| manifolds vs headers [message #296246] |
Fri, 26 February 2016 12:54  |
erichb
Messages: 22
Registered: February 2013
Karma: 0
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Junior Member |
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My driver side is J passenger side is H. Is that correct or did PO deviate
Both leak, i pulled passenger last fall and had a previously welded crack repaired. I didnt waste the remflex gasket on it yet since i have leaks at the donuts as well. Which means i prob have to get right at the manifold first and then get the section from manifolds to newer mufflers done right
So how much can i waste on manifolds before it makes sense to just go with the 355y header
PO looks to have put in the 2.5 double muffler set up in . Prob within a few years as it looks solid. The tubes from manifolds to mufflers restrict down at the bends quite a bit so those need to be done better and probbaly supported better since the connections dont fit tight
If i could find good manifolds i would probably remove back to the y and put single muffler in rear all with the 2.5" 3" would be better, but not sure it woukd improve any noticeable amount to scrap good material
Thoughts ???
73 Canyonlands, Fresh TH425 and FD, Bags and Pins updated. Needs A/C, Top and Front service....Minneapolis
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| Re: manifolds vs headers [message #296249 is a reply to message #296246] |
Fri, 26 February 2016 15:10  |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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Senior Member |
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It's hard to find replacement manifolds.
Most people put Thorley headers after they crack.
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: manifolds vs headers [message #296252 is a reply to message #296246] |
Fri, 26 February 2016 16:23 |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
Karma: 0
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Senior Member |
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With headers, plan to put some high temp protection on the plug wires and speedometer cable.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: manifolds vs headers [message #296259 is a reply to message #296246] |
Fri, 26 February 2016 18:46 |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
Karma: 1
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Senior Member |
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I went with the Thorley headers. No issues in the past three years, Just be careful with items next to the hot header. Some say the transmission governor is difficult to remove with headers.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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| Re: manifolds vs headers [message #296261 is a reply to message #296246] |
Fri, 26 February 2016 19:09 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Erich
455 Manifolds
LH 407103
RH 411970
Are the numbers for the correct exhaust manifolds.
The donuts can be fussy to get sealed. Do you still have the springs on the studs?
I bought new donuts at NAPA and had success.
Did you resurface the repaired manifold --the local machine shop was charging $30 each to essentially put them on a big belt sander.
I may be in the minority but I prefer the manifolds over the headers. I believe they produce less noise and engine compartment heat.
Dennis
erichb wrote on Fri, 26 February 2016 12:54My driver side is J passenger side is H. Is that correct or did PO deviate
Both leak, i pulled passenger last fall and had a previously welded crack repaired. I didnt waste the remflex gasket on it yet since i have leaks at the donuts as well. Which means i prob have to get right at the manifold first and then get the section from manifolds to newer mufflers done right
So how much can i waste on manifolds before it makes sense to just go with the 355y header
PO looks to have put in the 2.5 double muffler set up in . Prob within a few years as it looks solid. The tubes from manifolds to mufflers restrict down at the bends quite a bit so those need to be done better and probbaly supported better since the connections dont fit tight
If i could find good manifolds i would probably remove back to the y and put single muffler in rear all with the 2.5" 3" would be better, but not sure it woukd improve any noticeable amount to scrap good material
Thoughts ???
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: manifolds vs headers [message #296263 is a reply to message #296261] |
Fri, 26 February 2016 19:42 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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With the Remflex exhaust gaskets, you may not need to run your exhaust manifold across a belt sander operation. They are quite forgiving, if applied according to Remflex instructions. Remember the middle bolt is not designed to tighten up the manifold. It provides initial alignment and gives you something to hang the gasket and manifold on, while re-installing the manifold. Tighten snug, do not muscle it down. If over-tightened, it pulls the manifold out of alignment with the block and will lead to early failure of the Remflex gasket.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: [GMCnet] manifolds vs headers [message #296266 is a reply to message #296252] |
Fri, 26 February 2016 20:03 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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And either remove, cut away, or add protective shielding to the right wheel
well liner. I wound up cutting away the heat distorted ABS and replacing
that section with aluminum
Ken H.
On Fri, Feb 26, 2016 at 5:23 PM, jerrod winter wrote:
> With headers, plan to put some high temp protection on the plug wires and
> speedometer cable.
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: manifolds vs headers [message #296274 is a reply to message #296246] |
Fri, 26 February 2016 21:49 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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erichb wrote on Fri, 26 February 2016 11:54My driver side is J passenger side is H. Is that correct or did PO deviate
Both leak, i pulled passenger last fall and had a previously welded crack repaired. I didnt waste the remflex gasket on it yet since i have leaks at the donuts as well. Which means i prob have to get right at the manifold first and then get the section from manifolds to newer mufflers done right
So how much can i waste on manifolds before it makes sense to just go with the 355y header
PO looks to have put in the 2.5 double muffler set up in . Prob within a few years as it looks solid. The tubes from manifolds to mufflers restrict down at the bends quite a bit so those need to be done better and probbaly supported better since the connections dont fit tight
If i could find good manifolds i would probably remove back to the y and put single muffler in rear all with the 2.5" 3" would be better, but not sure it woukd improve any noticeable amount to scrap good material
Thoughts ???
I'm not a fan of headers. They are a last resort if you cannot repair your cast iron manifolds. If your original manifolds are not cracked, do what you have to do to seal them. If they are cracked, a decent repair is probably not worth while. However, I feel that good originals are available either form members or Cinnabar. Headers have a lot of additional issues such as engine compartment heat and related hacks, governor and dipstick accessibility, etc.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] manifolds vs headers [message #296332 is a reply to message #296327] |
Sun, 28 February 2016 01:54 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Cost of a new manifold exceed the header units.
Should you use the Springfield ignition wires, they hold up to the heat and
the ceramic coating works well to contain heat and corrosion plus you can
gain power as long as you do few things correctly.
We supply lot of them, and receive positive results.
On Sat, Feb 27, 2016 at 6:29 PM, Terry wrote:
> 10-4 on the shielding, Ken
> --
> Terry Kelpien
> ASE Master Technician
> 73 Glacier 260
> Smithfield, Va.
>
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: manifolds vs headers [message #296388 is a reply to message #296360] |
Mon, 29 February 2016 00:05 |
JohnS
Messages: 126
Registered: December 2014
Location: Vacaville, CA
Karma: -2
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Senior Member |
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Manny makes a left side header which allows removal of the governor with the header in place.
John Shutzbaugh, Vacaville, CA, ncserv@aol.com;
78 Buskirk stretch, "What were we thinking?"
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