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Chevy Performance Tech Q&A - November 2014

Kevin McClelland Sep 19, 2014
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By now you know MasterCard's "priceless" campaign. Just this last week I had one of those moments at the expense of my son Daniel. He had just picked up one of the latest issues of this famous magazine and started to read my editorial, in which I explained to you readers that "Daniel changes projects like he changes socks." "What do you mean!?" This was simply priceless for me, considering…

We're currently building the exhaust system for his LS2-powered Mazda RX-7 and completing the cooling system and wiring, generally trying to finish up this multi-year project, and he rolls home a '74 Vega wagon to build into the ultimate "foot brake" bracket car by swapping in our LT4 small-block out of the Malibu wagon. And just last week he was hitting me up for my spare Super Gas 502 BBC to put into a Super Gas Roadster that he wanted to buy off of eBay. He loves to look through my shed in the back to see what engines or transmissions are lying around without a home. He believes if there is a good engine in the shed it needs to find a home between some framerails! The bottom line here is that he has a lot of projects and he needs to finish one (or all) before moving on.

Just this last week he came to me with an eBay listing for a set of AFR CNC-ported LS1 cylinder heads with very low miles at a very reasonable price. He had this twinkle in his eye, so I asked what these would be for. I can never tell, as we're constantly talking about new engine projects. He's already bored with the e.t. and speed of the wagon with the LS3 and wants me to build a 427 short-block to swap in. Well, his plan was to pick up these heads and install them on his '03 Z06 Corvette daily driver. I wanted to slap him upside the head. Now I know exactly what my dad thought when I was growing up taking apart perfectly good street cars and throwing parts at them. I tried to explain to him that I really didn't think this was a good idea, but the next evening he was off to pick them up. He's now gotten a set of SLP 1.85 rockers. At least I've talked him into sticking with the production Z06 camshaft to keep the California Smog Police happy. The heads have an E.O., making them legal to swap. To round out this upgrade, he purchased a set of "take off" C6 LS7 exhaust manifolds and catalytic converters, which will bolt up to this C5 Vette and closely mate (at least that's what he told me) to his production titanium C5 Z06 exhaust system. Not a problem, Dad, just another project.

If you remember from last month, I had been at dragstrips, racing for the past three weekends in a row and was looking forward to some simple yard work. Well, that didn't happen. Again, Daniel wanted to go out to Irwindale and run his Corvette for the first time down the 'strip. He said, "Why don't you bring the wagon out and run the Summit ET series race in Super Pro?" Being the good dad that I am, off to the track we went. With all the tuning, and the diet I put the car on last year, it carded its best e.t. and mph to date. The 3,250-pound wagon ripped off a 6.44 at 105.38, with a 1.395 60-foot! We were floored and we were just above the 6.40 e.t. limit for chassis cert at Irwindale. Unfortunately, I lost in the semis, but a great day nonetheless.

To round out this month, we raced the Pacific Street Car Association race last weekend at Fontana. Daniel finally put the wagon in the winner's circle for the first time with the LS3 engine. We were close to making it an all-Mac winner's circle as I broke out by 0.003 in the semis of Bracket 1 again! Maybe someday soon we can get that Big Mac winner's circle photo with three generations of Macs. Until then, we'll just keep trying. That truly will be "priceless!"

Who needs to turn?

Q: I have read the many suspension and brake upgrade articles in your magazine in recent years and I like what I see. However, I rarely see mention of the stock steering components and linkages being upgraded when a rack-and-pinion setup is not being added. I would think 40-plus-year-old steering components would be just as important to upgrade as the brakes.
 Did I miss something, or are the steering box and linkages being overlooked? Thanks for your help.

John Tonkinson

Southington, CT

A: Most suspension upgrade articles are just that, suspension. Should the steering gear have been replaced? In most cases we would agree with you. The 40-year-old production steering box, drag link, pitman arm, idler arm, and tie-rod ends die over time. Also, how many curbs has the car smacked into while parking over the years? Then you go to align the thing after this killer upgrade of tubular control arms (and probably badass shocks) and you have bent parts.

Personally, anytime we've upgraded or just replaced all the ball joints and bushings on the front suspension we've hit the Moog catalog to purchase all the components that are still available for the application. Getting all the play out of the steering wheel is a welcome upgrade when you're flying down the 'strip or between cones.

Replacing the steering box with a close-ratio/high-effort box is one of the best upgrades for early muscle cars. The 18:1 steering gear can give you a real workout as you're trying to drive the car with some spirit. You can try to adjust out some of the play in the box from it driving 40 years on center, but when you turn the wheels, the box will start to bind up since there's no clearance. You can get your steering gear rebuilt to get it back to factory specs. Lee Manufacturing is a one-stop shop for rebuilding GM steering boxes and tuning for your application.

Thanks for bring up this topic. It will make our readers think about the total front suspension rebuild.

Sources: lee-powersteering.com, moogproblemsolver.com

Double clutchin'

Q: What are the pros and cons of using an 11-inch clutch over a 10.5-inch clutch with a small-block? Are 11-inch clutches best with big-block, high-horsepower, high-torque engines? I have two small-blocks: a 302 and a 406 in my first-generation Camaros for cruising only, no strip time. What about lightweight flywheels? I use Muncie M20 and M21 transmissions.

Mark Simmons
Fort Collins, CO

A: First, let's talk about the silly little matter of a half inch. Did you know that the L88 Corvette used a 10.4-inch diaphragm clutch? These were killer clutches that took tons of torque and kept coming back for more. They also had a curved diaphragm spring, which helped prevent the clutch from staying on the floor at high engine speeds. The first diaphragm-sprung clutches would make things pretty exciting when the pedal would stick to the floor when you're rowing through the gears at high engine speeds. Needless to say, this was one of the reasons you needed a scattershield back in the day, as they would fly apart when you over-revved the engine. We've used many of the 10.4-inch L88 clutches over the years, straight from GM. While looking for a more affordable alternative, we came across an OE supplier that sold into the aftermarket replacement clutch market. Later, working with GM, we came to know that Lamellen und Kupplungsbau (LuK) out of Germany was the original-equipment supplier for the clutches used in the LT5 Corvettes with their dual-mass flywheels. Also, any of the ZF six-speed-equipped Corvettes use this clutch package. LuK has a replacement 10.5-inch clutch for the Corvette application, and we've probably used at least five of them over the years, and recommended many to friends. These diaphragm clutches are a great street-performance clutch with a ton of clamping force with very low pedal effort.

LuK offers its RepSet 10.5-inch replacement clutch in both the 10-spline disc (PN 04-021) and the '70-and-later 26-spline disc (PN 04-019). We would use these clutches all day long in a street-performance application. They'll give you great service and wear for years. You can find them online from many online distributors for right around $100! The kit includes a new pressure plate, disc, throwout bearing, pilot bushing, and a clutch lineup tool. You can't beat the quality for the dollars.

We usually reserve the 11-inch clutches for high-torque/heavy-load truck applications. We've had more issues with clutch chatter with the larger 11-inch disc than with 10.5-inch clutches. As for lightweight flywheels, for street use we prefer sticking with steel wheels. With aluminum wheels you can have flex issues, which will drive you nuts keeping a good air gap in the clutch when hot. The factory lightweight GM flywheels are the best, coming in at 15 pounds and cast from nodular iron steel. This flywheel (PN 14085720) fits '85-and-earlier, two-piece rear seal, neutral-balanced engines, and is perfect for your 302. It will really wake up the throttle response of your small-blocks, and make a big-block flat nasty.

As for your 406, unless it's internally balanced, you'll need to use a counterbalancer to use this lightweight GM neutral-balanced wheel. Speedway Motors (SM) offers a counter-balance plate (PN 916-15375) that bolts between the crankshaft flange and the flywheel. This is a simple solution for the counterweighted flywheel or flexplate used on the 400 small-blocks. SM also offers a bolt-in counterweight for big-block Chevys so this wheel can be used. Give Speedway a call for more information at 402.323.3200.

Sources: chevrolet.com/performance, schaeffler-aftermarket.us, speedwaymotors.com

Cleaner fuel

Q: I have a question on the new EPA requirements on removing the sulfur from gasoline. I believe this will be mandated in 2017. I have a Chevy big-block with a carburetor. I'm sure many other readers have the same. Big-block, small-block, built, or stock with carburetors—will the removal of sulfur affect our older engines? As in the '70s, the removal of lead in the fuel drove us to install hardened seats for the valves, and the last few years with the removal of lead in the oil has forced those with flat tappet cams to use a lead additive [ZDDP].

Does the sulfur act as a lubricant added to the fuel, or is it a natural byproduct of the refinery? Does the sulfur affect the octane rating as well, or will it make no impact? I'm sure one way or the other it will wind up hitting us in the wallet.

I look forward to the magazine coming in the mail and turn right to the Q&A section. I have written in the past and you have answered my questions and concerns with great results. Thank you.

Mike R.
Westland, MI

A: Thanks. Glad we could be of assistance. Yes, our government is at it again, and you're spot on when you say it's going to hit us in the wallet. Let's take a look at a couple of facts.

Sulfur is a natural element of crude oil and varies from well to well and by region around the world. I'm sure that you've heard of Brent "sweet" crude when they talk about the price of a barrel of crude. The Brent crude is always about $10-$12 per barrel over the WTI crude prices. What they mean by sweet crude is that it's very low in natural sulfur, around 0.05 percent by volume. Now if there is "sweet," then there is "sour," and it can have as much as 14 percent sulfur! Based on what crude your refinery is producing gasoline from, you can see that you are going to yield less by volume with the sour crude. Most of the crude that makes it to refineries comes in between 0.1 and 3.0 percent sulfur. Some refineries cannot process high-sulfur crude or get the refined gas down to the new limits mandated by the EPA. This is also where the expense of the refining process is going to come from, as petroleum refiners may have to shut down plants and we'll lose capacity by going to the new 10-ppm fuels.

The California Air Resources Board mandated back in 2000 to reduce the sulfur in motor fuel from 300 ppm down to 30! This is the California blend you may have heard about. Similar low-sulfur gasoline is already in use in Europe, Japan, and South Korea. This fuel is delivered to California and selected urban areas of the U.S. This was a 90 percent reduction without any issues. Now they want to take the sulfur down to 10 ppm. This will begin in 2017 nationwide, with the advent of the Tier III emissions reduction. The EPA claims this reduction in sulfur will increase the efficiency of the catalytic converter, giving us cleaner air. They also claim that this change in our fuel will help avoid up to 2,000 premature deaths each year and 50,000 cases of respiratory ailments in children, saving $6.7 to $19 billion annually in health care costs. The EPA states that this change will only add two-thirds of a penny to per-gallon gasoline costs. The oil refiners claim that that two-thirds penny per gallon will be more like 6 to 9 cents per gallon. Living in California where we have a one-off special blend of fuels, and a special price point at the pump, we're more likely to see the latter figures.

The bottom line is getting the sulfur out of our motor fuel is a very good thing. It will reduce emissions, reduce acid rain, and will not hurt the performance of our engines. Just expect the pump to hit your wallet.

Valley vent

Q: I am building a 406 small-block Chevy for street/strip use. The combination is as follows: a 0.030-inch overbore Chevy 400 block; Scat 3.750-inch crank; Eagle 5.700-inch rods; SRP flat-top, dual-valve-relief pistons; COMP Cams 292 mechanical roller cam; AFR heads with reworked 210cc intake runner and 70cc chamber; Edelbrock Victor Jr. intake; and Holley (Carb Shop) 928-cfm carb. This beast is going into my '72 Concourse (Chevelle) wagon tipping the scales at 4,240 pounds with me in it. The rest of the drivetrain is rounded out with a Mike's TH400 with 4,000-stall converter and 4.56 gears. Should I use valley vent tubes or oil restrictors, or both? Thanks for your time and answer.

Mike Spencer
Lancaster, CA

A: This wagon should be two tons of fun! Wagons are great for traction and your little 400 is going to make a good deal of torque. Make sure you send us a photo with it hanging the front wheels.

Reducing the oil flow to the top of the engine with restrictors was done to focus the oil volume to the main and rod bearings at high engine speeds. It also reduces the windage created by the oil leaking past the lifters over the connecting rods. The first use of restrictors was back in the '70s, before there were better oil pumps and oils to withstand the high stresses caused by increased engine speeds. Creating 10 psi of oil pressure per 1,000 rpm is easy these days with the proper bearing clearances and the proper pump for the application.

Since you plan to limit the street driving for this engine, and run a roller camshaft, we would not recommend oil restrictors. Also, for racing applications we don't run restrictors as we've had too many problems with roller tappet needle bearings. The lifters need all the oil they can get as most roller lifters are only lubricated by splash from the oil being flung off the connecting rods. This is another reason you don't want to idle a roller lifter engine down too low—1,200 to 1,400 rpm is a good place to keep the lifters happy. Also, restricting the oil flow to the lifter will keep the oil from cooling the valvesprings. Heat is what kills valvesprings the quickest. For all of these reasons we would not recommended restrictors.

As for the valley tubes, we would use these. There is no reason for the additional oil to run down from the valley across the rotating assembly. As you are detailing your block, make sure you grind all the casting flash from around the oil drain-back holes at the rear of the valley. You can have significant flashing around these drain-back passages. You want all the oil to return through these as they direct the oil down to the rear of the pan, and mostly past the rear counterweight of the crankshaft.

Make sure that you come by and say hi at Fontana with your wagon. We would love to check it out and watch it make a pass. Good luck with your project.

Ticking bomb

Q: I am a longtime subscriber to this magazine, and I usually learn something with your column. I have a '65 El Camino (402 big-block, four-speed, Torch Red), but my question is about my '98 Silverado Z/71 with the Vortec 350. She has just over 124,000 very well-maintained miles (was my dad's truck first). Right around 122,000 miles, she started ticking when started in the cold weather and would last about 30-45 seconds. I changed the oil and went with Brad Penn 10W-40 and a quart of Lucas oil additive, and the noise went away, Well, 1,400 miles later it came back louder and longer. I tried a valvetrain cleaner with no success. I was told to run a quart of ATF in it for a few days then change my oil. I did that and went with the same Brad Penn 10W-40 and Lucas. The noise is gone again. I have talked to several friends and their Chevys did the same thing around the same mileage; one friend has over 250,000 miles on his and it still makes noise. People seem to think this is normal, but I cannot accept this. I was also told to go back to 5W-30 and not worry about it. Have my lifters reached the end of service? Is this normal? The truck starts and runs great—it's just that irritating noise on startup. Help me, please! Thank you in advance.

Dan Casserilla
Nashville, TN

A: Slight engine noises can be very irritating. As our engines age like fine wine, they can change their personalities. We understand your frustration and wanting a quiet engine. Let's take a look at a couple of possibilities.

First of all, running a quart of ATF with your engine oil is like giving the engine a bath. The detergent levels of the ATF are much greater than standard engine oil. The hydraulic roller lifters in your engine are not at the end of their useful life. Is it possible that you have deposits on the internal check valve or the internal plunger of the lifter? Absolutely. We believe you have deposits preventing the check valve from sealing perfectly and as the engine sits overnight the lifter bleeds down. This will occur on the lifters that are holding open the valves when the engine is at rest. Over the course of the night this spring pressure is pushing down the plunger in the lifter. When you start the engine the next morning, the lifter must be refilled with oil. Until this is completely filled, you will have valve lash on that specific valve.

You didn't say how long it's been quiet since the ATF bath of the internals of your engine. You mentioned that you're currently using Brad Penn motor oil with a quart of Lucas oil stabilizer. We've found that the Lucas is a good additive, but the increased viscosity of the additive tends to separate from the base engine oil. It's not my first choice. We recommend going back to the factory fill weight of 5W-30 oil and use Mobil 1 Extended Performance full synthetic motor oil. Mobil 1 is an official Dexos1 licensed product for GM vehicles. This is the only oil that GM used as a factory fill on the LS engines. The Mobil 1 is also high in detergents and will keep the components clean over time.

If these "shim in a can" solutions don't resolve your ticking tappets, you'll need to replace the hydraulic roller lifters. This isn't a tough job, just time consuming. The factory intake gaskets are prone to leakage and at 124,000 miles they are probably due for replacement.

Try the oil change route first, and if all else fails, lifters will do the trick. Good luck hunting down that pesky tick!

Source: mobiloil.com



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