Home » Public Forums » GMCnet » [GMCnet] Intake Manifold Crossover Port Measurement
| [GMCnet] Intake Manifold Crossover Port Measurement [message #200611] |
Mon, 04 March 2013 18:00  |
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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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G'day,
As noted I have a couple of OEM intake manifolds in Houston that I intend to fill the crossover with Hard Blok.
I want to make some stainless steel plates to stick in the ports to stop the hot exhaust gases from impinging on the Hard Blok after
it is filled.
I need the measurements of the crossover ports in the manifold.
Anybody got one off that they can measure for me?
Please check both sides of the manifold; driver and passenger.
Regards,
Rob M.
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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] Intake Manifold Crossover Port Measurement [message #200643 is a reply to message #200611] |
Mon, 04 March 2013 21:24  |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Rob,
You might want to wait til you get to Texas and measure your actual manifolds.
I'll try not to confuse you.
I just looked at 3 manifolds.
2 of them have: driverside port 2"X1" Each of them have a boss above the crossover for mounting an egr valve. (I think)
Passenger side port is 1 5/8"X1" this side has boss for choke stove.
The other manifold has no boss for mounting egr valve-
both sides are 13/4"X1"
I have a block off plate recently removed from my 455 manifold- made and installed years ago by Bob Lamey and Miguel Mendez.
It was installed in the passenger side and measures 17/8"X11/8"
It is larger than the OEM port because the opening was relieved to allow the plate to fit inside the opening and flush with the manifold face. As Ken H. describes in one of his tutorials.
Hope that helps.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: [GMCnet] Intake Manifold Crossover Port Measurement [message #200681 is a reply to message #200678] |
Tue, 05 March 2013 08:33 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Rob,
As you know, when you completely block the crossover you lose the function of the OEM choke. I think most people convert to an electric choke.
Bob Lamey and Miguel handled this by only blocking the passenger side and by drilling a ~3/8 inch hole in the plate. This allows some heat to enter the crossover and activate the OEM choke. It has worked in my coach for 75,000 miles. I pulled the manifold on Sunday and found almost no baked oil crud on the bottom and there are still no cracks in the bottom or the carb mounting boss.
The plate was not stainless in is only about 1/8" thick. It was still firmly in place with only a small bit of erosion after all those miles.
My point- there is more than one way to skin the cat.
Good luck with your project and enjoy your 2013 Tour of America.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: [GMCnet] Intake Manifold Crossover Port Measurement [message #200687 is a reply to message #200681] |
Tue, 05 March 2013 09:39 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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| gbarrow wrote on Tue, 05 March 2013 07:33 |
Rob,
As you know, when you completely block the crossover you lose the function of the OEM choke. I think most people convert to an electric choke.
Bob Lamey and Miguel handled this by only blocking the passenger side and by drilling a ~3/8 inch hole in the plate. This allows some heat to enter the crossover and activate the OEM choke. It has worked in my coach for 75,000 miles. I pulled the manifold on Sunday and found almost no baked oil crud on the bottom and there are still no cracks in the bottom or the carb mounting boss.
The plate was not stainless in is only about 1/8" thick. It was still firmly in place with only a small bit of erosion after all those miles.
My point- there is more than one way to skin the cat.
Good luck with your project and enjoy your 2013 Tour of America.
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Or...you could do what I did (and I think, Chr$) when I installed the Rockwell manifold and forget about the choke completely. Here in Arizona, even throughout the winter (it does get below freezing here sometimes, just ask Larry W.) I don't miss having a choke. Just a couple extra pumps on the throttle and the engine starts right up. By the time the air pressure is up, the engine is warm enough to drive. I set the unhooked choke to just barely close and it fully opens as soon as the engine heat makes it's way up to the choke housing on the carburetor. It works fine.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Intake Manifold Crossover Port Measurement [message #200703 is a reply to message #200687] |
Tue, 05 March 2013 11:23 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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| Carl S. wrote on Tue, 05 March 2013 08:39 |
Or...you could do what I did (and I think, Chr$) when I installed the Rockwell manifold and forget about the choke completely. Here in Arizona, even throughout the winter (it does get below freezing here sometimes, just ask Larry W.) I don't miss having a choke. Just a couple extra pumps on the throttle and the engine starts right up. By the time the air pressure is up, the engine is warm enough to drive. I set the unhooked choke to just barely close and it fully opens as soon as the engine heat makes it's way up to the choke housing on the carburetor. It works fine.
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Just to clarify, I set the choke so that it is ALMOST all the way open. This gives me a high idle at start up and it opens completely within a few minutes of run time.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Intake Manifold Crossover Port Measurement [message #200741 is a reply to message #200678] |
Tue, 05 March 2013 21:20 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Rob,
Without looking at or measuring an intake manifold, I think 1/4" is too
thick for your filler plates -- you may require too-deep recesses. I KNOW
it's thicker than needed: 1/8" plain steel is more than enough. And since
you're pouring the crossover, I personally wouldn't even bother with
milling the manifold: Just use 0.030" or so SS plates and trimmed gaskets.
JMHO,
Ken H.
On Tue, Mar 5, 2013 at 9:01 AM, Robert Mueller wrote:
> Gene,
>
> Thanks!
>
> From what you've noted below I'm going to make four plates 2 1/4" x 1 1/4"
> x 1/4" so they can be cut down to size when I fill the
> manifolds.
>
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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] Intake Manifold Crossover Port Measurement [message #200747 is a reply to message #200741] |
Tue, 05 March 2013 21:45 |
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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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Ken,
Good point!
I may just forget about recessing the manifold and just make the plates fit snugly in the port.
I'll drill and tap a hole in the center for a stainless steel screw that the Hard Blok can adhere to and keep them from falling out.
IIRC the port in the head is smaller than the port in the manifold.
Regards,
Rob M.
-----Original Message-----
From: Ken Henderson
Rob,
Without looking at or measuring an intake manifold, I think 1/4" is too
thick for your filler plates -- you may require too-deep recesses. I KNOW
it's thicker than needed: 1/8" plain steel is more than enough. And since
you're pouring the crossover, I personally wouldn't even bother with
milling the manifold: Just use 0.030" or so SS plates and trimmed gaskets.
JMHO,
Ken H.
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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] Intake Manifold Crossover Port Measurement [message #200751 is a reply to message #200747] |
Tue, 05 March 2013 22:18 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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After reading your posts twice I'm still confused as to what you are trying to accomplish. What is wrong with just using block off plates by Dick Paterson or maybe Mondello?. I know and have used Dick's plates and they work well. He engineered the plate thickness to match the fiber gaskets that he supplies. His gasket crush to around .020" and his plates (which wont crush) are around the same .020" thickness. Call Dick for the exact thickness because what I gave you is from memory and could easily be incorrect.
I have to assume the Mondello plates' thickness matches (after crushing) whatever size gasket that Mondello is supplying or is recommending. I have no personal knowledge to back up that assumption.
It seems to me that you are trying to fashion a stainless plate to go inside the intake manifold rather than use the Paterson or Mondello plates that get sandwiched between the intake manifold and the head. If that is what you are doing, do you also expect you use the Paterson or Mondello sandwiched plates?
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Intake Manifold Crossover Port Measurement [message #200757 is a reply to message #200753] |
Tue, 05 March 2013 23:38 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| captjack wrote on Tue, 05 March 2013 22:42 |
I think, as Jim Bounds stated, this wheel has already been invented. Here's a link to the Patterson product from Jim K.
http://www.appliedgmc.com/prod.itml/icOid/827
Many, including me, have used this with success.
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I know Rob knows about that product. That is a Dick Paterson built engine that he has taken apart. That is why I'm confused as to what he is trying to accomplish. I think he is trying to add a second blocking plate just inside the intake port next to the head. My confusion to his intentions is what I asked him about in my previous posting.
Do to the time zone difference I expect we will see an answer from him in the morning if he is not out chasing Kangaroos or Koala bears.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Intake Manifold Crossover Port Measurement [message #200761 is a reply to message #200757] |
Wed, 06 March 2013 05:05 |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
Karma: 5
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Senior Member |
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Ken,
Check Rob's reply to Jim Bounds. He is tring to figure out a way to
salvage a cracked intake manifold.
"The object of my "experiment" is develop a fix for intake manifold that
has a crack at the bottom of the carb plenum AND a crack in
the bottom of the crossover with no special tools or equipment."
On Tue, Mar 5, 2013 at 10:38 PM, Ken Burton <n9cv@comcast.net> wrote:
>
>
> captjack wrote on Tue, 05 March 2013 22:42
> > I think, as Jim Bounds stated, this wheel has already been invented.
> Here's a link to the Patterson product from Jim K.
> > http://www.appliedgmc.com/prod.itml/icOid/827
> >
> > Many, including me, have used this with success.
>
> I know Rob knows about that product. That is a Dick Paterson built engine
> that he has taken apart. That is why I'm confused as to what he is trying
> to accomplish. I think he is trying to add a second blocking plate just
> inside the intake port next to the head. My confusion to his intentions is
> what I asked him about in my previous posting.
>
> Do to the time zone difference I expect we will see an answer from him in
> the morning if he is not out chasing Kangaroos or Koala bears.
>
> Ken B.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
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Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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