Author Topic: 454 big blocks came in 2 different sizes?  (Read 762 times)

Offline 86LG4T5

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454 big blocks came in 2 different sizes?
« on: November 04, 2021, 05:53:51 PM »
According to O'Reilly's, the 1974 C30 had 2 different 454's.  One was actually 7436cc and the other was 7441cc.  And they recommend different carburetors depending on which one you've got.  Anybody heard of this?  Or how I know which one I have? Part #4-540 vs Part #4-504.

Offline Shifty

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Re: 454 big blocks came in 2 different sizes?
« Reply #1 on: November 05, 2021, 10:14:00 AM »
Drugs are bad m'kay?

There are different generations of 454, or 7.4 if you like, but there isn't a difference in cc's. 
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87 R30 3+3 Longbed (days of yore)

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Offline wz7u

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Re: 454 big blocks came in 2 different sizes?
« Reply #2 on: November 05, 2021, 08:51:52 PM »
According to O'Reilly's, the 1974 C30 had 2 different 454's.  One was actually 7436cc and the other was 7441cc.  And they recommend different carburetors depending on which one you've got.  Anybody heard of this?  Or how I know which one I have? Part #4-540 vs Part #4-504.
Greetings forum!
Have you tried to look up other years on the O'reilleys webpage or your application on Napa or some other website? Just for kicks I checked my 79 c20, 454: only one displacement listed.

I wonder if a programmer fell asleep at the keyboard and woke up with a start?
'79 C20 454/th400 "Pearl"

Offline VileZambonie

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Re: 454 big blocks came in 2 different sizes?
« Reply #3 on: November 06, 2021, 07:50:21 AM »
either number = 454 but not sure, it really has no relevance.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline 86LG4T5

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Re: 454 big blocks came in 2 different sizes?
« Reply #4 on: November 06, 2021, 05:32:08 PM »
It's actually relevant because they give a different carburetor depending on which 454 you choose.  Part #4-540 vs 4-504. 


Offline SilverMiner

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Re: 454 big blocks came in 2 different sizes?
« Reply #5 on: November 06, 2021, 06:50:17 PM »
It's actually relevant because they give a different carburetor depending on which 454 you choose.  Part #4-540 vs 4-504.

I went on the O'Reilly site and can confirm that they do in fact offer two different cubic centimeter capacities for a 1974 C30. This makes no sense at all as others have already pointed out. For this reason alone red flags should be raised.

I'm more concerned with the fact that you are considering buying a remanufactured TOMCO QuadraJet. None of the companies who remanufacture QuadraJets have good reputations due to the fact that they acquire bulk lots of core carbs and then slam the individual parts together in a more or less random fashion. This completely fouls up the original calibration for a particular engine, trans and gearing combo as specified by the GM engineers. Reman carbs are commonly referred to as Franken-Carbs because nobody knows where the parts originated from. QuadraJets are uniquely specific to particular setups and don't lend themselves well to random swapping.

I fully support your desire to stay with a QJet but would strongly caution against spending good money on a remanufactured one. If you still have access to the original carb it will respond extremely well to a proper rebuild at a far lower price than what you will spend on a Franken-Carb. If you don't have the original, as a Qjet fan it pains me to admit you will probably be more successful buying a new Edelbrock or Holley versus fighting the headaches with trying to get a reman carb to work properly. Qjets are inherently challenging - increasing the difficulty level by swapping incompatible parts just makes everything miserable.

Offline VileZambonie

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Re: 454 big blocks came in 2 different sizes?
« Reply #6 on: November 07, 2021, 07:37:47 AM »
It's actually relevant because they give a different carburetor depending on which 454 you choose.  Part #4-540 vs 4-504.

I've never seen a difference in carburetors based on calculated CC's but manufacturers did do what they could to be in compliance with the gov and somewhere in the fine print may be a way to make some data manipulation happen. The carburetor choice should be based on emissions compliance and original equipment options. Nevertheless, there it is in front of you saying Vin Z, Vin Z meaning the engine itself is the same engine. I'd be interested to see some documentation on using CC's to ID differences in the same exact engine.
,                           ___ 
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              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline bd

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Re: 454 big blocks came in 2 different sizes?
« Reply #7 on: November 07, 2021, 09:51:49 AM »
Well, researching the original GM parts book reveals there were only two Quadrajet 4-bbl carburetors called out for the 1974 C30 454 V8 engines.  P/N 17050608 was used with California emissions having EES.  P/N 17054708 was used for federal emissions without EES.  EES stands for Evaporative Emission System (a carbon canister).

The parts book also shows two 454 engine codes for 1974 C/K chassis.  "TRJ" was used with manual transmissions, "TRW" was used with THM 400 automatic transmissions.

So, it appears that the O'Reilly parts book is ambiguous.  The difference in carburetors is actually based on California versus federal emissions, not mysterious subtleties of engine displacements.

Rich
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In other words... if people learn by making mistakes, by now I should know just about everything!!!
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Offline 86LG4T5

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Re: 454 big blocks came in 2 different sizes?
« Reply #8 on: November 08, 2021, 11:47:43 AM »
A lot of good info here, thanks fellas.  If I can't find a reputable shop to rebuild the one I've got, I'll probably go with Edelbrock.

Offline SilverMiner

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Re: 454 big blocks came in 2 different sizes?
« Reply #9 on: November 08, 2021, 07:40:18 PM »
A lot of good info here, thanks fellas.  If I can't find a reputable shop to rebuild the one I've got, I'll probably go with Edelbrock.

So you still have the original carb? This is fantastic news - does the ID match one of the two either 17050608, 17054708 as researched by bd? Is your engine close to stock or has it been heavily modified as in new heads, big cam, crazy pistons with high compression, etc.

If you are even moderately mechanically inclined, rebuilding the Qjet yourself to a high degree is definitely within your grasp. If you have a local shop who is comfortable with QuadraJets even better, but you can absolutely get it done yourself. Go to https://cliffshighperformance.com/ and purchase one of his kits. No special tools required - the magic juice in the kits includes an ethanol-proof accelerator pump, brand new air bleeds and superior paper gaskets. If you have a hot-rodded and modified engine they will build a custom kit for you complete with new jets plus metering rods, and the detailed info to modify the internal circuits. I know I sound like I am getting a commission for pumping Cliff Ruggle's products but in reality I'm just a very happy repeat customer who has rebuilt quite a few QuadraJets which have made their drivers very happy, including one hot-rod 383.

Going the Edelbrock route will likely work for you as well - there are many good reasons why they sell so many of them and they are so easily available. The Edelbrock clone of the Carter AFB has survived decades for good reasons, but if you value efficiency plus performance nothing tops a well tuned QuadraJet. But don't throw out that old Qjet because there are still some of us out there who value them, particularly those that haven't been molested and abused by a reman outfit and are in near original condition.

Offline haroldwca

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Re: 454 big blocks came in 2 different sizes?
« Reply #10 on: May 21, 2022, 03:26:13 PM »
+1 for Cliff Ruggles. He’s the one to consult for anything related to the Quadrajet.