Header Clearance

[m_owing]

You’ve heard it a million times. Headers don’t fit. Flowtech unequal shorty, stock 1988 5L. They’re rubbing the steering shaft. I tried unbolting the steering column and moving it, also ground some of the sharp edges of the knuckle joint but it’s still rubbing. I really don’t want to hammer a dent in that spot the nice ceramic coating will suffer. I should be able to slide the shaft out from the firewall more, moving the knuckle. How far can a knuckle joint angle until it won’t turn properly?

Any ideas are appreciated
23862

[ZR]

Motor mounts a little sagged can cause it?
Sometimes a shim / washer or two under the stud where it goes through the K member will give you enough clearance (or between block and motor mount). Also possible K member is not in square / pushed off to one side.
Headers not fitting, yup ridiculous how common it is, yes even with uber expensive headers.

[bbriann]

^^^^ Motor Mounts...you beat me too it...stock motor mounts are designed for certain motor torque and age don't help. Harder Poly Mounts fixed issues i had years ago to limit engine movements...

[m_owing]

Sigh... I shimmed the mounts and it’s barely any different. I haven’t tried yet, but I don’t think I can drive it at all right now.

I’m thinking mounts and maybe a steering shaft, are the aftermarket shaft joints slimmer?

[LX89]

I once installed Mac unequal shorty headers in my 89 with stock engine/heads and imo it wasn't worth it.
When they eventually rusted out causing exhaust leaks I put the stock headers back on.

There were no clearance issues with them and no performance gain I could notice.
Actually it felt like more torque with the stock headers.

[m_owing]

I once installed Mac unequal shorty headers in my 89 with stock engine/heads and imo it wasn't worth it.
When they eventually rusted out causing exhaust leaks I put the stock headers back on.

There were no clearance issues with them and no performance gain I could notice.
Actually it felt like more torque with the stock headers.

I’ve had so many problems with exhaust I almost want to go back to stock! I’m replacing a set of unequal Mac headers that rusted full of holes like yours. These new ones are stainless with a ceramic coating. They can’t rust, right?

[Ponyryd]

Sigh... I shimmed the mounts and it’s barely any different. I haven’t tried yet, but I don’t think I can drive it at all right now.

I’m thinking mounts and maybe a steering shaft, are the aftermarket shaft joints slimmer?

If they’re old mounts they’re probably collapsed, depends how much you shimmed them, I guess. Pretty simple to do though, why not keep going till it clears? Are they 1 3/4” primaries?
Also is the engine centred? You can move it a bit from one side to the other because of the slots in the subframe.

[m_owing]

If they’re old mounts they’re probably collapsed, depends how much you shimmed them, I guess. Pretty simple to do though, why not keep going till it clears? Are they 1 3/4” primaries?
Also is the engine centred? You can move it a bit from one side to the other because of the slots in the subframe.

I thought about more shims but the mount bolts are actually pretty short, I wanted lots of thread in the block.

The slots you speak of, you mean the slots in the K member the mount stud attaches to? I thought about that, didn’t get a good look at it but from online info there is a “locating pin” on the mount that aligns with a hole near the slot. That would limit the travel but it’s worth a shot. If it’s that easy I don’t know what more people don’t do that for header clearance at least short term.

And yes, 1.75” primaries. I picked my material first and didn’t pay attention to the primary size. These were the only ones that were both stainless and ceramic (under $500, at least).

[ZR]

I know it'll hurt taking a hammer to new headers but a dent won't make an ounce of perf difference. Can make a pretty clean job of it by marking, removing, lay one hammer against it and strike with another (eye protection in place please).

[Ponyryd]

I thought about more shims but the mount bolts are actually pretty short, I wanted lots of thread in the block.

The slots you speak of, you mean the slots in the K member the mount stud attaches to? I thought about that, didn’t get a good look at it but from online info there is a “locating pin” on the mount that aligns with a hole near the slot. That would limit the travel but it’s worth a shot. If it’s that easy I don’t know what more people don’t do that for header clearance at least short term.

And yes, 1.75” primaries. I picked my material first and didn’t pay attention to the primary size. These were the only ones that were both stainless and ceramic (under $500, at least).

Yes, shim the lower stud where the mount goes into the subframe, not the upper engine mounts. You can also use a level on the intake, to allow you to possibly just shim the driver’s side to get the clearance you need, and ya, there are locating pins, but they don’t mean much at all, more a reference point than anything.

[m_owing]

I know it'll hurt taking a hammer to new headers but a dent won't make an ounce of perf difference. Can make a pretty clean job of it by marking, removing, lay one hammer against it and strike with another (eye protection in place please).
There you go with your blacksmithing again. I won't do it!


Yes, shim the lower stud where the mount goes into the subframe, not the upper engine mounts. You can also use a level on the intake, to allow you to possibly just shim the driver’s side to get the clearance you need, and ya, there are locating pins, but they don’t mean much at all, more a reference point than anything.

Couldn't even get the mount-kmember nuts off. Impact and everything. I let it soak in penetrating oil and I'll take a torch to it. Might order new mounts anyway. But I won't get a chance to get back to my work space for a while.

In the meantime I decided to look at other headers and noticed something I didn't before. I put together a collage thinking someone like myself might stumble upon this thread way in the future and it may help

All shown are drivers side header. NOT to scale. The headers on the right all follow the same primary routing, with the '1st' and 'last' primary going to the 'outside' of the collector. The column on the left are a bit different. Curious enough, the MAC picture are the ones I took off the car (full of holes) but fit nonetheless, and have the same orientation as the Flowtechs that didn't fit, perhaps the primaries on the MACs are 1-5/8", I know the flowtechs are 1-3/4"

23890

[RedSN]

^^^interesting collage of various popular shorties.
Looking at that, I’m quite happy with my BBK’s

[m_owing]

Installed Prothane motor and trans mounts and BBK ceramic unequal shorty headers. One side mount to kmember nut was stuck real bad, it took a plumbing torch and impact to get it loose.

For those who don't know or might be interested, 87-93 mustangs used 2 different style motor mounts. from 87-90ish hard tops had 1 style, and convertibles had another. From around 90ish-93 Ford used the 'vert style' mounts on both hard tops and convertible mustangs.

The vert mounts apparently bring the engine down slightly (0.5"-1" from what I've read) compared to the original hard top mounts.

Prothane mounts are said to be designed after the early 87-90ish hard top mounts, Energy suspensions are said to be modeled after the convertible mounts.

I have an 88 and since I wanted header clearance, I went with the Prothanes to keep the engine up. And look at all that clearance!

You can't see the rubber on my OEM mounts but they were hard and cracked pretty bad.244412444224443

[LX89]

Were the two motor mount flange nuts you removed the locking type with a serrated base?

[m_owing]

Were the two motor mount flange nuts you removed the locking type with a serrated base?

The nuts removed were in bad shape. One needed a torch. They were flanged but I don’t think serrated. Not sure if they had any kind of lock. I bought grade 10 nylon locking nuts and flat grade 10 washers to replace. Both zinc plated. If you need some I have lots left over! I can ship for a few bucks.

[LX89]

My 89 Mustang shop manual mentions self locking bolts and nuts for the motor mounts that must be replaced with new ones when removed.

Just wondering if your car had self locking bolts/nuts for the motor mounts.

[ZR]

If using the old nuts n worried it could back off, lil dab of loctite and your golden.
Original nut is typically this style with a cast in washer.
Many of the aftermarket mounts (if they include a nut) are poly lock.

https://www.macleanfoggcs.com/assets/1/7/MFCS_Mundelein_Uni-Torque_05_WEB.jpg

[LX89]

I've been looking at the Summit Racing foxbody kit that is possibly made by Energy Suspension going by part of the part number.
They don't include the motor mount nuts.
Nuts are 14mm x 2 I think.

The Summit kit is much cheaper than the over priced Energy Suspension mounts.
https://www.summitracing.com/parts/SUM-7741124

[ZR]

All too many try to give you the idea a part is made by company A by using a similar (or even exact same) part number when it's not. Those look like a more OE style stamped bracket. Hard to say how good until you have then in your hands, see if they fit and how long they last. For me, wish the softer / no vibrations added / fit like a glove OE mounts were still available.

[LX89]

All too many try to give you the idea a part is made by company A by using a similar (or even exact same) part number when it's not. Those look like a more OE style stamped bracket. Hard to say how good until you have then in your hands, see if they fit and how long they last. For me, wish the softer / no vibrations added / fit like a glove OE mounts were still available.

Did you read the reviews on those Summit motor mounts?
They look good.

Parts store motor mounts are junk and OEM Ford is no longer available so what would you recommend?

[m_owing]

Like I said above, the stock nuts didn't appear to have a serrated flange. I bought self locking nylon nuts with matching washers (the same setup maximum motorsports includes with their solid mounts) and yes m14x2mm nuts. Made sure they were grade 10 and zinc plated.

Those summit mounts look like the vert mounts. So if you have stock mounts from before 1990, they may lower the engine a bit. I ordered my prothanes from https://alteredfox.com/collections/engine/products/motor-mounts-transmission-mount-kit-prothane-61905

I think what ZR means is that the OEM style mounts (probably rubber) have more flex than polyurethane (energy suspension, prothane and summit) so they don't transfer as much vibration to your car. You can get OEM from rock auto but I think you have to reuse parts of the metal bracket.