Chevy Performance Q & A - Performance Q & A

Kevin McClelland Dec 1, 2009 0 Comment(s)

Here We Go Again!
We're finally settled down in our new Southern Californian home, and the immediate renovations to support a gearhead like myself are just about complete. Storage for race cars, trailers, and parts-and working space-can be tough to come by. We were lucky enough to find a house with enough space, and with a little imagination (money), we made it all work. Our realtor loved me and my wife, Lisa, because we could pull up in front of a house he wanted to show us and not even get out of the car: "That won't work to fit all my junk!"

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With the new location comes new projects. As I've written in the past, we picked up a '68 Nova for my son, Daniel. After replacing the floors and getting close to tearing the car completely down, Daniel had a change of heart, so off to the famous Pomona Swap Meet went the Nova. We sold off the car and all the parts we had collected. The engine is on the chopping block to fund the installation of a Gen IV L92 into our Malibu Wagon race car.

Here's where things get a little crazy. Can you make a Chevy out of anything? Well, we're going to try. Daniel had been following this one car for 18 months and was finally able to buy it. It's a '94 Mazda RX-7 Touring. The '93-95 RX7s were a very limited offering in the States, and with the advent of OBD II in '96, Mazda gave up bringing them here. The twin turbo rotary engine is long gone, since it expired back in 2000. We're currently in the market for a totaled '05-06 GTO to rob the Gen III LS2 6.0L and T56 six-speed to drop right in. This killer conversion is supported nicely by a group of followers on V8RX7forum.com. Samberg Rod and Custom sells a very nice tubular front subframe kit and T56 transmission mount that allows you to bolt the Gen III right in, and SuperPro out of Australia has a 28-piece polyurethane bushing kit to solid up the suspension. Hinson Supercars sells an inboard bumpsteer correction kit to compensate for the relocation of the steering rack, and also offers a Wilwood clutch master system to adapt directly to the T56 slave.

With a GTO as a donor, you can build a completely California-emissions-legal swap that gives you C-6 Corvette aerodynamics in a 2,800-pound package. Best of all, you keep the very neutral 50/50 weight bias of the RX-7. We've already purchased a pair of Cadillac LSA Gen IV supercharged cylinder heads and Gen IV Corvette inlet manifold. for down the road. This, with a matching mild camshaft, should get us in the 475hp range. After these upgrades-and when we blow up the diff-we will upgrade to an Explorer 8.8 centersection, and add a rear-mounted turbo.

This is the plan, and we're going to stick to it! This is a several-year process to get us to the turbo car. I'm sure we'll run into many challenges changing a Mazda into a Chevy. Check out the V-8 RX7 forum and some of the 10-second LS-powered RX7s on YouTube-you'll see why we want to build one.

Taxpayers' Dollars At Work!
Q: I saved my re-enlistment bonus specifically to build this engine: a maximum-street 598ci BBC mountain motor. It's based on a Dart Big M Sportsman tall-deck (4.6-inch bore), utilizing an Eagle 4340 stroker assembly (4.5-inch stroke, 6.7-inch rods), JE pistons (10.3 CR), and AFR 345cc aluminum heads with Comp Cams 1.7 ProMagnum roller rockers. The preliminary induction system is an Edelbrock Super Victor and 1,050-cfm Dominator (no nitrous), but some form of EFI is contemplated for later.

The host will be my '55 Chevy gasser-style Pro Street, with (currently) 4.10:1 gears and a five-speed manual with overdrive. The car will see some limited strip action, but I'm not seeing anything but around-town driving in warm weather. The application is closer to the race end of the spectrum than street (if you see what I mean).

My primary problem has been camshaft selection. I plan to use a mechanical roller, but nobody seems to have much experience with motors of this size on the street, and the recommendations from camshaft companies range from under 250 to over 300 degrees duration (all at 0.050 inch). My own intuition leans toward net lift over 0.700 inch and a 108 or 110 intake centerline, but I must admit I'm stumped when it comes to duration. I'm leaning toward the 250 end of the scale (e.g., Comp Cams 286RX-8; 253/260 @ 0.050; 0.727/0.729; 108; 3,200-6,200 rpm), but I'd hate to restrict breathing in a monster that can rev like this-not to mention that one cam-company expert recommends over 310 duration!

I'd sure love to hear your take on any aspect of this build. Thank you.
Larry Browning
Wimberley, TX

A: With the current economic meltdown, and taxpayers' dollars going to everyone from Wall Street to automakers, this is the best use of taxpayer dollars we've heard of! Building a killer Tri-Five with a nasty big-block just as a toy gets our vote. Thanks for re-enlisting and keeping our country safe and free. Let's talk about your camshaft selection.

Since 1996 we've probably built eight different pump-gas big-blocks and have helped many other people with combinations including drag-only, mud bog truck, street, and marine use. All the engines have been very reliable and make great power for their compression and skunk-piss gas! One thing we were told early on by Tim Wusz of Rockett Brand Racing fuel (a fuel engineer at 76 at the time) is that pump gas doesn't like to run much above 7,000 rpm. We've focused on the torque-making potential of these engines and had a blast doing it.

If it was ours, we'd work around a camshaft that spec'd out at 270-275 duration at 0.050 inch tappet lift on the inlet side, and 280-285 on the exhaust side. Also, you don't want the separation angle so tight. We'd bring it in around 112 degrees, with 110 at an absolute minimum, and no wider than 114. Install the inlet centerline at 108-109 degrees. Your cylinder heads flow extremely well to 0.800 inch lift. Pushing the lift with regularity will kill the valvesprings. Low 0.700s will work well.

Finally, to the real problem. The roller tappets will be the issue with this engine's durability. Many years ago our old friend Cole Quinnell had a very nasty '57 Chevy that was built while he was a staff writer at Hot Rod magazine. It had a very similar big-block to yours, and we installed a Crane Street roller camshaft that spec'd out in the low 260s at 0.050 and mid-0.650 inch lift range. He drove it on the Hot Rod Power Tour, we think around 1997. It ran great, killer power, and about 1,800 miles in it lost a roller tappet right before the last stop on the tour. He adjusted the valves every night of the tour, making sure he wasn't losing a roller. Well, he ended up wiping out the roller, which put the tappet body right into the lobe of the camshaft

There has been quite a bit of roller tappet innovation, with Isky's new Red Zone lifters with their EZ-Roll solid-bearing, needle-free tappets. These replace the needle bearings with a solid bearing in the roller wheel that rides directly on the axle of the tappet. These proprietary solid-bearing raceways are pressure-fed by three separate passages in the tappet body from the oil gallery. The secret in using this solid-bearing design is to keep it well lubricated to remove the heat. You won't want to install any type of oil restrictors to the lifter galleries, which would reduce the oil to the tappets. They were tested in drag-race engines for over three years before being released for sale to the racing public. We may have an answer for racing engines and endurance engines. With conservative lobe designs and manageable valvespring pressures, we believe they will live on the street. Check with Isky for the proper application; three endurance grades are available to suit your exact requirements.

If you go with a mechanical roller design, and the specs listed above with your package, your engine should easily produce around 800 hp and well over 700 lb-ft of torque. This would be a very fun ride, rowing the gears down the boulevard.
Sources: compcams.com, iskycams.com

Which Pitman Arm?
Q: I drag race a '65 Chevelle that still has the factory gearbox. I got one from the junkyard out of a '91 S-10 along with the pitman arm; the new gearbox bolts up just fine, but I cannot find a pitman arm that will work with the Chevelle's drag link. I can weld the two arms to make one fit the Chevelle, but how many people would trust a welded pitman arm? What do you recommend for my choices of pitman arms, or do I need to get away from the S-10 gearbox and do something totally different? Any help would be highly appreciated.
Jason Lynch
Via email

A: The S-10 is a great place to pick up a manual steering box for any of the Chevelles (A-bodies). We did the same thing when building our '80 Malibu, but the S-10 box we got out of the yard was full of water and the recirculating balls of the steering box were pitted and scored. As luck would have it, we purchased a brand-new '80 Malibu manual steering box (one of three left in the country) from our buddy Ken Casey. They are completely gone now. Ken said the original power pitman arm from your '65 Chevelle should connect right up to the S-10 box. The S-10 box should be the same spline count and size as the Saginaw 800-series power box that came original on your Chevelle.

Finally, please don't weld pitman arms. It's been done many times on conversions, and unless you are skilled in the art of preheat, proper weld process, correct welding rod, and cooling techniques, it could all go wrong. Losing your steering at speed is no fun. Bolt your Chevelle together and enjoy at the track.

Standing Or Seated
Q: I just received Summit's rotor and pad set for my '79 Camaro. One rotor has an "L" on it and the other has an "R." To play it safe I looked into your Jul. '09 issue and found a discrepancy. "Tomato Fire" (page 73) shows slots in one direction, and "Darkness" (page 80) shows slots facing the other way. Wouldn't the slots on "Tomato" actually trap the gases? Doesn't this affect stopping distance? I want those babies to work at the end of a quarter-mile!

Also, for once and for all, isn't right or left side determined when a person faces the front of the car? I've had to argue this a few times, especially when dealing with some "service" (muffler, door repair) outfits. Good magazine. Keep it up!
Ray Banks
Via email

A: All references to the identification of the side of the vehicle is determined from being seated in the driver seat. It is not from standing in front of the vehicle facing it. I'm sure you've had quite a few arguments with service people and parts suppliers over the years. Hope this helps in the future

On to gas-slotted rotors. For the pictures you mention, yes, they differ on each vehicle. Not knowing the markings from the manufacturer we'd have to say the direction on the "Tomato" is correct, with the slots venting the gases outward when the wheel and rotor assembly rotates counterclockwise on the left-front wheel (there's that side thing again).

Mouse-Motored Monza
Q: I'm looking for a converter recommendation for my '79 Chevy Monza Pro Street. It weighs around 2,700 pounds and has a built 333-cid small-block with a Comp Cams XE294H cam with 0.519/0.523 inch max lift and 250/256 duration at 0.050 inch tappet lift. The engine is topped off with a Team G intake, a 750-cfm carb, Sportsman II heads (mildly ported), and 10.4:1 compression. It has a TH350 trans and a 12-bolt with 4.10:1 gears, and I run a 29x12.5-inch tire. I'm looking for a stall converter that will retain some street manners for local cruise nights and such. By no means is this car just a street cruiser. I'm told 3,800-4,000 stall should be fine. I have built a few cars, all with standard shift. This is my first automatic, so any help would be great. Thanks.
Craig Winter
Norton, MA

A: A 3,800- to 4,000-stall converter may be a little tight for your short-stroke 333-inch small-block. It won't really start making any power until 4,500-5,000 rpm and probably will pull strong to the 7,500-plus range! This puts you in the range of a loose 10-inch converter or a tight 8-inch. The 10-inch will be much more affordable, but the 8-inch will be quite a bit less rotating weight for your little Mouse. We've got two B&M converters, a 10-inch and an 8-inch, and used both of them behind the pump-gas 350 in our wagon. The 10-inch will flash to 5,000 rpm, and the 8-inch is slightly tighter. The engine revs noticeably faster with the 8-inch, and about 0.05 second quicker and 1 mph faster.

To have a converter spec'd out for your application, contact Les Figueroa at FigSpeed. We could spit out a couple of part numbers for both converters, but as the B&M racing representative, Les has years of experience and a wealth of knowledge on torque converter selection. He's put us into the right converter based on our combination of engine power, vehicle weight, transmission type, and gearing. When you're buying a premium converter, getting the right one the first time is a great savings.
Source: figspeed.com

Early Sport Compacted
Q: I am in the planning stages of an engine swap for my '83 Chevette, and I seem to be getting frustrated. The motor going in is a 3.3L 200-cid out of my '78 Malibu. I have found a cam, but when it comes to other performance parts, everything I find is for a V-8 small-block. Headers and valve covers, I'm afraid, I may need to build myself. I can't hardly build my own aluminum intake and performance heads. (Not yet.) Do you have any suggestions where I might find some parts for 90-degree V-6 performance?
Adam Steppe
Oval, PA

A: Hopefully, you're adding many other upgrades to your Chevette than just power! The rear suspension, with its tiny differential and semi-torque tube drive, isn't going to take much power. Also, the brakes were too small for the car when it was original from the General. As a line mechanic in the late '70s I had to repair all the Chevettes that came through the door! The deal I made with the other line mechanic at the time was I had the LUV trucks, diesel trucks, and diesel Montes. The other mechanic did the vans, Vegas and Monzas, then we split the gravy. I hated Vegas and vans.

You have many options for the 90-degree V-6 Chevy. The really good ones are the Vortec 4.3s produced from '92 up. These engines featured hydraulic roller camshafts and Vortec-style iron heads. These heads are very much like the famous L31 Vortec 350 small-block heads that have turned many 350 small-blocks into 400hp engines right out of the box. Your '78 3.3L, 200-cid 90-degree is the least desirable of the V-6s. We'd rummage through the junkyards for an L35 CPI-injected, 4.3L, 262-cid V-6. The L35s were rated at 190 hp SAE and 245 lb-ft of torque, stock. This will kick your Chevette around much better than your 3.3L slug and its whopping 95 hp and 160 lb-ft of torque

Next, check with Comp Cams for a nice hydraulic roller upgrade. For an inlet manifold, check out Edelbrock's Performer 90-degree V-6, PN 2111, which will allow you to run the square-flange carb of your choice. Stay with 600 cfm and below for good all-around performance. CFR Performance offers chrome steel center-bolt valve covers under PN HZ-7458 and HZ-9812 to fit your V-8-minus-2. As for headers and engine mounts, you're on your own. We've read where you reverse the factory transmission crossmember and elongate the trans mount hole approximately 3/4 inch. This places the engine and transmission in the proper location. The factory pan will need to be notched approximately 11/2 inches to clear the steering gear. You will also need to modify the oil pump pick-up for the reduced pan sump.

Hope this helps on your quest for two more lungs in your Chevette. Again, step up to the larger 4.3L over your wimpy 3.3L. After all that work, we don't want you to be disappointed!
Sources: cfrperformance.com, compcams.com, edelbrock.com

Hot Cam Heritage
Q: I was a CHP subscriber about 10 years ago but had strayed from the flock. I've now returned to my roots, "getting into" the car hobby. Over the years I've modified the first car I purchased new, at 18, and it will probably be the only car I will ever own. It's an '84 Monte Carlo (non-SS), which currently has a 383 stroker with a one-piece seal, AFR 195cc heads (older PN 1038), an Edelbrock 3,500 Performer RPM Pro-Flo EFI system, a TCI Streetfighter TH350 transmission with a TCI 2,400-stall, an 11-inch breakaway converter, a GMPP PN 24502586 LT4 Hot Camshaft, and Dynomax 1 5/8-inch shorty headers into a 21/2-inch exhaust with Dynomax 2 1/2-inch Super-Turbo mufflers. The engine has flat-top SRP pistons rated 9.7 CR with 76cc chambers, but since my older AFRs have 74cc chambers, I assume the CR is closer to 9.8:1. Is this compression ratio adequate for use with the LT4 Hot Cam? This cam was designed for the LT1- and LT4-equipped Vettes to go SCCA stock-class road racing, so I was told, and those engines were 10.4 and 10.8 compression, respectively. Do I have enough compression at 9.8:1, providing my engine was zero-decked? I believe the CR may be closer to 9.5:1, since the engine was originally built with a Comp Cams 08-412-8 hydraulic roller with 212 degrees duration at 0.050 inch, and the engine builder didn't want the cranking compression to be excessive. Thank you much for your opinion, Kevin, and it's nice to be back home.
Steven Telkes
Saddle Brook, NJ

A: Welcome back. We're sure you'll feel warm and safe real soon. And we think your engine will love the Hot Cam. Let's go over a few facts.

The Hot engine was developed as an upgraded crate engine using the '96 LT4 long-block from the Vette. I was lucky enough to be involved with this project from its inception. What we were trying to do was create a higher-performance crate engine for the GMPP lineup. The ZZ3 was the big man on campus at the time, and the factory LT4 had great cylinder heads and a good amount of squeeze, as you mentioned. This engine lent itself to big power improvements with a simple camshaft swap, a dual-plane aluminum high-rise inlet, and a Holley 750-cfm carb. We had the engine development completed and the engine in my '65 El Camino. The car was back in Detroit for all the GM brass to drive and enjoy when the Flint Engine Plant decided not to take on any other engine combinations. It didn't make any sense running this engine down an off-line assembly system, because the cost to the public would be just too high. This is when GMPP released the Hot Cam package, which came complete with the cam, aluminum 1.6 rockers, LT4 springs, caps, spring seats, keepers, and valve seals. There was a different Show Room Stock camshaft that Wheel to Wheel developed for the SCCA race cars. This had several more degrees of duration and was designed around the mini tunnel-ram of the LT1s and LT4s.

Your 9.5-9.8:1 compression will do just fine with the Hot Cam. Compression isn't what it's all cracked up to be. If you have great airflow with the proper valve timing events, you can make really good power. The more efficient the cylinder heads are in both airflow and combustion efficiency, the less you have to rely on compression. The AFR heads always have good Brake Specific Fuel Consumption numbers on the dyno; this is a measurement of how well the engine turns fuel into work. The lower the numbers the more work you're getting out of the fuel. Install the Hot Cam without a worry. Enjoy!

LT1 To LS
Q: My '97 F-body has an LT1-series engine with a number of miles on it, and I was thinking about a new engine. I've read many articles about engine swaps and upgrades but have not seen any about people upgrading from an LT1 to the LS series. Can this upgrade be accomplished for a reasonable price? What types of complications, if any, are involved with such an upgrade? Thanks in advance for your thoughts. Marcus Jones Via email

A: The main reason you haven't seen many engine swaps on the fourth-gen Camaro is the relative low cost of those cars. Also, the LT engine is a decent-performing engine from the start. It's not like you have a third-gen Camaro with a TBI 305. It's a very straightforward swap, and the General has done all the work for you.

First, find a buddy in the used car business. Next, find the closest CoPart insurance auction in your area. Get your buddy with his dealer's license to go to the insurance auction and find a '98-and-up Camaro with an LS engine and the trans package of your liking. You'll find many cars that have rearend damage that totals the vehicle. This will give you all the components necessary to do the swap. Spec'ing out all the component parts to covert the engine would be a lot of money. Between harness, controller, and transmission differences, it could really run up in price. Picking up a totaled Camaro for around $3,000-$4,000 and getting everything you need in one stop is the way to go.

Several years ago, a good friend was doing just this, picking up totaled Camaros and pulling the LS1s and T56s out to sell. He could sell the engine and trans for more than the purchase price of the Camaro, and the rest of the parts off the car were gravy. Check out the CoPart website for an auction in your area. Happy hunting. Source: copart.com

Throttle Lag
Q: have an '01 Chevy Silverado with a 5.3L engine and an aftermarket MagnaCharger supercharger. I ordered a set of Zex spark plugs to replace my TR6 NGK V Power plugs because Zex claims its plugs are a better application for my supercharged engine. How do you feel about the 160-degree thermostat I used to replace the factory thermostat?

Also, I noticed-even from the beginning of the supercharger install-that when I mash the throttle, the truck seems to hesitate before it takes off. What can I do to resolve the hesitation I'm getting when I mash the gas peddle real quick at the beginning of idle or quick takeoff? The hesitation seems to get a little better as the truck warms up. It runs great medium to top end, with no hesitation once it gets going. Thanks. Larry Boatman Via email

A: When you supercharge or increase the cylinder pressure by other means than the atmosphere we have to breathe, you create more heat in the cylinder. With this increased heat, you change the heat range requirements of your spark plugs. The Zex spark plugs are a cooler heat range to accommodate the differences in the increased cylinder pressure. As with any spark plug, they are offered in many heat ranges. The Zex plugs were developed around nitrous use, and with nitrous you have immediate and extremely violent heat changes in the combustion space. Living through these events and giving you a good service life is where they shine.

As for your hesitation, the MagnaCharger system is a very well-engineered retrofit supercharger. The inlet manifold below the blower is a very short runner design. One of the conditions you may be experiencing is that the factory LS truck intake manifold is a very long runner design, which boosts slow-speed torque. Also, the throttle valve has been moved farther away from the inlet valve, which creates more volume in the inlet system. All these factors can give you the feeling of a delay in engine response.

Now, you said you have installed a 160-degree thermostat to the mix. You also mentioned that the hesitation seems to be less the warmer the engine gets. This sounds like the engine could be on the lean side, and the cooler the engine runs the more pronounced. MagnaCharger is constantly refining its calibrations with new tuning variations. Your best bet is to contact the company and make sure you have the latest calibration for your vehicle. Also, don't forget to mention you're running the 160 stat. The calibration is based on the engine operating on the factory 195 thermostat; this could be most of your issue. MagnaCharger can bring your Silverado right into line.
Source: magnacharger.com

Diesel On
Q: I have a '69 Chevelle with a newly built 383 stroker, a 280 Comp Cam camshaft, an Edelbrock Performer RPM intake, an Edelbrock 800-cfm carburetor, Top Line aluminum heads, ACCEL 416 S short header plugs with a 0.045 gap, a Mallory distributor, and timing at total advance of 3,000 rpm at 36 degrees.

The engine runs great, but my problem is that when I turn it off, half the time it diesels. Any suggestions?
Dave Weaver
Via email

A: Dieseling usually comes from combustion chamber heat and a carburetor in which the throttle blades pass too much fuel and air at idle. With your Comp Cams 280 camshaft, you're probably running an idle speed of 800-900 rpm. With the throttle open this far, it's a prime candidate to run on, and on, and on!

First, make sure your Mallory distributor's mechanical advance is closing back to your base initial timing setting at idle. Sometimes after revving the engine up and having a higher engine idle speed, the springs in the mechanical advance can't close down the advance. Once this is corrected, pick up an Idle Compensator Kit from Edelbrock (PN 8059), a 12-volt solenoid, and a mounting bracket that attaches to the carburetor. This kit is usually used for holding up the idle speed when the A/C is engaged. You'll want to send 12 volts to this solenoid whenever the ignition is on, and use it to set your base idle speed. Back off the carburetor's idle speed screw until it just barely keeps the blades open. This will close the carburetor down to basically no air and fuel when you shut off the ignition, and the engine will stop. This is the best way to control pesky dieseling issues. Back in the early '70s, all GM vehicles used some type of idle dashpot (this is what they called them back then) to set the idle speed. This prevented engine dieseling.
Source: edelbrock.com

Ain't Going to Be Smooth
Q: Where can I find out how to swap a big-block Chevy into my '95 Chevy Camaro? I already have the engine and just need some info on what should be done to make the install go smoothly.
Ray Pergl
Alta Loma, CA

A: That would be a very nice swap. However, with the design of the fourth-gen Camaro, GM pretty much shot us all in the foot for a big-block engine swap. As you know, half the engine sits underneath the windshield. Also, the engine can only be removed or installed from below. With the height of the big-block engine and any type of performance inlet manifold, the carb is in the base of the windshield. We've seen a couple swaps into drag race cars. They had handmade tubular front subframes, engine mounts, and totally custom headers, and the cowl was cut back to the windshield to clear the four-barrel throttle body. You couldn't even put a Holley carb on this thing because the float bowls wouldn't clear the glass.

If you want to pick up a very clean third-gen Camaro, it will accept your big-block easily. Sorry to not have an easy answer. Again, it would be a cool car, and it can be done if you're willing to cut the car up and do a complete custom installation.

Technical questions for Kevin McClelland can be sent to him at chevyhi@sorc.com.

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