Subscribe to the Free

June 2010 Chevy High Performance Letters - Performance Q & A

Tom Truty May 5, 2010
View Full Gallery

Fitting Tribute
Several months ago, Henry wrote about the passing of one of our very good friends, 100 percent hot rodder Terry Stevens. As Henry wrote, he was going to keep Terry's passing to himself, as was I; however, the events of the past weeks have lead me to write this.

chp_02_o June_2010_chevy_high_performance_letters Drawing 2/3

I met Terry by phone back in the late '80s when I was working for Jim McFarland at McFarland Inc. We were like the UL laboratory of the aftermarket and had no affiliation with any aftermarket company. This is how Terry's and my paths crossed. He called me weekly for help with his early-'80s shortbed Chevy 1/2-ton truck in which he'd installed a ZZ3 engine that he loved to race.

His next project was a unique choice. Henry wrote about the '78 Caprice Terry built for the Car Craft Real Street eliminator. I worked with Terry specing out this Caprice, and he lovingly referred to it as a Caprice SS! This car was originally owned by his lovely wife Sue's mother. Terry had a vision and built this car from the ground up. It was equipped with a 406 small-block with AFR heads, a Comp hydraulic roller, a B&M TH700-R4, Hotchkis suspension, Bonspeed wheels ... I think you get the picture. He was so proud to complete the Real Street competition.

Terry and I collaborated on all his projects and we became very close friends. The first time we met in person was at the 2000 Autolite Nationals, when he had a layover in Sacramento. He was a United Airlines pilot at the time and he and his co-pilot came over to see me race. As luck would have it, he and his co-pilot joined us in the winner's circle that afternoon. In 2002, Terry and Sue came to California and vacationed with my family at Disneyland, and they stayed on for the NHRA points meet at Pomona. About a month after this race, Terry dropped a bomb on me by saying "I've put Daniel in my will and he will get the Caprice someday!" Well, this didn't mean much except that it was a very nice gesture from a very close friend. This really changed its meaning when we all heard Terry was fighting for his life with cancer. I was back visiting Terry and Sue for their 40th wedding anniversary party and he brought me through the milk barn of their old dairy farm, and there sat the Caprice. It hadn't been driven for many years, and he reminded me that it would be on its way soon. I did everything I could to convince him that Daniel would never get it.

chp_01_o June_2010_chevy_high_performance_letters Editor 3/3

Fast-forward to a couple of months ago. A transporter dropped off the Caprice to its new home. Without a race car for the 8th Annual Bracket Nationals in Las Vegas, my wife, Lisa, said I should race Terry's Caprice. After several weeks of thrashing to get everything ready, we were off to Vegas. On the opening day I won the Sportsman class going six rounds in the mighty Caprice SS. The spirit of Terry and Sue's mom rode with me every round and I was very proud to get a win in Terry's car. I know there were smiles from heaven over Vegas.

I'm In Trouble Now!
Q: My brother has a '71 Chevelle, a decent daily driver, but I'm not sure if it's a true SS. What makes this car an SS, or how do we tell? Any info would be great. Thanks!
Pittsburg, PA

A: The purists are going to either hate me or love me with this answer. There is nothing in the VIN or body tag that designates a Chevelle/Malibu as a Super Sport. For '71 the SS option is a collection of Regular Production Options placed on either a 2-door sport coupe, 4-door sport sedan, or 2-door convertible. These cars could have been SS-350s, SS-454s, or Heavy Chevy options. This collection of RPOs could include from SS Hood and Deck Lid Strip code D88, Special Performance front and rear suspension code F41, SS-454 code Z15.

Now it's time to take a little search around your brother's Chevelle. Under the back seat is usually where Chevrolet put the buildsheet as the vehicle was assembled. This sheet will list all of the RPO production codes, which will let you decipher what your Chevelle was originally equipped with. If there isn't one under the rear seat, check between the fuel tank and the trunk floor. This one is a little tougher, as you will need to drop the fuel tank. If you're lucky enough to get your hands on the original buildsheet you'll need a road map to tell you what all the RPOs mean. The best reference book we know of for this is the Catalog of Chevelle, Malibu & El Camino ID Numbers 1964-87 by Cars & Parts magazine. This book is a wealth of information on all A-body Chevrolet products. It will decode your VIN, body number plate, engine number, and Protect-O-Plate. The book is distributed by Motorbooks International under catalog ID number 119465AE. You can contact Motorbooks directly and have the book drop shipped right to you. This is a must have for any Chevelle enthusiast. Good luck with your search. Source:

It's A Spring Thing
Q: My '69 Camaro is about to get a 350 LT1. I have disc brakes and 2-inch drop spindles that I purchased from Performance Online. The brakes consist of 13-inch rotors with dual-piston aluminum calipers. To round out the frontend package, I also have a set of Performance tubular A-arms. I intend to put QA1 single-adjustable shocks on it. What front springs do I use, stock or 2-inch drop? It will be used for street and maybe an occasional dragstrip or autocross. Also, it will have A/C. Thanks for your help.
Scott Langston
Fort Wayne, IN

A: Which front springs you choose is completely dependent on what you wish to use your car for. You stated that you would like to drive it on the street, play on the dragstrip, and toy with autocross. All three of these disciplines take different types of springs and finding a happy medium can be a challenge.

What do you wish the ride height to be? The aftermarket drop spindles have already lowered the car 2 inches by moving the spindle centerline up 2 inches in relationship to the lower ball joint. If you also install 2-inch lowering springs, the car will be 4 inches lower than stock. The front subframe may find the pavement driving around on the street in normal driving. You need to answer this question first. Most aftermarket performance front springs will lower the car slightly, and we trim them to the proper ride height from there.

Springs are designed differently for handling versus the dragstrip. For handling you'd want to increase the spring rate of the spring to prevent body roll and load the outside tire for grip. In drag racing you aim to run the lowest spring rate possible that will support the weight of the car. A light spring-rate spring that is highly compressed will aid in the weight transfer to the rear tires on the launch. We would go for a street-handling performance spring. Check with Eaton Detroit Spring; we've used them several times to make springs for oddball applications. Eaton has the factory prints from all the domestic auto manufacturers in the muscle car years and could build you a big-block spring-rate Camaro spring that will give you a stock ride height, or build the spring at the ride height you wish based on your measurements. Give Eaton a call for more information and visit the website and bone up on Spring Tech 101. This is a very informative handbook to educate you on the finer points of spring design and selection. Source:

Q: I recently purchased one of Chevy's limited-production ZZ430s (s/n 028) from a Boss motorcycle. It seems the owner wanted to upgrade to a 502/502! The engine came with none of the paperwork you normally get from Chevy (detailed parts list, engine dyno sheet, and general info). I've requested this info from several Chevy/GM forums and GM Performance dealers, but either no one has something they can share or they are unwilling to do so. Can you help me? Photocopies or scanned documents would be incredible, or a contact person would help.
Bud Byers
Clinton, IL

A: The ZZ430 was plenty of power for the previous owner's bike. Wait 'til he figures out how much weight he's added with that large-block between the framerails. But that's his problem, not yours.

For factory documentation, give our buddy Ken Casey a call at Burt Chevy. You can reach him at 800.345.5744 and we're sure he will not only love to hear the story about your ZZ430, but he'll be able to help you out. Source:

Roots Blower On LS3
Q: I'm having a difficult time finding a Roots-type blower that will work with a Vintage Air Front Runner drive system in my '69 Camaro. My motor is an LS376/480 crate motor (LS3 and a Hot cam), installed on a Chris Alston front clip. I'd like to keep my stock 2-inch cowl-induction hood if possible. Any advice?
Cris Gross
Colleyville, TX

A: The cleanest package out there in a Roots-type blower will be the MagnaCharger Eaton blower system. The complete system for the 2010 Camaro LS3 kicks out over 500 hp on the stock Camaro engine. Boosting your LS376/480 crate engine would push the power very close to the 600hp mark. The MagnaCharger blower is designed to increase the rwhp by 20 hp/pound of boost. With a simple 6-8 pounds of boost, your '69 could be really nasty! Call Eaton for more information and the best components to work with your accessories.

Will this system bolt up to your Vintage Air Front Runner system? We're not sure. The Vintage Air kit is a very nice compact front drive. You will not find a bolt-on system that will line up with the aftermarket drive system. Our suggestion is to adapt the MagnaCharger to the Vintage Air front drive. MagnaCharger may be able to help you align the blower drive pulley with the Vintage Air drive system. This will at least get you halfway there. You'll need to change idlers and tensioners to make sure you get a minimum of 180 degrees of belt wrap around the blower pulley to limit slippage.

Finally, your factory cowl hood may need some internal trimming of the sheetmetal to clear the blower. If you're not willing to cut up a factory cowl hood (we don't blame you), you could always go with a fiberglass replica. You'd still get the 2-inch stock look but with the internal clearance you'll need.

Send us an update when you get the blower on your LS376/480! We're sure it's going to scare you, but in a good way. Good luck. Source:

Use The Web
Q: I have a good many Clevite 77 bearing sets and would like to know where I can find out what applications they would fit. They are all new sets and have the numbers on the box. I have both standard and 0.010-inch undersize, and I also have some Federal-Moguls. Where might I find this information? Thanks.
William Munson
Batchelor, LA

A: We often use the mail-order websites' search tools. They are very up to date with the latest manufacturer information. Just visit the site of your choice and find the manufacturer's code at the front of its part numbers. Using the manufacturer's identification code and the part numbers of your bearings, it will pull them up for you to purchase. Once you have found the bearings on the site, then you can check the application. This is a selection on the product page. It will list what engines your bearings are designed to fit.

Hopefully, the mail-order sites won't be upset that I've sent them a potential customer. You never know what else you need once you get there. My biggest complaint is that once I've confirmed an order, I always remember something else I needed. There goes the shipping and handling again! Sources:,,

Filter/Regulator Follies
Q: On page 43 of your Nov. '09 issue, when you were modernizing your '72 Nova, you mentioned using a '99-and-newer fuel filter/regulator combination. Can you write out the instructions as to which fuel line goes to which outlet on which end of the filter can? Thank you very much.
Larry Van Unen
Priest River, ID

A: The filter you're talking about is the filter/regulator combo that GM used first in 1999 on LS1-powered Corvettes. This unit was put into service when GM converted the engine to a single-line, returnless fuel system. The fuel filter/regulator is mounted back by the tank in the original application. For our swap application it allows you to install this filter right at the tank, or in front of your high-pressure pump. This eliminates that hassle of running a return line the length of the vehicle.

The filter has three ports: two nipples and one female pushlock connector. The inlet feed and outlet returns are the nipples, and the regulated outlet is the female connection. The inlet from the pump is the 3/8-inch nipple on the perimeter of the end cap of the filter. The 5/16-inch outlet return comes out of the center of the same end cap of the filter as the 3/8-inch inlet. On the opposite end of the filter you have the one 3/8-inch female port that is the regulated outlet port of the filter.

This extremely inexpensive combo part is very handy for plumbing up EFI fuel systems. The regulated fuel pressure is 58 psi constant, and there is no vacuum bias in the fuel pressure from this type of regulator. The GM part number for this is 10299146, and the ACDelco (usually a bit cheaper) number is GF822

Deluxe Hop-Up
Q: I have a 350 H.O. Deluxe GM Performance 330 HP Engine. Can I put on the ZZ4 aluminum heads and feel a significant difference? Will it be worth it, or should I put in a cam and the heads?
Chevy High Follower
Via email

A: The 350 H.O. Deluxe comes equipped with a pair of Vortec iron heads and an updated 350hp, 350-cid, hydraulic flat-tappet camshaft. This is a great base engine that performs very well. If you were to swap to the aluminum L98 Vette (ZZ4) cylinder heads you'd realize minimal gains. The iron Vortecs are based on the iron LT1 heads, which are quite a bit better than the L98s. They would give you about 10 hp from the CR bump. Now, if you wanted to give the ZZ4 heads a quick port job, which entails bowl work on the intake, and throat, bowl, and guide boss work on the exhaust, you can see around a 30hp gain with the heads. The beauty of the ported heads is that they kick out some killer torque numbers. The small inlet runner makes these heads really work. We'd take these ported heads and swap them onto a ZZ4, then stepping the power numbers up into the 380hp range, but the torque would climb into the 430s. This would really wake up a ZZ4.

If you're looking for more power, swap out your camshaft for a hydraulic roller. The H.O. Deluxe block will accept '87-and-up roller hardware. The Lunati Voodoo PN 60121 would be a great fit. This camshaft is designed for an LT1/LT4 EFI engine package, and specs out at 219/227 degrees of duration at 0.050-inch tappet lift, 0.515/0.530-inch max lift, ground on 112 centers. The idle quality would suffer slightly, and you'd need a 2,200- to 2,400-stall converter, but this would really wake up the Deluxe, especially if you port those ZZ4 heads, pushing the horsepower well into the 400 range and keeping everything happening under 6,000 rpm. Source:

Early Chevy Power
Q: My '51 Chevy Sedan Delivery holds a '68 large-journal 327. It currently dynos at 211 hp and 241 lb-ft at the rear wheels. The engine is 0.040-inch over, 9.5:1, 882 heads with 1.94/1.50-inch intake/exhaust valves, with a Crane 204/214-duration cam, 0.469 lift, a dual-plane manifold, an Edelbrock 750-cfm flowing through Sanderson 15 /8-inch block huggers flowing into 21/4-inch tubes through 24-inch MagnaFlows, and HEI for spark. I'd like to boost the horsepower and torque about 100 at the rear wheels and wonder what you would recommend. For instance, how much power would come from a set of 13/4-inch equal-length headers flowing into 21/2-inch tubes, and will the larger-diameter exhaust gain horsepower but cost torque? I've been looking at Edelbrock upper engine kits (cam, heads) and they seem promising, but you may think another combination is an equal alternative. If I want the most accurate reflection of horsepower at the rear wheels, should I be looking for absolute loss figures for each component of the drivetrain, or stick with a generally accepted percentage? Is there a significant difference in rating on different kinds of chassis dynos?

I know my car doesn't fit your mag's usual profile so it may not be column-worthy. I hope I still might receive a response.
Mick Toney
Tucson, AZ

A: Any Chevy-powered vehicle is worthy of our advice. You have a very cool cruiser. My dad is in the process of restifying a '51 Sedan Delivery, installing a MagnaCharger-blown LS1, a B&M TH700-R4 trans, and a Speedway Engineering Quick Change rearend. He is about three-quarters of the way through the project. It's going to be one nice ride when he's done. Let's check out your 327.

Adding 100 hp and torque to your baseline is boosting the power of your base engine over 30 percent! That's quite a jump and will change the personality of your current engine quite a bit. Driveline losses are in the 18 percent range based on many factors: manual trans versus automatic, differential type, and engine accessories. We commonly use 18 percent as an average power loss. I've run engines on the engine dyno, then stuffed them into their cars and run them on a chassis dyno. I've seen as little as 14 percent loss with a manual-trans '70s muscle car, and as high as 25 percent on an F-brand small-block with automatic trans and a 9-inch diff! That one is the highest I've seen.

The best thing I can say about dynos is that you don't race dynos. Chassis dyno power measurements vary from brand to brand, and from cell-or lack thereof-that they are mounted in. You can usually compare data from a SuperFlow to a SuperFlow or a Dynojet to a Dynojet, but I don't like to compare across brands. Their correction factors vary in the ways they manipulate the data. The safest way is to compare all changes on the same dyno.

The header change you're mentioning will add a few ponies, but as you stated you'll give up some torque with the 13/4-inch tubes. The 327 is totally happy with 15/8-inch primary pipes. If you wish to go to full-length headers we'd stick with 15/8-inch primaries. A set of full-length headers over your block huggers will give you around the same horsepower but should boost the torque by about 10 to 15 lb-ft from the tuned length of the long-tubes.

Let's get back to your original question. Taking 18 percent loss into your numbers, your little 327 is producing approximately 250 hp and 284 lb-ft of torque. To kick the power up to 350 hp is going to take a set of aluminum heads, a larger camshaft, and the supporting inlet manifold. Edelbrock produces some very nice top end packages for small-blocks. This all goes back to the way you drive the car and what personality you want it to have. Most street rods are mellow cruisers that you want to enjoy the drive. We can easily give you 50 hp and torque gain without killing the driveability.

Here is my 75 hp and torque boost: Start with a set of the new Edelbrock E-Street aluminum cylinder heads. They feature 185cc inlet runners, hardened spring seats, and heli-coiled threaded rocker bosses unlike the low-cost import aluminum cylinder heads. They are offered in two combustion chamber sizes; if you go with the 70cc heads (PN 5073) you'll get a nice 0.5 compression bump over your iron 882s. Match these heads with a Performer RPM PN 7101. The RPM Air-Gap will give you a few more ponies; however, we've run into carburetor icing issues with the Air-Gap. Again, we don't know your intent.

Finally, go with a Comp Cams XE256H camshaft. This is a relatively short cam with 212/218 degrees duration at 0.050-inch tappet lift, 0.447/0.454-inch max lift, ground on 110 centers. These above components will give you at least a 75hp boost over the current package you're running with minimal impact to the driveability to the vehicle.

Finally, stick with your exhaust system for this package. We don't think changing out to the long-tube headers and larger exhaust system will be the difference. The 21/4-inch dual exhaust you currently have will support the 330 crankshaft horsepower we believe you'll be producing. Sources:,

Technical questions for Kevin McClelland can be sent to him at



Connect With Us

Get Latest News and Articles. Newsletter Sign Up

sponsored links

subscribe to the magazine

get digital get print