Author Topic: "Hot Slot" equipped cast iron intake manifold modifications..  (Read 37078 times)

Camaroon

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #15 on: February 13, 2012, 07:22:10 PM »
Looks like we have continued dissent in this thread on the correct installation location for the "tin plate" or "stainless steel baffle " that is used to reduce hot slot exhaust heat from direct contact with the forward portion of the carb base.
69pace says:  The "tin plate" goes on top of the manifold then the fiber gasket then the carb. 
jeff68 disagrees with 69Pace, jeff says: Intake manifold, then gasket, then heat shield, then carb
JohnZ agrees with jeff, John says: use a stainless steel baffle between the carb baseplate and the carb gasket

tmodel66

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #16 on: February 13, 2012, 08:32:43 PM »
The AIM shows gasket on the intake then baffle on page L35/L34 A-6. Although it's BB it is the lower HP with Quadrajet carburetor. The baffle is for protection of the carb so Figure the application would be same for all the Quadrajets?
Daniel  
'69 SS 350/4 speed  Fathom Green--POP

JohnZ

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #17 on: February 14, 2012, 04:50:17 PM »
The AIM shows gasket on the intake then baffle on page L35/L34 A-6. Although it's BB it is the lower HP with Quadrajet carburetor. The baffle is for protection of the carb so Figure the application would be same for all the Quadrajets?

That's correct - the L-78 had an aluminum intake with a Holley, and didn't have the "hot-slot".
'69 Z/28
Fathom Green
CRG

Mike S

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #18 on: February 14, 2012, 07:20:06 PM »
 I've read that the metal plate against the throttle base doesn't seal good in some situation when there is a slight warp in the baseplate.
I've been using the gasket-metal-gasket stack for years with success (along with plugged slot holes).
The extra ~.030" from the second gasket made no difference in the choke function at all.


Mike
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Restored

69pace

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #19 on: February 16, 2012, 05:34:27 AM »
I've read that the metal plate against the throttle base doesn't seal good in some situation when there is a slight warp in the baseplate.
I've been using the gasket-metal-gasket stack for years with success (along with plugged slot holes).
The extra ~.030" from the second gasket made no difference in the choke function at all.


Mike

If the Hot Slot is still active the fiber gasket will roast out in no time leading to leaks. The tin conforms to the surface and doesn't leak if its is the right gasket. It has to be the thin one not the 1/4 inch pseudo spacer. 
1969 Z-11 350/300 with 4 Speed
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1967RS/SS

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #20 on: December 17, 2012, 04:44:27 AM »
What is the method to use when using headers with original cast iron intake/Q-jet carburetor setup?  Would you still need to block these holes?   
1967 RS/SS L-48
Van Nuys 01C
Joe

bertfam

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #21 on: December 18, 2012, 03:13:32 PM »
Quote
What is the method to use when using headers with original cast iron intake/Q-jet carburetor setup?  Would you still need to block these holes?

Yes. The hot slot "fix" is so you don't warp the Rochester carb. (or start a fire!!)

Ed

1967RS/SS

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #22 on: December 22, 2012, 01:15:32 AM »
Quote
What is the method to use when using headers with original cast iron intake/Q-jet carburetor setup?  Would you still need to block these holes?

Yes. The hot slot "fix" is so you don't warp the Rochester carb. (or start a fire!!)

Ed


What about the exhaust manifold heat valve?  Just leave it off if you have headers?
1967 RS/SS L-48
Van Nuys 01C
Joe

Mike S

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #23 on: December 22, 2012, 01:41:05 AM »
I don't think you can use it with headers because how would it fit? I have never seen it like that anyways.

Mike
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Restored

1967RS/SS

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #24 on: April 08, 2013, 03:04:56 AM »
Need some help guys.  I am at the point now where i will be putting my quadrajet back onto my iron manifold.  After reading about the hot slot problems I am scared of a fire!

I plan to plug hot slot holes with steel plugs and remove heat riser flapper (doesn't get too cold here in southern California).  i will be leaving the riser body in place for that original look.

Do I still need to use the stainless steel baffle underneath the gasket?

Also, the guy that rebuilt my quadrajet included what looks to be a spacer with the rebuild.  It's about 1/4" thick and seems to be made of plastic.  Do I need this as well?
1967 RS/SS L-48
Van Nuys 01C
Joe

JohnZ

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #25 on: April 08, 2013, 03:53:24 PM »
I plan to plug hot slot holes with steel plugs and remove heat riser flapper (doesn't get too cold here in southern California).  i will be leaving the riser body in place for that original look.

Do I still need to use the stainless steel baffle underneath the gasket?

Also, the guy that rebuilt my quadrajet included what looks to be a spacer with the rebuild.  It's about 1/4" thick and seems to be made of plastic.  Do I need this as well?

You must have removed the headers you mentioned earlier if you're going to use the heat riser valve; there's no way to use the heat riser valve with headers.

The stainless baffle goes under the carb on an L-35, on top of the gasket, as shown in the Assembly Manual.
'69 Z/28
Fathom Green
CRG

1967RS/SS

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #26 on: April 08, 2013, 08:39:25 PM »
I plan to plug hot slot holes with steel plugs and remove heat riser flapper (doesn't get too cold here in southern California).  i will be leaving the riser body in place for that original look.

Do I still need to use the stainless steel baffle underneath the gasket?

Also, the guy that rebuilt my quadrajet included what looks to be a spacer with the rebuild.  It's about 1/4" thick and seems to be made of plastic.  Do I need this as well?

You must have removed the headers you mentioned earlier if you're going to use the heat riser valve; there's no way to use the heat riser valve with headers.

The stainless baffle goes under the carb on an L-35, on top of the gasket, as shown in the Assembly Manual.

Yep, never installed the headers and just kept the manifolds. Thanks for your help...
1967 RS/SS L-48
Van Nuys 01C
Joe

mickeystoys69RSSS

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #27 on: May 06, 2015, 01:16:40 AM »
Is there any way to tell if my intake has a cross over without removing the carb? I know I have a riser valve but I have no idea if it works or has been modified?

Boston14

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #28 on: May 06, 2015, 11:20:25 PM »
What year, engine, and intake casting number do you have?
boston14

1969 SS/RS 350 Convertible
Dover White with Black Top and D90 stripe, Red Standard Interior

mickeystoys69RSSS

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Re: "Hot Slot" equipped cast iron intake manifold modifications..
« Reply #29 on: May 06, 2015, 11:27:52 PM »
What year, engine, and intake casting number do you have?

late '68 built 1969 Model L34 396/350HP with TH400 Auto trans. The intake casting number: 3931067 cast date H 5 8 or August 5th 1968 time 11:00