LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

MAC header fitment

Old 04-06-2017, 03:29 PM
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MAC header fitment

so i just recently purchased a full set of mac mids. i got everything the headers ,gaskets,bolts,y-pipe,ORP. they have full egr hook up an o2 this is going on a 95 z28 A4, the guy im having or trying to get them to do the install is worried about them hitting the AC lines, roasting the starter with heat soak an i guess general fitment issues. I got them ceramic coated from MAC. i was wondering if anyone had them ever installed an had any issues like he states. hes a very reputable engine builder. Hes a guy i trust to do the job right so im basically just looking for some answers to give him. hes done two LT1 an LS1 cars in the past an said on the one the ac lines needed to be removed simply wouldnt work. then said about the starter heat soaking but ill wrap them. i already have plug heat boots for them. an the driverside manifold bolt fell out an i have a slight leak so basically this needs to be done anyway. any info on fitment an install would be greatly appreciated.
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Old 04-07-2017, 01:33 PM
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Re: MAC header fitment

I've had mac mid length headers on for 10 years now. No real issues.

Heat soak on the starter had been an issue. On the rebuild I replaced it but can't say just at the moment what I used (a vert version). I also replaced all the crappy starter cables with some decently sized ones which makes the difference.
The heat soak is manageable but if you stop for fuel you might find it needs a couple of minutes to cool off or starting is hard.
Excellent headers and they don't hang too low if you lower the car as well. Main reason I got them.

Huh
Mitch
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Old 04-07-2017, 02:17 PM
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Re: MAC header fitment

You can get a heat shield for a (generic) starter. Wires and A/C lines can be wrapped with flexible reflective shielding.
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Old 04-07-2017, 04:46 PM
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Re: MAC header fitment

well the mechanic came by today an he looked at the headers an he insists the bottom AC line has to moved or taken out or modified to have the header fit right. Also he said he does not thing that the headers will clear the steering shaft. but he threw a number at me for install an i said ya thats fine. gave me a look like i was nuts. i more or less think he doesnt want to get into a big project but none the less he said ok. He is going to either get a wrap for the starter or make a custom shield for it. an look for a set of wires with wrap on them. also replacing the bolts that came with the kit with ARP locking bolts. Did you have any issue with the AC line its on the passenger side lower side. i see what hes talking about but idk looks like to me the header will work. what more or less worries me is the steering shaft hitting the tube. but the first tube on the driver side is single an it slides into the set i thought this was to clear up any issue with the shaft but i could be wrong. any input? he said im looking for more problems then i know an im only going to gain like 5hp lol. i think with what i already have which is a programmer tune , catback , CAI , comp cam , bigger valve springs , an a corsa catback ill make more then 5hp off them.
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Old 04-08-2017, 09:03 AM
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Re: MAC header fitment

The steering nuckle is tight and iirc I left the plastic cover off it. Might have needed a small tap but nothing heavy.
AC wasn't an issue.
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Old 04-08-2017, 03:26 PM
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Re: MAC header fitment

So does that steering shaft go through the headers? Like through I mean between the tubes. Do you have any problems with them hitting it because of engine movment? My engine mounts are good an all but I'm just wondering if it's just a good idea to put a small dent in them right around where it would hit. If it does hit. An did you weld the pipe that slides or just clamp it? I just don't want issues with it leaking or hitting obviously. I think with my mods these headers will give me good gains. I need a good dyno tune but in Wilkes barre pa there really is no one I know of to get one done for the car.
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Old 04-08-2017, 05:55 PM
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Re: MAC header fitment

So does that steering shaft go through the headers? Like through I mean between the tubes. Do you have any problems with them hitting it because of engine movment? My engine mounts are good an all but I'm just wondering if it's just a good idea to put a small dent in them right around where it would hit. If it does hit. An did you weld the pipe that slides or just clamp it? I just don't want issues with it leaking or hitting obviously. I think with my mods these headers will give me good gains. I need a good dyno tune but in Wilkes barre pa there really is no one I know of to get one done for the car.
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Old 04-10-2017, 06:26 PM
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Re: MAC header fitment

Yes I think so. Can't remember. Not a problem though. Clamped is fine. Do the clamp tight before fitting the ORY as it's harder to tighten with the ORY fitted. Get the ORY snugged up fairly tight to the motor.
You'll like the upgrade
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Old 04-11-2017, 03:46 PM
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Re: MAC header fitment

I've Mac mids on my 95Z 6 speed. No problems with the AC line nor the starter. I too left the plastic cover off the steering joint. The steering coupler rubs just slightly on one header tube. I've read it is possible to loosen the steering column and shift it just enough to completely clear the headers. The coupler does not go through the headers.
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Old 04-22-2017, 05:47 PM
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Re: MAC header fitment

thanks for all the help guys. car is gone now to the installer. so we shall see how it goes. i hope all goes smooth. looking forward to this been waiting along time to put headers on the car. itll be coming back with headers , no cat, an yukon 3:73 gears.
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Old 05-11-2017, 07:12 AM
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Re: MAC header fitment

How did the header install go? Any big problems? The AC line and Steering ?
How is the change in driveability and performance?
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Old 04-25-2018, 08:10 PM
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hi sorry for the almost year reply here. the mechanic couldnt get the car in at all till now. so ive waited a year. the driver side went on so easy. just took a little tap in the one tube for the steering shaft. but the passengerside well this is a nightmare. the starter had to come out. then slightly bend the AC line. now finally the header is up there come to find out the two center holes are about 1/16 off so the bolts wont go in the head straight. nor will the front only one that lines up on the tube rear to the engine. I cannot ****ing believe it. i have to call mac tomorrow an WS6 where i bought them to see wtf is going on. i could make the holes a tad bigger but im afraid it may cause them to loosen over time. or i wonder if they gave me the entirely wrong header. an that is why he had such a hard time with it. hopefully WS6 or MAC will help me out if they dont then ill have to modify them which would be super crappy considering the money you pay for them. I got ARP header bolts for them with a 5/16 head just because the regular bolts you get with them have such big heads you cant turn the bolt without hitting the tube. this has become a nightmare build.
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Old 04-28-2018, 02:54 AM
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Re: MAC header fitment

Thought i was the only one. My last 94 had those wonky a.c. lines you mentioned.. Except I tried to make the first primary a slip fit looked like crap. Threw them away and ported the manifolds. . Now My 93 has so much more room. It's awesome. I can get all spark plugs with relative ease.
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Old 05-02-2018, 03:42 AM
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Re: MAC header fitment

my mac mids fit great. they don't come close to anything, especially the ac lines.
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