HO Aluminum Intake ID
 

Hey gang - since I've never held a factory aluminum intake (I'm talking '71-'72 455HO here) nor seen one side-by-side with the reproductions, how can you tell them apart?

Or, in other words, what's the easiest way to identify that you're looking at an actual factory OEM intake vs. a reproduction?

There's one for sale in a facebook group currently that's supposedly OEM but it has terribly aligned port openings. I've heard that the repros are really bad for this but the factory intakes should be pretty good, right? At least no worse than the typical iron intake?

Original ones if used on a stock motor should have cast iron exh crossover rivited to the intake by the sheet metal heat sheild.
Also the heat Crossover’s themselves are different between 69 thru 71 and 72.

The repro one have those badly misaligned port exits and the depth of the plenum is not as deep as a original one.
The also means all the runners are not as tall as a original one.

I have heard tell that there is a 5 to 8 hp difference in a original and the repro!

The original intakes are also sketchy on port alignment. That's why the aftermarket intakes are, because from what I was told, they used an original for the mold, and that's how the ports were. That was even discussed on here years ago.

Even some of the iron intakes have wonky port alignment. Steve C sent me a picture the other day of his original 70 RA III iron intake and the port alignment on that was quite a bit off on a few.

I've purchased the repo aluminum RAIV/HO intake a few years ago, and although port alignment was very slightly skewed, it only took a few minutes with the grinder to clean it up and has worked perfectly fine for me for several years now.

In fact, I've done back to back testing with it compared to my original 70 RA III iron intake and they perform identical with no difference what so ever in performance.

Only the 1972 intakes had the crossover heat shield riveted on.
 

The 1969-1971 intakes and crossovers did not have any rivets.

There are several visible differences between NOS and repro intakes.

The most noticeable is that the repro intakes have a raised, oval area around the casting number, as shown in the first picture below versus the NOS intake in the second picture.

Port sizing is much closer on factory intakes than on repros, although the later factory intakes were sometimes sloppy.

Good luck!

The re-pop I had brought to me for installation could not be used without extensive welding at the top of multiple port openings. It would have altered the exterior appearance of the manifold but would have functioned. Customer didn't want it to look that way and returned it for a refund. Came from the "Parts Place" They refunded his cost without much argument. He ended up just going with a nice 68-72 iron unit and removed the cross over.

Might be of interest....

Factory Cast-Aluminum Intake Manifold Comparison - Intake Uptake Revisited

https://www.motortrend.com/how-to/hp...ld-comparison/

Then the 'advertisement'.....

The Parts Place 1971 Pontiac 455 HO reproduction intake manifold

https://www.youtube.com/watch?v=lrQFB-hNKqo



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1972
 

1972 455HO original.

That is not what I've read or heard about the repro RAIV/HO intakes as people have posted here. Granted these repros will work fine but nothing is better than the original part. The repros are popular because they are readily available and relatively cheap. That said, I would never put a repro on an original RAIV car or HO. I would look for an original. manifold.

Here are some screenshots from the ad. From what Joe's Garage said, it looks like a factory unit based on the casting number but damn, that port alignment is terrible.

The Zig-Zag port opening alignment looks bad but is not a big issue. Meaning it can be dealt with by grinding and filling with epoxy to correct. The one brought to me however, was so horribly shifted out of position, there would be no roof left for a gasket seal without welding up the roof, regrinding the flange and shaping it from there. What just blows me away, is if the people involved KNOW they don't have the ability to produce a decent casting, PLEASE leave enough material in the part to fix it without welding! Having to weld it all up and re-machine adds so much cost, you are getting close to used parts prices. At least an HO piece. Much easier to remove material than add it back in. Ask any carpenter!

another thing to be aware of is the service replacement intakes sold over the counter after the originals... they had the plenums not as deep as originals & some reported a small reduction in HP over true originals although im sure its minimal.

the date code for a true original will be within a small range of the cars year, SR intakes will be dated after 69-72, ive seen them dated as late as mid to late 70's. i saw that intake on FB but you cant see the date in the pics, would be worth asking for a pic or to confirm the date. theres a few threads on here you can search for regarding this, rocky rotella did some research on the details of this. just something to be aware of when paying the prices for claimed originals.

What he said!

My SR 72 HO I bought in 79 ports were a little off but nothing like the repop RAIV I bought. Had to have weld added in several spots.

It's a widely known fact that port alignment on many of the original pieces are the same way. They used a factory piece for the mold, that's why the repop stuff is the way it is. Just look at Will's picture or other factory stuff. Steve C can even show you his factory iron manifold that is the same way..

You can watch this video that Steve posted and 5 minutes in hits on that very subject https://youtu.be/lrQFB-hNKqo

People have posted here about this issue for years, in fact there is a thread about this from years back, one of the forum members I believe is who supplied their factory intake for the mold back when the repops first hit the market. Maybe ask Skip, I believe he was involved or knows who was.
I guess apparently no one was willing to step up to the plate that has one of these manifolds with the seldom seen perfect ports to pour the mold. ;)

& SD wont port the repro intakes anymore due to bad port alignment or core shift issues.

That's interesting because the repop RAIV I bought had very slight port mis-alignment and only required slight touch up with a grinder and slapped it on the car. I bought mine maybe 5-6 years ago.

I think it depends on how far you want to take it. Some of these aftermarket heads have the roof pretty high where even iron intakes get pretty sketchy. Some of the repop aluminum pieces are worse than others.

My repop RAIV actually has a decent amount of meat at the top. Probably enough to get by without welding for a mild port job and raising the roof a pinch.

I had to clean up the original HO piece on the 455 I built a couple years ago, and those were on a set of Dan Barton ported 7F6 heads that flowed 285 cfm. The port match was off to begin with but wasn't bad when I was done.

The goofy as cast intake ports on my original '70 factory intake are pictured in post #9 here:

https://forums.maxperformanceinc.com...d.php?t=693767



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Thanks Steve.. was looking for that post. Notice Scott posted in there about his iron intake and misaligned ports as well.

This stuff on OEM intakes is more common than apparently many here realize. Surprising some act like it's news. You can see this has been a discussion for many years, this one going back almost 10 years.
Trying to find the post of the repop aluminum stuff when it hit the market and who used their factory intake to base the molds off of.

just saying what dave has posted on his website now for information purposes. for his intake porting service he wont do the repro RA & HO intakes.

Yeah I know, he runs a CNC program for that stuff to mimic his heads and probably doesn't want to tweak it. I imagine it's as much of that as it is that less people want to modify those factory aluminum intakes anyway and he sees less of it these days. Not worth the hassle.

I find there is usually enough material for at least a basic RAIV port.