MassVette,

I can't tell if the ZZ454 is the same otherwise as the 454HO except for heads... Oval port heads seem right on for street driving at lower rpms. I would want to resuse all the stock parts on the outside (intake manifold, exhaust, etc...) because I am worried about keeping the stock look - I love the '73 functional cowl induction system - and getting the hood to close if the carb sits up too high. Since you went 3x2 you did the same thing, in a way...kept the stock height under your hood. Both motors have same blocks - mech pump bosses, etc? Strange that your block wasn't set up for the clutch - it's the only one I can find that Chevy advertises as having that feature!

Thanks!

 

As far as I can see they're the same motor, except that one has 118cc rectangular port iron heads, giving 8.75:1 c.r., and the other is a 110 cc aluminum oval port, giving 9.6:1 c.r. The cam & pistons are the same. Frankly, I'd use a hotter cam than 510/540 that's in the motor, in conjunction with the rectangular ports- which don't perform as good as the large ovals until 3000+ rpm's.
I dunno about the clutch pivot boss on the current HO454- but I'd double check it. All in all, it's been a great, rugged, trouble-free & reliable motor!

 

MassVette,

All this is just too cool! I went to GM Parts Direct and added three engines to my wish list - now sharing for consideration of the forum. Note that the 502HO is within $50 of the price of the ZZ454. Of course the 502 expressly states that electric fuel pump is required... Tough call between those two - and of course the 454HO remains a solid candidate as well.

Your Wish List

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GM PART # 12498777
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $7,746.90
OUR PRICE: $5,422.83


DESCRIPTION: ENGINE
12498777 ZZ454/440 Crate Engine
The ZZ454/440 offers tremendous value in a big-block crate engine. Based on the proven 454 HO with its Gen VI 454 block, the addition of GM Performance Parts Signature series aluminum heads reduce weight and increase horsepower to 440, up from the 454 HO's 425.

The ZZ454 shares its forged crankshaft and connecting rods with GMPP's 454 HO and the family of famous 502 crate engines, so you know it's strong. Forged pistons fill the block, and a steel roller camshaft times the valves. Complete with dual plane intake manifold, water pump, torsional damper and automatic transmission flexplate, the ZZ454 is one value packed big-block crate engine.

With its throttle responsive 9.6 to 1 compression ratio, the pump gas friendly ZZ454 is a great choice for muscle cars, bracket racers and off-road truckers. Just add your 850 CFM carb, GM HEI distributor, and 2 1/4" primary headers and you're ready to rip.

The ZZ454/440 is intended for use in 1979 and earlier pre-emission street vehicles and any year off-road vehicles.

GM Crate Engines are horsepower rated to SAE Standards.

Technical Notes: ZZ 454/440 Technical Information
Horsepower 440 @ 5250 RPM
Torque 500 @ 3250 RPM
Max. Recommended RPM 5500 RPM
Compression Ratio 9.6:1
Block 12550307 Cast Iron - Four bolt mains
Crankshaft 14096983 Forged Steel
Connecting Rods 10198922 Forged Steel
Pistons 10215228 Forged Aluminum
Piston Ring 12523921
Camshaft 24502611 Hydraulic roller;
Lift: .510" I, .540" E.;
Duration @ .050: 211º I, 230º E.
Timing Chain 10114177 Single Roller
Cylinder Heads 12363390 Cast aluminum 110 cc combustion chambers
Intake Valves 12366986 2.19"
Exhaust Valves 12366988 1.88"
Rocker Arms 12368082 1.7:1
Torsional Damper 10216339 8"
Flexplate 10185034 14"
Valve Lash Net Lash Fuel 92 Octane
Spark Plugs #4 Rapid Fire Gap .045
Ignition Timing 4º BTDC

Technical notes: For manual transmission applications use flywheel P/N 14096987 and a suitable 11" clutch assembly. Distributor P/N 93440806 or melonized distributor gear P/N 10456413 must be used on all crate engines with steel camshafts.


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GM PART # 12568774
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $6,723.84
OUR PRICE: $4,706.69


DESCRIPTION: 454 HO ENGINE
The 454 HO offers tremendous value in a big block crate engine. Based on the Gen VI block, this 425 horsepower cast iron head engine is a great choice for that muscle car in the garage. We've heard of several of our customers replacing their rare matching number 396, 427 or 454 with our 454 HO in order to drive their car on today's gasoline without fear of destroying their classic engine.The HO stands for high output, it also stands for big valves, rectangular ports, forged pistons, forged steel crankshaft, forged connecting rods and four bolt mains. Sounds a lot like the performance big blocks of the late 60's doesn't it? When you add in the steel roller camshaft, shotpeened rods, windage tray, one piece rear main seal and high speed single roller timing chain, it starts to sound more like the performance big block of the new millenium. And it is. The 454 HO makes 500 ft.lbs of torque with its rectangular port open chamber cylinder heads. With 118cc combustion chambers, the modest 8.75 to 1 compression ratio loves today's pump premium and has no appetite for lead, octane boosters or other fuel additives. Its 2.19" intake and 1.88" exhaust valves and high lift .510"/.540" roller cam let it breathe with the best of the early muscle motors. With your carburetor, HEI distributor, exhaust system you've got a muscle cruiser worthy of your time, effort and expertise. And, if you want to use your muscle car's fuel system with a mechanical fuel pump, you can because the 454 HO Gen VI block has a conventional style fuel pump boss. The 454 HO is not intended for marine use, and should only be used in 1976 and earlier pre-emissions street vehicles or any year off road vehicles.

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GM PART # 12568778
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $7,845.84
OUR PRICE: $5,492.09


DESCRIPTION: 502 HO ENGINE
12568778 502 HO There is no replacement for displacement, and torque is king. With 550 Ft. Lbs. of torque the 502 HO will launch your car harder than you thought possible. With its 450 horsepower and awesome torque the 502 HO may have the best power to dollar ratio going. If your car is all steel, you'll appreciate the power of the 502 HO and if your car is a light weight racer, say 2300 pounds, the 550 ft.lbs. of torque will put a big ol' grin on your face. This engine is awesome. Starting with a Gen VI four bolt main block, we fill it with forged pistons, forged 4340 steel connecting rods with 7/16" bolts, a 1053 forged steel crankshaft, and a steel roller camshaft. Then we torque down a pair of big breathing rectangular port heads with 2.19" intake and 1.88" exhaust valves. With their 118cc combustion chambers yielding a streetable 8.75 to 1 compression ratio, this engine is ready to rock on readily available pump premium. We then top it all off with an aluminum dual plane intake manifold and dress the engine with a cast iron water pump, 6 quart oil pan, windage tray, 14" flexplate and torsional damper. So, all you need to do is provide an 750 cfm carburetor, HEI ignition system, headers with 2"x30" primaries and low restriction mufflers and a car with big sticky tires. Sounds simple, and it is. Check with your GM Performance Parts Authorized Center for specific oil pan needs for your application. The 502 HO requires an electric fuel pump because the 502 Gen VI block has no mechanical fuel pump boss. The 502 HO is not intended for marine use, and should only be used in 1975 and earlier pre-emissions street vehicles or any year off road vehicles.

 

I wish Id known about this before. I designed my own plate and used existing tapped holes and created one more tapped hole nearby. It works fine but was tricky.

 

If you wanna know anything about Corvettes- you're in the right place!

 

I just discovered Sallee Chevrolet in a "Crate Motor" web search.

http://www.sallee-chevrolet.com/Crat...rformance.html

These guys sell all the GM crate engines plus they do modifications and sell those engines as well. For a real trip, just check out their Ultimate Street 502 and their 572 engines! Of course, for my present needs I noticed that they sell GM-listed partial engines for the 454 and the 502. You can get the 454 engine (short block, pan, no cam) for ~$3,000. This is the Gen VI block with the same pistons as the 454HO and the ZZ454. For ~$4,000 you can get the same in a 502 flavor that includes the ZZ502 cam. Either would require me to also buy a new flywheel for ~$100. Also, either option would allow me to use my heads, intake and exhaust from the original 1973 engine in my car.

I also can't tell (if I go with a new long block or whole engine) if the new GM heads would accept the chrome valve covers I use now (for Gen IV) which I got from Zip as reproduction vintage big block pieces. I like them because they have the wire looms and oil drippers. I will also continue to run my stock a/c system. Any other compatibility issues I am missing?

Very interesting to consider...thoughts?

 

The nice thing about 454HO and 502HO engines are they would be a good platform for adding a blower at a later date.

The compression is low and one member here said the cam in them is good for a blower engine.

The thing about the 502 is the thought of having over 500 ci is so COOL. Many people don't realise they make engines that big!

 

As I continue my musings...I re-read the book "How to Restore and Modify Your Corvette 1968-1982" by Richard Newton and published by Motorbooks International. This is a great book that all should own! Anyway, the author goes on and on about how great Racing Head Service was with his engine. I know that RHS was with Competition Cams - they were across the street in Memphis - but now I get nothing when I do a web search for RHS. Did they go out of business? They are a possibility for yanking my engine and trucking it to them to do a high-tech rebuild... Would like to know if this would compare to the ZZ454 that I will otherwise want to have! Thoughts? If not RHS, any other companies that are known for rebuilding a customer engine better than a local machine shop can? I would want the specs from the ZZ454 - that is plenty of power and torque for me - love those aluminum heads too!

 

Just hoping someone has one of their engines and knows the current status of the company...

 

Just in case I were to go with a motor like a ZZ502, am I justified in having fear of mounting a pump in the rear by the gas tank? Is it safe and are there kits to shield the wiring from switched power source back to the pump? I am sure many of you use electric pumps, I just don't have that experience, so far...

 

You guys from St Louis Nice cars. I will have to come check you guys out when I come home in the spring time...well if my car is done by then anyway. LOL does this place look familiar?http://www.classiccarandtruckclubofb.../mine/the3.jpg Babar state park. I miss the leaves changing colors. Sorry got off the subject I will be quiet now


Semper Fi

 

Guys,

I read another book (my household goods finally arrived here!) and I found some clipped articles from CC, HR and Corvette Fever. As a result I am starting a new thread about Crate Engines and Recon Auto Reman doing my old engine for me... Please jump over there and we can continue the bench racing, garage dreaming, etc...

New Thread is here: http://forums.corvetteforum.com/show...post1549031631