Why can't Edelbrock produce a decent trans am manifold?
 

It's common knowledge that the pontiac edelbrock performer is not as good as even the stock cast iron pontiac restricted secondary manifold.

I took a mold of on of the runners to see what we were dealing with. The runner dimensions near the plenum are 1.275 by 1.720= 2.19in2, compared to 1.1 by 2.07=2.277in2 for the stock 6x cylinder head port sizes.

Why on earth would edelbrock produce a manifold with runners 4% smaller than a standard pontiac head port?

I'm kind of stuck running the performer because I've got the aluminum D port heads, and I'm trying to keep it looking stock so torquers and RPM manifolds are out.

All edelbrock needs to do is take a stock 455SD manifold and recast it out of aluminum. I'm sure they'd sell lots
Attachment 655663

Attachment 655664

I put an edelgarbage on my ta, stock one was better. One day I’ll swap it back. First, you gotta file off their logo and paint it. That’s what I did.

The SD455 manifold would be a poor choice to copy. It has a complicated EGR system and a restricted plenum because of it. No need to copy the aluminum HO/RAIV manifold as they were being made by GM at the time.

The Performer manifold was designed to be an improvement over OEM manifolds on mostly stock 75-79 smog motors and it usually did just that. It came out in the early 80's when there were millions of engines like that, so Edelbrock wanted to make a manifold for those potential customers. The flat carburetor flange could be an advantage on almost every vehicle out there but the Trans Am.... Fwiw

The days of Edelbrock developing Pontiac intake manifolds are long behind us now.

For most people a ported iron or reproduction RAIV or 455 HO intake will easily handle the job and fit exactly like it needs to for cars with Trans Am shakers and low clearance fiberglass Formula hoods.

The only company that’s currently designing and putting out different new Pontiac intakes is Kauffman Racing Equipment or KRE. Maybe they’ll consider producing a Trans Am specific intake if they find the demand is great enough.

Edelbrock sadly is no longer a player, especially so since being sold after the passing of Vic Edelbrock Jr. to venture capitalists who have zero intention of expanding their product line.

If you scanned one, there's great things going on with 3d printing these days, carbon is crazy expensive but the point being, if you want it bad enough, you can make a better one.

Hell I made a 12-1 bolt on crank trigger kit for us, not cheap to design or fast but it's awesome to have done it. I guess if could recoupe if I offered it for sale so you could too.

If I win the lottery, I'll have someone make me a manifold using whatever technology

I don't have a problem with EGR, or exhaust crossovers. My (3156?) performer has EGR, and so would any reproduction I would make. I also need a crossover because I live in a colder climate.

I've heard the Ram Air reproduction is not very good, but I might buy one and graft a performer crossover onto it, and fake an EGR boss for authenticity

As far as normal driving, my performer/stock qjet runs extremely well. It starts easy, runs smoothly warming up, and has reostatic response in normal driving. My beef is that I'm likely losing 30hp/750rpm at the top end

What’s your hp goal?
If you’re not looking to make over 430 hp then the performer will do that, and even with 455 cid under it.

A 800 cfm Q-jet and a 1/2” spacer is the what’s needed to top 400 hp.

If we are pretty universally stating that the stock intakes are better, and you are looking to stay stock height. I don't understand why you are feeling like you are stuck using the Performer?

Why not invest a little bit of money into a ported stock intake and use that?

Exactly this.

A ported later EGR iron intake is as good as anything up to about 500 horsepower. Just because your heads are aluminum doesn’t mean to have to go to great lengths to put a specially fabricated aluminum intake on that really buys you nothing power-wise and saves a paltry 20 pounds which on a 3700 pound car amounts to nothing.

The ‘73-‘74 EGR intakes with the massive passages underneath are the heavy ones. The ‘75 and up ones are much lighter and even with their D-shaped secondary openings perform on par with even the pre-EGR intakes.

Don’t most people with aluminum heads interested in performance use a RPM intake and an aftermarket drop base air cleaner on second gen’s?

When I was building my RAIV motors for NMCA I ordered a Performer (Super Shops) because Edelbrock does advertise them as "better than stock" . Flow bench showed otherwise compared to my HO intake. I even call tech and they just spouted the same thing even though I told them no it flows worse. Granted not bad but less. Luckily I could swap it for T2 to use on another motor.

Weird deal the 73 SD intake actually picked up flow over not intake at .3! Less HP hit in factoring with iron vs aluminum factory intakes so I could pull some weight out but car ran the same. And that 45 lb intake with that crazy EGR stuff was heavy. The later EGR manifolds not quite as heavy.

On a TA with a Shaker a Performer is 0.5" lower in back than a factory intake so affects the Shaker appearance. and using an angler spacer with the long bolts up fron on a Q jet is a little difficult!
I used an HO on my first E head motor for awhile until a found and extra Shaker base to tweak for a Holly. Then swapped a T2 on it. The HO was restricting it.

Someone on another forum recently posted the intake manifold below. He said that it’s lower than a Performer RPM and better than the Performer. It looks like a clone to me but no idea what it was cloned from but might be worth a shot?

https://www.ebay.com/itm/11653460384...d48b6593ad1540

Looks like an RPM clone to me.

Me too but the poster said that it fits under his hood just fine.

https://www.gtoforum.com/threads/alu...7#post-1052387

Poor man's Extrude Hone ?

Muriatic acid available from Home Depot.
Highly corrosive it will "acid etch" the inside of aluminum intakes and remove material. Contain it inside the intake by using stainless steel plates at the port openings.

On one example using the Performer RPM intake the divider was about 0.200" thick before and about 0.070" after.
Parting line flash was removed inside the plenum area. Material from the intake runners is removed.
Amount of time and/or changes with fresh solution will affect amounts of material removed.

( Side note: Info intended as conversation only. I'm not suggesting to anyone to use this method )


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An aluminum manifold in a colder climate means faster, leaner warmups. When i first bought the car in 1975, the EFE stopped working. The car would not run. With an aluminum manifold, EFE is not needed. I'm running fairly lean: 15 AF at idle, 16.5 at 70mph for fuel economy and emissions.

You are likely right, but running a cast iron manifold strikes me as archaic

I think I'm a bit of an eccentric. I had also bought a holley dominator in '76. I tried running it with the q jet and it was a dog. I even went to holley in detroit and talked to the engineers to find out why. They said "use a holley carb" so I put om a 600 holley double pumper. It really woke the car up. I used that until a decade ago when I put in the performer I had bought in the early 90s. The holley performed great, but I missed the Q jet moan. There is no perfect solution.

I think I'm mostly annoyed that edelbrock missed the mark so badly

What are you meaning colder climate? Do you drive her through winter? I am up here in BC Canada. And wile I don't drive my TA in winter, I do when it's cold spring/falls Performer intake on a 455HO stroker with 800 Qjet manual choke and she runs just fine

How happy are you with the performer in the upper rev ranges, ie, 5-5500 rpm?

And yes, with the performer it runs great under all conditions, including warmup with the automatic choke. I've got a wide band AF meter. When I start the car, it says 11:1. By the time I'm at the end of my street, 14:1. A couple of blocks later, 15:1

Perhaps I'm demanding too much to expect optimum power too.

Curious: Is there enough meat on a cast iron intake flange to use on a high port head? I unwisely tossed the restricted secondary cast iron years ago in disgust.

The factory manifolds are already being cast out of aluminum for years. Just get one of those. I can tell you they work a hell of a lot better than the performer and they accomplish a few things for you. They look stock because they are, they will fit the shaker without jacking stuff, it's aluminum so it matches your heads, and they perform as good as the iron intake.

I've done back to back testing with them out of the box on a high 12 second car and it was identical in et and mph to the factory 70 RAIII iron intake.

Easy solution

I've heard that crap so many times that, "if you want a good running engine that it has to have a holley carb on it", what a load of crap that is.......:gag:

My personal experience is running 400, as well as 455 second gen T/As with a street dominator intake for customer cars, autocross cars and my own personal car with only reworked Q jets on them contradicts whoever told you only a holley carb will give you good performance on that intake.

If it were true, why would holley make the carb flange so you can bolt a Q Jet directly to their intake? The intake doesn't know what the brand name of the carb it's bolted to does it? The metering of fuel is all that the engine cares about.

Super stock classes run in the 9s and are required to run Q jets on them. so much for restricting performance.

The Q jet has much more versatility built into it than any other holley carb does and a ton more money spent on developing, and testing them. The Q Jet is also very adjustable to allow it to fit so many applications, and it seems that many in the performance arena have no understanding of the complexity of the carb. If you don't understand how something works, you surely can't expect someone to make correct adjustments to make it optimum in a performance application.

If you want an aluminum intake that will allow the scoop to be functional an Edelbrock P4B will fit the bill. However it isn't going to flow any more air than the already scienced out iron factory intake.

The truth is Pontiac engineers made such a good intake that the aftermarket has nowhere to pick up performance over it in a 2 plane intake. That's why the single planes can pickup performance over a 2 plane when it comes to more than a street engine, say above 500 HP. The factory dual planes are already very good as designed.

FWIW, all my racing efforts were topped with Q jet carbs, be it drag racing, circle track, or autocross. As you can see in my signature pics I was successful using the Q Jet in all the venues. I wish I had a dollar for every time I was told by a competitor that my cars would run much better with a holley on them, how much better could I run than first place? LOL.....:D

I quit listening to recommendations from people that weren't very knowledgeable decades ago, all they do is hold you back.

I mean, the Performer line of intakes dates back to I think 1982 from a quick Google search. Thats older than me, and Im in my 40s. So I think you are splitting hairs a bit when a stock iron intake seems archaic compares to a 40 year old aluminum design.

We can say Edelbrock missed the mark, but they sure have sold a lot of those Performers. So did they? And they are fairly big turds across all makes when compared to other offerings. They are just particularly big turds on Pontiacs because the factory intake is better than average.

40 years later we are better at the science of making power, and better at dispensing good information. At the time the prevailing thought was probably if its sold at the speed shop its better than factory. And who was there to tell them otherwise. This is also the same era of "my buddies 327 jumps coke cans in the rain" and "3/4 race cams". Its hard to fault the company for an old design (that strangely still sells).

They may have had some data that showed if you put it on a smogger head it picked up a tenth. When they go for a redesign in the RPM, making it taller for more performance potential is an obvious choice. Unfortunately that choice hurts the shaker crowd.

The Tomahawk intakes are in the stock location and work really well on 500 HP engines. 455s have plenty low end with a small single plane intake like the Tomahawk.

I don't think anyone will design a 2-plane manifold better than the factory manifold that will fit under a shaker hood without a lot of modifications. For example, this engine in the link below made almost 600 HP on a factory aluminum intake.

https://forums.maxperformanceinc.com...d.php?t=797155

A little port work will wake up a factory aluminum intake. Back to back testing on my 462 the ported intake picked up 56hp and 28TQ over a stocker.

Buy a repro RAIV intake and port match it if you want to appear stock.

You could just put on a Torker II and paint the intake and heads. It will look close enough to stock to draw very little attention. With the shaker and pan in place, there isn’t much to see if it’s all painted blue.

Correspondence from Edelbrock in 1974
 

Even then Edelbrock found it difficult to improve upon a stock Pontiac manifold.

I love qjets. On a two plane manifold, it works, and almost as importantly, sounds great.

As far as using a qjet on a holley dominator, I went to holley in detroit and talked to the engineers when I was unhappy with the behavior. They said to use a holley. In the catalog, it even said, "best performance with a square bore carb". It didn't say this for other makes.

The beauty of a holley is tunablity. You can change jets easily on the car. Accelerator pump tuning is very easy. On a qjet, accelerator pump tuning is limited. One big problem with the qjet on the dominator was soggy response in part throttle driving, that I fixed easily with the double pumper by upping shooter size

Carbs do not just supply a generic amount of air an fuel. Since we are dealing with a two-phase flow, distribution is important. To this end, holley thottle bodies pivot towards the middle, qjets, to the back.

30 years ago, when I tried the qjet on the dominator, wide range AF meters did not exist. Perhaps it would have helped.

Besides the aluminum version of the RAIV manifold that has numerous complaints on poor quality and not lining up with the ports on the heads what other aluminum factory intakes are being reproduced? I’m unaware of anything else, the OP stated that he doesn’t want one of those due to the numerous issues/complaints.

Hi Bob that letter is great thanks for sharing

Another car I know fairly well is the Porsche 911SC. Porsche claims 180hp for this car using a 6500rpm redline and a 34mm port size

Based on the edelbrock performer runner area of 2.19in2, I calculated the hp a pontiac should make on the basis of runner area and volumetric efficiency. I used .95 vol.eff for the porsche, .85 for the pontiac. The number I came up with was 330, with an rpm redline of 5900. This would of course be net hp. This assumes an optimum cam. Edelbrock says idle to 5500, and the crane cam I used was power up to 5600rpm.

I did the same calc using the holley dominator that has a runner area of 2.5 in2 and the calculation was 380hp

Thanks for this, and to all the other posters too. I'm still not able to "like" posts on my pc, for unknown reasons.

"The truth is Pontiac engineers made such a good intake that the aftermarket has nowhere to pick up performance over it in a 2 plane intake. That's why the single planes can pickup performance over a 2 plane when it comes to more than a street engine, say above 500 HP. The factory dual planes are already very good as designed." Sirrotica Quote.

I have often wondered how frustrating it must have been for Edelbrock to spend time and financial resources to produce an aluminum intake manifold for Pontiac engines that was just a lightweight turd? They tried more than once too. The production iron intake and Q-jet carb that Pontiac made millions of was still the best performing set-up for engines up to 450-500 HP. That demands a whole different level of respect for Pontiac engineers vs say the "mighty Chevy" engines. Bolt virtually any aftermarket part including intake manifolds on a Chevy engine and it improves it! What does that say about the engineering that went into the original components? To me it says allot more about how good and well engineered the Pontiac engine was and a little less about how bad Edelbrock stuff was. JMO

The complaints are unwarranted. Weve discussed this many times how these intakes were patterned off the original pieces. Even iron intakes are documented as being the same. If it bothers someone you guys should be more than capable of spending a few minutes with a grinder to clean up the ports if desired. But I've ran them right out of the box with no discernable power difference over the iron piece. If you want stock appearance and an aluminum intake it's still the best option going, and they work perfectly fine.

In fact I've had 3 of them in my hands as of recent and I've made over 500hp and almost 600 ft lbs. With them on mild 455's in untouched unported form.

If we were talking about a max effort build I wouldn't even be looking at a dual plane anyway so you have to ask yourself what are we really doing here?

Dyno tests on my RAIV 400 motor stingy dyno though muffler my HO and a 800cfm 73 SD SR Q ket , a 3310 holley on a T1 and then a T2 all dynoed the same HP. Single planes lower TQ at bottom end. Q jet on the T1 at the track killed bottom end even with a 4000 stall and 4.56s. Gained a couple of MPH but lost so much 60 ft ran slower.

First E head 455. My cleaned up 72 HO SR intake, UD 259/262 solid roller through 3" exhaust-swap at track from a 73 SD QJet reworked by the Carb Shop Brad Urban swapped WITH an open adapter a Demon 850 DP(when they were first out and good) idled better out of the box and picked up 0.3 seconds! So much for an adapter killing things. Later swapped on a single plane T2 and the Demon idled even better and picked up enough to kill the torque convertor and trans(stock rebuilt 350). Not an at the track swap so can't tell you identical exact increase. But with a new looser TQ convertor asnd built TH 350 picked up 0.75 seconds! That was about a 550-575 HP motor.

I have some posts and pictures on my Repop RAIV intake and it took a second one to get OK ports but they still needed weld and a lot of grinding to even get close to a FelPro 1233 gasket! But it is pretty close now.

So all depends on what you are trying to do I do think a stock intake is getting to be the "restrictor" at about 500 HP. Why even back in the day of unported heads in SS they used a Nash or even the Torker 1!

Footnote that first E head motor with the first convertor and the HO intake and Demon in an HPP Shootout in the 100 degree Dallas heat was low 12s instead of high 11s liek it was in good air, but Floyd Hand's car was the same usually high 11s-and a Holley!

I have never seen a OE iron intake with near as much misalignment as the repop aluminums, They do a fine job on the externals but the mold placement for the internal runners leaves alot to be desired, Its not so bad to have the material there to remove to make right but when material is flat out missing or a divider is kicked way over .. no thanks

A tidbit for interest.....

"The Iron's ports are all over the place as far as casting alignment and sizes go. Number's 7, and 8 measure right at 1.900" tall, where the rest average out from 1.950" to 2.010" tall. The picture shows the odd (1-3-5-7) side of the intake, and clearly shows that you'd have a pretty good vacuum leak at #7. Same goes for #8 on the other side."

See post number 9 here:

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


.

That has been my experience as well. I have had my hands on 4 of them. 1 I just sent back. 2nd one took about $700.00 worth of welding, shaping and fitting to make a decent manifold out of it. 3rd one needed the tops of the runners welded to provide some gasket sealing surface. 4th one going on iron heads needed 3-4 hours of massaging to line everything up, no welding required. But the gasket sealing area was about 1/8" flange. I understand they have a very low price point. I do think most people would have no problem paying an extra $100.00-150.00 for a manifold that actually fit correctly so it could also perform well without allot of work.

Every manifold with the exception of possibly the SP2P will support 400 HP. Almost every manifold will support 500 HP with some work. Many of the available manifolds will feed a 600 HP motor. The Victor will make well over 1k HP without welding. There's more than one cast manifold out there that will make more than 1,100 HP without welding. I feel we are fortunate to have so many choices. Maybe I look at things differently, but I'd pick one and finish the project.

Don't get me wrong, I wish everything was perfect and would "bolt on" but in my world that is seldom the case.

PS the reproduction intake manifold quality concerns have been beat to heck on this Website. Thousands have been sold and very few returned. Looking at it from almost every angle, the availability of that manifold was a huge win.... Like it or not.


Maybe we can go back to harping about the 041 cam, the IA1 blocks or the Butler wide-ports; the days a nine second Pontiac was unheard of and staying in front of a 5.0 Mustang was an accomplishment.


I also find it interesting that a pretty pricey intake manifold was brought to market recently that appears to have fuel distribution issues. Not a lot of complaints about that one.... I guess if one pays a lot of money for a poorly functioning intake manifold it's best to pretend it's great

Rant over and thanks for listening :D

You'll have to do some more searching, there have been plenty of pics posted all over this forum of misaligned factory iron intakes. Misaligned factory raIV and HO intakes. The mold for the repop was from one of those factory manifolds. So you get what you get, the same thing Pontiac did 50+ years ago.

I've messed with enough of the repops to know they work. Dividers kicked over I have never seen so not sure what you're talking about there. Port alignment sure, but nothing overly alarming or different than Ive seen on factory intakes.

I really think this stuff has just gotten so blown out of proportion everyone has gotten gun shy and most of the commenters just follow the herd so to speak without any real experience with it.
Like Paul mentions, thousands sold and only a few returned? Those few are all you'll ever hear about in a public forum because that's how people are. Ya just have to take it with a grain of salt, do your own thing and not worry about the few :)

Problem solved. Darbikrash makes a nice (blower) manifold
and he's going to make a custom lid for the shaker guys.

:D :popcorn:

Thanks all for the comments, I have followed this topic here for some time and I have been hesitant to get a HO copy, but not any more and I’m certain once its on I’m going to wonder why I didn’t sooner.

I’ve port matched a few iron intakes to a ra4 gasket,,, gets a little close at the top. I ordered an after market ra4 intake hoping it would be close. After laying on the ra4 gaskets for a port match it was paper thin coverage at the top of the port in a few places. The iron intakes were always much better in that area. For me to feel comfortable using that aluminum intake I would have needed to add some weld at the top for a good seal. I sent it back.

https://forums.maxperformanceinc.com...d.php?t=874887

If you can find one, the very last production runs Edelbrock did of the PB4 intake that was a spread bore pattern were probably the best dual plane Aluminum intakes made that work with all the standard shaker and RA pans, performance was pretty equal to a stock intake. Why Edelbrock dropped it and went with the performer has always been confusing to me. I don’t know, but possibly short comings on the performer go back to Edelbrock trying to make EGR provisions with the performer design, which made some of the runner smaller. I have never seen a Performer for a Pontiac with the EGR provisions, but I have understood they do exist? In that time frame Edelbrock made similar changes for EGR compliance, on other brands, making there stock replacement intakes worse.

Here is a PB4 side by side with a modified stock intake, you can see it has more volume on some of the runners. Personally I am not willing to trade the RPM intake for a design that fits a shaker. I love the RPM intakes. I would certainly trade the performer design for the PB4 though!

Do you mean carbon fiber filament?

Yes there was a Performer EGR version.

All the P4B's have a flat carburetor pad and cause issues with the shaker fitting as they came from the factory.

Every QP4B I've seen has issues fitting with an HEI. The rear runners sweep back towards the firewall and make it a real tight fit for the distributor. I'm pretty sure there is only one Q-jet version and it was most likely put into production around 1973.

Edelbrock replaced all the x4B manifolds with the Performer. Some possible reasons; EPA legal designs, improved modern runners, spread bore or square bore compatibility, having the ability to accept current bolt on accessories and re-selling the "new and improved" manifold to current x4B manifolds. I remember the magazines pushing the modern designed manifold and talking about how great it worked. This was the early 80's and there were millions of late model "performance" vehicles on the road that needed all the help they could get.

Some pictures in here of my SR 72 HO intake and the Repop RAIV. several areas even the bottom corners had to have weld added as they were maybe 1/16" sealing. I have seen a lot of factory intakes and none were as bad as the repops. The SR HO I bought new in 79 was about D port sized and yes different port sizes but there is plenty of material around them to seal even a slightly taller port than the 1233 gasket.
https://forums.maxperformanceinc.com...ht=RAIV+intake

My car has the EGR version, #3156. I don't have a pic handy. I'm likely an outlier in the car hobby community in that I like to keep all the emissions equipment when possible.

As a result, I'm running fully function egr and cats on a '75 car. The dual cats are 200 cell metallics. In the brief time I tried running no cats, I realized I could not be in the garage with the running car and not have to wash my clothes to get rid of the smell.

The emissions equipment once saved my car. The car was running in the garage and all of a sudden, the idle speed went up? There is a switch that goes to manifold distributor vacuum on a hot engine to up fan speed. What had happened is that the thermostat failed closed (for the second time!!).

I've only deleted the EFE as it won't work with the aluminum heads and is not needed with the aluminum performer.