Home » Public Forums » GMCnet » [GMCnet] Frohmader's article (blocking crossovers) on WebRodder
| [GMCnet] Frohmader's article (blocking crossovers) on WebRodder [message #173587] |
Sat, 16 June 2012 20:40  |
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Doc Frohmader, who owns a GMC MotorHome, just completed and posted an
article on WebRodder detailing the procedure for blocking the intake
crossovers on the Olds engine. It's a good read with several photos.
Be aware - if you do the work yourself be fully aware of the risks. Take
Doc's cautions seriously unless you enjoy scoffing or being a Monday
Morning Quarterback.
The link is below. I'll be adding it, with his blessing, to the GMC on
WebRodder page of gmceast.com in about a three weeks. Right now I'm away
from my work computer and can't make changes to the website while touring
the West by motorhome.
Byron Songer
Louisville, KY
News and Web Editor, GMC Eastern States
http://www.gmceast.com
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Byron Songer
Full-timing to enjoy the USA
Former owner but still an admirer
GMC paint schemes at -
http://www.songerconsulting.net
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| Re: [GMCnet] Frohmader's article (blocking crossovers) on WebRodder [message #173589 is a reply to message #173587] |
Sat, 16 June 2012 20:59  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Byron,
The link got lost in Cyberspace.
http://www.webrodder.com/article.php?AID=615&SID=60
This is a good way to block the crossovers. The problem that quite a few
people run into is that the intake manifold off a GMC is cracked.
I have two OEM cast iron manifolds in Houston, one is cracked the other is
not. I intend to clean the cracked one and fill the crossover with Hard Blok
and install it and see if it works.
If it does we've killed two birds with one stone!
I think I'll use Doc's method of plugging the crossover but I'll install the
SS plate in the intake instead of the heads. The plugs will be thicker and
have a trapezoidal shape to them. I can taper the sides of the port in the
manifold so the fit tightly. I'll drill a hole in them and tap them for a
counter sunk SS screw which will extend into the crossover and when the Hard
Blok hardens they will be held in place.
I bought the Hard Blok from Summit for $100 and if it works we've got a
cheap fix for cracked intake manifolds that anyone can do.
Regards,
Rob M.
-----Original Message-----
From: Byron Songer
Doc Frohmader, who owns a GMC MotorHome, just completed and posted an
article on WebRodder detailing the procedure for blocking the intake
crossovers on the Olds engine. It's a good read with several photos.
Be aware - if you do the work yourself be fully aware of the risks. Take
Doc's cautions seriously unless you enjoy scoffing or being a Monday
Morning Quarterback.
The link is below. I'll be adding it, with his blessing, to the GMC on
WebRodder page of gmceast.com in about a three weeks. Right now I'm away
from my work computer and can't make changes to the website while touring
the West by motorhome.
Byron Songer
Louisville, KY
News and Web Editor, GMC Eastern States
http://www.gmceast.com
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Frohmader's article (blocking crossovers) on WebRodder [message #173603 is a reply to message #173587] |
Sat, 16 June 2012 22:25 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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Hi feelers
It looks like the documents are in FLASH which apple won't allow To work on iPhone ( I don't known what else) could that be your problem? I know it's my problem.
John
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: [GMCnet] Frohmader's article (blocking crossovers) on WebRodder [message #173620 is a reply to message #173589] |
Sun, 17 June 2012 05:55 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Byron,
That's a great article; thanks for guiding us to it and arranging to add it
to our archives.
Rob,
I think you mis-interpreted Doc's photos -- he DID install the plates in
the manifold, not the heads.
It was surprising to me that he used a hand-held grinder to cut the
recesses for the plates. For many years, Alex Sirum & Co. have used an
ordinary wood router for that purpose. With an ordinary 1/4" carbide
cutter, it's very easy to cut to a precise depth. Alex has a template for
the job. I've done it a couple of times, including on the Cad 500,
free-hand. A burr such as shown in Doc's photo might work even better than
the carbide bit -- but I doubt it. I question the need for tapered edges.
Another surprise is that he used the "turkey tray" gasket. I've had good
luck leaving the plates very slightly proud of the manifold and using
composite gaskets which can compress around that protrusion to help hold
the plates securely. Without the heated crossover, I see no reason to
protect the underside of the manifold (actually protect the oil). In fact,
letting the oil help heat the manifold may be beneficial. Also, I have
more confidence in the sealing ability of the composite gaskets than a bit
of crimped steel.
JMHO, with far less experience than Doc Frohmader.
Ken H.
On Sat, Jun 16, 2012 at 9:59 PM, Robert Mueller wrote:
> Byron,
>
> The link got lost in Cyberspace.
>
> http://www.webrodder.com/article.php?AID=615&SID=60
> ...
> I think I'll use Doc's method of plugging the crossover but I'll install
> the
> SS plate in the intake instead of the heads. The plugs will be thicker and
> have a trapezoidal shape to them. I can taper the sides of the port in the
> manifold so the fit tightly. I'll drill a hole in them and tap them for a
> counter sunk SS screw which will extend into the crossover and when the
> Hard
> Blok hardens they will be held in place.
>
> I bought the Hard Blok from Summit for $100 and if it works we've got a
> cheap fix for cracked intake manifolds that anyone can do.
>
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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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: [GMCnet] Frohmader's article (blocking crossovers) on WebRodder [message #173636 is a reply to message #173620] |
Sun, 17 June 2012 09:57 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
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Senior Member |
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There are obviously several reliable ways to block the crossover. The basic idea is right on and why to do it as well. I do not use the turkey tray as others said. I use the Mr. Gasket 404 fiber intake set with Mondello's plates. Works fine and we don;t cut into the head to do it. Right on about the choke and I would say just about every motor we open has this crack. If that's the only crack on the intake, adding the blockoff plates returns that intake to a reliable level. There should be no fear in using the original intake that has this specific crack. We have had 100% good results from doing this.
There is another issue associated to doing this. I feel this crossover went a long way in balancing the exh. of the motor. Now that we have done away with it I feel it more important than ever to remove the 2 mufflers in favor of one down the line in the rear. Not only does this do many good things for heat & noice but allowing the heads to balance their exh. pressures can only be a good thing. This is the reason we blow out so many mufflers.
Jim Bounds
------------------------
________________________________
From: Ken Henderson <hend4800@bellsouth.net>
To: gmclist@temp.gmcnet.org
Sent: Sunday, June 17, 2012 6:55 AM
Subject: Re: [GMCnet] Frohmader's article (blocking crossovers) on WebRodder
Byron,
That's a great article; thanks for guiding us to it and arranging to add it
to our archives.
Rob,
I think you mis-interpreted Doc's photos -- he DID install the plates in
the manifold, not the heads.
It was surprising to me that he used a hand-held grinder to cut the
recesses for the plates. For many years, Alex Sirum & Co. have used an
ordinary wood router for that purpose. With an ordinary 1/4" carbide
cutter, it's very easy to cut to a precise depth. Alex has a template for
the job. I've done it a couple of times, including on the Cad 500,
free-hand. A burr such as shown in Doc's photo might work even better than
the carbide bit -- but I doubt it. I question the need for tapered edges.
Another surprise is that he used the "turkey tray" gasket. I've had good
luck leaving the plates very slightly proud of the manifold and using
composite gaskets which can compress around that protrusion to help hold
the plates securely. Without the heated crossover, I see no reason to
protect the underside of the manifold (actually protect the oil). In fact,
letting the oil help heat the manifold may be beneficial. Also, I have
more confidence in the sealing ability of the composite gaskets than a bit
of crimped steel.
JMHO, with far less experience than Doc Frohmader.
Ken H.
On Sat, Jun 16, 2012 at 9:59 PM, Robert Mueller wrote:
> Byron,
>
> The link got lost in Cyberspace.
>
> http://www.webrodder.com/article.php?AID=615&SID=60
> ...
> I think I'll use Doc's method of plugging the crossover but I'll install
> the
> SS plate in the intake instead of the heads. The plugs will be thicker and
> have a trapezoidal shape to them. I can taper the sides of the port in the
> manifold so the fit tightly. I'll drill a hole in them and tap them for a
> counter sunk SS screw which will extend into the crossover and when the
> Hard
> Blok hardens they will be held in place.
>
> I bought the Hard Blok from Summit for $100 and if it works we've got a
> cheap fix for cracked intake manifolds that anyone can do.
>
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Unsubscribe or Change List Options:
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| Re: [GMCnet] Frohmader's article (blocking crossovers) on WebRodder [message #173658 is a reply to message #173587] |
Sun, 17 June 2012 14:34 |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
Karma: 0
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Senior Member |
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Jim may have an excellent point about the manifold providing an exhaust crossover.
For those of us that have headers and dual mufflers, I wonder if there is room before the mufflers to fit a crossover pipe to serve the same function? Mine are quite new, but I can see where this could be a problem down the road.
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: [GMCnet] Frohmader's article (blocking crossovers) on WebRodder [message #173742 is a reply to message #173589] |
Mon, 18 June 2012 10:20 |
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Rob, thanks for pointing out the error of my way and discovering the
location of the article.
The link didn't get lost in Cyberspace. It didn't get copied into my
email. Why is it we humans have these circuit problems in our gray matter?
Or is it the wiring from the brain to the fingers?
At any rate, good discussion.
Doc doesn't follow the 'Net nor is he an official member of any club. He's
a bit of a loaner but does enjoy sharing information. He's also done some
things to help out Mary since Joe died. While Joe Mondello focus on racing
engines Frohmader's emphasis is on street machines. There's a wealth of
experience with the Olds engines in those guys.
Byron
ATTENTION: This reply is in reference to what is provided belowŠ
>Byron,
>
>The link got lost in Cyberspace.
>
>http://www.webrodder.com/article.php?AID=615&SID=60
>
>This is a good way to block the crossovers. The problem that quite a few
>people run into is that the intake manifold off a GMC is cracked.
>
>I have two OEM cast iron manifolds in Houston, one is cracked the other is
>not. I intend to clean the cracked one and fill the crossover with Hard
>Blok
>and install it and see if it works.
>
>If it does we've killed two birds with one stone!
>
>I think I'll use Doc's method of plugging the crossover but I'll install
>the
>SS plate in the intake instead of the heads. The plugs will be thicker and
>have a trapezoidal shape to them. I can taper the sides of the port in the
>manifold so the fit tightly. I'll drill a hole in them and tap them for a
>counter sunk SS screw which will extend into the crossover and when the
>Hard
>Blok hardens they will be held in place.
>
>I bought the Hard Blok from Summit for $100 and if it works we've got a
>cheap fix for cracked intake manifolds that anyone can do.
>
>Regards,
>Rob M.
>
>-----Original Message-----
>From: Byron Songer
>
>Doc Frohmader, who owns a GMC MotorHome, just completed and posted an
>article on WebRodder detailing the procedure for blocking the intake
>crossovers on the Olds engine. It's a good read with several photos.
>
>Be aware - if you do the work yourself be fully aware of the risks. Take
>Doc's cautions seriously unless you enjoy scoffing or being a Monday
>Morning Quarterback.
>
>The link is below. I'll be adding it, with his blessing, to the GMC on
>WebRodder page of gmceast.com in about a three weeks. Right now I'm away
>from my work computer and can't make changes to the website while touring
>the West by motorhome.
>
>
>Byron Songer
>Louisville, KY
>News and Web Editor, GMC Eastern States
>http://www.gmceast.com
>
>
>_______________________________________________
>GMCnet mailing list
>Unsubscribe or Change List Options:
>http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>_______________________________________________
>GMCnet mailing list
>Unsubscribe or Change List Options:
>http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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--
Byron Songer
Full-timing to enjoy the USA
Former owner but still an admirer
GMC paint schemes at -
http://www.songerconsulting.net
|
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|
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| Re: [GMCnet] Frohmader's article (blocking crossovers) on WebRodder [message #173816 is a reply to message #173742] |
Mon, 18 June 2012 18:40 |
|
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
|
Senior Member |
|
|
Byron,
You're welcome!
BTW your mental acuity is just fine; you're just like most of the rest of us and suffer "senior moments." This phenomenon disturbs
some people, I for one am happy the good Lord has allowed me to hang around for 65 years (so far). If he throws in a few challenges
that's OK by me! ;-)
BTW Doc published what I would call the Caddy 500 bible Big Inch Cadillac; it is chock a block full of info on how to build one so
it stays together. It's the document that details how to build a 540 cu in monster like JimK's. Doc doesn't mention turbo charging,
that's Jimmy's personal touch. I would love to know how much power his monster puts out on a dyno. I'll bet it's well in excess of
500 HP.
Regards,
Rob M.
-----Original Message-----
From: Byron Songer
Rob, thanks for pointing out the error of my way and discovering the
location of the article.
The link didn't get lost in Cyberspace. It didn't get copied into my
email. Why is it we humans have these circuit problems in our gray matter?
Or is it the wiring from the brain to the fingers?
At any rate, good discussion.
Doc doesn't follow the 'Net nor is he an official member of any club. He's
a bit of a loaner but does enjoy sharing information. He's also done some
things to help out Mary since Joe died. While Joe Mondello focus on racing
engines Frohmader's emphasis is on street machines. There's a wealth of
experience with the Olds engines in those guys.
Byron
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Frohmader's article (blocking crossovers) on WebRodder [message #173896 is a reply to message #173742] |
Tue, 19 June 2012 06:37 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
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Senior Member |
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|
Rob,
Â
Have been preoocupied at the shop and unable to spend any time here.
Â
I appreciate the size of the blocked off crossover and the question of how much engine balancing could possibly go on there. I would say this, it is a known fact that balancing a motor with the exhaust is a valid concept, Ford makes a point of it and in that it seems that GM does not at least with pipes on the exhaust that the crossover must play some part in the theory. Blocking the crossover off is something GM did not make provisions to do and doing it farces you to address stuff like the choke that blocking the corssover off must have other results.Â
Â
The GMC has a constant problem of doing bad things to mufflers namely bursting them. Being so close to the motor with such a long pipe after them obviously is part of the problem of blowing up mufflers I feel relocating a single muffler in the back goes a long way to protecting your muffler investment, allowing the heads to see eachother without having to blow through those mufflers can only be a good thing for the head balancing concept.
Â
Link all of that with the fact that 1 muffler is cheaper than 1 and stock diameter pipes are easier and thus again cheaper that having to bend up 3" pipes that swedge through the openings in the frame--- not only do I feel there is some technology working for you in some capacity being cheaper should appeal to the purse strings which seems to be an overwhelming reason for people to do stuff. Other than making sure you have good heat shielding to the bottom of the coach back at the muffler, I do not see a downside of adopting a single muffler system. If the theory of balancing the motor with a direct Y pipe with the crossover blocked is only 10% effective, the cheapness and lack of noise and heat under the main floor of a single muffler system should still make the mod desirable.
Â
We clean, magtnaflux, block off and use a fiber gasket set on every motor we do. We're getting a motor delivered to us maybe today for runin before shipping it out to EK. You can follow the run in on my site, it will have blocked off crossover, an original intake-- no Y pipes, we're just blowing the exh. straight back.
Â
Jim Bounds
--------------------------
________________________________
From: Byron Songer <bsonger@songerconsulting.net>
To: gmclist@temp.gmcnet.org
Sent: Monday, June 18, 2012 11:20 AM
Subject: Re: [GMCnet] Frohmader's article (blocking crossovers) on WebRodder
Rob, thanks for pointing out the error of my way and discovering the
location of the article.
The link didn't get lost in Cyberspace. It didn't get copied into my
email. Why is it we humans have these circuit problems in our gray matter?
Or is it the wiring from the brain to the fingers?
At any rate, good discussion.
Doc doesn't follow the 'Net nor is he an official member of any club. He's
a bit of a loaner but does enjoy sharing information. He's also done some
things to help out Mary since Joe died. While Joe Mondello focus on racing
engines Frohmader's emphasis is on street machines. There's a wealth of
experience with the Olds engines in those guys.
Byron
ATTENTION: This reply is in reference to what is provided belowÅ
>Byron,
>
>The link got lost in Cyberspace.
>
>http://www.webrodder.com/article.php?AID=615&SID=60
>
>This is a good way to block the crossovers. The problem that quite a few
>people run into is that the intake manifold off a GMC is cracked.
>
>I have two OEM cast iron manifolds in Houston, one is cracked the other is
>not. I intend to clean the cracked one and fill the crossover with Hard
>Blok
>and install it and see if it works.
>
>If it does we've killed two birds with one stone!
>
>I think I'll use Doc's method of plugging the crossover but I'll install
>the
>SS plate in the intake instead of the heads. The plugs will be thicker and
>have a trapezoidal shape to them. I can taper the sides of the port in the
>manifold so the fit tightly. I'll drill a hole in them and tap them for a
>counter sunk SS screw which will extend into the crossover and when the
>Hard
>Blok hardens they will be held in place.
>
>I bought the Hard Blok from Summit for $100 and if it works we've got a
>cheap fix for cracked intake manifolds that anyone can do.
>
>Regards,
>Rob M.
>
>-----Original Message-----
>From: Byron Songer
>
>Doc Frohmader, who owns a GMC MotorHome, just completed and posted an
>article on WebRodder detailing the procedure for blocking the intake
>crossovers on the Olds engine. It's a good read with several photos.
>
>Be aware - if you do the work yourself be fully aware of the risks. Take
>Doc's cautions seriously unless you enjoy scoffing or being a Monday
>Morning Quarterback.
>
>The link is below. I'll be adding it, with his blessing, to the GMC on
>WebRodder page of gmceast.com in about a three weeks. Right now I'm away
>from my work computer and can't make changes to the website while touring
>the West by motorhome.
>
>
>Byron Songer
>Louisville, KY
>News and Web Editor, GMC Eastern States
>http://www.gmceast.com
>
>
>_______________________________________________
>GMCnet mailing list
>Unsubscribe or Change List Options:
>http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>_______________________________________________
>GMCnet mailing list
>Unsubscribe or Change List Options:
>http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
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_______________________________________________
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