HELP-----Intake Manifold

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Feb 8, 1998
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Arch,

Should be no problem with the stock air cleaner. IIRC, the Edelbrock
Performer manifold raises the carb and air cleaner around three inches over
the Toro manifold(the Toro being one inch lower than a standard 455
manifold). I think Darren Padget has this setup, which is what prompted him
to come up with his version of the raised hatch. Hopefully he'll chime in
here too.

BTW, according to their web site(bottom of
http://www.edelbrock.com/automotive/man_selec.html), Edelbrock measures
manifold height by laying a straightedge lengthwise across the carb mount
and measuring from the manifold gasket sealing surface to the lower edge of
the straightedge. The measurements for the Olds 455 Performer are
front-2.50", rear-3.90". According to the website, average the two for
carb mounting height.

HTH,
Patrick

> My real question is can I still use the stock air
> cleaner?
 
Arch:

I believe that Dick Paterson uses an Edelbrock manifold also. I was in his
coach at FC and he has a raised engine compartment cover. Go to his web
site (http://paterson-gmc.com/~gmc/motorhome.html) and scroll down to the
bottom of the first page and click on the e-mail link to send him e-mail
about it.

Paul Bartz

From: Patrick.Flowers
[mailto:Patrick.Flowers]
Sent: Tuesday, October 19, 1999 11:38 AM

Arch,

Should be no problem with the stock air cleaner. IIRC, the Edelbrock
Performer manifold raises the carb and air cleaner around three inches over
the Toro manifold(the Toro being one inch lower than a standard 455
manifold). I think Darren Padget has this setup, which is what prompted him
to come up with his version of the raised hatch. Hopefully he'll chime in
here too.

BTW, according to their web site(bottom of
http://www.edelbrock.com/automotive/man_selec.html), Edelbrock measures
manifold height by laying a straightedge lengthwise across the carb mount
and measuring from the manifold gasket sealing surface to the lower edge of
the straightedge. The measurements for the Olds 455 Performer are
front-2.50", rear-3.90". According to the website, average the two for
carb mounting height.

> My real question is can I still use the stock air
> cleaner?
 
Mondello says they can and do weld and remachine the intake manifolds.
Mine had a large crack, and they said it could be fixed, I opted for
another one that was not cracked but .......
gene

> GMCers
>
>I need help. Machine shop just called. Intake manifold is cracked in two
>places. They advise that it is to bad to repair. I know that if I put on the
>Elderbrock manifold that Patrick talked about that I am going to have to
>modify the hatch. My real question is can I still use the stock air
>cleaner? Any other thoughts on manifolds would be useful. I will wait
>until I hear from some of you before I do anything.
>
>I would also like to add this note. I took the manifold off and cleaned it.
>Then I bead blasted it. The thing was all new and shinny. I went over
>it with a fine tooth comb. I COULD NOT see any cracks. Since I had
>heard so many stories about cracked manifolds I decided to have it
>magna-fluxed just to be sure. You know the rest of the story.
>
>Take Care
>Arch
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
 
I wonder if you could leak test the manifold? Blank off the carb and port
openings(1/4 inch plywood and some RTV would probably work) and pressurize
it by inflating a balloon attached to the vacuum port. If the balloon
deflates, spray with with soapy water to find the leaks.

Patrick

> Arch - there are often some small surface cracks that usually
> occur on the radius curve near where the base of the carb
> mounts. These cause no problems. If that is the case with
> yours, the manifold might still be used.
 
Arch,

You can use:

http://www.edelbrock.com/automotive/search.html

to find dealers in your area. A search for "Atlanta" shows Advance Auto,
Autozone and PEP Boys among the national chains listed. Call around to see
if there's one in a warehouse somewhere - maybe your luck will improve!

Also possible that Mondello has a couple stockpiled.

Good luck!
Patrick

>
> Big problem----The 455 Elderbrock manifold--2151 is on national
> back order until next month at the earliest. Going to check with
> a speed shop in St. Louis. Anybody know of any squirreled away
> any where?
>
> Take Care
> Arch
>
 
Arch this is the main reason to rework the heads and eliminate the exhaust
crossover.

> GMCers
>
>I need help. Machine shop just called. Intake manifold is cracked in two
>places. They advise that it is to bad to repair. I know that if I put on the
>Elderbrock manifold that Patrick talked about that I am going to have to
>modify the hatch. My real question is can I still use the stock air
>cleaner? Any other thoughts on manifolds would be useful. I will wait
>until I hear from some of you before I do anything.
>
>I would also like to add this note. I took the manifold off and cleaned it.
>Then I bead blasted it. The thing was all new and shinny. I went over
>it with a fine tooth comb. I COULD NOT see any cracks. Since I had
>heard so many stories about cracked manifolds I decided to have it
>magna-fluxed just to be sure. You know the rest of the story.
>
>Take Care
>Arch
>
>
 
did you try mondello he stocks them

>GMCers
>
>Big problem----The 455 Elderbrock manifold--2151 is on national
>back order until next month at the earliest. Going to check with
>a speed shop in St. Louis. Anybody know of any squirreled away
>any where?
>
>Take Care
>Arch
>
>
 
I know you want everything to be 'right' but I'd also ask your magnaflux guy
if its the intake or crossover portion that's beyond repair. If your
blocking off the crossover, it isn't quite as critical unless the cracks are
effecting the cylinder runners.

I say this from the assumption that you aren't too keen on the new hatch
cover. If you aren't opposed to that, I'd get a better breathing manifold
and be done with it.

With the other things you're doing, it'd be a shame to have that good cam
and valve job, then strangle it with that old 'smashed down' cast manifold.

mg

| -----Original Message-----
| From: owner-gmcmotorhome
| [mailto:owner-gmcmotorhome]On Behalf Of Gcbr
| Sent: Tuesday, October 19, 1999 11:00 AM
| To: gmcmotorhome
| Subject: Re: GMC: HELP-----Intake Manifold
|
|
| In a message dated 10/19/99 10:38:38 AM Central Daylight Time,

| > I think Darren Padget has this setup, which is what prompted him
| > to come up with his version of the raised hatch. Hopefully
| he'll chime in
| > here too.
|
| Patrick
|
| Thanks going to wait 24 hrs before making a decision. That way I can get
| all the input.
|
| Take Care
| Arch
 
remember when you have an RV cam you will get some twitch of the vacuum
gauge due to the valve overlap,Mine does it and runs fantastic.

>In a message dated 10/19/99 3:20:54 PM Central Daylight Time, grady
>writes:
>> With the other things you're doing, it'd be a shame to have that good cam
>> and valve job, then strangle it with that old 'smashed down' cast manifold.
>>
>Mark
>
>I agree with you. The Mag guy said that I would have a vacuum leak.
>I think there is more than that. There are a whole set of problems. One
> cylinder with low compression. By pumping up each cylinder we
>determined it was an exhaust valve leak. Going in proved us right.
>Going in also told us all the intake valves were sealing well. Then
>why did we have a twitch in the vacuum gauge? I think there are
>more problems than the Mag guy is seeing. I think there is an exhaust
>leak into one of the runners. I have never liked that manifold anyway.
>Dont like a hump in the floor but I dislike it less than the manifold.
>Still hoping I hear from Dick and Darren before I have to make a
>decision by 9am in the morning.
>
>Take Care
>Arch
>
>
 
The total rise from stock to Edelbrock came out to 2.75" difference. The
stock air cleaner setup will work. The one problem you may have is that
the snorkel for the air cleaner will be at the wrong level to go under
the compartment opening as it is as stock. You will have to bend the
snorkel down or cut it off and extend it with a flexible duct. There are
lots of options with the snorkel setup. Let your imagination run to come
up with one you will like. I still have a cover which will give you
2.75" extra on hand. If interested I can send you details. Darren

>
> Arch,
>
> Should be no problem with the stock air cleaner. IIRC, the Edelbrock
> Performer manifold raises the carb and air cleaner around three inches over
> the Toro manifold(the Toro being one inch lower than a standard 455
> manifold). I think Darren Padget has this setup, which is what prompted him
> to come up with his version of the raised hatch. Hopefully he'll chime in
> here too.

Darren Paget
76 Experimental
Another Fab Day
paget
http://www.TZEplus.com
 
I have a stock GMC cam and they are an RV cam, with valve overlap. I have
no vacuum leaks in mine and yes it is more than a little twitch on the
vacuum gauge. But the engine really runs strong.

I have a hard time believing that Caspros cam is a zero overlap cam. You
have got one of the best cams for the 455 (in my humble opinion).

>In a message dated 10/19/99 11:16:34 PM Central Daylight Time,

>> remember when you have an RV cam you will get some twitch of the vacuum
>> gauge due to the valve overlap,Mine does it and runs fantastic.
>>
>Tom
>
>I agree with you but this twitch was with a stock GMC cam. It was also
>a little more than a twitch. BTW Chuck from Caspro called and said the
>Caspro GMC cam is a zero overlap cam. What do you make of that?
>It would give you high vacuum but little else----nice to have brakes
>but I want to be able to get to the point that I need brakes----what do
>you think?
>
>Take Care
>Arch
>
>
 
> I may have an extra set of cross over plugs left when I get done.

Hi Arch,

Guess I missed the post but what cross over plugs did you get? I believe I
read that some of them burns thru, and was just wondering if you found
different ones? Thanks for info. Hear anything on steering gears?

Ron&Gina
73 Pumpkin-Rose
Ft. Mohave, AZ.

- ----- Original Message -----
From:
To:
Sent: Tuesday, October 19, 1999 12:59 PM
Subject: Re: GMC: HELP-----Intake Manifold

> In a message dated 10/19/99 2:40:51 PM Central Daylight Time,
warner

> > Arch this is the main reason to rework the heads and eliminate the
exhaust
> > crossover.
>
> Tom
>
> The guy at the machine shop could not believe that this one had
> lasted that long on a motorhome. He said they were bad about
> cracking when used in a car. Thats why I had it magna-fluxed.
> I may have an extra set of cross over plugs left when I get done.
> I had already ordered a set and now I find that a set comes with
> the manifold. We shall see.
>
> Take Care
> Arch
 
Well you are proof Arch that it is possible and you should measure to make
sure the standard chain will fit.
Could have been a disaster if you had ordered the normal one and it had
jumped timing and crunched pistons and valves

>In a message dated 10/19/99 11:54:59 PM Central Daylight Time,

>> I have a hard time believing that Caspros cam is a zero overlap cam. You
>> have got one of the best cams for the 455 (in my humble opinion).
>>
>Tom
>
>Thanks I sure hope so. I am just getting in a little deeper than I wanted
>to but what the he**. BTW had to go with a .005 under timing chain. So
>I guess the motor was line bored when it was overhauled.
>
>Take Care
>Arch
>
>
 
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