4.0L HO Header Fitment Issue

[kryptronic]

MODS:  This post pertains to a 95 YJ, although contains questions and pictures applicable to the 91/92 HO MJ platform.  I was instructed to post it in the pub, and it would be moved to tech, if necessary.  Thank you.

 

I'm currently building a 95 YJ Wrangler ahead of my 91 MJ.  Both share the same drivetrain and systems (HO).  I'm using much of what I do on the drivetrain for this particular YJ as the 'recipe' for the MJ.  I'm currently working on the 4.0L HO engine, and have run into a bit of an issue.  I would be grateful for the sage advice of fellow CC members on this.  Here is a pic of the HO in question:

 

 

The engine is original to the YJ, was cast in 1994, and is identical to the setup found on the 91/92 MJ.  It uses the square HO intake and the desireable HO 7120 head.  This engine has 36,000 original miles on it and is mated to an AX-15 in front of an NP231.  This engine has gotten cleaned up, painted, all the aluminum blasted and cleared, all new felpro gaskets, new 4 hole injectors, new cooling, etc.  I didn't touch any internals.  Clean up and extreme tune up.

 

I've learned over the years that the farther away you move from stock on Jeep builds, the more mods you have to make to compensate.  It's the nature of the beast, and it's a compounding issue.  With this engine, the only mod I made that I would consider a true departure from stock was the introduction of a header instead of using the stock exhaust manifold.  I opened up the exhaust a bit with a free flow cat and muffler, and want to top that off with a header. 

 

NOTE: Please don't turn this into a debate as to whether or not a header is necessary, or offers any advantage.  I'd like to run one.

 

As luck would have it, I have an issue.  I used a DNA Motoring header I bought for cheap ($70) on eBay which had a ton of good reviews all over the net.  I believe it's the same style as the APN header everybody recommends for the HO.  I would have paid twice as much for an APN, if I could have found one.  Price isn't the issue here, but I'm of the opinion no header for a 4.0L is worth any more than $200.

 

With the header installed, the step washers that secure the header/intake mounting bolts are not perpendicular to the bolts.  You can see it in the following pics:

 

 

 

It's not terrible, but not straight.  I was doing a web search on this and inadvertently (again) stumbled across a CC build thread (forget who, apologies) where the club member had to grind down a portion on each of the step washers to get them to sit flat.  Is that what I have to do here?  Or is this not bad?  After measuring, the header flange is thinner than the stock manifold flange by the amount the step washer is tilted (the stock setup doesn't do this).

 

Additionally, there's a clearance issue near the bottom of the block where the oil pan attaches.  The gap between the header output flange and the block is almost non-existant.  The stock gap on my MJ is more like 1/4". 

 

 

The output flange is big enough to grind at least 1/8" off of it and still allow the gasket to sit on it completely.  It's got a much bigger diameter than stock.  I'm not sure it that will still be enough, though.

 

So, what to do?  Do I send it back, and if so, does anybody have any recommendations for something that will fit without issue and in the $200 and under price range?  Or, do I mod it?  If it can be modded.  Comments and help are very much welcome.  Thank you.

[Pete M]

is there such thing as a thicker exhaust gasket out there in the world?

[kryptronic]

3 minutes ago, Pete M said:

is there such thing as a thicker exhaust gasket out there in the world?

 

If you mean the output gasket that the downpipe fits over, I have no idea.  The header came with one, and I have a Crown OEM replacement, and they're both the same.  The output flange on the header (the piece the downpipe connector bolts through) has a bigger outer diameter than stock, so I could grind that to increase clearance, but I'm not sure if I can get more than 1/8" or so out off of it.  The output pipe and gasket fitment are fine.  It's just that the output flange is nearly rubbing the block.

[Pete M]

I mean the gasket where the flange bolts to the block.    I'm not sure why one would exist, but I know head gaskets come in different thicknesses so maybe an exhaust gasket would too.  

[schardein]

3 minutes ago, Pete M said:

I mean the gasket where the flange bolts to the block.    I'm not sure why one would exist, but I know head gaskets come in different thicknesses so maybe an exhaust gasket would too.  

Intake and exhaust on the head is one gasket.  Thicker gasket would move both the intake and exhaust= same issue.

 

[Pete M]

well, phooey on that then.   

[schardein]

I think you are on track with replacing the stock exhaust manifold, as they are extremely prone to cracking.  The height difference at the cylinder head appears minimal in the pics.  I'd guess it wouldn't be an issue.  The clearance at the exhaust flange is close, and considering everything will expand when it gets hot, I don't think I would run it as is.  You could grind the flange slightly and probably be ok, but I would also fit the downpipe on there and see if you will also have to grind the attaching flange on the exhaust pipe.  If the answer is yes, at that point I would return the header and look at other options.

 

Just to clarify, it sounds like you are saying the header is exiting the same place as the stock manifold (which is important for the downpipe and rest of the exhaust to fit properly), it is the extra thickness that is the problem.  If the header isn't exiting in the right place, I would return it.  Does it come with it's own downpipe?  I am guessing it is designed to use the stock pipe.

 

Finally, if you were to replace the header, I would go with this https://www.rockauto.com/en/catalog/jeep,1995,wrangler,4.0l+l6,1185274,exhaust+&+emission,exhaust+manifold,5860

I got two of these type manifolds from the junkyard and used them on my XJ and MJ with no problems.

[kryptronic]

56 minutes ago, schardein said:

I think you are on track with replacing the stock exhaust manifold, as they are extremely prone to cracking.  The height difference at the cylinder head appears minimal in the pics...

 

Thanks for the input.  Hearing the height difference looks minimal is good to hear.  It is minimal maybe 1/32" off, but those washers are not at 90 degrees as they should be.  Being not-a-mechanic, I don't know if what I'm looking at here is normal (and why step washers are used by the factory), or if what I'm seeing is a bad thing.

 

I have room to grind that output flange up to 1/8" before I run into what would be the mounting surface for the output gasket.  I'm just not sure if 1/8" of clearance is enough if I do grind.

 

I checked downpipe against the output and it's significantly smaller in diameter, matching the stock output flange's size.  Both the stock manifold and this header look to dump in the exact same location, give or take 1/4".  I'm using the stock downpipe, and could cut weld it's mounting bracket to any location I want, if fitment is off at all.  The rest of the exhaust will not be mounted until this header situation is straightened out.

[Jeep Driver]

Wow, had to read a novel to get to the question....................lol

 

No, you cannot leave it like that. 

 

Use washers that at the same diameter at the OEM, grind out the moon shape of the intake so that the washer makes up the difference in thickness on the exhaust side. To be clear.......you will use two washers per bolt, new behind the old. 

I had to do the same except that the exhaust (AFE) was thicker than the intake........opposite of yours. 

 

 

[Jeep Driver]

On the clearance issue.............

 

Looks like you've taken  your time, nice job, but now you've cheaped out on the important parts. 

 

Banks or AFE...........yeah, expensive but worth it. 

[HOrnbrod]

Quick question: Does this "overseas" manufacturer make a header for the later HOs with the horseshoe manifold? If so, is it a different part number? Maybe you have the wrong header. I remember my Mike Leach header fit perfectly when I had the older square manifold, and when I switched to the newer manifold it changed the position of the outlet dump just a bit. But neither position was as close as yours looks.

 

Maybe Won Hung Lo was having a bad day when he welded up your unit........

[DirtyComanche]

I have that header on my XJ.

 

Umm, it would probably be best if I go find the pictures...  But let's put it this way, it wasn't a bolt on.

 

I filed or ground down the flanges on my intake to be the same thickness as the header.  I didn't want to modify the washers as I wanted to preserve their cone shape, and make sure they seated as well as possible to ensure leak free operation.

 

The flange never would fit.  I cut it off and welded a V-band onto it instead.  It doesn't point the right way anyways, and I wanted a V-band for compactness and adding a flex pipe.

 

I also had to grind the #6 runner on the intake manifold as it was actually wedged against the header tube and prevented the intake from sitting square, which would almost certainly have lead to a leak.

 

Personally I'd probably not buy that POS header again, unless I was again intending to mod it anyways.  I believe it's luck of the draw if they built it to spec and it fits or not, although the flange is too thin either way.  I bet most guys jut crank the bolts in and figure it's fine.

[kryptronic]

On 11/17/2017 at 5:33 PM, Jeep Driver said:

Banks or AFE...........yeah, expensive but worth it. 

 

I'm almost to the point where if I could guarantee fitment without modification, I'd pull the trigger.  And based on your responses concerning my issues, and my own feelings, I think this header is going to be returned.

 

On 11/17/2017 at 5:44 PM, HOrnbrod said:

Quick question: Does this "overseas" manufacturer make a header for the later HOs with the horseshoe manifold?

 

This header is supposed to fit with both the earlier square intakes like mine, as well as the later horseshoe intakes, according to the manufacturer.  Reviews indicate the header was likely manufactured based on the square intakes as there were fitment issues reported with the horseshoe versions (guys had to dent tube 4 I believe).  There were hundreds of excellent fitment reviews on this, and people talking about great welds and minimal bluing.  Looks like a good unit, but it is what it is.  I was hoping for a good one, I guess.

[DirtyComanche]

41 minutes ago, HOrnbrod said:

Maybe Won Hung Lo was having a bad day when he welded up your unit........

 

Nah, he was having a good first day at his new job of building custom Jeep headers!  It's a real step up from the last one, where he was painting children's toys with lead based paint, since he now makes $13 a month!

[kryptronic]

5 minutes ago, DirtyComanche said:

Personally I'd probably not buy that POS header again, unless I was again intending to mod it anyways.

 

OK, you pretty much sold me with your post.  I'm sending this back.  I'm not even sure on exact downpipe fitment and just thinking about modding then coming into a downpipe issue is going to make me go insane.  There's no way I'm grinding on my stock intake.

 

So, this is going back.  Any recommendations on headers known to fit an HO 4.0L without problems or clearance issues?  Jeep Driver recommend Banks or AFE but that pricing is a little salty.  I'd do it if that's what's got to be done, though.  I've already heard Pacesetters have fitment issues, so they're out.

[HOrnbrod]

5 minutes ago, DirtyComanche said:

 

Nah, he was having a good first day at his new job of building custom Jeep headers!  It's a real step up from the last one, where he was painting children's toys with lead based paint, since he now makes $13 a month!

 

   

[schardein]

Here is my vote.  Relatively inexpensive and fits.

 

I have a Borla header on a 91 4.0HO that I had in my CJ7 for about 15 years.  Got it for a steal off ebay.  Can't say I noticed any better performance from that motor compared to my 91 XJ or 91 MJ that are running the manifold shown in that photo at 1/8 the price.  All three motors are also running the later horseshoe intake manifold.  

 

I suspect you are set on using your stock intake, but the newer intake also requires the use of a different p/s pump bracket, which coincidently is much more user friendly when it comes to installing and adjusting the serpentine belt.

[HOrnbrod]

^^ Concur with the above. Just for belt maintenance alone the intake swap is worth doing. And on my stroker it made an additional 12HP on the dyno.  

 

[87Warrior]

I didn't have any glaring problems with Pacesetter on this '99 4.0 with the horseshoe intake other than stripping the paint and applying real header paint. I did have to grind the cone washers some so they would sit flush.

 

 

[kryptronic]

Thanks for all the info, guys.  I did some measuring, which I probably should have done prior to purchase.  My stock exhaust manifold has a flange on the head side with a width of 0.5".    The header I have is 0.4".  The earlier square-style intake manifold appears to be happiest with a 0.5" flange.  I am curious as to the flange width on the later horseshoe-style intakes everybody else is running.  I have some interest in the reported HP gains, as I understood switching to the later intake style had no effect, other than the potential to decrease horsepower (JP Magazine 4.0L Myths Busted).  HOrnbrod is running a stroker.  Anybody have any data on a 4.0L and any HP gains switching intake styes? 

 

Concerning the header, the eBay seller got back to me about the return and asked about the fitment issues.  I just directed them here. 

 

So now I'm on the search for a header with a 0.5" flange.  I'm wanting to do either 409 or 304 stainless.  Looking at the Banks 51327 (409, revolver style), Rugged Ridge 17650.51 (304, APN style), and another one on eBay noted as USA made, and heavy duty (409, APN style).  These are the only ones I can find with a reported 0.5" flange.  Any others out there?  I just want this to be bolt on without mods anywhere, and for it to dump to the stock location.  Price is not a consideration at this point.

[HOrnbrod]

If price is not an issue, keep an eye out for a Mike Leach long tube header - they pop up on Ebay occasionally. These were retailed back in the day by Mopar Performance. I think John Jackson found one recently on Ebay. And whatever you get, be sure to incorporate a flex joint as close to the header collector as possible to prevent exhaust system cracks. 

 

https://comancheclub.com/forums/topic/49000-prevent-exhaust-headermanifold-cracks-with-a-flex-joint/?tab=comments#comment-498637

[DirtyComanche]

2 hours ago, kryptronic said:

Rugged Ridge 17650.51 (304, APN style)

 

The chances of a Rugged Ridge parts actually fitting is probably lower than the chances of a Chicom eBay part fitting...   At least that's my experience with them, I have not purchased that header.

[Jeep Driver]

36 minutes ago, DirtyComanche said:

 

The chances of a Rugged Ridge parts actually fitting is probably lower than the chances of a Chicom eBay part fitting...   At least that's my experience with them, I have not purchased that header.

Rugged Rubbish, I think you mean. 

[kryptronic]

1 hour ago, DirtyComanche said:

 

The chances of a Rugged Ridge parts actually fitting is probably lower than the chances of a Chicom eBay part fitting...   At least that's my experience with them, I have not purchased that header.

 

30 minutes ago, Jeep Driver said:

Rugged Rubbish, I think you mean. 

 

OK, then.   Thanks for that.  I was under the impression that Rugged Ridge was a branch of Omix-Ada.  I've never had a fitment issue with an Omix-Ada replacement part, so that's why the Rugged Ridge header made the list.  Figured there wouldn't be any fitment issue.  Two votes against is good enough not to warrant an experiment.  Rugged Ridge has been crossed off the list.

 

3 hours ago, HOrnbrod said:

If price is not an issue, keep an eye out for a Mike Leach long tube header - they pop up on Ebay occasionally. These were retailed back in the day by Mopar Performance. I think John Jackson found one recently on Ebay. And whatever you get, be sure to incorporate a flex joint as close to the header collector as possible to prevent exhaust system cracks. 

 

 

A flex joint in the downpipe is definitely planned.  I figured that would aid in compensating for any alignment issues.  Concerning the Mike Leach header, what's the flange thickness at the head?  I think you said it had no fitment issues with the older square-style intake manifold as well, right?

[kryptronic]

Also, the Clifford 57-2015 has made the list, but not sure what to do about a downpipe on that one.