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Chevy Crate Engine Performance Parts - Performance Q&A

Kevin McClelland Jun 1, 2006
0605_chpp_01_z Crate_engine_parts Kevin_mcclelland 2/1

Crunch Time, Part II
Several months ago I wrote to the fact that I had 18 days to get my son's Chevelle done for the last drag race of the year. Well, I didn't make it and he had to race his mom's '02 Honda Odyssey van! It certainly wasn't the same experience as racing his Chevelle, but he had fun anyway. A few months later and the first points race of the season was upon us. The race was last Sunday, and when did we finish the car? Saturday afternoon. Nothing like cutting it close.

With all big projects, you hope they turn out like you planned. As for the Mini Mac Malibu, I couldn't have asked for more. It was a hand-me-down project in which we installed a dead stock '89 L98 TPI 350 left over from a former GM project, a TH400 that came out of my dad's '55 Chevy, 11-inch front disc brakes, also from my dad (from his '70 Gran Sport), and the 12-bolt posi from my '65 El Camino. We did spend some money on 17x8 billet American Eagle wheels, take-off '04 GTO tires, a complete Vintage Air system, and a complete Hotchkis suspension, and we got a lot of help from Year One.

We rolled onto the dragstrip with too low of gears (4.10s), early shift points (4,000 rpm because we ran out of time), and 25 miles of testing from the house to the track. Daniel heated up the M&H G-60 DOT tires, staged, and ran 14.10 at 92 mph on the very first pass! When we were putting the car together, I figured it would run 14-flat with the stock engine and all the added weight. Needless to say we were very happy, and the look on Daniel's face was worth all the hard work. Eventually, we'll work our way into the paint and body, but for now we're going to drive it a while and just enjoy our creation. I want to thank everyone who came up to us at the track, saying they'd read about it in the magazine and got to enjoy the day with us. Good luck on your own projects.

Chip And Dip
Q I have read your responses to reader questions and realize your work with GM on the replacement crate engine for third-generation Camaros. Can you provide direction or suggestions on where to locate a PROM for this kit? Apparently, the entire kit is no longer available, but I was able to obtain most of the major pieces through my local dealer with the exception of the PROM (PN 24502457). The dealer has been super, but can't get the PROM from GM-the GM Parts Locator could not find one either. I am currently using the stock ECM with an aftermarket PROM designed for the original LG4, but I know the advance curve is inadequate for the 350. Any help you can provide to locate this PROM or a suitable aftermarket part number is truly appreciated. Thanks in advance for your time and consideration.
Gary Friday
Via e-mail

A Gary, it is a very sad day when the General decides to discontinue a part we have come to love and cherish. It kills me every time I call Ken Casey and ask him to look something up, and lo and behold it's gone! He just let me know last week that the '96 Corvette LT4 inlet manifold had left us. If you have one, hold on to that beautiful red manifold. Let's see if we can find you a PROM.

Mark McPhail and I originally did that project for GM. It was groundbreaking at the time to have a 50-state emissions-legal 300hp engine package for a Camaro. It took many hours of camshaft development and calibration to satisfy the smog police and reach the horsepower bogy Mark wanted. The PROM is the heart of the package's drivability and emissions legality. I think we've found a way for you to come up with a chip. Contact GMCOPO; they have a limited supply of the Camaro Performance Package PROMs in stock. They also have the capability to produce custom chips that a customer may desire. Go to, or call (248) 879-9129-the chips won't last long. Good luck with your project.

502 To Go GoQ I have a '68 El Camino with a 350 and a four-speed M-21. I want to add a 502 crate engine. Will I need to do anything special to make it fit? I'm also looking for a nice setup for a clutch and flywheel combination and a good set of headers that will fit with the least amount of hammering in. I want this car to be a driver with plenty of power, but very reliable. Any pointers you can give will help. Thanks in advance!Jeff SalvatiniPalatine, IL

A Jeff, the engine bay of an early A-body just isn't happy until it has a big-block sitting in it! Any of the 502 crate engines from GM Performance Parts are a great choice for a nice street driver. Let's look at some of the parts that will help you out.

Hooker offers a nice set of headers in their Super Comp line that are full-length 1 7/8-inch primary pipes, 35 inches long with 3 1/2-inch collectors. These headers fit in the engine compartment with minimal, if any, hammer love with a Ford Ignition Tool (32-ounce ball-peen hammer). You can pick these headers up from Hooker under PN 2250HKR. The only thing I don't like about these headers is the ground clearance. If the car is very low, you may have a problem. For more information, contact Hooker at (270) 781-9741, or online at If you plan on setting your Camino in the weeds, look at a set of Hedman medium-length headers, which have much shorter primary pipes and the collectors are moved up alongside the bellhousing. The primary pipes are 1 3/4-inch with a 3-inch collector. With this design you can suck the exhaust up under the car and clear the nastiest speed bump. The headers are sold under PN 68610. Hedman says that in some cases with aluminum heads, you may need to notch the header flange for them to clear the lower row of cylinder head bolts. This is no big deal and can either be done with a bench grinder or small handheld grinder. For more information, contact Hedman Hedders at (562) 921-0404, or online at

With over 550 lb-ft of torque on tap, you will need a good clamp between the engine and your M-21. The Dual Friction Centerforce clutch gives you the best of both worlds. They give you a smooth, light pedal effort with the maximum amount of clamping force to tame your big-block. The Centerforce Dual Friction 11-inch pressure plate and disc is sold under PN DF735552. To round out your link between the engine and trans, go with one of their billet-steel flywheels. The Gen V and VI H.O. big-block Chevys have a specific counterweighted flywheel for those engines. Centerforce sells that wheel under PN 700148. This will keep the shakes out of your driveline. You can reach Centerforce at (928) 771-8422, or online at for more information.

Stop The FlexQ I own a '66 Malibu and I'm planning on swapping the engine. It currently has a 230ci I-6 and I want to add some power, just to have fun on the street and maybe take it to the track once or twice a year. I've been toying with the idea of dropping in a 383 or 427 small-block, or even a 454 or 509 big-block. I probably don't need to go beyond 500 hp, and everyone has an opinion on whether I should go big or small. Most arguments for a small-block are that I can get the power and it will be cheaper and lighter. My question is, regardless of the engine I choose, can the car can handle that much power without stiffening the frame. I've already purchased a 12-bolt posi with 4.10 gears and I plan on using a TH350 or TH400 trans. What are my options for stiffening the frame besides a rollcage-and is it even necessary? Thanks for your time.Richard WilsonVia e-mail

A Richard, it's always the same old question. Should I run a big-block or a small-block? You have mentioned many of the small-block's finer points. However, you failed to mention the impressiveness of a fully built Rat in the engine bay of your '66. We think that you could go either way and be very happy.

One of the nice things about the A-body is that it has a full-perimeter frame under them. The El Caminos have a fully boxed frame; however, they will only fit under El Cams and Wagons. For serious street fun and a trip to the track once and a while, the stock frame is more than adequate. There are a few things that will stiffen it up. We would install polyurethane body mounts, which help strengthen the frame by tying the frame and body together. Pick up a set from Energy Suspension under PN 3.4111. This set comes with all the upper and lower body mounts and sleeve and washer hardware. Check with Energy Suspension for more information at (949) 361-3935, or online at

Also, we would install upper to lower rear control arm pick-up point braces. The factory used these in the later big-block cars. Hotchkis Performance has produced a really nice pair they call Trailing Arm Mount Braces. These braces bolt in between the upper and lower pick-up points and are adjustable to fit right in. They come with all the necessary hardware and are direct bolt-in. This brace will reinforce the upper control arm cross-member of the frame. The A-body's rear suspension was prone to wheel hop; many of those crossmembers have been ripped right out of the frame when drivers weren't careful. These braces will eliminate that chance. This brace kit is sold under PN 1403. Give Hotchkis a call for more information at (887) 466-7655, or go online at

Aussie RacerQGreetings from down under. I am a subscriber to CHP, and your column is the highlight of an already brilliant magazine and I eagerly await each issue. I have some questions for you regarding the ZZ4 crate engine I am planning to buy and install in my project car (a '74 HQ Holden Monaro GTS). This car was factory-equipped with a 350 Chevrolet engine, TH400 automatic trans-mission, a 3.08 rear-axle ratio, and 14-inch wheels.

Will I be able to run the stock stall-speed torque converter with this combination, as I do not want to go to a higher stall speed unit if I can avoid it? Is the manifold vacuum sufficient to operate the power brake booster and vacuum modulator? And with the ZZ4 roller camshaft, is the fuel-pump pushrod compatible? I have noticed that the after-market produces fuel-pump pushrods with a roller tip, a bronze tip, and a ceramic tip. Should I use one of these, or does the ZZ4 come with a fuel-pump pushrod from the factory? For a carburetor I am trying to decide between a Holley 650 or 750 double-pumper or a Barry Grant Demon (PN 12802010CZZ4), which is offered as being calibrated to suit the ZZ4. I remember reading in one of your columns that you prefer the double-pumper over the vacuum-secondary carb, and that the 4779 Holley was correctly calibrated for the ZZ4. Naturally, I would like to install a carb that will require little or no calibration changes if possible. If it were up to you, which way would you go? Is the D-shaped port the same dimension as that found on the Fast Burn heads? Will a set of headers designed to suit Fast Burn heads match up properly to the ZZ4 heads? Thanks for any help you can give.Mark HeatonAustralia

A Mark, Holden has build very cool cars for years. They were very close to their brothers Chevy built up here. Thankfully, the drivetrains were exactly the same and you can interchange out any of the performance components designed for a Gen I small-block. Let me see if I can get through all your questions.

The ZZ4 engine was GM's first performance crate engine, and also an emissions-legal engine swap for third-generation Camaros. When the engine was designed, the power bogie was set at 350 hp in off-road trim, but it still had to meet strict emissions compliance for the Camaro. With that, you get the benefit of the engine having very high idle vacuum for a 350hp engine and a great deal of very slow speed torque. Yes, you may retain your original stall torque converter, and the engine will support your power brakes and vacuum-modulated shifts from your TH400.

You're sharp in catching the relationship between the steel billet roller camshaft and your fuel-pump pushrod. Yes, the aftermarket has a few options, but I would stick with the factory-engineered part. The '87 and '88 carbureted LG4 305s and LM1 350s used a specially designed fuel-pump pushrod to mate with the billet roller. The pushrod received a special heat-treat process to work with the steel camshaft. The pushrod is sold under PN 3704817. You should be able to order one from your local Holden dealer or mail order through Ken Casey at Burt Chevy. He can be reached at (800) 345-5744.

The Holley 4779 750-cfm double-pumper is a no brainer. We've used several on those engines with great success. The Barry Grant Demon is dyno-calibrated for this engine, too, and I'm sure you would be very pleased with its performance. Pick up either and enjoy. As for the headers, yes, the L98 aluminum heads that are on the ZZ4 have a similar D-port design like the Fast Burn heads. However, the ZZ4 ports are slightly smaller. If you pick up a header that fits the Fast Burn heads, they will work great with the ZZ4 heads.

When you get your Monaro GTS up and running, send us a timeslip and a photo so we can run it. Wish we could come down and go for a ride. Good luck with your project. [I second that, it would be great to see more Monaros in action. -Henry D] CHP

If you have a technical question for Kevin McClelland, send him an e-mail at:

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