Mac Headers

[86bluecobra]

I have a 351w in my 86 stang and was wondering if anyone out there is using mac headers? the reason i ask is i was looking at the flange on them. well there really isnt a flange per say. kinda a individual tube flange for each pipe connecting to the heads. is this a good setup? are there exhaust leak problems because of this design?

 

[86bluecobra]

need some help here peeps

 

[95GTAODE]

Some people have had problems with warping and some haven't. The individual flanges make them easier to install, but if you take them off after they have been on awhile, sometimes you need to use a prybar to get the flanges to line back up with the heads again. Apparently it's a hit or miss type thing.

 

[ss93cobra]

Some people have had problems with warping and some haven't. The individual flanges make them easier to install, but if you take them off after they have been on awhile, sometimes you need to use a prybar to get the flanges to line back up with the heads again. Apparently it's a hit or miss type thing.

My experience with this particular issue is that they need to be persuaded only if going on a different car. Maybe I've just got been lucky though...

 

[vristang]

I am running this set-up. 351w block with mac shorties in a 90GT. I have found that I have to thread the header bolts in a specific order. If not it will not go together and I will cross thread the bolt into the head. Still it is easier if I pry on the last tube (make this the longest tube) to start the last bolt.
I have had no leaks around the flanges. Even after smoothing down the weld on the inside of the flange.
Come to think of it the 302 headers were pretty good too.

 

[illwood]

Before the crash, there was a thread on some MAC headers that a guy had for sale on eBay. The guy had nothing but bad things to say about them and he said that they killed gaskets and about every time he took them off, he would have to open up the holes a bit to get them back on because they warped from heat cycling.

Don't have any personal experience, but it does seem possible for that to be a problem.

 

[91_Mustang]

I have MAC shortys on my 302. i have to use the prybar every time i put them back on, wich is often cause they keep blowing gaskets.

 

[vristang]

I've only had one gasket failure with my headers, and that was because I didn't retorque the bolts after running the motor for a while. Oops!!!

 

[OL' WHITEY]

30,000 plus miles on my MAC shortys and not one single problem. No leaks, etc. Mine are rusting a little. Juat surface rust. I've never had them back off, so I can't say about taking them off and putting them back on over and over again.

 

[Flavadave4]

i had to use a prybar to get them back on last month after about 5000 miles of use.....they are not any easier to install than the other brands from what ive seen. i would NOT recomend using them just beacause they warp and are a PITA to work with once they have been used

 

[04sleeper]

I will have to agree with most here. Nothing but problems from MAC headers.
Due to the problems with lining up the bolts with a pry bar and thin wall tubing, I will never buy their products again.

 

[vristang]

Seems a little harsh 89sleeper. The real question is how do the above mentioned problems compare to other brands of headers, and what is the price difference. I know that when considering perfomance/$ MAC headers are the best deal out there, just a little time consuming to install sometimes. I would recommend learning how to bolt them up properly. For example start with the AFT most bolt and work FWD. Be sure to leave the H-pipe bolts loose, even the ones on the AFT end. This can make a big difference. But if you are taking the headers out frequently, it may be worth a few extra dollars to simplify the process.
Best of Luck!

 

[04sleeper]

Seems a little harsh 89sleeper.

Not really. Seeing as how I used to buy nothing but MAC headers because they were one of the only companies out there that sold headers when I started working on Mustangs about 15 years ago. Now that there are a lot more companies and I have learned from my experiences I would say that it is not harsh. Just a decision made by me from 15 years of working on Mustangs.

 

[SamSnyder]

I've had Mac unequal lengths on my GT40 heads for 8 or 9 years with no real problems. The warping factor did play when I rebuilt, but a prybar (actually, a barbell bar stuck into each exhaust flange while I stood on the collector) got all the exhaust flanges back to where they were supposed to be. Mine also came with the original nickel plate finish, which I don't know if they're still using, and Foamy Engine Brite cleaner washed that finish off like it was water. But they work OK. I might get them again since they're still about the cheapest out there. Since they've worked OK for so long for me, I couldn't say it would be worth it to spend any more on a shorty.