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[General] How To Fit HM 4 into 1 headers 5.7l/6.0l

GUS009

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On the weekend i fitted a set of 4 into 1 from HM Headers and with very little experience and had great success taking me a total of 4 hours including removing a broken manifold bolt :). These are the fitting instructions for HM120SS/HM121SS short 4 into 1s with a few tips I leant along the way, but the methods will be similar for any header when you don't have to modify the rest of the exhaust system.

1. Disconnect the negative off the battery.
2. Remove engine cover/s
3. Pull all plug leads out
4. Spray all bolts and nuts that you will be removing with WD-40 (or CRC or whatever)
5. Undo the 12mm bolt that holds the ABS brake unit in and move it over onto the intake manifold out of the way.
6. Undo the 10mm bolts that hold the coil packs on the LHS (otherwise you will struggle to get the manifold past the heat shield) don't worry about them on the RHS they can stay on.

Non-HSV vehicles
RHS (drivers side) Fitment


1. Remove the dipstick tube (undo the bolt on the bracket the pull it straight up, its best to put a phillips head screwdriver with a slightly smaller diamiter to the tube in the tube, then use some vise grips to pull it out. (The screwdriver is just to stop the tube from closing up when you put the vise grips on so make sure it fits snug)
2. Undo the 13mm nuts on the flange of the connecting pipe on the RHS of the original exhaust manifold fitted to the engine. Keep these nuts as they will be used for fitment of the new header. (once you have removed; one of the nuts the other is quite easy to remove so do the one you reach easiest first)
3. Go through and crack all the 13mm manifold bolts, be very careful with these; you don't want the heads to break off as its a pain in the ass to get them out and they are 20 bucks a piece.
4. Once they are all successfully cracked take them out one by one be sure not to lose them as you will need them for fitment of new header.
5. Now you can pull out the old manifold (bringing it forward as you lift it out) and throw in your new shinny header. (You can reuse the gasket if its done under 150,000kms but i would recommend replacing it anyway)
6. Line up the flange and start your nuts from engine bay there is better access for you hands, slide in the gasket and start the 13mm bolts in for the header.
7. Tighten the up the flange nuts (from under car), Then tighten up the manifold bolts first to 11ft/lbs and then to 18ft/lbs.
8. Move ABS brake unit back over into original position, Put the plug leads back in.

RHS Complete!!! :)


LHS Fitment

1. Undo the flange of the connecting pipe on the LHS of the original exhaust manifold fitted to the engine. (again keep the nuts)
2. Crack all the manifold bolts carefully, and remove them.
3. Pull out original manifold and replace it with your new header. (this is a tight squeeze to get the new header in, i tilted mine up vertically and pushed it down the firewall to get it past the heat shield)
4. Line up the flange and start the nuts from the engine bay (again for better access) slide gasket in and start the manifold bolts.
5. Get under the car again and tighten the flange nuts, then tighten the manifold bolts up first to 11ft/lbs and then to 18ft/lbs
6. Place the coil packs back in position and do the bolts back up, plug the leads back in, throw the engine cover/s on, put the negative back on the battery and your good to go!!!!!

Also don't worry about smoke coming off the headers when you first start it, its just the crap burning off that they put in them to make them look pretty, wait five or so minutes for that **** to burn off and then check for any leaks.

I bought the headers off ebay from boltonperfomance for $475 a bargain for a brand new set of stainless steal 4 into 1s.

more info on these headers here
HM Headers | HM120SS
 

OFF T4P

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nice thread mate. i fitted some pace maker 1 7/8 4 into 1 with 3.5 out let to my vx the other week and i wish they were that easy to fit. i had to relocate the clutch line disconnect power steering rack and drop it down an cut the starter motor bracket up just so them big mofo's could fit in there but i dout you would have to do this for normal smaller 4 into 1's. i recommend using a hoist if fitting big pacys as they are one piece and you will have to get the front end fairly high to slot them in from the bottom on the drivers side. I had to pull them all out again last weekend when i fitted my blower and changed all the power steering lines and pump and rack what a mission is all i can say. Have fun.
 

GUS009

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ha thanks mate, i searched and searched for a cheap set that i could fit easy enough without pulling to much out, granted not the same power gains but worth it. what supercharger did you go with? and how did you go about getting it tuned?
 

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you defiantly got a good deal with them headers would of made a good power difference ay. i use to have tri y's. 4 into 1's p!ss all over them. i went with a vortech v2 only running 6psi for now will upgrade to gilmour and cooler in a few months. I am still running it in so i am still running capa's tune they just retune the standard ecu . after about 1000km i will take it in for a dyno tune and power run.
 

GUS009

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yeah i was happy. i have been looking into a blower and the v2 look great bang for buck. so how difficult was it to install? and is the tune included in the price? and wats it like to drive :)
 

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yea mate easy to install only takes a couple of hours. yea v2's are good still upgradable down the track to. yea tune is included in the price but you will have to put it up onto a dyno after 1000 kms or so just to re-tune (might squeeze a bit more out of it) and check every thing is all good. its nice to drive once you hit 3000rmp it gets going really well. i wouldn't mind a bit more down low but a cam throttle body and maybe a bigger manifold would help the response a bit more.
 

GUS009

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haha mate the more ya get the more ya want aye. yeah fair enough so its a good rig then, now i just need to start savin my pennys
 

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nice thread mate. i fitted some pace maker 1 7/8 4 into 1 with 3.5 out let to my vx the other week and i wish they were that easy to fit. i had to relocate the clutch line disconnect power steering rack and drop it down an cut the starter motor bracket up just so them big mofo's could fit in there but i dout you would have to do this for normal smaller 4 into 1's. i recommend using a hoist if fitting big pacys as they are one piece and you will have to get the front end fairly high to slot them in from the bottom on the drivers side. I had to pull them all out again last weekend when i fitted my blower and changed all the power steering lines and pump and rack what a mission is all i can say. Have fun.
Yep agreed Looks like Im going to have to drop the rack a bit to clear the current Blackops 1-3/4 into 3" 4 into 1s....
 
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