Cliff's Quadrajet Parts and Rebuild Kits
Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: jbplanck on June 18, 2013, 12:37:48 PM
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Part order is this: intake manifold, thin metal plate (no sealer from factory), thick gasket, then carb.
The thin metal piece goes on such that the formed parts go down into the intake, covering the EGR well to direct the air/fuel mixture into the intake with a minimum of turbulence. The little holes in it meter the exhaust gas passed by the EGR valve (when activated). Mine is wasted from a square bore holly installed by previous owner.
Can I do without it? Is there an aftermarket replacement for this, part number? I am installing a rebuilt year/car correct q-jet.
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For reference this is a 1979 Trans Am Pontiac 400 block.
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Here is the square bore adapter. It used 4 hex bolts to attach to the intake manifold, and the holly mounted on the 4 studs seen below. Last picture shows the EGR chamber cast in the primary holes.
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You really don't need it, but if you're going correct, try the Perfomance Years forum. See if anyone has one. Heck, Cliff might have one.
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I didn't realize they used those well into the 70's. I thought they disappeared in the early 70s.
I know Holley/Mr Gasket repro them for the early cars.
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You really don't need it, but if you're going correct, try the Perfomance Years forum. See if anyone has one. Heck, Cliff might have one.
Thanks Ethan1, that seems to be the consensus on other forums. However, I would still like to find one as it provides smoother air-flow (less turbulence) through the primaries. But, I also want to drive my car so I am getting close to forgoing it for now.
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I didn't realize they used those well into the 70's. I thought they disappeared in the early 70s.
I know Holley/Mr Gasket repro them for the early cars.
Thanks Shark Racer, I will check Holley and Mr. Gasket out.
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Neither did I, Steve.
This is for the early cars.
http://www.pysales.com/IW_Products.m4p.pvx?;MULTI_ITEM_SUBMIT
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(http://www.pysales.com/images/pyq10x.jpg)
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That's the one. It was there to prevent the exhaust gases from boiling the underside of the carb...
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(http://www.pysales.com/images/pyq10x.jpg)
Not the same item as the one I need, thanks though. My piece is not flat on both sides, it is not a shim. The primary holes are punched through to create a flange on the bottom side. You can see it in one of my pictures above where I am holding the plate. It is very black as the Holley carb I removed was running too rich.
From what I have found about this plate the EGR system vented into the primary holes which are sunken in the intake manifold. They are sunken because the entire primary bore area was casted with a recess to accept the EGR gasses. However, this created some turbulence with the normal air flow from the carb. To counter this the plate has the primary flanges on the back side pressed out in a cylindrical press ( like a gromet) the same diameter as the missing ( hollowed out in cast to accept EGR vent) intake primary bore material in the manifold. This then restored the air flow eliminating the turbulence.
There is minor debate to how this might impact performance when removed. Most believe it is minimal or non relevant and can be removed. But still, I would like to replace it if possible.
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Here is another one:
http://quadrajetparts.com/rochester-quadrajet-parts-quadrajet-gaskets-seals-quadrajet-base-gaskets-quadrajet-stainless-steel-heat-shield-013-thick-p-375.html
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Here is another one:
http://quadrajetparts.com/rochester-quadrajet-parts-quadrajet-gaskets-seals-quadrajet-base-gaskets-quadrajet-stainless-steel-heat-shield-013-thick-p-375.html
Really appreciate your help, but that is not it, it is the same as the other one you posted. From the qjet parts website...
"Stainless steel metal shim (.013" thick) is used with a base gasket on some models with exhaust gases under the carburetor to avoid "burn thru". Stainless Steel heat shield goes directly under carburetor and above 'composition' base gasket."
Mine is not a heat shield. It goes between the intake manifold and base gasket. Notice above goes between the carb and base gasket.
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I kn.ow it is not the correct one. You said you were curious about the holley and mr. gasket one. This is the one Shark Racer was. referring to. Geez.
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I kn.ow it is not the correct one. You said you were curious about the holley and mr. gasket one. This is the one Shark Racer was. referring to. Geez.
My apologies Ethan, I didn't know that was directed to Shark Racer.
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No apologies needed. Have you tried eBay as well? I will keep my eye out for you. I look for parts for people all the time. If I just had a part number, I could probably find it for you. :)