Home » Public Forums » GMCnet » Intake cross over block - looking for opinions
| Intake cross over block - looking for opinions [message #221768] |
Mon, 09 September 2013 12:13  |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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I've been trying to button up the exhaust leaks on my engine. I had the exhaust gaskets blow out again, for the second time and ordered the Remflex from Jim and had my mechanic put them in. In his effort he did a smoke test and said that the intake gaskets were leaking exhaust as well, so I'm going to have him replace those. So here is my question. I have the chance to block off the ehaust ports if I should. My mechanic was questioning doing that. First question is, would I really want to block that port? Would it not cause back pressure on the gasket and possible develop a exhaust leak again with it? And if I plan on going eventually to a TBI system, would the boiling issue go away anyhow? To date I have not experienced anytime of boiling issue with it.
Tom Geiger
76 Eleganza II
KCMO
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| Re: Intake cross over block - looking for opinions [message #221771 is a reply to message #221768] |
Mon, 09 September 2013 12:29  |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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I am not an expert. I blocked my crossover this spring, and I am happy.
I think almost all the engine experts would tell you to block the crossover:
the late Joe mondello created and sold plates to block the cross over.
Dick paterson sells and provides needed cross over blocking.
Jim Bounds utilizes the same practice.
it has been discussed many times. on the net, and I have never heard a negative effect blocking the crossover on the olds 455.
it was a simple process... I got what I needed from a vender, that included detail instructions over the phone once I got the intake off the engine.
if you search and read archives on the net.. the negative to not blocking the cross over, not only the fuel boiling is potential for a cracked intake.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Intake cross over block - looking for opinions [message #221773 is a reply to message #221768] |
Mon, 09 September 2013 13:00 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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I'd say yes for sure. I have the Paterson blockoff intake gaskets that I got from JimK. Not only does the intake stay MUCH cooler, I don't boil the gas out of the carb when I stop. Before, you could literally HEAR the gas boiling in the carb. Now the intake is no hotter than the block according to my IR thermometer.
I've noticed no negative side effects at all.
Plus, I'm VERY, VERY sensitive to intake gasket problems after losing my engine to coolant contamination in the oil.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: Intake cross over block - looking for opinions [message #221777 is a reply to message #221768] |
Mon, 09 September 2013 13:30 |
djeffers
Messages: 219
Registered: June 2004
Karma: 2
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The exhaust cross over is helpful to a cold engine. It hastens the warm up period for the carburetor and intake manifold.
Whether to block the cross over or not depends on how much time the engine will spend in warm-up mode relative to warmed up travel time.
If you plan on making lots of 10 minute drives to the local store or 5 minute drives to the corner Quicky Mart in a cold climate, then don't block the cross over.
If you plan on drives that last for long periods, like hours, then blocking the cross over is beneficial.
A blocked cross over helps prevent excess heating of the fuel in the carburetor bowl in hot weather, a cause of vapor lock.
Additionally, a cast iron block and intake manifold will hold the heat for an hour or so when stopped, even in cool weather. Again, the cross over is not needed.
A small downside is that, if the engine stumbles when cold, you could have to give the engine a few minutes of warm up time in very cold weather. A good idea anyway for other reasons, like cold oil flow.
For a GMC coach, we recommend to block the cross over.
Don and Susan Jeffers
78 Eleganza II
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| Re: [GMCnet] Intake cross over block - looking for opinions [message #221805 is a reply to message #221791] |
Mon, 09 September 2013 16:39 |
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jaholland
Messages: 565
Registered: June 2010
Location: Sweet Home Alebamy
Karma: 0
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~ tgeiger ;
On our '78 Eleganza II I had the Aluminum
Edelbrock Preformer Intake Mani Crossover
Filled And Used RemFlex Gaskets.
New RemFlex Header Gaskets and Header/Exaust
Gaskets. It Eliminated The Noise ~
~ Joe ~
NEXT PROJECT
How On The World Can I Quiet Down That Barbarian?
{just wondering if remflex makes onan muffler gaskets}
/_]*[__][] *[__|] ~ * '73 TZE063V101887 "
"
O----------OO--]* ~ '78 TZE168V100234 "
"
" Joe & Lavelle " "
"
'sweet home alebamy'
[Updated on: Mon, 09 September 2013 16:44] Report message to a moderator |
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| Re: [GMCnet] Intake cross over block - looking for opinions [message #221806 is a reply to message #221805] |
Mon, 09 September 2013 16:43 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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| jaholland wrote on Mon, 09 September 2013 16:39 |
~ tgeiger ;
On our '78 Eleganza II I had the Aluminum
Edelbrock Preformer Intake Mani Crossover
Filled And Used RemFlex Gaskets.
New RemFlex Header Gaskets and Header/Exaust
Gaskets. It Eliminated The Noise ~
{wonder if remflex makes onan muffler gaskets}
~ Joe ~
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Joe
Remflex sells sheet gasket material and I recall someone got a small piece to make an Onan exhaust gasket.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: Intake cross over block - looking for opinions [message #221807 is a reply to message #221768] |
Mon, 09 September 2013 16:44 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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another thing to add:
I wanted to know for sure I had good intake situation, so by pulling the intake, it cost me $40 to have it baked out/cleaned. and a professional to tell me it was not cracked. and another $10 in good engine paint.
so by pulling and reinstalling the intake, I know know for sure that I have no leaks on the intake side. it got put together with the correct gaskets, sealant, and like I said, checked for cracks.
so if I have performance issues, even though there could still be a problem there, i think I can look elsewhere first.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Intake cross over block - looking for opinions [message #221828 is a reply to message #221816] |
Mon, 09 September 2013 18:07 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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you only need the crossover heat when it's cold out.
If you don't drive your coach in the winter, block it off.
If you do drive it in the winter, what are you thinking!
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] Intake cross over block - looking for opinions [message #221831 is a reply to message #221771] |
Mon, 09 September 2013 18:25 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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I'm no expert either - nor did I stay in a Holiday Inn last night, those a$$hats don't allow dogs in most of their facilities - but when the intake comes off either of my engines for any reason, whatever goes back won't have the crossover. Many of the folks on this forum who <are> experts recommend it. Further, balancing good vs bad it's no contest. He who can't afford an electric choke can always put in a manual one.
--johnny
--------------------------------------------
On Mon, 9/9/13, Jon Roche <lqqkatjon@gmail.com> wrote:
Subject: Re: [GMCnet] Intake cross over block - looking for opinions
To: gmclist@temp.gmcnet.org
Date: Monday, September 9, 2013, 5:29 PM
I am not an expert. I blocked my crossover this
spring, and I am happy.
I think almost all the engine experts would tell you to
block the crossover:
the late Joe mondello created and sold plates to block the
cross over.
Dick paterson sells and provides needed cross over
blocking.
Jim Bounds utilizes the same practice.
it has been discussed many times. on the net, and I have
never heard a negative effect blocking the crossover on the
olds 455.
it was a simple process... I got what I needed from a
vender, that included detail instructions over the phone
once I got the intake off the engine.
if you search and read archives on the net.. the negative to
not blocking the cross over, not only the fuel boiling is
potential for a cracked intake.
--
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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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] Intake cross over block - looking for opinions [message #221837 is a reply to message #221828] |
Mon, 09 September 2013 18:57 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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I'm thinking, Minnesota winters and Georgia winters are degrees apart.
--johnny
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On Mon, 9/9/13, Keith V <my427v8@hotmail.com> wrote:
Subject: Re: [GMCnet] Intake cross over block - looking for opinions
To: gmclist@temp.gmcnet.org
Date: Monday, September 9, 2013, 11:07 PM
you only need the crossover heat when it's cold out.
If you don't drive your coach in the winter, block it off.
If you do drive it in the winter, what are you thinking!
--
Keith
69 Vette
29 Dodge
75 Royale GMC
Mounds View. MN
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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] Intake cross over block - looking for opinions [message #221853 is a reply to message #221837] |
Tue, 10 September 2013 00:03 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Block it and be done with it. It may have been OK in a 455 powered Toronado but on an GMC ..
It burns the paint off of the manifold,
If burns any hose left laying on top of the crossover,
It chars the oil that it splashed on the bottom of the manifold,
It cracks the manifold over time making is useless,
It boils fuel in the carb,
It unnecessarily heats up the top of the engine.
If one of the mufflers plugs up the crossover gets extra hot causing all kinds of additional problems.
To my knowledge all aftermarket manifolds come standard WITHOUT the crossover. So block it now or be prepared to buy a $700 new one in the future. Also be sure to replace the manifold gasket where the choke heater tube inserts into the manifold. This gasket being bad is what ignited my engine fire.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
[Updated on: Tue, 10 September 2013 04:51] Report message to a moderator |
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| Re: [GMCnet] Intake cross over block - looking for opinions [message #221876 is a reply to message #221768] |
Tue, 10 September 2013 08:13 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Absolutely, positively, block them off. No back pressure issues. If they
are not blocked off, you indeed do have fuel boiling issues whether or not
you are aware of it.
Steve F.
On Mon, Sep 9, 2013 at 10:13 AM, tom geiger <tgeiger@burnsmcd.com> wrote:
>
>
> I've been trying to button up the exhaust leaks on my engine. I had the
> exhaust gaskets blow out again, for the second time and ordered the
> Remflex from Jim and had my mechanic put them in. In his effort he did a
> smoke test and said that the intake gaskets were leaking exhaust as well,
> so I'm going to have him replace those. So here is my question. I have
> the chance to block off the ehaust ports if I should. My mechanic was
> questioning doing that. First question is, would I really want to block
> that port? Would it not cause back pressure on the gasket and possible
> develop a exhaust leak again with it? And if I plan on going eventually to
> a TBI system, would the boiling issue go away anyhow? To date I have not
> experienced anytime of boiling issue with it.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Take care,
Steve
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| Re: [GMCnet] Intake cross over block - looking for opinions [message #221877 is a reply to message #221781] |
Tue, 10 September 2013 08:16 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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What Gene says is correct. It really doesn't help warm up. The bottom of
the intake plenum is heated by the Xover and any puddled fuel that
accumulates is vaporized by the heat. That might have been a good thing in
the 70's and 80's, but it is a PITA in this century. Block 'em if you've
got 'em.
Steve F.
On Mon, Sep 9, 2013 at 12:34 PM, gene Fisher <mr.erfisher@gmail.com> wrote:
> the real answer is
>
> it stops the cracking of the intake manifold
>
> warm up is just sort of a state of mind :>)
>
> because the aluminum replacement intake manifolds
> -leak
> - sit too high
> - block the cross over any way
>
> gene
>
>
>
>
> On Mon, Sep 9, 2013 at 10:13 AM, tom geiger <tgeiger@burnsmcd.com> wrote:
>
> >
> >
> > I've been trying to button up the exhaust leaks on my engine. I had the
> > exhaust gaskets blow out again, for the second time and ordered the
> > Remflex from Jim and had my mechanic put them in. In his effort he did a
> > smoke test and said that the intake gaskets were leaking exhaust as well,
> > so I'm going to have him replace those. So here is my question. I have
> > the chance to block off the ehaust ports if I should. My mechanic was
> > questioning doing that. First question is, would I really want to block
> > that port? Would it not cause back pressure on the gasket and possible
> > develop a exhaust leak again with it? And if I plan on going eventually
> to
> > a TBI system, would the boiling issue go away anyhow? To date I have not
> > experienced anytime of boiling issue with it.
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
>
>
>
> --
> Gene Fisher -- 74-23,77PB/ore/ca
> “Give a man a fish; you have fed him for today --- give him a URL and
> -------
> http://gmcmotorhome.info/
> Alternator Protection Cable
> http://gmcmotorhome.info/APC.html
> _______________________________________________
> GMCnet mailing list
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--
Take care,
Steve
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| Re: [GMCnet] Intake cross over block - looking for opinions [message #221887 is a reply to message #221837] |
Tue, 10 September 2013 09:08 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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| Johnny Bridges wrote on Mon, 09 September 2013 18:57 |
I'm thinking, Minnesota winters and Georgia winters are degrees apart.
--johnny
|
Georgia doesn't have winter....
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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