| Aluminum Intake [message #59361] |
Wed, 07 October 2009 22:47  |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Senior Member |
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Does the AC bracket have to be totally removed to get the intakes switched? I just glanced at my iron one today and that bracket looks like it is in my way. I guess the hole in the bracket has to be worked on to fit the hole in new intake so it will need to come off anyway. Just checking.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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| Re: [GMCnet] Aluminum Intake [message #59387 is a reply to message #59361] |
Thu, 08 October 2009 11:18  |
Rick Denney
Messages: 430
Registered: January 2004
Karma: 0
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Senior Member |
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Dan Gregg writes...
> Does the AC bracket have to be totally removed to get the intakes
> switched?
Yup. I did the manifold and the compressor replacement at the same
time because of that.
In the case of the rear heater hose fitting, the factory used several
fitting sizes over time, apparently. Mine was the right size, but my
old hose fitting in the iron manifold could not be removed, so I
bought a new fitting anyway. Dorman (I think) makes a "Help!" part
that provides a restriction hole only a little larger than the factory
fitting. That's what I used, and everything seems happy.
And, yes, you may need to replace a bolt or two with a shorter bolt.
The manifold casting changed over the years, which affected the length
of at least one bolt.
Rick "who had to pull the carb to retorque the manifold, too" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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| Re: Aluminum Intake [message #59415 is a reply to message #59361] |
Thu, 08 October 2009 13:38 |
bobby5832708
Messages: 237
Registered: November 2006
Location: Winter Springs FL
Karma: 3
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Senior Member |
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Dan,
Several things to add:
1. Before you install the new manifold, bolt the carb to it and make sure the secondary throttles open properly. I had to grind about a 1/8" relief as the throttle blades would hit the manifold and not open. Good for gas mileage, bad for performance! From what I've heard this is fixed on later manifolds, I bought mine in Jan 2008.
2. Have a shop vac with a crevice tool to clean out the chunks of carbon that will fall off the turkey tray gasket and onto (into) the engine. I was surprised at the amount and size of the carbon pieces that had formed under the exhaust crossover area.
3. I had to enlarge the hole in the A/C bracket slightly to get the bolt in. I think the newer manifolds have this fixed also, not really sure though.
4. The vacuum port just behind the carb is different. If I remember correctly, the original was 1/8 pipe thread and the new manifold is 1/4.
Have fun!
Bob Heller
2017 Winnebago 29VE
Winter Springs FL
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| Re: [GMCnet] Aluminum Intake [message #59430 is a reply to message #59422] |
Thu, 08 October 2009 15:28 |
Rick Denney
Messages: 430
Registered: January 2004
Karma: 0
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Senior Member |
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Dan Gregg writes...
> I need to look for the bolt torque specs and the pattern of
> tightening also.
The sequence is in the maintenance manual.
I tightened to 15-20 ft-lbs, let it sit for a while, then tighten to
the prescribed 40 or 45 (memory fails me here). Then, I waited a day
for the goo to cure, and then ran the engine through a couple of
thermal cycles. I then pulled the carb (to make room for the torque
wrench) and retorqued the bolts (and they needed it).
Rick "no problems since then" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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| Re: [GMCnet] Aluminum Intake [message #59432 is a reply to message #59431] |
Thu, 08 October 2009 16:16 |
Rick Denney
Messages: 430
Registered: January 2004
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Dan Gregg writes...
> Thanks Rick, I printed that. What gaskets did you buy for your's?
I used Dick Paterson's gaskets with the stainless steel block-off
plates. I figured those plates would protect against exhaust gases
eroding the surface of the aluminum.
Rick "belt and suspenders" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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| Re: [GMCnet] Aluminum Intake [message #59443 is a reply to message #59430] |
Thu, 08 October 2009 16:09 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Rick,
IMHO the torque sequence in the manual is "backwards" it torques the outer
end bolts first and works towards the center. I raised this question a
couple of weeks ago when I was installing mine and the consensus that was
that was for intake manifolds being sealed with the steel turkey tray
gasket. Also the 40 ft lb noted in the MM seemed high so I only torqued mine
to 30 ft lb.
Jim K provided a Mr. Gasket P/N 404 gasket kit with my manifold which has a
much thicker fiber gasket. The gasket is solid and seals the carb heat port
in the heads. I do agree with you that it is possible for the exhaust gases
to erode the gasket and attack the manifold but I figured I'd be long gone
by the time that happened. It will give the FO something to complain about
the PO! ;-)
Per the recommendations of Steve Ferguson / Dick Paterson I glued the
gaskets on to the heads with Gorilla snot, used Permatex Black RTV on the
front / rear and torqued the manifold to 10 ft lb - waited 10 minutes - 20
ft lb - waited 10 minutes - 30 ft lb - waited overnight - 30 ft lb. I
started with the middle bolts and worked outwards in an "X" pattern. I will
re-torque them after several heat cycles as per your recommendations next
year.
Regards,
Rob Mueller
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
'75 Avion - USA - The Parts Coach TZE 365V100324
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Rick Denney
Sent: Friday, October 09, 2009 7:29 AM
To: Dan Gregg
Subject: Re: [GMCnet] Aluminum Intake
Dan Gregg writes...
> I need to look for the bolt torque specs and the pattern of
> tightening also.
The sequence is in the maintenance manual.
I tightened to 15-20 ft-lbs, let it sit for a while, then tighten to
the prescribed 40 or 45 (memory fails me here). Then, I waited a day
for the goo to cure, and then ran the engine through a couple of
thermal cycles. I then pulled the carb (to make room for the torque
wrench) and retorqued the bolts (and they needed it).
Rick "no problems since then" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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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] Aluminum Intake [message #59858 is a reply to message #59452] |
Mon, 12 October 2009 10:12 |
Rick Denney
Messages: 430
Registered: January 2004
Karma: 0
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Senior Member |
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Bob Drewes writes...
> You need to dry fit the aluminum intake and see how the ports match
> up with the heads. When the bolt for the A/C compressor bracket does
> not align, that is the clue that something is not correct, namely
> the intake is shifted to the left and there is a mis-match of the
> ports. This was the case with both intakes I tried. You can use
> compression paper for a make shift gasket for each side and compress
> the manifold down with the bolts, then remove the intake and see
> where the port marks are on the paper. You could also use blue
> marker paste and that will show the port match.
Good advice. I did that, though I used a straightedge to make marks on
the end of the intake to identify the line along the upper edge of the
ports and another line along the lower edge of the ports. Then, I made
similar marks on the heads. My port alignment during dry fit was
excellent, and that was reinforced by the proper gap over the gallery
end walls. But the AC bracket still missed by just enough to keep the
threads from engaging.
Any time we reverse-engineer an existing product, we have to follow
only a projection of the rules. The originals would have followed the
original rules. But any time one is setting up a new intake manifold
(no matter what it's made of or who made it), those checks are needed
to make sure it is sitting square on the cylinder heads.
It is also true that prior head work can mess up the relationships a
bit.
Rick "noting that the bracket bolt location is at the end of a long
chain of angled measurements and machine work" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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