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AOD + MAC long tube headers test fit

Jonk67

Jonk67

Well-Known Member
Well thanks to Steve (sellersrodshop) for allowing me to borrow his hoist I was able to pull the stroker off the stand, put it on a block and mount the AOD to it and test fit the MAC longtube headers. I knew there would be some contact from pre measuring but expected the drivers to be worse than the passengers side. Drivers side head mount is held off 1/4" at the bottom of the exh. flange and the passengers is standing off 3/4" from meeting. I actually expected them to be much worse.

Drivers:
IMG_0550.jpg


IMG_0549.jpg


IMG_0569.jpg


Passengers:
IMG_0552.jpg


IMG_0553.jpg


IMG_0570.jpg


They both hit first where the mounting flange contacts the pan mounting surface:
IMG_0557.jpg


IMG_0565.jpg


Looking for options to correct this, first step will probably be to cut the welds that hold the mounting rings on and see how much space that gives me. I don't weld, what's the best tool to use to cut the welds which are spaced apart luckily - grinding wheel?

I figure I can rotate them, cut the 1" out that sits against the pan at that point if needed (once welded back on they should be strong enough with the 'C' shape welded all around as long as the missing piece is between the mounting holes?). I asked Steve about heating the tubes one at a time and bending them inward towards the head which should kick the collector outwards? but he advised that it's difficult to get the tubes to line up flat again and they may angle away from be flush again for a good exh. gasket seal.

Steve's suggestion was to cut the collectors 3/4 of the way around just after all 4 tubes come together (~4" before the mntg. flange), then bend it outward and have the opened up area welded back up effectively putting a ~10*-?* bend for example in the end moving it away from the trans.
Any other ideas/suggestions?

I really like they way these look/mount as it appears they will clear my PS w/o a drop bracket as advertised, I think they'll breathe well with my AFR165's. I figured anything short of stock logs or shorties would need cutting/fitting anyway. Not worried about cutting welding on painted headers as I painted them with VHT and had them baked to 600*, I can always touch up after weld and have them cooked again.

I think I'll also have an O2 bung welded in while I'm at it in case I go for tuning or buy my own wideband later.

First guy to tell my wife where her striped hall floor mat went gets it :beat
Suggestions welcome,
Jon
 
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Short of looking for different headers, I would cut the flange and rotate about 45 degrees and cut, bend and weld the collector as steve mentioned. Even after that though, once your able to get them to bolt to the heads, youre going to be hugging the trans a bit closer than I would be comfortable with.. Part of modding these cars is trial and error. This means making things work or cutting your loses and looking for another set.
 
Thanks Ryan, I agree they fit snug, I'll probably fab some heat shields for the sides of the trans. so they don't heat it up, should be easy enough once I know what clearance i have.
These are the only headers I know of that are affordable (<$500) that fit with PS and no drop bracket, if I have to change headers I'd just go with shorties but I want the benefit of the long tubes if I can keep them.
Jon
 
Thanks Steve, it might be a couple weeks, I have back to back trips half of this week (Chattanooga) and next week (Tx again).
Jon
 
No way will the passenger side work and you'd be wasting your time rotating the collector flange. You can see that the contact point for that particular header is at the thinner portion of the collector ring, so rotating it won't gain you any more clearance. Short of cutting the headers up you could always heat them up and bend them out, but that will mess up your header coating.
 
The plan is to cut through the collector pipe about 4" up from where the collector ring is just after the 4 pipes come together and it is one pipe, then cock it outwards 10*-20* and reweld so it points more straight back. The collector ring will be welded back on and if needed I think we can remove and inch of the collector ring for more clearance between the bolt holes and weld it all the way around like a 'C'.
The header coating is just spray can VHT high temp that has been baked in a powdercoating over in 3 stages up to 600* so if I have to repaint some of them and have them cooked again not a big deal or $.
Thanks, Jon
 
Ah I'm following you now. For some reason I had though you were going to break the welds on the flanges and rotate the flange and then reweld. Nevermind! :sad
 
I'm in Brazil for a couple weeks but if you need to stick the whole deal in the back of a truck and take it to Steve's I'll volunteer the truck (and even drive).
 
Hey Craig, thanks for the generous offer, I'll keep that in mind if it comes to that.

I hope to break the flange rings loose first and see if that gives me enough clearance to mount flush to the head then mark the collectors where we need to cut them to get the space I need. Then take them off the engine and take em' to Steve in the trunk of the car, if it turns out I need to take it as a package I'll get in touch with you. I'm traveling for a week and a half anyway so nothings happening fast...
Thanks, Jon
 
make sure to mark a top centerline on the tube while its bolted up so when we cock it out a few degrees, it wont be pointing in a funny angle when we reweld.

on another note, i got one of your control arms finished up yesterday. still need to cut the access holes in the other boxing plate, then it will be ready to weld up.
 
I'll be sure to mark them before removing. I was going to but the collector rings loose this weekend if I can, what's the best thing to use to cut those spaced apart welds? I think I'll get a better centerline mark if I can get the headers to sit flat against the exh. ports which may happen once the rings are off.
Thanks again for cutting and welding those reinforcement plates!
Jon
 
Looks like they're welded pretty well but every 1" or so, not continuous:
IMG_0569.jpg

Jon
 
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I understand the plan to fix your problem, but looking at the below picture do not feel that it will be enough to clear on the passenger side.


IMG_0553.jpg



Look at the gap on the head/header mating flange.

To close that gap AND have ANY clearance between the collector pipe and the trans you'll have to cut more than the collector pipe. I'm thinking that all four tubes a few inches forward of the collector will either need to be heated/bent or cut/bent/welded. There's no way that cutting and angling JUST the collector pipe will give enough clearance on the passenger side. It'll probably work "okay" on the driver's side, but NOT on the passenger side.

If it were me, I'd re-evaluate cutting the headers. As it stands right now you could sell the headers to recoupe some of their purchase price. Once you start cutting/heating/bending/welding that option is pretty much lost forever. If the existing plan fails to achieve the desired results you're out $500.

There's got to be a better alternative at the moment. Cutting/heating/bending/welding the existing headers should only be considered as a "last resort" alternative.
 
Thanks for the input Dave, the headers were a used fleabay score and I only have ~$100 into them as is (headers, blast, paint, cooked). I do fear that the passengers side will touch farther up, I'm going to remove the collector rings first as it shouldn't be difficult to tack them back on if the pipes don't fit for a resell. Once the flanges are off it'll let the headers sit as flat as they can before cutting the collectors or pipes themselves and give me a better idea of actual pipe clearance. I'll update when I'm back home next week (in Dallas this week) and get the rings off for starters.
Jon
 
How about putting a 6-10 foot steel tube in the collector and using leverage to bend it outward. You'll have to secure the engine somehow as the leverage will pull the whole engine over. Another option would be to stick shorter tubes in both collectors and use a porta-power, maybe even a scissor jack, between the two. Removing the tranny would make it much easier to spread the headers out (and fully secure the headers to the heads first). You might even be able to use short 4x4s to spread the load along the length of the collector, with the jack between them.
 
Another option would be to stick shorter tubes in both collectors and use a porta-power
Click to expand...

This would be my solution to the problem. There are several ways to "spread" the headers, but the easiest would be to remove the transmission, install the ill-fitting headers, strap the engine and transmission onto a trailer and around lunchtime head down to the nearest body shop with a couple $20's in your pocket. It wouldn't take but 5 minutes to set up a porta-power to bend the headers outward and the removed trans could be used to verify when enough clearance was obtained.

Hydraulic pressure is a wonderful thing!
 
I had toyed with the idea of heating the header tubes just before the collector and putting a pipe in the end of the collector and prying out but never thought of the portapower idea with the trans. off. Do you think the tubes would just give and bend slowly enough to spread? I just have a fear that the welds at the head would break loose instead or some other collateral damage would occur, anyone actually tried this before?

I have the stock heads still and a spare 351W bare block, would it be a better idea to temp. bolt the old heads to that and mount the headers to that setup vs. my nice alum. AFR's?

Wonder if the guys at the firestation just down the street would want to test their portapower out for 5 min?

Great ideas guys, I won't be back home from current Dallas work trip until late Fri. so maybe this weekend or coming week I may get to try this.

Thansk, Jon
 
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