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Old 09-05-2021, 05:38 PM
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Default WTB NEED SD455 Intake Manifold

Where have all the SD455 intake manifolds gone? Need to buy an SD455 intake to finish my SD project. Dating not terribly important, will consider all conditions.

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Old 09-16-2021, 03:45 AM
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Anyone? Even rumors of one?

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Old 10-01-2021, 02:51 AM
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SD455 bump!

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Old 10-25-2021, 03:46 PM
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Bump again!

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Old 10-25-2021, 10:21 PM
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what would you be willing to pay for one?

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Old 10-26-2021, 12:42 PM
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Many got replaced with aluminum intakes and were subsequently tossed when the owner decided he was going racing. I knew a guy with a 74 SD automatic that was raced in the 70s & 80s. Pretty much everything but block & heads were replaced with aftermarket equipment. The owner passed away a couple of years ago, and his son has the car now. He is looking for all of those parts his dad tossed years ago, and is getting a nasty case of sticker shock. At the time, I told him where he could get an intake for $3200, a carb for $3000, and a distributor for $1800. He said those prices were too high, so he's still looking. I suspect he'll eventually give up and either keep it old school street/strip or sell it.

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Old 10-26-2021, 05:18 PM
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Which one ?

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Old 10-26-2021, 11:07 PM
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Quote:
Originally Posted by muscle_collector View Post
what would you be willing to pay for one?
I've only seen 3 for sale in the last 2-3 years, when I didn't need one of course. One was very rusty but had all the attached parts including EGR for $2650. Another nice but bare one sold for either $3200 or $3600. A third one the asking price was $4000, but was never able to determine what the final sale price was.
I'd love to find one for $2650 today but I'm sure that's dreaming (big time).

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Old 10-27-2021, 12:43 AM
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Default Too bad so many of these got scrapped.....

You'll be hard-pressed to find one that is in any way affordable. Unless the seller has been living in a monastery or a nunnery or something.

The real-world value for an LS2X intake is between $4k and $5k.

We've got a buddy who settled on a factory aluminum #485640 intake and crossover. That's the intake that Pontiac used on the prototypes and developmental engines, until they realized that they had to use EGR to get the emissions handled.

And the other $2k paid for his forged crank and rods......

Good luck!

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Old 10-27-2021, 10:05 AM
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It's the law of supply at demand. If prices rise high enough you'll see some starting to hit the market. If somebody decides to repop the SD intakes, I suspect you'll see more originals will go up for sale at reasonable prices.

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Old 12-27-2021, 03:42 AM
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Back actively searching again! (Survived Thanksgiving and Christmas,...and so did my wife!!)

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Old 12-27-2021, 11:08 AM
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Call Barry

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Old 01-16-2022, 07:48 PM
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Did you find one yet?
What year is your car?
Is that the aluminum intake with cast crossover?

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Old 01-16-2022, 08:47 PM
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Default Factory SD455 intake were not aluminum, although the prototypes had a 485640 intake.

Quote:
Originally Posted by moparcolt View Post
Did you find one yet?
What year is your car?
Is that the aluminum intake with cast crossover?

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The 485640 aluminum intake and cast-iron 1972-only cast-iron exhaust crossover were slated to be used on the SD455 engine during the design process.

However, by the time the 1973 SD455 engine got to the production stage, the EPA demanded an EGR valve be fitted to reduce emissions. So the engineers at Pontiac revised/reworked/re-designed a cast-iron intake with the EGR valve to use on the SD455.

They also closed off the back of the scoop because the 'drive by' WOT noise from the quadrajet was excessive.

So the OP would be looking for an LS2 or LS2X intake. They're few and far between.

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Old 01-16-2022, 08:50 PM
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Gotcha, just checking, I have a 72 455 HO intake

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Old 01-16-2022, 08:54 PM
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Quote:
Originally Posted by moparcolt View Post
Gotcha, just checking, I have a 72 455 HO intake

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I have considered using a '72 HO intake as a temporary measure until I find a more correct intake. Could you give me more info on your manifold? Some pics would be nice.

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Old 01-17-2022, 05:10 AM
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Default There are two different intakes that are recognized as 'correct' for 1972 455HO.

The early number - which was actually designed for the SD455 engine - is 485640. That one would be correct for a 'prototype-correct' build, and is the intake that was on our SD455 TA when we bought it. Its' casting number fits into the SD455 engine part numbers sequence, with 485225 connecting rods and 485216 heads and etc.

The later number is 488945. Same intake but not 'numbers correct'. It's the intake used on a majority of 1972 455HO engines and sold over-the-counter until well into the 1980s.

And then you'll need the 1972-only exhaust crossover.

We've got a couple of 485640 intakes and correct 1972-up crossovers.

If you're interested message us and we can discuss. Thanks.

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Old 01-17-2022, 10:38 AM
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Any idea how long Pontiac sold the HO intakes over the counter?

I've got a 483674 intake (for 1971 455HO) dated November 1975. I remember trying to buy a 1970 Ram IV intake from the dealership in the early 1980s, and I thought I was told only the 1972 455HO intake was available.

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Old 05-30-2022, 08:47 PM
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Quote:
Originally Posted by Joe's Garage View Post
However, by the time the 1973 SD455 engine got to the production stage, the EPA demanded an EGR valve be fitted to reduce emissions. So the engineers at Pontiac revised/reworked/re-designed a cast-iron intake with the EGR valve to use on the SD455.
FYI, EPA does not dictate engine design. They only dictate the emission limit for a given model year. ‘73 had a significant NOx reduction from ‘72 levels. EGR is the most effective method to reduce NOx without radically reducing fuel economy (at least using 70s technology). Most manufacturers added EGR in ‘73 as a result.

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Old 05-31-2022, 03:44 PM
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Default Pontiac was forced to add the EGR by the emissions mandates issued by the EPA.

Since using an EGR valve was the ONLY known solution that would accomplish the lower emissions levels at that time, the EPA basically forced ALL automakers to adopt the technology.

The EPA probably didn't send them each a letter saying "You will have to use an EGR valve", but the requirements they set basically did that for them.

My point was that, given the amount of extra heat generated in the intake by the EGR valve, Pontiac fell back on the durability of a cast iron intake for the production SD455 engine.

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