Reply
 
Thread Tools Search this Thread Display Modes
 
Old 09-25-2003, 05:48 PM   #1
RivetAddict
 
swebster's Avatar
 
1986 34.5' Airstream 345
Louisville , Kentucky
Join Date: Feb 2003
Posts: 1,861
Images: 4
Factory Headers?

Saw these listed on ebaymotors today as "factory headers". I have these on my 86. Were these a replacement for the cast iron manifolds? The ebay seller mentions solving the problem of cracking manifolds. I've been saving up for a Thorley/Flowmaster replacement some day...are there any advantages/disadvantages to keeping these on the MH? Everyone I talk to tells me about cracking manifolds so I'm not sure if I should feel better with these or not.
Attached Thumbnails
Click image for larger version

Name:	headers.jpg
Views:	209
Size:	19.6 KB
ID:	3241  
__________________

__________________
Steven Webster
1986 Airstream 345 Classic Motorhome
AIR 1760
swebster is offline   Reply With Quote
Old 09-25-2003, 05:58 PM   #2
Rivet Master
 
87MH's Avatar
 
1978 31' Sovereign
Texas Airstream Harbor , Zavalla, in the Deep East Texas Piney Woods on Lake Sam Rayburn
Join Date: Jan 2003
Posts: 2,435
Images: 292
"Factory Headers"

Steve:

I have the same set up on my '87. I did not know if it was added or factory. I have not found in the documentation where any work was done to the exhaust, so I am leaning toward the "factory" installation.

The expansion joint in the middle sure can't hurt.

With 75,000 miles on it, I don't have any exhaust problems.

I do have a vaccuum powered throttle valve installed just downstream of the manifold on the drivers side manifold only.

Even though the valve is free, I often wonder if this valve is the source of my pitiful gas mileage.

I only get 4-5 mpg, on the initial retrieval trip I recorded 7-8 mpg.

Only thing done to the motor since then was new plugs and plug wires.
__________________

__________________
Dennis

"Suck it up, spend the bucks, do it right the first time."

WBCCI # 1113
AirForums #1737

Trailer '78 31' Sovereign

Living Large at an Airstream Park on the Largest Lake Totally Contained in Texas
Texas Airstream Harbor, Inc.
87MH is offline   Reply With Quote
Old 09-25-2003, 06:06 PM   #3
RivetAddict
 
swebster's Avatar
 
1986 34.5' Airstream 345
Louisville , Kentucky
Join Date: Feb 2003
Posts: 1,861
Images: 4
163,000 on mine but a "rumored rebuild" 8K ago. Must have been done at some point as I can't believe a stock 454 would still run so well after pulling a 345 this far!

I have that valve as well. I've been getting a good 7 - 8 mpg after several trips. Also replaced cap, rotor, wires, made carb adjustments and plugs (all at the dealer) before going on first trip. Still feel like the carb needs some love though.

I'm sure one of our gurus will help on this one. If I do replace these with headers I'm not sure what do I do with all of that "extra" junk on the current manifolds/headers. Looks like an air pump sends air through smaller SS manifolds into the exhaust headers at each port. I actually think I have a small leak in one on the drivers side which I first feared was a cracked manifold.
__________________
Steven Webster
1986 Airstream 345 Classic Motorhome
AIR 1760
swebster is offline   Reply With Quote
Old 09-25-2003, 08:28 PM   #4
Rivet Master
 
LOST , Hawaii
Join Date: Jun 2002
Posts: 2,193
Factory manifolds, GM's admission there was a cracking problem.

There is an exhaust passage through the intake manifold and both heads. The valve should close when the engine is cold, the exhaust heats the manifold up faster.

John
__________________
74Argosy24MH is offline   Reply With Quote
Old 09-26-2003, 01:57 PM   #5
Rivet Master
 
87MH's Avatar
 
1978 31' Sovereign
Texas Airstream Harbor , Zavalla, in the Deep East Texas Piney Woods on Lake Sam Rayburn
Join Date: Jan 2003
Posts: 2,435
Images: 292
There is an exhaust passage through the intake manifold and both heads.....

John:

If I interpret your post correctly, there is an exhaust "cross flow" from the driver's side manifold, through the intake manifold, and exiting the curb side manifold when the exhaust back pressure valve is closed? (Engine is cold.)

Wow, that's a new one on me. Lots to learn.

Taking it one step further, with no vacuum to the back pressure valve controller, a spring holds the valve in one position, immediately upon starting, vacuum causes the valve to go full to the opposite position.
That being the case, as the engine warms up, the vacuum SHOULD BE dumped, letting the valve return, via holding spring power, to the original cold, non-running position?

I ask this, because there is no indication of valve position on the valve itself.

I started to disassemble the valve, but one of the three studs would not free, and I torqued it up a bit, so not wanting to cut, drill, and e-z- out a stud, I left it alone.

I have a "point and read" thermal indicator on order, but this information will be helpful in determining the proper operation of the exhaust back pressure valve.
__________________
Dennis

"Suck it up, spend the bucks, do it right the first time."

WBCCI # 1113
AirForums #1737

Trailer '78 31' Sovereign

Living Large at an Airstream Park on the Largest Lake Totally Contained in Texas
Texas Airstream Harbor, Inc.
87MH is offline   Reply With Quote
Old 09-26-2003, 02:02 PM   #6
Just a member
 
thenewkid64's Avatar
 
1978 28' Argosy 28
Tampa Bay , Florida
Join Date: Mar 2002
Posts: 4,539
Images: 21
Send a message via AIM to thenewkid64 Send a message via Yahoo to thenewkid64 Send a message via Skype™ to thenewkid64
Dennis,

There is a GMC Coach site that does a ton of rebuilds on the 455 engines. They quite often fill this crossover port with molten metal when rebuilding the top of an engine. I am not sure why, but it has been an area of frequent trouble, from what I have read this is a weak point that tended to crack.



Link to the page where they show this.

Pouring molten Zinc into the crossover port
Attached Thumbnails
Click image for larger version

Name:	pour_the_zinc[1].jpg
Views:	180
Size:	72.4 KB
ID:	3260  
__________________
Brett G
WBCCI #5501 AIR # 49
-------------------------
1978 Argosy 28 foot Motorhome

Wise men talk because they have something to say; fools, because they have to say something. -- Plato


thenewkid64 is offline   Reply With Quote
Old 09-26-2003, 04:15 PM   #7
Rivet Master
 
LOST , Hawaii
Join Date: Jun 2002
Posts: 2,193
Quote:
Taking it one step further, with no vacuum to the back pressure valve controller, a spring holds the valve in one position, immediately upon starting, vacuum causes the valve to go full to the opposite position.
That being the case, as the engine warms up, the vacuum SHOULD BE dumped, letting the valve return, via holding spring power, to the original cold, non-running position?
Yes, it should close when cold and let the exhaust flow normally when warm. I doubt if all the exhaust flows through the manifold, it isn't a very large opening.

GM Coop is classy. All I ever did was jam aluminum foil into the intake and use the filler that came with the intake gasket.

John
Attached Images
 
__________________
74Argosy24MH is offline   Reply With Quote
Old 09-26-2003, 04:28 PM   #8
RivetAddict
 
swebster's Avatar
 
1986 34.5' Airstream 345
Louisville , Kentucky
Join Date: Feb 2003
Posts: 1,861
Images: 4
So if I went the Thorley (or Banks if I win the lottery) you would simply remove this gear and plug up the openings? Any advantage to just keeping the stock manifolds and adding a flowmaster exhaust?
__________________
Steven Webster
1986 Airstream 345 Classic Motorhome
AIR 1760
swebster is offline   Reply With Quote
Old 09-26-2003, 04:59 PM   #9
Rivet Master
 
LOST , Hawaii
Join Date: Jun 2002
Posts: 2,193
If you don't have to worry about emissions testing tear it all off and go with the headers. Using a free flowing exhaust is better than stock, but the header swap is where you will really improve performance and mileage.

John
__________________
74Argosy24MH is offline   Reply With Quote
Old 09-26-2003, 05:45 PM   #10
RivetAddict
 
swebster's Avatar
 
1986 34.5' Airstream 345
Louisville , Kentucky
Join Date: Feb 2003
Posts: 1,861
Images: 4
John thanks! Good to know. KY doesn't test over 15,000 lbs so mine is immune. Now I just need enough freelance work to get the header purchase past the budgeting queen! Maybe I take a queue from Brett and go with the...it's suddenly broken routine!

Seriously, I have kind of a PO special for an exhaust system. Some original and two mufflers that were literally crushed to fit (not pretty)...so going free flow has been in the plan. Add a new carb and a Tornado and maybe I'll see 10+ mpg some day!
__________________
Steven Webster
1986 Airstream 345 Classic Motorhome
AIR 1760
swebster is offline   Reply With Quote
Old 09-26-2003, 06:05 PM   #11
Rivet Master
 
LOST , Hawaii
Join Date: Jun 2002
Posts: 2,193
Quote:
Some original and two mufflers that were literally crushed to fit (not pretty)
I have heard of shade tree mechanics, now we've got cave man mechanics. You won't have to imitate Brett, rust will take care of them pretty fast once the aluminizing layer gets busted and scraped up.

John
__________________
74Argosy24MH is offline   Reply With Quote
Old 08-30-2004, 01:20 PM   #12
Rivet Master
 
87MH's Avatar
 
1978 31' Sovereign
Texas Airstream Harbor , Zavalla, in the Deep East Texas Piney Woods on Lake Sam Rayburn
Join Date: Jan 2003
Posts: 2,435
Images: 292
Header Question for Gear Heads

Hey, guys.....

Could anyone identify which manufacturer might have made these headers?

I picked them up at Colaw's in May of 2004, I know they came off of a 454 and seemed to be in pretty fair shape overall - just had a light coat of surface rust when I inspected them. The "shelf" on the curb side manifold is a heat shield, the chrome "handle" appears to be a mounting assist.

A company here in Houston "Metalized" the surface with the new "Kolene" process. Great people to do business with -- ask for "Eric".


http://www.houstonplating.com/


Here are the photos of the Headers after the "Kolene" plating (coating) process.



Thanks.
Attached Thumbnails
Click image for larger version

Name:	Header1.JPG
Views:	119
Size:	26.5 KB
ID:	8538   Click image for larger version

Name:	Header2.JPG
Views:	118
Size:	22.2 KB
ID:	8539  

Click image for larger version

Name:	Header3.JPG
Views:	122
Size:	24.4 KB
ID:	8540  
__________________
Dennis

"Suck it up, spend the bucks, do it right the first time."

WBCCI # 1113
AirForums #1737

Trailer '78 31' Sovereign

Living Large at an Airstream Park on the Largest Lake Totally Contained in Texas
Texas Airstream Harbor, Inc.
87MH is offline   Reply With Quote
Old 08-30-2004, 01:27 PM   #13
RivetAddict
 
swebster's Avatar
 
1986 34.5' Airstream 345
Louisville , Kentucky
Join Date: Feb 2003
Posts: 1,861
Images: 4
Hmmm. They definately do not look like my Hedmanns. Long primaries. What is that plate on the pass side for?
__________________
Steven Webster
1986 Airstream 345 Classic Motorhome
AIR 1760
swebster is offline   Reply With Quote
Old 08-30-2004, 01:29 PM   #14
RivetAddict
 
swebster's Avatar
 
1986 34.5' Airstream 345
Louisville , Kentucky
Join Date: Feb 2003
Posts: 1,861
Images: 4
oh...just re-read your post...heat shield. I think the "handle" is actually for the hot air intake to your air cleaner horn.
__________________

__________________
Steven Webster
1986 Airstream 345 Classic Motorhome
AIR 1760
swebster is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Dealing with the factory Silvertwinkie Commercial Listings 1 02-18-2004 11:08 AM
Factory Work Info newae General Repair Forum 21 12-18-2003 04:44 PM
Factory visit dtbw On The Road... 1 11-01-2003 03:43 AM
International AS Factory Mod Pahaska 2002 - 2005 International 7 10-10-2003 04:22 PM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 07:00 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.