Home » Public Forums » GMCnet » Best Practice - Aluminum or HardBlok in manifold?
| Re: [GMCnet] Best Practice - Aluminum or HardBlok in manifold? [message #341452 is a reply to message #341451] |
Sun, 03 March 2019 21:30   |
emerystora
Messages: 4442
Registered: January 2004
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There are many different alloys of aluminum with a wide range of melting points.
The typical aluminum (cans, etc.) that people melt down to fill the manifold are typically low melting point material.
Emery Stora
77 Kingsley
Frederick, CO
> On Mar 3, 2019, at 7:37 PM, Bill Van Vlack via Gmclist wrote:
>
>
> If the Rockwell AL manifold holds up to exhaust temperatures, why wouldn't aluminum fill + block-off plates?
> --
> Bill Van Vlack
> '76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
> November 2015.
>
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| Re: Best Practice - Aluminum or HardBlok in manifold? [message #341455 is a reply to message #341454] |
Sun, 03 March 2019 23:34 |
Bill Van Vlack
Messages: 419
Registered: September 2015
Location: Guemes Island, Washington
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I like the idea of welding plugs in the manifold, but I understand welding cast iron is a special skill and I don't know how to qualify a potential welder.
I might consider the aluminum manifold if it was available, but it's not. I understand Mondello has the patterns but is not making them at present. Also... are there alternatives that are less expensive and just as effective to address a cracked cast iron manifold.
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid November 2015.
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| Re: [GMCnet] Best Practice - Aluminum or HardBlok in manifold? [message #341456 is a reply to message #341454] |
Sun, 03 March 2019 23:38 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Bill,
your correct, welding cast iron takes a oven to pr heat and after welding
some, the heat it up and remove stress.
Currently the Rockwell style Aluminum intakes are on Back order for few
weeks.
I have heard that one guy started burning the area. Again I say you must
address the muffler issue.
On Sun, Mar 3, 2019 at 9:32 PM Bill Wevers via Gmclist <
gmclist@list.gmcnet.org> wrote:
> There's more than one way to block the crossover.
> If you know someone who can weld cast iron, they can
> seal up the crossover with steel plugs. Or you can
> purchase a Rockwell replacement manifold if you like.
>
>
> --
> Bill Wevers GMC49ers, GMC Western States
> 1975 Glenbrook - Manny Powerdrive, OneTon
> 455 F Block, G heads
> San Jose
>
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--
Jim Kanomata
Applied/GMC, Newark,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: [GMCnet] Best Practice - Aluminum or HardBlok in manifold? [message #341458 is a reply to message #341456] |
Mon, 04 March 2019 00:05 |
James Hupy
Messages: 6806
Registered: May 2010
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Bill, if it is any use, I presently am working on a 455 with a Rockwell
aluminum manifold. I has been running for 2 years, over 24,000 miles. The
rod bearings failed, so it came apart. It was fitted with Paterson intake
gaskets and SS block off plates. They were still well sealed up and
undamaged when we took it apart.
Jim Hupy
On Sun, Mar 3, 2019, 9:49 PM Jim Kanomata via Gmclist <
gmclist@list.gmcnet.org wrote:
> Bill,
> your correct, welding cast iron takes a oven to pr heat and after welding
> some, the heat it up and remove stress.
> Currently the Rockwell style Aluminum intakes are on Back order for few
> weeks.
> I have heard that one guy started burning the area. Again I say you must
> address the muffler issue.
>
> On Sun, Mar 3, 2019 at 9:32 PM Bill Wevers via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> There's more than one way to block the crossover.
>> If you know someone who can weld cast iron, they can
>> seal up the crossover with steel plugs. Or you can
>> purchase a Rockwell replacement manifold if you like.
>>
>>
>> --
>> Bill Wevers GMC49ers, GMC Western States
>> 1975 Glenbrook - Manny Powerdrive, OneTon
>> 455 F Block, G heads
>> San Jose
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
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| Re: [GMCnet] Best Practice - Aluminum or HardBlok in manifold? [message #341459 is a reply to message #341456] |
Mon, 04 March 2019 01:02 |
Bill Van Vlack
Messages: 419
Registered: September 2015
Location: Guemes Island, Washington
Karma: 14
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So if your manifold is cracked, it's because the mufflers are not (or were not) balanced. Yep,I can see that... Any differential back pressure would create a constant flow of hot exhaust gasses through the crossover.
But would that same differential, if the crossover were blocked (or never there, as in many vehicles with dual mufflers) be a problem?
Certainly worth checking if the mufflers are unbalanced...just not sure how one would so that - (assuming they are of good quality, look identical, and sound just fine). Cut them open? Do some sort of flow test? Or should the whole exhaust system be replaced with a single pipe system no matter what?
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid November 2015.
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| Re: [GMCnet] Best Practice - Aluminum or HardBlok in manifold? [message #341460 is a reply to message #341459] |
Mon, 04 March 2019 01:10 |
Bill Van Vlack
Messages: 419
Registered: September 2015
Location: Guemes Island, Washington
Karma: 14
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Senior Member |
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Jim H...
Looking at photos of the Rockwell manifold, it doesn't appear that it has crossover ports, therefore wouldn't need blockoff plates.
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid November 2015.
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| Re: Best Practice - Aluminum or HardBlok in manifold? [message #341461 is a reply to message #341429] |
Mon, 04 March 2019 03:19 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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You use the stainless steel block off plates to prevent very hot exhaust flow from the exhaust ports in the intake manifold. Then the intake is running at near engine temperature around 200 degrees. With out the plates the intake manifold in that area runs very hot and changes temperature constantly depending on engine load. Every GMC I have ever seen has run hot enough there to burn off the paint. I have not measured the temp there but I would have to guess that it is constantly changing between 500 and 1500 based on engine load, and crossover exhaust flow under the changing loads. Restricted mufflers just exacerbate the problem. So put the plates in and resolve the problem. The manifold will then run at near constant engine temperatures of 200 F. or less.
Filling the manifold after installing the plates is a different issue. It is only necessary if you are attempting to seal an existing manifold crack. I'll let others comment on what to use but keeping mind the filler material only has to withstand temps of a little over 200 degrees or so rather than the original 500 to 1500 that was necessary before the plates were installed. It seems to me that anything with a melting point of over 300 degrees ought to work. The rate of expansion between 0 and 200 degrees when compared to the cast manifold might be a concern when choosing the filler. Choose the filler that others like Larry or Col. Ken have successfully used in the past and be done with it.
I have no suggestion on which filler which is best. My intake is blocked and I never needed to fill the manifold. I did watch Col. Ken at a rally 10 to 15 years ago with a cast frying fan and a big torch, heat up some metal and fill a manifold. I thought the metal was old pistons but it may have been the Mondello stuff.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
[Updated on: Mon, 04 March 2019 03:22] Report message to a moderator |
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| Re: [GMCnet] Best Practice - Aluminum or HardBlok in manifold? [message #341463 is a reply to message #341461] |
Mon, 04 March 2019 04:57 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Ken,
According to this album date, I first filled an intake manifold's exhaust
crossover in 2007:
http://www.gmcmhphotos.com/photos/g3115-plugging-intake-manifold-exhaust-crossover.html
The rally we had at Lake Park, GA where we filled some more was probably in
2008 or so.
The manifold I first filled stayed on the 455, undamaged, until I changed
to the Cad500 a few years later. It's either just been installed, or is
about to be, on the 455 of a friend who's gotten disgusted with the "dog
house" required over his Edelbrock manifold. He'll use SS plates as well.
Another block off method that I haven't seen mentioned is one I heard Alex
Sirum used to do. I did it to someone's manifold with good results: Using
an ordinary router with a straight 1/4" carbide bit, cut a 1/8"x1/8" groove
around the exhaust port on each side of the manifold. Into that recess,
fit a piece of steel to sit flush with the manifold flange. AFAIK, that's
worked well.
The material I always used to fill manifolds was "Mondello Metal" -- a zinc
alloy, IIRC. I don't know whether his successors stil sell it. I've heard
of others using old aluminum pistons. The iron skillet and fish cooker
shown in my album would probably work with that also. I have no
experience, nor confidence in, the "hard block" compounds, even though John
Beaver, my local NASCAR engine builder uses it frequently in dragster
engines. The objective there is not to provide sealing, as is needed for a
cracked manifold. BWDIK?
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com
On Mon, Mar 4, 2019 at 4:22 AM Ken Burton via Gmclist <
gmclist@list.gmcnet.org> wrote:
> You use the stainless steel block off plates to prevent very hot exhaust
> flow from the exhaust ports in the intake manifold. Then the intake is
> running at near engine temperature around 200 degrees. With out the
> plates the intake manifold in that area runs very hot and changes
> temperature
> constantly depending on engine load. Every GMC I have ever seen has run
> hot enough I have not measured the temp there but I would have to guess that
> it is constantly changing between 500 and 1500 based on engine load, and
> crossover exhaust flow under the changing loads. Restricted mufflers just
> exacerbate the problem. So put the plates in and resolve the problem.
> The manifold will then run at near constant engine temperatures of 200 F.
> or
> less.
>
> Filling the manifold after installing the plates is a different issue. It
> is only necessary if you are attempting to seal an existing manifold
> crack. I'll let others comment on what to use but keeping mind the
> filler material only has to withstand temps of a little over 200 degrees or
> so
> rather than the original 500 to 1500 that was necessary before the plates
> were installed. It seems to me that anything with a melting point of over
> 300 degrees ought to work. The rate of expansion between 0 and 200
> degrees when compared to the cast manifold might be a concern when choosing
> the
> filler. Choose the filler that others like Larry or Col. Ken have
> successfully used in the past and be done with it.
>
> I have no suggestion on which filler which is best. My intake is blocked
> and I never needed to fill the manifold. I did watch Col. Ken at a rally 10
> to 15 years ago with a cast frying fan and a big torch, heat up some metal
> and fill a manifold. I thought the metal was old pistons but it may have
> been the Mondello stuff.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
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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: Best Practice - Aluminum or HardBlok in manifold? [message #341470 is a reply to message #341419] |
Mon, 04 March 2019 07:14 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Well, the muffler's welded onto the pipes, so I can't see inside - I'll figure Matt is likely correct and it has two tubes before the inputs join. The fitted manifold has no crossover so it's a moot point. Says RPM on it in one place, and clears the hatch with a spacer and an MAD Atomic injector fitted.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Best Practice - Aluminum or HardBlok in manifold? [message #341479 is a reply to message #341470] |
Mon, 04 March 2019 08:50 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Bill,
You are very correct.
Too bad others are not seeing that.
People never even look at or address the mufflers when looking at what need
to be done to keep coaches running.
If one drives the coach like a Old Lady and half ok mufflers, then you can
run with AL fill in the intake , most of you have NO clue as to condition
of your exhaust till it makes noise.
I have a full blown lift at our shop so I can at least view the system.
Good way to tell is by looking at the intake, if you see white heat marks,
you have exhaust issue.
On Mon, Mar 4, 2019 at 5:24 AM Johnny Bridges via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Well, the muffler's welded onto the pipes, so I can't see inside - I'll
> figure Matt is likely correct and it has two tubes before the inputs join.
> The fitted manifold has no crossover so it's a moot point. Says RPM on it
> in one place, and clears the hatch with a spacer and an MAD Atomic injector
> fitted.
>
> --johnny
> --
> Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> "I forgive them all, save those who hurt the dogs. They must answer to me
> in hell" - ol Andy, paraphrased
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
--
Jim Kanomata
Applied/GMC, Newark,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: [GMCnet] Best Practice - Aluminum or HardBlok in manifold? [message #341510 is a reply to message #341479] |
Tue, 05 March 2019 10:44 |
Bill Van Vlack
Messages: 419
Registered: September 2015
Location: Guemes Island, Washington
Karma: 14
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Following up on Emery's comment earlier, the alloy that the local foundry would use is A356. Melting point 1100-1200 deg F.
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid November 2015.
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| Re: Best Practice - Aluminum or HardBlok in manifold? [message #341627 is a reply to message #341419] |
Sun, 10 March 2019 17:49 |
mercdave
Messages: 45
Registered: May 2014
Karma: 2
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Ok folks, time for me to fess up, I own the engine that has the bulged Patterson block-off plates. Yes, Jim Hupy, the engine did have other issues, 180K miles of issues, stock timing chain that has aprox 20 deg of slack. I suspect, without any proof, that the stock GMC manifolds flow differently from one another and that could be one of the reasons that the intake runs so hot on the GMC compared to the Toronado... well that AND 12,000 lbs! For reference, this coach did NOT have front mufflers, it had only one in the rear. The Y pipe is a conglomeration that I would be embarrassed to say I created, if I had created it.
There you go, I accept responsibility helping Bill along in this endeavor.
I put a few pictures of the blockoff plates on the photo site today, click through them, there are 3.
It looks like I need to update my sig file, 1973/23 #295 will be parted out.
Dave L
Lynnwood, Wa.
1976 GMC 26' Edgemonte Rear Twin
1973 GMC 23' Rear-Ended, Totaled
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| Re: [GMCnet] Best Practice - Aluminum or HardBlok in manifold? [message #341628 is a reply to message #341627] |
Sun, 10 March 2019 18:23 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Dave, none of my comments were intended to criticize, but to be
informative. I would take a very critical inspection of that rear muffler.
It needs to be very free flowing, and unrestricted. It needs to be intended
for truck use, not passenger car. Dan Gregg nearly burned his coach to the
ground with a similar exhaust configuration. Mandrel bent tubes are
available and are well worth the $$$$.
Jim Hupy
On Sun, Mar 10, 2019, 3:50 PM Dave via Gmclist Ok folks, time for me to fess up, I own the engine that has the bulged[/color]
> Patterson block-off plates. Yes, Jim Hupy, the engine did have other issues,
> 180K miles of issues, stock timing chain that has aprox 20 deg of slack. I
> suspect, without any proof, that the stock GMC manifolds flow differently
> from one another and that could be one of the reasons that the intake runs
> so hot on the GMC compared to the Toronado... well that AND 12,000 lbs!
> For reference, this coach did NOT have front mufflers, it had only one in
> the rear. The Y pipe is a conglomeration that I would be embarrassed to say
> I created, if I had created it.
> There you go, I accept responsibility helping Bill along in this endeavor.
> I put a few pictures of the blockoff plates on the photo site today, click
> through them, there are 3.
>
>
> http://www.gmcmhphotos.com/photos/1973-2723/p66065-wp-20190310-14-40-31-pro-2.html
>
> It looks like I need to update my sig file, 1973/23 #295 will be parted
> out.
> --
>
> Dave L
> Lynnwood, Wa.
>
> 1976 GMC 26' Edgemonte Rear Twin
> 1973 GMC 23' Rear-Ended, Awaiting Rebuild
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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