Manifold---the posibilities

[heinz wittenbecher]

Hi Arch,

I'm not running the Edelbrock, but when I had the heads redone about 30k ago
I had the machine shop close the crossovers off on the heads.

They welded them and machined them. When I got them back it was as it they
never existed.

No change was made on the Offenhauser Intake Manifold, i.e. nothing closed
off/added there.

I don't have any temps prior to the change.
All I can tell you is that the Offenhauser intake hasn't changed color

Heinz

- ----- Original Message -----
From:
To:
Sent: Sunday, October 24, 1999 4:55 PM
Subject: GMC: Manifold---the posibilities

> GMCers
>
> Please understand that I have had way to much time to think this
> weekend. I have spent the entire weekend hand sanding and painting
> the radiator frame, radiator and AC condenser with brackets.
>
> Here is my questions and thoughts. First does anybody have the
> Edelbrock Performer 2151 running with the crossovers blocked off?
> If so how well does it warm up and does it take a long time?
> Nate does your Caspro engine have the crossovers blocked?
>
> Now are there any of you running even the stock manifold with the
> crossovers blocked off? Not with a 1/4 inch hole or some other
> modification----I mean BLOCKED OFF?
>
> Now if I cant get a real world answer to those questions here is
> my next one. To some of you engineering types. How much heat
> do I need down there? Will the engine provide enough heat to keep
> the lady running on a cold day? Now here is the killer question.
> What if I welded a couple of bungs on top of the manifold and put
> hot water through the crossovers? If I also put in a manual heater
> shutoff valve I could let the lady have heat on a cool day and shut
> it down on a hot day.
>
> I am not looking for the correct answer here----just your thoughts.
> No solutions just ideas.
>
> Take Care
> Arch 76 GB IL
>
>

 

[thomas g. warner]

Give you a couple of ideas and you decide Arch.

1. The aluminum edelbrock heads have no exhaust crossovers and the engine
runs fine and lots of horsepower.

2. Mondello says in his technical reference manual that filling the exhaust
heat riser pasages is not recommended in winter driving.

3. I am going to do it however do not intend to drive much in cold weather
except to leave NY and go to Florida.

I think the heat from the air cleaner snorkle is heat enough in the winter.

>GMCers
>
>Please understand that I have had way to much time to think this
>weekend. I have spent the entire weekend hand sanding and painting
>the radiator frame, radiator and AC condenser with brackets.
>
>Here is my questions and thoughts. First does anybody have the
>Edelbrock Performer 2151 running with the crossovers blocked off?
>If so how well does it warm up and does it take a long time?
>Nate does your Caspro engine have the crossovers blocked?
>
>Now are there any of you running even the stock manifold with the
>crossovers blocked off? Not with a 1/4 inch hole or some other
>modification----I mean BLOCKED OFF?
>
>Now if I cant get a real world answer to those questions here is
>my next one. To some of you engineering types. How much heat
>do I need down there? Will the engine provide enough heat to keep
>the lady running on a cold day? Now here is the killer question.
>What if I welded a couple of bungs on top of the manifold and put
>hot water through the crossovers? If I also put in a manual heater
>shutoff valve I could let the lady have heat on a cool day and shut
>it down on a hot day.
>
>I am not looking for the correct answer here----just your thoughts.
>No solutions just ideas.
>
>Take Care
>Arch 76 GB IL
>
>

 

[heinz wittenbecher]

Right,
no difference in driving, etc.

I wouldn't notice pinging as the knock sensor and efi computer would retard
it faster than one (at least I) could notice but when I monitor timing
advance I don't see the knock sensor kicking in very often.

Certainly no noticable adverse effects but equally no positive effects
directly attributable to the close-off.
However, it would stand to reason that air inlet temp would be less than
with a crossover that used to discolor the intake.

FWIW: I've relocated my air cleaner to just behing the alternator to reduce
some noise out front. I've had no problems running it there and I'm
guesstimating that at least in part it's due to cooler engine compartment
temps, which in turn is due in part to the closed cross-over.

Another FWIW... I havn't posted my last compression readings yet, but they
were equally as good as the previous ones and the plugs looked excellent.
Good enough that I made no seperate notations as to coloring... all even, a
nice brown.

Considering my swallowed exhaust valve some 30k ago, I'm pleased with the
readings and performance at 130-ish K on second go-around 455.

Heinz

> In a message dated 10/24/99 7:14:37 PM Central Daylight Time,

> > They welded them and machined them. When I got them back it was as it
they
> > never existed.
>
> Heinz
>
> I hope what you are saying is that you noticed no difference in
> driving the lady. May I assume that? Any difference in "ping"?
>
> Anything you can tell me will be listen to. Thanks for the reply. I
> now know more than I did.
>
> Take Care
> Arch
>

 

[mills2]

>
> > I think I dont want any heat in there in the summer. The engineer types
> > may well tell me different. My thoughts are that I want as cool a fuel
> > charge as possible in summer---winter--dont know----could be wrong.
> >
> > I sure hate to blow my status as a computer jock but I must admit I
> > dont know what SWAG means. :>(
> >
As I recall only function for the cross-over and the heating of intake air
is to
make sure that the gasoline vaporizes and stays vaporized rather than
ending up in a puddle on the bottom of the manifold. The reality is that you
want the air as cold (dense) as possible without causing the gasoline vapor
to condense (dense air has more oxygen molecules for a better burn).
This is (was) the theory as I learned it 25 some odd years ago.

Jim
'73 Canyon Lands
Aurora, CO & Havre, MT

 

[thomas g. warner]

I dont think I would run water through them. If I were to keep the cast
iron heads and I still might , I intend to have the crossovers welded shut.

I am not really worried about not having exhaust circulation

>In a message dated 10/24/99 10:50:12 PM Central Daylight Time,

>
>> Give you a couple of ideas and you decide Arch.
>
>Tom
>
>Thanks for the excellent post. Do you think running water through them
>might be a good compromise? It looks like it would not be that hard to
>do. Oh well just thinking to much.
>
>Take Care
>Arch
>
>

 

[ron & gina]

Hi all,

Was thinking of updating heads/intake in near future and wanted to do
blocking of crossovers, But besides crossovers all other heating systems on
the engine has been removed/disconnected ie. air cleaner system hot air.
Would this hurt my cold start/running? I believe I'm in one if not the
hottest place in the nation and don't plan on going to where there is ice,
but might get down to the 50 or hi 40degs. Any thoughts? Thanks

Ron&Gina
73 Pumpkin-Rose
Ft. Mohave, AZ. (0600, 51degs. its cold) >

- ---- Original Message -----
From:
To:
Sent: Sunday, October 24, 1999 8:49 PM
Subject: Re: GMC: Manifold---the posibilities

> Give you a couple of ideas and you decide Arch.
>
> 1. The aluminum edelbrock heads have no exhaust crossovers and the engine
> runs fine and lots of horsepower.
>
> 2. Mondello says in his technical reference manual that filling the
exhaust
> heat riser pasages is not recommended in winter driving.
>
> 3. I am going to do it however do not intend to drive much in cold weather
> except to leave NY and go to Florida.
>
> I think the heat from the air cleaner snorkle is heat enough in the
winter.
>
>
>

> >GMCers
> >
> >Please understand that I have had way to much time to think this
> >weekend. I have spent the entire weekend hand sanding and painting
> >the radiator frame, radiator and AC condenser with brackets.
> >
> >Here is my questions and thoughts. First does anybody have the
> >Edelbrock Performer 2151 running with the crossovers blocked off?
> >If so how well does it warm up and does it take a long time?
> >Nate does your Caspro engine have the crossovers blocked?
> >
> >Now are there any of you running even the stock manifold with the
> >crossovers blocked off? Not with a 1/4 inch hole or some other
> >modification----I mean BLOCKED OFF?
> >
> >Now if I cant get a real world answer to those questions here is
> >my next one. To some of you engineering types. How much heat
> >do I need down there? Will the engine provide enough heat to keep
> >the lady running on a cold day? Now here is the killer question.
> >What if I welded a couple of bungs on top of the manifold and put
> >hot water through the crossovers? If I also put in a manual heater
> >shutoff valve I could let the lady have heat on a cool day and shut
> >it down on a hot day.
> >
> >I am not looking for the correct answer here----just your thoughts.
> >No solutions just ideas.
> >
> >Take Care
> >Arch 76 GB IL
> >
> >
>

 

[richard bachert]

Rick, SWAG = "Scientific Wild Ass Guess."
Dick 75 PB in Atlanta

>
>> I think I dont want any heat in there in the summer. The engineer types
>> may well tell me different. My thoughts are that I want as cool a fuel
>> charge as possible in summer---winter--dont know----could be wrong.
>>
>> I sure hate to blow my status as a computer jock but I must admit I
>> dont know what SWAG means. :>(
>>
>
>Arch,
> Not to belabor a point, but my "history of manifold/air cleaner heat "
>treatise a week or so ago touched on this. To reiterate: To my knowledge,
>the 1958 Edsel/Mercury/Lincoln 410 - 430 cu. in. V8 was the first to feature
>a thermostatically-controlled air cleaner inlet. (They used a tapered pin in
>wax element just like a cooling system thermostat, rather than the
>vacuum-operated system we have on our GMCs, but the effect was the same;
>intake air maintained around 100 - 110F.)
> The significant point to me is that the big FoMoCo V8 had NO exhaust
>crossover passage, instead relying upon the air cleaner preheat system and
>such radiant heat that the cam/lifter valley (eventually) provided to warm
>the incoming mixture, prevent carburetor icing, and vaporize the fuel
>properly. I may be wrong, but I'm pretty sure that IF your air cleaner inlet
>temperature control system is working properly, and you have an electric or
>manual choke, you can block off the %*!@?^#! heat riser without problems.
> My .02. HTH.
>
>Rick Staples
>'75 Eleganza
>Louisville, CO
>

 

[ron & gina]

Thanks for info Rick,

Won't do change for awhile, But I believe I'll block mine off when I get to
that point!!!!!!! Thanks again for all the info!!!!

Ron

- ----- Original Message -----
From:
To:
Sent: Monday, October 25, 1999 9:16 PM
Subject: Re: GMC: Manifold---the posibilities

>
> > besides crossovers all other heating systems on
> > the engine has been removed/disconnected ie. air cleaner system hot
air.
> > Would this hurt my cold start/running? I believe I'm in one if not the
> > hottest place in the nation and don't plan on going to where there is
ice,
> > but might get down to the 50 or hi 40degs. Any thoughts?
>
> Ron,
> Will it affect cold starting? Not at all, as that is strictly up to
the
> choke to supply a rich enough mix to start.
> Will it affect warm-up? Definitely, although the degree wiil depend
upon
> your local weather. If you were to do a lot of short trips (like the
typical
> car) you might experience some oil dilution by unburned fuel, and the
> cylinder wall wash-down (where raw gas washes so much oil off the
cylinders
> that they and the rings wear excessively) that goes with it. Most GMCs
don't
> get that sort of use, so this caveat may not apply to you. If you have a
> properly calibrated and adjusted electric choke (or manual choke) you can
> compensate for the slow warm-up you will get. Living in warm climate
helps
> of course. Periodically sniffing the dipstick to check for unburned gas
will
> help you monitor the situation.
> The remaining hazard is carburetor icing. Below-freezing temperatures
are
> NOT necessary to cause this one. In fact it occurs most often around 35 -
45
> F, in damp or wet weather. As the damp air (and fuel) pass by the
throttle
> plate, they expand greatly in the relative vacuum of the intake, dropping
> their temperature a lot. (That's how your AC works: expanding gas absorbs
> heat, cooling things.) Naturally, some of the moisture freezes. At idle
and
> low throttle openings, it can quickly clog up the space around the
throttle
> plate, causing a stall. (That's why pilots manually turn on the
carburetor
> preheat when preparing to land. Not fun to have your engine stall on
final
> approach...) I've usually experienced it at stoplights in cold, damp
> weather, 40 F +/- 5. Again, if you live in a warm and/or very dry
climate,
> you may get by.
> Myself, I want to be prepared for whatever mother nature throws at my
GMC.
> Maybe not the -75 F of Fairbanks at its worst, but I've driven many miles
at
> -30 F, and expect my vehicles to handle it. I also want to be prepared
for
> rain, sleet, snow (and gloom of night for that matter!). That's MY little
> hang-up, YMMV.
> Good luck.
>
> Rick Staples
> '75 Eleganza
> Louisville, CO
>