- Thread starter
- #21
need more power for my '74 454
- Thread starter dsbjc4
- Start date
Hib Halverson
Technical Writer for Internet & Print Media
From a performance standpoint, the two biggest problems with the 454 in a 74 are low compression and an awful intake manifold design. Neither are cheap to fix.
Before you begin a modification program for your 74, you need to decide if you're going to change the hood or not. There are few high-performance intake manifolds available for BBs in C3s with stock hoods and there are no intakes suitable for racing. If you want to free-up the engine to make even a modest increase in power output, you need to change the hood to one which will clear a better intake manifold.
My suggestion is you go the alternate hood route then add an Edelbrock Performer RPM manifold and camshaft package and headers. I'd also pull the heads give them what many cylinder head porters call a "street port and polish" and have the larger "L88" intake valves (2.19-in) installed. For a carburetor, I'd either retain the stock Quadrajet but modified to suit the new engine set up or I'd go to a 750 Holley carb.
Needless to say, you also need to add a low restriction exhaust system, appropriate changes to the ignition system and spark curve and the usual cooling system enhancements.
An engine set-up like that is going to make 420-440 hp. If you go as far as changing pistons to raise the compression to 9.5:1, you might see 465.
Before you begin a modification program for your 74, you need to decide if you're going to change the hood or not. There are few high-performance intake manifolds available for BBs in C3s with stock hoods and there are no intakes suitable for racing. If you want to free-up the engine to make even a modest increase in power output, you need to change the hood to one which will clear a better intake manifold.
My suggestion is you go the alternate hood route then add an Edelbrock Performer RPM manifold and camshaft package and headers. I'd also pull the heads give them what many cylinder head porters call a "street port and polish" and have the larger "L88" intake valves (2.19-in) installed. For a carburetor, I'd either retain the stock Quadrajet but modified to suit the new engine set up or I'd go to a 750 Holley carb.
Needless to say, you also need to add a low restriction exhaust system, appropriate changes to the ignition system and spark curve and the usual cooling system enhancements.
An engine set-up like that is going to make 420-440 hp. If you go as far as changing pistons to raise the compression to 9.5:1, you might see 465.
- Thread starter
- #23
thanks for all the advice. that souds like a great idea but i don't know if i want to cange the hood, exhaust is no prob. 2 1/2" pipes and headers. what headers do you think would fit best? is there a good intake out there that would work with out changing the hood?
74bigblock
Well-known member
see if this is a small enough file...
- Thread starter
- #25
74bigblock
Well-known member
dsbjc4 said:
Tnx! Mine's an Auto. I didn't want another stick... I've got a 98 Trans AM with a 6 speed, and my knees are going to s h i *.
It's a gorgeous day out by us... about 45 and sunny. Good day to powerwash her. Unfortunately, mine is in a corner at my mechanics place. We had some issues with the Hooker Sidemount headers.
- Joined
- Feb 13, 2003
- Messages
- 5,475
- Location
- Ottawa, Canuckistan
- Corvette
- 1973 coupe L82 (gone as casualty of divorce)
Re: more power for my 454
You should be able to inspire enough extra horsepower using your stock block. As Hib said, the real restrictions are the intakes and the exhaust (but isn't that always the problem?
) so with a cam change & headers, you'll get the most bang for your buck. The next step would be changing the hood and addressing the intake & carb. Good luck!!
Hib, I've heard of some guys cleaning up & polishing the inside of these 454 intakes and gaining HP but I've never seen any testing. Any thoughts?
Remember, bolt-on also means bolt-off so as long as you save the old parts, you can bolt them back on at any point. If you thinking of restoring the car in the future, THROW AWAY NOTHING. Save those rusty exhaust bolts, save everything because you never know what the future holds. Another great idea is to record (ie: photograph with explanation) before you remove any parts so you'll know what it looked like and what changes you'v made. Some guys go as far as removing the old #-matching engine and bagging it up (sealed so no condensation) then put whatever motor you want in for driving. It doesn't sound like you're that far gone.dsbjc4 said:
You should be able to inspire enough extra horsepower using your stock block. As Hib said, the real restrictions are the intakes and the exhaust (but isn't that always the problem?
) so with a cam change & headers, you'll get the most bang for your buck. The next step would be changing the hood and addressing the intake & carb. Good luck!!Hib, I've heard of some guys cleaning up & polishing the inside of these 454 intakes and gaining HP but I've never seen any testing. Any thoughts?
J
jfb4548
Guest
Re: Agreed...
Maybe if their racing trucks!:gap
c5d said:
Maybe if their racing trucks!:gap
G
goGM
Guest
Current Big Block performance choices
You have several good cost effective options from GM Performance that will give you way more performance and preserve your matching #s investment value.
Option one is a 454 HO crate motor which will replace your 1974 (so you can restore it to correct condition). The engine block is drilled for a clutch linkage arm stud if you have a manual transmission but the engine is shipped with an automatic transmission flexplate (some optional parts are listed after the specs which below).
454 HO Specs
Horsepower ..................... 425 @ 5250 RPM
Torque .......................... 500 @ 3250 RPM
Max. Recommended RPM ..... 5500
Compression Ratio ............. 8.75:1
Block ............................ 12550307 Cast Iron - Four bolt mains
Crankshaft ...................... 14096983 Forged Steel
Connecting Rods ............... 10198922 Forged Steel
Pistons .......................... 10215228 Forged Aluminum
Piston Rings .................... 12523921
Camshaft ........................ 24502611 Hydraulic roller
Lift: .510" I, .540" E.
Duration @ .050: 211o I, 230o E.
Timing Chain ................... 10114177 Single Roller
Cylinder Heads ................. 14096801 Cast iron 118cc combustion
chambers
Intake Valves ................... 14097045 2.19"
Exhaust Valves .................. 14097049 1.88"
Valve Springs ................... 14097002
Rocker Arms .................... 12523976 1.7:1
Torsional Damper .............. 10216339 8"
Flexplate ........................ 10185034 14"
Valve Lash ...................... Net lash
Fuel ............................. 92 Octane
Spark Plugs ..................... MR43T Gap .045
#10 Rapid Fire Gap .045
Ignition Timing .................. 4° BTDC
Technical Notes: For manual transmission applications use flywheel 14096987 and a suitable 11" clutch assembly.
Distributor P/N 1104067 or melonized distributor gear P/N 10456413 must be used on all crate engines with steel camshafts.
Option two may require a bit of adaptation to install a Gen VI based big block. GM Perfomance offers a ZZ502 with 550 lb-ft of torque and 502 HP. The torque curve on this beast starts at over 500 lb-ft from just over idle RPM. I've had a car with this type of tune and it's the most awesome street tune imaginable. The only way to descibe it is to imagine your accelerator pedal directly connected to your speedometer needle (instant speed changes at any street speeds). That engine does not accept mechanical clutch linkages (no stud hole provided), so some type of hydraulic linkage would be needed (ala late model Camaro/Firebird).
The ZZ502 can be ordered as a compete engine, a complete partially asembled engine (heads and manifold unattached to allow for easy porting), or a base kit (no mainfold or carb to allow for personal selections.
The beauty of these approaches is getting exactly what you want (with the latest factory engine technology) and not having to wait for step by step engine rebuild projects to get your car on the road.
Check out GM Performance Crate Engines at http://www.gmgoodwrench.com/gmgoodwrenchjsp/perfparts/home.jsp
Good luck!
You have several good cost effective options from GM Performance that will give you way more performance and preserve your matching #s investment value.
Option one is a 454 HO crate motor which will replace your 1974 (so you can restore it to correct condition). The engine block is drilled for a clutch linkage arm stud if you have a manual transmission but the engine is shipped with an automatic transmission flexplate (some optional parts are listed after the specs which below).
454 HO Specs
Horsepower ..................... 425 @ 5250 RPM
Torque .......................... 500 @ 3250 RPM
Max. Recommended RPM ..... 5500
Compression Ratio ............. 8.75:1
Block ............................ 12550307 Cast Iron - Four bolt mains
Crankshaft ...................... 14096983 Forged Steel
Connecting Rods ............... 10198922 Forged Steel
Pistons .......................... 10215228 Forged Aluminum
Piston Rings .................... 12523921
Camshaft ........................ 24502611 Hydraulic roller
Lift: .510" I, .540" E.
Duration @ .050: 211o I, 230o E.
Timing Chain ................... 10114177 Single Roller
Cylinder Heads ................. 14096801 Cast iron 118cc combustion
chambers
Intake Valves ................... 14097045 2.19"
Exhaust Valves .................. 14097049 1.88"
Valve Springs ................... 14097002
Rocker Arms .................... 12523976 1.7:1
Torsional Damper .............. 10216339 8"
Flexplate ........................ 10185034 14"
Valve Lash ...................... Net lash
Fuel ............................. 92 Octane
Spark Plugs ..................... MR43T Gap .045
#10 Rapid Fire Gap .045
Ignition Timing .................. 4° BTDC
Technical Notes: For manual transmission applications use flywheel 14096987 and a suitable 11" clutch assembly.
Distributor P/N 1104067 or melonized distributor gear P/N 10456413 must be used on all crate engines with steel camshafts.
Option two may require a bit of adaptation to install a Gen VI based big block. GM Perfomance offers a ZZ502 with 550 lb-ft of torque and 502 HP. The torque curve on this beast starts at over 500 lb-ft from just over idle RPM. I've had a car with this type of tune and it's the most awesome street tune imaginable. The only way to descibe it is to imagine your accelerator pedal directly connected to your speedometer needle (instant speed changes at any street speeds). That engine does not accept mechanical clutch linkages (no stud hole provided), so some type of hydraulic linkage would be needed (ala late model Camaro/Firebird).
The ZZ502 can be ordered as a compete engine, a complete partially asembled engine (heads and manifold unattached to allow for easy porting), or a base kit (no mainfold or carb to allow for personal selections.
The beauty of these approaches is getting exactly what you want (with the latest factory engine technology) and not having to wait for step by step engine rebuild projects to get your car on the road.
Check out GM Performance Crate Engines at http://www.gmgoodwrench.com/gmgoodwrenchjsp/perfparts/home.jsp
Good luck!
Glensgages
Well-known member
{goGM, if the phone hadn't rung while I was posting, I'da beat you to the punch!!!}
So far in this thread, I've seen nothing mentioning 'budgetary-concerns'.
dsbjc4 has a numbers-matching last-year-of-the-Rat Corvette, and wants more power, presumably WITHOUT jepoardizing his pride & joy, so I'll throw-out THIS idea:
Have you considered 'tagging & bagging' your OEM 454, and dropping-in a new, crate-motor (with warranty) from your local Chevy dealer?
The '03 catalog lists:
'454 HO' (425 HP/ 500 ft/lb TQ);
'ZZ 454/440' (440 HP/500 ft/lb TQ);
'HT 502' (338 HP/512 ft/lb TQ);
'502 HO' (450 HP/550 ft/lb TQ);
and the 'ZZ502/502' (502 HP/567 ft/lb TQ).
{the HT502 is basically a 'truck/towing' motor, making just 338 HP, but having 512 ft/lb of TQ, too <same as a Buick GSX>; MUCH MORE than an LS-4...}
ALL are designed for today's pump-gas, and (I'm guesing?) much of your existing hardware (exhaust, bracketry, etc.) will fit, too.
If/when you decide to go the 'NCRS-route', put the OEM motor back-in, and sell-off the crate-motor, or use it in your 'next' project.
Even tho my '82 'ONLY' has the lowly 200 HP Cross-Fire, it has just 21,000-miles. I'll 'tag & bag' the original motor, then build another CFI.
Just my $.02 worth.....
So far in this thread, I've seen nothing mentioning 'budgetary-concerns'.
dsbjc4 has a numbers-matching last-year-of-the-Rat Corvette, and wants more power, presumably WITHOUT jepoardizing his pride & joy, so I'll throw-out THIS idea:
Have you considered 'tagging & bagging' your OEM 454, and dropping-in a new, crate-motor (with warranty) from your local Chevy dealer?
The '03 catalog lists:
'454 HO' (425 HP/ 500 ft/lb TQ);
'ZZ 454/440' (440 HP/500 ft/lb TQ);
'HT 502' (338 HP/512 ft/lb TQ);
'502 HO' (450 HP/550 ft/lb TQ);
and the 'ZZ502/502' (502 HP/567 ft/lb TQ).
{the HT502 is basically a 'truck/towing' motor, making just 338 HP, but having 512 ft/lb of TQ, too <same as a Buick GSX>; MUCH MORE than an LS-4...}
ALL are designed for today's pump-gas, and (I'm guesing?) much of your existing hardware (exhaust, bracketry, etc.) will fit, too.
If/when you decide to go the 'NCRS-route', put the OEM motor back-in, and sell-off the crate-motor, or use it in your 'next' project.
Even tho my '82 'ONLY' has the lowly 200 HP Cross-Fire, it has just 21,000-miles. I'll 'tag & bag' the original motor, then build another CFI.
Just my $.02 worth.....
- Thread starter
- #31
I would love to be able to drop a new 454ho in my 74, but there is budget problems. I have to redo the interior and get a fresh coat of paint put on. not to mention new ball joints, tie-rods ,bushings,engine bay paint, and any other things that may come up. I am trying to get the most bang for my buck with out going crazy. the only thing I am saving on is that I will be doing most of the work myself.
thanks for all the advice, this is a great site, with alot of informative people.
dsbjc4
thanks for all the advice, this is a great site, with alot of informative people.
dsbjc4
B
bigvette1
Guest
A full tune up and some minor changes will wake the 74 bb up.
1. New plugs, Accel or MSD 8.5mm wires
2. Air filter. Consider a K& N for higher flow.
3. New mag pickup dist. or a HEI conversion and an MSD 6al or Crane HI-6 ignition box along with the matching coil. Box up the origional distributor on the shelf.
4. Set up your timing for base and 36 degrees total with a faster advance curve. You want it all advance in by 3000 rpms. Stock setup does not let it come on until about 4500-5000.
4. Freshen up the Q-Jet with a good cleaning and rebuild. Set up this is a strong carb. Consider Lars Grimsrud on this forum or on the Corvette Forum to rebuild and calibrate the carb.
5. Consider a set of roller tip rockers and lash adjust. Both Crane and Comp Cams make a good set for about $150.
See where you are at this point. All of this will move to a stronger buildup if desired. As others said - the aftermarket intakes do not fit under the stock hood. The only one is the Edelbrock Torker II and that is a single plane vs the dual plane intake. (whole other topic)
Good luck and enjoy.
1. New plugs, Accel or MSD 8.5mm wires
2. Air filter. Consider a K& N for higher flow.
3. New mag pickup dist. or a HEI conversion and an MSD 6al or Crane HI-6 ignition box along with the matching coil. Box up the origional distributor on the shelf.
4. Set up your timing for base and 36 degrees total with a faster advance curve. You want it all advance in by 3000 rpms. Stock setup does not let it come on until about 4500-5000.
4. Freshen up the Q-Jet with a good cleaning and rebuild. Set up this is a strong carb. Consider Lars Grimsrud on this forum or on the Corvette Forum to rebuild and calibrate the carb.
5. Consider a set of roller tip rockers and lash adjust. Both Crane and Comp Cams make a good set for about $150.
See where you are at this point. All of this will move to a stronger buildup if desired. As others said - the aftermarket intakes do not fit under the stock hood. The only one is the Edelbrock Torker II and that is a single plane vs the dual plane intake. (whole other topic)
Good luck and enjoy.
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