Vintage Oldsmobiles Curved Dash, Limited Touring, Models 40, 53, 66; Series 60, 70, 90

Olds 394 Intake manifold question

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Old Feb 6, 2024 | 11:52 AM
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Olds 394 Intake manifold question

Good afternoon,

My 1957 Olds Super 88 currently has a 1963 Olds 394 engine. The intake is a 2 barrel. Does anyone know if a 4 barrel intake manifold from 1957/1958 will work? It looks similar but wanted to ask.

Thanks.
Old Feb 6, 2024 | 04:29 PM
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Looking at pictures of the 4 barrel 371 and 394 intakes, I can't really tell any difference. If anyone knows, please let me know. Either way I decided to buy the 4 barrel intake. The seller only wanted $25 for it and it does not have any cracks and the intake surfaces look perfect.
Old Feb 6, 2024 | 05:55 PM
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I was told by Ross Racing Engines that 371 intakes will not fit 394s, so as long as it's a 394, you should be good. I thought I could make spacers to put a J2 on a 394, and he said it wasn't worth the trouble. Offy makes a 3x2 intake.

Last edited by fleming442; Feb 7, 2024 at 02:07 AM.
Old Feb 6, 2024 | 09:19 PM
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Originally Posted by fleming442
I Edelbrock makes a 3x2 intake.
That's Offenhauser, not Edelbrock, that makes the 3X2 intake for 394's
57 & 58 manifolds will not fit '59 and up.
Old Feb 7, 2024 | 02:08 AM
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Sorry about that; I fixed it.

So, it's a year thing, not deck height? Or, are they one in the same?
Old Feb 7, 2024 | 07:36 AM
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Yes, deck was raised in '59.
Old Feb 7, 2024 | 08:15 AM
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So, the only difference is the deck height causing the ports not to align? Is there any fix or adapter for that? Either way, it was an inexpensive chance I took.
Old Feb 7, 2024 | 10:38 AM
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The deck height was probably raised to improve rod angularity.
The only fix, is to put that manifold on E-Bay and look around for a 59 thru 64 four barrel intake.
If you have deep pockets, and want something really cool, Exeter Auto supply can get you new 3X2 or dual quad manifolds.
EAS - New Product Page (exeterautosupply.com)
Old Feb 7, 2024 | 10:49 AM
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Thanks. Time to sell or trade it. As always, thanks so much for all the information!!
Old Feb 7, 2024 | 07:13 PM
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My dad put a 394 olds motor in his 57 with offenhauser manifold for tri power and said it was the best engine ever he was drag racing on the street and track and beating everybody. He said it was the perfect setup. Even 409 chevys were no match
Old Apr 16, 2025 | 09:46 AM
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Is there a specific casting number for the correct 4 barrel intake manifold to fit my 1963 394 engine? I've seen many listed on ebay but they all have different casting numbers. I found one local and it has the casting number 590677 or 580677 (hard to read the second digit). It also says D1 on the passenger side by where the carb bolts on.

Last edited by WikedOldsmoileSupe88; Apr 16, 2025 at 09:49 AM.
Old Apr 16, 2025 | 04:18 PM
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Also, what is a good price for one of these? I've seen prices on Ebay that are $350. Seems high to me.
Old Apr 16, 2025 | 06:13 PM
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Originally Posted by WikedOldsmoileSupe88
Is there a specific casting number for the correct 4 barrel intake manifold to fit my 1963 394 engine? I've seen many listed on ebay but they all have different casting numbers. I found one local and it has the casting number 590677 or 580677 (hard to read the second digit). It also says D1 on the passenger side by where the carb bolts on.
Any '59 thru '64 394 four barrel intake will bolt on any '59 thru '64 394 engine.
The carb flange is also the same.
The differences in casting numbers came in location of vacuum port outlets for power brakes etc.
The 573XXX numbers were from '59 and '60 engines
The 580XXX number was from '61 or '62.
And the 381XXX and 382XXX numbers were used in '63 and '64.
Any of those manifolds will work on your 394.
The local one is probably the best choice, no shipping

Last edited by Charlie Jones; Apr 16, 2025 at 06:17 PM.
Old Apr 16, 2025 | 06:25 PM
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Originally Posted by WikedOldsmoileSupe88
Also, what is a good price for one of these? I've seen prices on Ebay that are $350. Seems high to me.
One E-Bay guy started bidding at $259.
394 Oldsmobile Intake Manifold 4BBL # 573323 Olds 88-98 Clean! 1959-1963 Holiday | eBay
Old Apr 17, 2025 | 05:25 AM
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Originally Posted by Charlie Jones
Not a bad looking intake...but that thermostat surface would have a date with my milling machine!
surface of the moon...
surface of the moon...
Old Apr 17, 2025 | 06:16 AM
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Thanks for the comments. The one local is a lot cheaper but I'm concerned about the intake mating surface. Is this ok? I don't have a milling machine, only sand paper on a flat surface to try and clean this up. Thoughts? Thanks.







Last edited by WikedOldsmoileSupe88; Apr 17, 2025 at 06:20 AM.
Old Apr 17, 2025 | 07:45 AM
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I think with some time and effort, you should be able to square up those surfaces with a flat surface/bar and sandpaper. Most intake gaskets have a bit of thickness to them to help seal up those ports. Looking those pics, I'd love to sandblast and machine that beauty. I'm kinda on the hunt for a 4 barrel manifold too. Planning on looking for one at the Oldsmobile Homecoming swap meet in June.

Are you going to block off the exhaust crossover ports? I know that a lot of guys do that with the 394 manifolds. I was speaking to a carb guy about that recently...he said that unless you are driving the car in cold weather, all that crossover does is evaporates some of the fuel. Anyhoo, there are q few post in the forum discussing those ports.
Old Apr 17, 2025 | 08:02 AM
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Thanks for the fast reply. I guess I will take a chance on this one.
Old Apr 17, 2025 | 08:11 AM
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Originally Posted by Tyroma
Not a bad looking intake...but that thermostat surface would have a date with my milling machine!
surface of the moon...
surface of the moon...
Lucky you!
You have a milling machine.
I had to do mine with a large flat file. Fortunately Fusick makes repop water necks.
Two barrel water neck won't work.

Last edited by Charlie Jones; Apr 17, 2025 at 08:13 AM.
Old Apr 17, 2025 | 08:16 AM
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Yeah! Milling machine makes quick work of cleaning up surfaces like this...BUT...not when it's still on the car! For those, a big old file is what I use as well.
Old Apr 18, 2025 | 06:48 AM
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Sadly, that intake deal did not work out. After we agreed on a price and agreed on the shipping he let me know he was keeping the water inlet neck, the temp sending unit and the coil mounting bracket. I did not care about the sending unit or the coil mounting bracket but I needed the water inlet neck. I let him know that but he said he did not care. I thought it was dishonest to post a picture of the item and come to an agreement on price/shipping and then tell me know he is taking parts off the manifold. He still wanted the same price. I guess if there is a positive...at least he told me all this before taking my money.
Old Apr 18, 2025 | 08:37 AM
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Originally Posted by WikedOldsmoileSupe88
Sadly, that intake deal did not work out. After we agreed on a price and agreed on the shipping he let me know he was keeping the water inlet neck, the temp sending unit and the coil mounting bracket. I did not care about the sending unit or the coil mounting bracket but I needed the water inlet neck. I let him know that but he said he did not care. I thought it was dishonest to post a picture of the item and come to an agreement on price/shipping and then tell me know he is taking parts off the manifold. He still wanted the same price. I guess if there is a positive...at least he told me all this before taking my money.
Have you posted an ad for a 4 barrel 394 intake manifold ? I doubt they are a scarce item !
Old Apr 18, 2025 | 09:13 AM
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I have not. But this one was somewhat local to me. The shipping is the issue due to the weight of these intake manifolds.
Old Apr 18, 2025 | 02:14 PM
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Originally Posted by WikedOldsmoileSupe88
I have not. But this one was somewhat local to me. The shipping is the issue due to the weight of these intake manifolds.
I guess you could be considered "local" by anyone, since you don't even have the state listed in your profile that you reside in. Edit your profile to show at least what state you live in. Then post an ad.
Old Apr 18, 2025 | 04:47 PM
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Originally Posted by OLDSter Ralph
I guess you could be considered "local" by anyone, since you don't even have the state listed in your profile that you reside in. Edit your profile to show at least what state you live in. Then post an ad.
Thanks for the advice but I've included my location on many, many different car sites when I've been looking for local parts and I get messages from all over the US. Saying where I'm at does not seem to help limit it too just local parts. But I did update my location. Thanks.
Old Apr 18, 2025 | 07:12 PM
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Originally Posted by WikedOldsmoileSupe88
Sadly, that intake deal did not work out. After we agreed on a price and agreed on the shipping he let me know he was keeping the water inlet neck, the temp sending unit and the coil mounting bracket. I did not care about the sending unit or the coil mounting bracket but I needed the water inlet neck. I let him know that but he said he did not care. I thought it was dishonest to post a picture of the item and come to an agreement on price/shipping and then tell me know he is taking parts off the manifold. He still wanted the same price. I guess if there is a positive...at least he told me all this before taking my money.
Reproduction water necks are available for $40 from Fusick.
Thermostat Housing - 1959-64 Oldsmobile 4V
Considering the cost of shipping, that may still make the local one a better deal.
Factor in that these aluminum necks are highly subject to corrosion, and the seller may have wanted to keep a piece of junk.
Old Apr 18, 2025 | 09:56 PM
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Originally Posted by WikedOldsmoileSupe88
Thanks for the advice but I've included my location on many, many different car sites when I've been looking for local parts and I get messages from all over the US. Saying where I'm at does not seem to help limit it too just local parts. But I did update my location. Thanks.
As far as that pitted surface on the thermostat housing goes, this is exactly what JB Weld was made for. Coat the surface with JB Weld, then sand or file the surface flat. Much quicker if the part is still on the engine than just filing. Works great.
Old Apr 22, 2025 | 03:25 PM
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On the topic of a 4 bbl swap, what's the gain? Specifically, on a low compression 394 (around 8.75:1) I believe about 280 HP with a 2 bbl carb is the expectation. I don't believe Olds put a 4 bbl on the H/L code 394, and it ran single exhaust. So if I were to put dual exhausts and a 4 bbl carb on a low compression 394, what kind of gains could I expect? I'd need to find a 4 bbl carb, the intake, the factory 4 bbl breather/air cleaner or go with an aftermarket air cleaner (and I like the factory air cleaner). Also, the linkages would be different, so I'd have to find 4 bbl linkages for it to work properly- and I'm running a slim jim trans, so I'd have to be careful to set up the "kick down" linkage correctly. Am I right about all that? And is it really worth it on a 1964 Dynamic 88, with the low compression engine? Unless I tear the engine down and replace the dished pistons with flat tops, and then I might as well put in a hot cam... That's a lot of work to get 345 HP (+/-) out of a 60+ year old 20 foot long 4500 lb rag top with drum brakes, 14" wheels, and no seat belts.
Old Apr 22, 2025 | 06:21 PM
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Not sure the gains on your engine. My engine is the high compression 10.25:1 engine with dual exhaust. I don't need the 4 barrel....just WANT the 4 barrel. Plus, my 2 barrel carb has been giving me a bunch of problems so I thought this would be a good route to go.
Old Apr 22, 2025 | 07:21 PM
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Originally Posted by WikedOldsmoileSupe88
Not sure the gains on your engine. My engine is the high compression 10.25:1 engine with dual exhaust. I don't need the 4 barrel....just WANT the 4 barrel. Plus, my 2 barrel carb has been giving me a bunch of problems so I thought this would be a good route to go.
That motor deserves a 4 bbl. I want one too- but I don't think it's something I'm going to do any time soon.
Old Apr 26, 2025 | 06:43 PM
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I have a 4 barrel intake off a 1961 Oldsmobile with a 394 (580677). I am selling it for $250 out of SoCal.

I also have an Offenhauser 3x2 Intake with rebuilt carburaters that I have listed on Facebook Marketplace for $800. According to the Offenhauser Catalog, the intake is a 5019 that will fit both a later 371 and 394 engine; I know it fits a 394 because I tested fitment on an Oldsmobile 394.


Let me know if your interested in either.

Rich
Old Apr 28, 2025 | 06:25 AM
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Thanks Rich for letting me know. I contacted you on Facebook.
Old May 4, 2025 | 11:53 AM
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Hey Dave, it was great meeting you. I hope that 4-barrel intake works out for you as you are doing exactly what I did with my dads 62 Dynamic 88. Hope to see you iun the near future when you get this project going and I get my transmission re-installed.

Rich
Old May 5, 2025 | 06:43 AM
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Hi Rich,

Thanks so much for reaching out and having the intake manifold I needed. Your intake was in WAY better shape than the first one. Thanks again!!
Old Sep 10, 2025 | 06:34 AM
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One more question about the 1963 Oldsmobile intake manifold. I'm going to swap it this weekend. I just realized I don't have a manual for this engine I have one for the car which is a 1957 Olds. I'm assuming the torque for the intake manifold bolts is 30 - 35 ft/lbs. Is that correct? Is there a tightening sequence? I ordered a manual for the 1963 last night but it probably will not be here in time. Thanks.
Old Sep 10, 2025 | 06:51 AM
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Old Sep 10, 2025 | 06:59 AM
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I just finished doing the four barrel swap on my 64
Before and after sand blasting, painting and oven curing
Before and after sand blasting, painting and oven curing
Freshly built 64 Rochester 4Jet
Freshly built 64 Rochester 4Jet
Manifold in place!
Manifold in place!
Ready to run!
Ready to run!
Old Sep 10, 2025 | 09:08 AM
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Thanks so much for posting this. That is a BIG help. Your swap looks great. Will post pictures of mine once it's done. Thanks again!!
Old Sep 10, 2025 | 09:17 AM
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Originally Posted by WikedOldsmoileSupe88
Thanks so much for posting this. That is a BIG help. Your swap looks great. Will post pictures of mine once it's done. Thanks again!!
No problem, Pal! I just so happened to have those pics on my phone from my recent intake swap. Happy to help. Looking forward to seeing pics of your swap.
Old Sep 10, 2025 | 04:54 PM
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Tyroma,
Did you find the linkage pieces for the throttle OK?
Does it shift OK?
I like those chrome valve covers.

Last edited by Charlie Jones; Sep 10, 2025 at 04:56 PM.



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