| Aluminum Manifold Installed [message #166354] |
Sat, 14 April 2012 21:47  |
Jon payne
Messages: 495
Registered: May 2008
Karma: 1
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Senior Member |
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Guys,
Finished installing the AL intake today. When I started it up it was running rough and would not idle. After it warmed up it would idle but still rough. Fearing the intake was leaking I connected my vacuum gauge (on the manifold) and was only reading around 12- 13 inches. For a reference, last time time I checked it was ~18" at idle.
Since I did pulled the distributor during the intake removal I was wondering if I installed it back in the same position as when I removed it. So I pulled #1 plug and set it at TDC (on compression stroke) and found that the distributor was installed correctly. However when installing the distributor cap i noticed that #8 was not seated all the way on the cap. Unfortunately when i removed # 1 plug wire the terminal end stayed on the plug so I need to repair the plug wire tomorrow.
QUESTIONS: If by chance #8 plug wire was not installed and therefore not firing could this account for the low vacuum? I am thinking yes.
If no or #8 plug wire came undone when I removed the distributor cap, what is the best method to check to see if the intake is leaking?
If it is leaking......damn!
I am very confident that the gasket did not slip during the install as it was glued on. If it is leaking I would be thinking it was the gasket itself.
Any advice you guys can offer will be much appreciated!
Jon
Jon Payne
76 Palm Beach
Westfield,IN
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| Re: Aluminum Manifold Installed [message #166355 is a reply to message #166354] |
Sat, 14 April 2012 22:13  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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If a cyl is not contributing, then yes you will loose rotational speed for a give throttle opening. Less pumping action is less vacuum. Also, it's almost inmpossilbe to get the dist back in exactly the same way as it was without retiming. Even with a thin scribe mark set you should check it. Did you check it before removing???---- if not then how do you know the number to get it the same? Retarted timing will cause loss of RPM and vacuum for same everything else.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Aluminum Manifold Installed [message #166357 is a reply to message #166354] |
Sat, 14 April 2012 22:26 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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| Jon Payne wrote on Sat, 14 April 2012 19:47 |
Guys,
Finished installing the AL intake today. When I started it up it was running rough and would not idle. After it warmed up it would idle but still rough. Fearing the intake was leaking I connected my vacuum gauge (on the manifold) and was only reading around 12- 13 inches. For a reference, last time time I checked it was ~18" at idle.
QUESTIONS: If by chance #8 plug wire was not installed and therefore not firing could this account for the low vacuum? I am thinking yes.
I am very confident that the gasket did not slip during the install as it was glued on. If it is leaking I would be thinking it was the gasket itself.
Any advice you guys can offer will be much appreciated!
Jon
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Jon,
I am sure sorry to hear this. Sooo frustrating.
My remarks are limited to the Rockwell manifold. I am not badmouthing it as it is light and I like it. But it is not an exact match of the iron version. Also forgive me if this is a repeat. We had a talk here about the manifold and so some of this is a repeat.
I am not sure #8 will cause fluctuation in vac, but slower idle will drag it down.
When you say it was glued on, what was it glued to. If it was glued to the head, I hate to say, but my opinion is that it is leaking. Two of us have had pretty severe leaks in #8, (Right Rear)
Please be careful if you drive it on any kind of a trip. I ate 7+ quarts in 400 miles. At 260 or so oil pressure was going to 0 when I stopped in LA traffic.
I have fuel injection. The first manifold attempt I found myself tweaking the fuel at idle. Dumb me, I never thought it was sucking air.
There is lots of talk about blocked crossover and I would block mine if I had iron... but... GM knew what they were doing with that idea. Engines had heat risers for years and years before smog laws, so it is not just an EPA thing. At idle, fuel can pool in the cool manifold and then get sucked down a cylinder in a "glob". So, do you still have the warming tube that connected to the snorkel on the air cleaner? One developer of fuel injection systems has suggested I think about putting that back in place. Again, GM knew what they were doing. Warm air is "bad" to many here, but fuel, especially when warming up does not vaporize in cold air.
Here is a picture of why I say you must glue the gasket to the manifold:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=43838&title=aluminum-intake-gasket&cat=500
Hope this helps.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: Aluminum Manifold Installed - Update [message #166418 is a reply to message #166354] |
Sun, 15 April 2012 13:59 |
Jon payne
Messages: 495
Registered: May 2008
Karma: 1
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Senior Member |
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Hi all,
Good news, installed the new plug wire and it now runs nice and smooth. Vacuum is much better. I set the timing and now I need to adjust the idles. I have a small coolant leak to fix first.
I think it is safe to say the gaskets are installed correctly and not leaking.
Regarding George's comments about heating the air and the need to vaporize the fuel, I noticed that the base of the carb was ice cold several minutes after starting. Since I have headers i never bothered to connect the heat riser. Since there is no more cross over to heat up the carb I will be reconnecting the hear riser
Jon
Jon Payne
76 Palm Beach
Westfield,IN
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| Re: Aluminum Manifold Installed - Update [message #166421 is a reply to message #166418] |
Sun, 15 April 2012 14:27 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Do not bother trying to warm up that carb. It will get hot enough on it's own. It is connected to a manifold that has hot coolant running through it. It also is bolted to an engine that is running at least 180 to 200 degrees. The bottom of the manifold is splashed with hot oil from the lifter valley.
There are many reasons for blocking the crossovers and they are all good. Keep in mind that the engine you are using was designed to go in a lighter weight car and when used in a 11,000 GMC it generates more heat because it is burning more fuel moving a heavier, higher wind resistance vehicle.
The last thing you want to do is heat up that carb more. We have enough problems with vapor lock and boiling gas out of the carb when running or on shut down. Do not add any heat to the carb area. Try to remove all heat from the carb area that you can. That was the main purpose in blocking the crossover in the first place.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Aluminum Manifold Installed - Update [message #166428 is a reply to message #166418] |
Sun, 15 April 2012 15:13 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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| Jon Payne wrote on Sun, 15 April 2012 11:59 |
Hi all,
Good news, installed the new plug wire and it now runs nice and smooth. Vacuum is much better. I set the timing and now I need to adjust the idles. I have a small coolant leak to fix first.
I think it is safe to say the gaskets are installed correctly and not leaking.
Jon
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This is excellent news. I agree, if it is warming up ok, don't worry about the icing. Once warm, it will all be hot. I was commenting because some were having warmup rough idle. Glad it is all good.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: Aluminum Manifold Installed [message #166438 is a reply to message #166354] |
Sun, 15 April 2012 17:10 |
Jon payne
Messages: 495
Registered: May 2008
Karma: 1
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Senior Member |
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Hi Dan
I glued the gasket to the intake using 3M 08001 Weatherstrip adhesive and I installed 3/8 inch bolts with the heads cut off to use as guides per Rob's suggestion, worked great! Also had to open up the end bolt holes on the gasket. Other than that when together nicely.
And thanks Ken for the advice. I'll forgo the heat riser for now.
Hey, I just posted my first youtube video showing the vacuum after the install of the manifold. Got 18" at idle. Seems pretty steady. Let me know what you all think.
http://www.youtube.com/watch?v=B-BXhsNdiBc&feature=youtube_gdata
Thanks guys for your advice! Pictures still to follow.
Jon
Jon Payne
76 Palm Beach
Westfield,IN
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| Re: Aluminum Manifold Installed [message #166439 is a reply to message #166438] |
Sun, 15 April 2012 17:41 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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| Jon Payne wrote on Sun, 15 April 2012 15:10 |
Hi Dan
I glued the gasket to the intake using 3M 08001 Weatherstrip adhesive and I installed 3/8 inch bolts with the heads cut off to use as guides per Rob's suggestion, worked great! Also had to open up the end bolt holes on the gasket. Other than that when together nicely.
And thanks Ken for the advice. I'll forgo the heat riser for now.
Hey, I just posted my first youtube video showing the vacuum after the install of the manifold. Got 18" at idle. Seems pretty steady. Let me know what you all think.
http://www.youtube.com/watch?v=B-BXhsNdiBc&feature=youtube_gdata
Thanks guys for your advice! Pictures still to follow.
Jon
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Looks good, Jon. Congratulations on a job well done. I've been putting this off because of all the problems I've been hearing about concerning this install. This is giving me more confidence. Thanks.
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] Aluminum Manifold Installed [message #166468 is a reply to message #166439] |
Mon, 16 April 2012 00:44 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Check your timing and bump it 2degrees.
Vaccume should be 17-19.
On Sun, Apr 15, 2012 at 3:41 PM, Carl Stouffer <carljr3b@yahoo.com> wrote:
>
>
> Jon Payne wrote on Sun, 15 April 2012 15:10
>> Hi Dan
>>
>> I glued the gasket to the intake using 3M 08001 Weatherstrip adhesive and I installed 3/8 inch bolts with the heads cut off to use as guides per Rob's suggestion, worked great! Also had to open up the end bolt holes on the gasket. Other than that when together nicely.
>>
>> And thanks Ken for the advice. I'll forgo the heat riser for now.
>>
>> Hey, I just posted my first youtube video showing the vacuum after the install of the manifold. Got 18" at idle. Seems pretty steady. Let me know what you all think.
>>
>> http://www.youtube.com/watch?v=B-BXhsNdiBc&feature=youtube_gdata
>>
>> Thanks guys for your advice! Pictures still to follow.
>>
>> Jon
>
>
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> Looks good, Jon. Congratulations on a job well done. I've been putting this off because of all the problems I've been hearing about concerning this install. This is giving me more confidence. Thanks.
> --
> Carl S.
> '75 ex Palm Beach
> Tucson, AZ.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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