately, if the collector moves forward, the cylinder 3 and 4 primaries will have to swing up and around like the TMH design. There's just no room along the heater box to go anywhere but straight down or straight up.

It's not the end of the world to run the 3 and 4 primaries up, forward, and around (it'll provede good spots for an EGR bung), I was just hoping to find a simpler option. Any ideas?

Here's a couple pics of the fox headers I'll be chopping up:

 

[Blown]

Good Luck! I want to make a custom set of downpipes with two high flow, high efficiency cats.

 

[CDW6212R]

I think there is room on the right side below the stock collector location, to move it down some. I'm not intending to make anything which is a replacement part to mate with existing parts. I'll move the collectors as needed where I like them to be, for best performance and easier servicing(R&R).

I think I already planned to route the #5 and #6 pipes out and around the steering shaft. I think there is enough room there to clear the shock tower and brake lines etc. The #7 primary looks like the hardest to do something good with, given the shaft and plug wires. The #8 will have to be very short like the #4 pipe, but maybe the collector can go back or down enough to gain space for a decent merge section. That's my main goals, the merge section and collector size and type, for both sides. The pipes just need to leave the head ports at a decent angle, and not have too many super sharp bends. Shorter and straight is way better than long with sharp bends.

 

[97Sandbox]

Finally took the plunge, can't resell them now!

Turns out these are 1-1/2" primaries, so I've been stuck trying to decide whether to reuse the header flanges and stick with 1-1/2" or buy new flanges and bump up to 1-5/8" primaries. I should be able to use these collectors either way, I'll just have to butt weld the larger tubes instead of sliding them in and fillet welding the lip of the collectors.

I'm starting to think it'd be easier to go with new header flanges and work from scratch. Especially considering the wacky re-routing that needs to be done on the passenger side.

 

[Josh P]

Finally took the plunge, can't resell them now!
View attachment 446482
Turns out these are 1-1/2" primaries, so I've been stuck trying to decide whether to reuse the header flanges and stick with 1-1/2" or buy new flanges and bump up to 1-5/8" primaries. I should be able to use these collectors either way, I'll just have to butt weld the larger tubes instead of sliding them in and fillet welding the lip of the collectors.

I'm starting to think it'd be easier to go with new header flanges and work from scratch. Especially considering the wacky re-routing that needs to be done on the passenger side.

I think you can buy the flanges with some tube already welded on. Once you figure out what works, sell me a set.

 

[410Fortune]

I’ve been looking at diy headers for some time now and I think I have a plan. Forget the stock collector
I want to make/ look at making a long tube header that replaces the entire manifold and down pipe. Will likely need to be a couple of pieces that bolt Together but maybe easier to run several 1.5” tubes around the engine like an old school long tube header rather then try so hard to match up
To the stock collectors. The header could include “primary cats”
For emissions dudes

I still like the idea of a log style header but a good point was made about the heat zones and that area needing to be cast. I am sure there is a way to maybe use thicker tube or?

Just spitballing here some more ideas, I think about this a lot when wrenching on these rigs, we need a tmh beater

 

[97Sandbox]

I like the idea of combining the header and down pipe. The stock collector locations make everything difficult. Built in cats are a good idea too, the company I work for now makes some sport bike mufflers that way.

 

[CDW6212R]

I’ve been looking at diy headers for some time now and I think I have a plan. Forget the stock collector
I want to make/ look at making a long tube header that replaces the entire manifold and down pipe. Will likely need to be a couple of pieces that bolt Together but maybe easier to run several 1.5” tubes around the engine like an old school long tube header rather then try so hard to match up
To the stock collectors. The header could include “primary cats”
For emissions dudes

I still like the idea of a log style header but a good point was made about the heat zones and that area needing to be cast. I am sure there is a way to maybe use thicker tube or?

Just spitballing here some more ideas, I think about this a lot when wrenching on these rigs, we need a tmh beater

Yes, the collector locations are not great. They were made for the assembly line, to be as close and compact as they could be, so moving them could help the header build.

I've looked hard at the left collector area many times. The fuel and brake lines are poorly located there, I hope to move them outboard later for a final header much later on. But below the collector is the front diff/pinion flange etc, that's the other big obstacle for a decent down tube. I'm aiming to use a CV at both ends of the driveshaft, I've ordered a Spicer Companion Flange, back ordered. That has a slightly different size and shape, I'll likely put that in with the 6R80 trans.

So I suggest designing and building the headers from the collector forward. Find a suitable collector that you can make fit in that space, and work the primaries to merge with it.

 

[97Sandbox]

I know I said in my Mounty thread I'd be putting headers on hold for a while...I think I've changed my mind. I started prepping my stock manifolds to go back on and after seeing how rough they are and knowing how much more work it might take to get the rusted bolts out of the exit flanges, I decided to just go for the headers.

Ran to the Speedway Motors HQ (less than 10 min from where I work) over lunch and picked up:

• Pair of 5/16" SBF header flanges
• Eight 1-5/8" mandrel bent tubing sections
• One 2-1/2" mandrel bent tubing section (for between collector and exit flange on passenger side)
• Two four-packs of plug wire sheaths

The bends are tighter than I expected having only seen pictures online (which is awesome) and everything looks to be well made.

Let the fun begin!

 

[410Fortune]

jealous!! I could spend some money at that store!!!
speedway diy mandrel exhaust kits are what I have been using, they are top notch for the $$$$! nice thick tube

 

[97Sandbox]

Yes, I was considering their full SBF header kit and it's definitely better bang for the buck. However, the kits and tubing assortments they sell don't come with the as much of the tight radius bends as I think I'll need, so I just bought the tight bend tubing a-la-carte.

I got as many tubes as I think I'll need plus one.

 

[Blown]

jealous!! I could spend some money at that store!!!
speedway diy mandrel exhaust kits are what I have been using, they are top notch for the $$$$! nice thick tube

X2 I keep them book marked and would be doing the same to make better downpipes.

 

[allmyEXes]

View attachment 444894

Now what are these manifolds? I have somehow totally missed thread until today. I have the 3 hashmark, NON "P" heads.

 

[410Fortune]

They are “log”’style
Manifolds for a 5.3 Chevy I believe
I used them as an example to show what I was thinking for making better flowing units for our 5.0
Then we discussed them and decided it would be tough to make them for our trucks because we cannot cast them, and welded pipe may not hold up to the “hot spots”
Right outside the combustion chamber.

 

[97Sandbox]

The factory-style cast F-series 302 manifolds are similar. Downpipe modification aside, I don't think they'd fit in an Ex bay (steering shaft and heater box). They also pinch down at the inlets just like ours.

The SBF head design makes it very challenging to have big inlets on a manifold that can still be bolted on. I really think welded tubing is the best option to maximize tubing ID and still be feasible to install.

 

[Turdle]

That is why you use tiny headed bolts for headers. The factory manifold inlets are pinched to allow a large headed bolt and tool.

Disregard this, as you'll use every 3/8 " wrench you own hitting the header bolts.

 

[Turdle]

Good Allen head bolts are also handy, find a ball end Allen socket to match

 

[Josh P]

Late 80s E series and the 351w bronco has a nice log style manifold.