TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > AMC V8 Engine Repair and Modifications
  New Posts New Posts RSS Feed - Header Hack
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

Header Hack

 Post Reply Post Reply Page  <12
Author
Message
Greyhounds_AMX View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Nov/14/2009
Location: Kansas City
Status: Offline
Points: 482
Post Options Post Options   Thanks (0) Thanks(0)   Quote Greyhounds_AMX Quote  Post ReplyReply Direct Link To This Post Posted: Aug/19/2016 at 8:35am
I found a set of 3" x 2-1/4" header reducers with a pretty gradual taper, cut off the 3-bolt flange, and ground off the nasty zinc plating.



Once the reducer is in place (and without the 3-bolt flanges) there's plenty of ground clearance.



The 2-1/4" reducers tie in to the original H-pipe with some mandrel bends and flex pipe. The connection between the header and the new piping to the h-pipe is made with a stainless band clamp.



Here's the passenger side header coming together. The initial test fit showed the collector needing to move up 2" and the forwardmost elbow needing to move up 1.5".



So I mounted it to the test head and built up wood to indicate where the original header boundaries were, then marked the new collector location and added spacers to show me where the elbow limits needed to be. Then it just takes some cutting and such to make it all it. On this side one of the middle tubes fit up good, one (#8) had no hope, and the other two were close. I was able to clamp the two close tubes into alignment and tack them, then heat the tubes cherry red with the torch to relieve the stress. The #8 tube needed some extra bend and twist to aim it away from the starter, and then a replacement tube with a section of mandrel bend at the end of it was grafted in.







One thing to note is that I did have to grind a little clearance into the mini-starter gear housing and grind a little off the block as well. That allowed me to clock the starter motor one more hole towards the engine and away from the header. At this point I can install and remove the header easily with the starter in place. I'd have to remove the header to get the starter out, but that's pretty easy.

Chris ("Mojo")
1968 AMX 390
Back to Top
White70JavelinSST View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Aug/08/2012
Location: Minnesota
Status: Offline
Points: 2608
Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Aug/19/2016 at 1:16pm
I'm likin it Chris.

The welds are pretty too !
70 Javelin SST, second owner, purchased 1972
Back to Top
Greyhounds_AMX View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Nov/14/2009
Location: Kansas City
Status: Offline
Points: 482
Post Options Post Options   Thanks (0) Thanks(0)   Quote Greyhounds_AMX Quote  Post ReplyReply Direct Link To This Post Posted: Aug/20/2016 at 10:17am
Thanks! This is a fun project and is really making me see why it's so hard to get a good set of headers. There's a lot of obstacles to miss.

On the drivers side I still ended up grinding a little off the strut rod bracket and putting a clearance dent into the header tube to make sure it doesn't hit. I'm not too worried about a few dings in the headers after watching the Roadkill episode where they dyno test the headers with all the dents in them. No big deal there.

I still need to add the O2 sensor bungs to each side. One will get a plug as I only have one sensor, but at least it'll give the ability to swap the sensor between sides if needed. Once that's done they go back to sandblasting, and then get paint. I'm going the cheap route in every way with these, so they'll get PlastiKote aluminum high heat paint like the hookups did. I've had good results with it over the years, and found that I can cure the paint pretty well with a MAPP gas torch. If they work out well they may get real Jet Hot some day, but I want to make sure the relatively short tubes perform well enough before spending that much on them, and there's still a chance that mods will need to be made to them as well for clearance, etc.
Chris ("Mojo")
1968 AMX 390
Back to Top
Greyhounds_AMX View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Nov/14/2009
Location: Kansas City
Status: Offline
Points: 482
Post Options Post Options   Thanks (0) Thanks(0)   Quote Greyhounds_AMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/08/2016 at 9:44am
I finished the O2 bungs and got them sandblasted again, then finally painted them. I'm using Plastikote HP-14 aluminum high temp paint. Two light coats, then wait an hour, then cure it with a MAPP gas torch. Final cure will come from running the engine.

This paint has worked really well for me in the past.




Chris ("Mojo")
1968 AMX 390
Back to Top
Greyhounds_AMX View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Nov/14/2009
Location: Kansas City
Status: Offline
Points: 482
Post Options Post Options   Thanks (0) Thanks(0)   Quote Greyhounds_AMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/17/2017 at 1:30pm

Well I finally have the exhaust done. Here you can see how the band clamps worked out. With the Wilwood pull slave on the drivers side I ended up with the O2 sensor on the passenger side.




You can also see the heat shields I made out of a big chunk of heat shield material I nabbed off a Corsica. At the tightest spot there's only about 1/2" of clearance, so I may have to tweak these a little depending on how the floor tends to heat up. 

The lowest point of the headers is about level with the bottom of the bellhousing.

 


Chris ("Mojo")
1968 AMX 390
Back to Top
304-dude View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Sep/29/2008
Location: Central Illinoi
Status: Offline
Points: 5540
Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Oct/17/2017 at 1:55pm
Real nice work! Tucked up pretty well.

If you get too hot on the floor, use an aerogel sheet between the heat shield and body.

I plan on using a lot of aerogel on my custom exhaust through the cold air duct / ventilation part of the kick panels and cowl, for through the fender output to side exhaust. Though, being a dropped suspension on my build side exhaust would not work without frame mods, thus my odd idea.
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
Back to Top
White70JavelinSST View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Aug/08/2012
Location: Minnesota
Status: Offline
Points: 2608
Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Oct/18/2017 at 6:57pm
Nice Work Chris.

Curious here, how did you route the tailpipes?

What mufflers are you using and can you make a video so we can hear the exhaust note?

Awesome work !

70 Javelin SST, second owner, purchased 1972
Back to Top
Scene One View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Jan/13/2014
Location: Friedens Pa.
Status: Offline
Points: 488
Post Options Post Options   Thanks (0) Thanks(0)   Quote Scene One Quote  Post ReplyReply Direct Link To This Post Posted: Oct/18/2017 at 8:52pm
Wow very nicely done!!
Back to Top
 Post Reply Post Reply Page  <12
  Share Topic   

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.063 seconds.
All content of this site Copyright © 2012 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or