September 2011 Chevy High Performance Q & A

Knowing When To Say When

Kevin McClelland Jul 28, 2011 0 Comment(s)
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Right now, I’m lucky enough that both of our race cars are running and don’t really need anything. I have three engines in mid build in the garage: the L-92 for the wagon (remember, I said they were both running) because I can’t leave well enough alone, the LS2 stroker for Daniel’s ’94 RX-7, and finally, a “Brand F” small-block for Charlie Allen’s P/SA Mustang Stocker.

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This past weekend Daniel shifted gears on a project we’d been thinking about for quite a while. If you remember back at least six months or so ago we visited the Pomona swap meet for something we could install an old powertrain in and were devastated by the prices for early Chevys in junk condition. Well, this took us another way and we looked for an early 240Z Datsun to install this small-block engine package. After quite some looking for a clean Datsun, we ran into the same high-dollar syndrome we saw with the Chevys.

Never to let much grass grow under his feet, Daniel came up with another plan. “Let’s build a track day car! We can pick up a second-generation RX-7 and drop the small-block in that.” It didn’t take him long to find a blown-up (a natural occurrence) ’87 Turbo II RX-7 that was straight, no leaks, no rust, and a $2,000 price tag. The car came with a bolt-in rollbar, aftermarket coilover adjustable shocks, and racing coil springs. The engine we have to drop in is a 406 with AFR heads, forged rotating assembly, a mechanical flat-tappet camshaft, and an RPM Air-Gap. This engine will produce an easy 500 hp and 500 lb-ft of torque. We’re going to back the engine with a trusty M21. This simple package will make the car plenty quick in a straight line, and the Mazda’s independent rear suspension and McPherson strut front will give us plenty of fun on the turns. All of this in a simple 2,750-pound package.

Yes, we could have found a Bow Tie to put these components into, but not for this cheap and with the handling capabilities this low-dollar track day car will have. Here in SoCal, we have many places to go out and play. Nearby is Fontana, which has monthly autocross events as well as open track days on the road course. The Adams Karting track in Riverside holds Time Attack events every Tuesday night and Drift night on Thursday. I know I said kart, but the track is large enough for one car at a time. I guess it’s time for me to get up off the couch and get back to work.

We love letters, especially technical questions. Submit your tech questions to Kevin McClelland at chevyhi@sorc.com. Regular shout-outs and good tidings are also always welcome.

Make Sure You Get Home

Q: I have a ’71 Chevy C10 pickup, and it is all steel that I race and some street use. I do drive it to the track, just 300 miles from my home here in Alaska. It has a 383 stroker with about 10:1 compression with the Edelbrock Performer RPM heads, intake, and cam. The carb is a custom-built Holley 4150 (670 cfm). The truck has run a best of 13.03 in the quarter with a consistent 1.80 60-foot. The speed is about 101 mph. I also use a built 700-R4 tranny with 3.73:1 gears and 26-diameter tires in the rear.

It seems to run very rich no matter what I do. I have run smaller jets and up to 72/76 jets. It has a size 9 on the power valve. No matter what I do it continuously gives me black plugs. I am trying desperately to lean it out, and get a bit more power so I can get into the 12s. No luck yet. Any ideas would be very helpful. It did the same with the 355ci engine it was in previously.

George Jorgensen
Fairbanks, AK

A: Three hundred miles one way is a long way to get to and from the track. We assume that you have a friend drive with you in another vehicle? Have you ever had to walk home after a bad day at the track? Can’t say that we’ve had to, but we have had broken cars on the trailer.

It’s really tough to tune a carburetor long distance, especially if it’s been modified. Baseline stock Holley carburetors are pretty easy to tune and find stock data that makes sense. Not knowing what’s been done to your carb puts us at a real disadvantage. What we’d recommend is to throw your carb into a box and send it down to our friends George and Bobby Vrbancic at the Carb Shop. We’ve known these guys since the early days of Pro Gas here in Southern California, racing together back in the late ’70s. They have been building engines and tuning carburetors ever since. Give them a call at 909.947.3575 to get information on recalibrating your carb to your current engine combination. They have an in-house DTS dyno that every recalibrated carburetor goes across to ensure that everything is dialed in before it gets to you.

Since the carb acted the same way on your old engine, and you have run through the jet game, I think you need a new baseline. The Carb Shop will be able to get you on the right side of the fuel curve. Oh, by the way, your truck runs pretty good already!

Source: customcarbs.com

Hippity Hop

Q: My ’69 Camaro has a Muncie four-speed and a stock monoleaf-spring rear suspension. I recently installed a ZZ502 big-block and now need to upgrade the rear suspension. I’m experiencing severe wheelhop and it feels like the springs are collapsing under most hard acceleration. I’m looking for your recommendation on springs, traction bars, and anything else you think should be considered to handle the new load and stiffen things up. I’d like to be reasonable with dollars but want to make smart choices that solve the problem the first round rather than cutting corners.

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Jim Jaeckel
Littleton, CO

A: We have firsthand experience with a ’67 Camaro with a big-block, Muncie, and monoleaf rear springs. Our good friend Bill Kimack came driving by the shop back in the early ’80s with the ’67 Camaro that he had just finished installing a mildly warmed-over 454. He wanted a picture of the car doing a burnout. We hopped (perfect word) into his Camaro and pulled right out in front of the shop. Bringing the rpm up and dropping the hammer, the rearend began to hop and we couldn’t get the clutch in quick enough, and the cluster exploded in his Muncie trans! Well, the car had just enough speed to roll right into the shop, where we pulled the trans and fixed it. What are friends for?

The monoleaf suspensions in the Camaros have always been a problem. This is especially true in the ’67 because both of the rear shocks were on the front side of the rear axlehousing. In 1968 they staggered the shocks and moved the driver side shock to the rear of the axle. This was a very weak change to try to help with the wheelhop issues. Also, in ’68-on, the higher-performance Camaros were equipped with five multileaf springs. This helped, but the aftermarket has stepped in with outstanding components for whatever use you are going to subject your Camaro to.

For Pro Touring and spirited road driving and track days, check out the component Hotchkis Suspension offers for the rear of your Camaro, complete rear suspension packages that give you multileaf rear springs, rear sway bar, and hardware. The rear springs are 3-inch lowering springs featuring a multileaf design with a 3/4-length overload spring to reduce axlewrap. The front mount is a high-durometer rubber and the rear mounting is a polyurethane bushing. This kit (PN 2413C) comes with the springs, bushings, and new shackles. Next, you need to tie all that torque your ZZ502 is kicking out with the rear unibody frame. Hotchkis offers beautiful weld-in subframe connectors (PN 4007) that feature 1.5x2.5-inch rectangle, 0.120-inch-wall tubing. They require no cutting to install, and give you the most ground clearance possible. They are powdercoated black and are supplied with a polyurethane subframe mount to attach the front mounting point.

Now, if you’re more of a “straight line” guy, check out what Calvert Racing has to offer for the rear of your Camaro. The Cal-Tracks traction enhancing devices for leaf-spring rear suspension have won more NHRA Stock eliminator titles than any other leaf-spring traction device on the market. Calvert also has two-piece monoleaf rear springs for Camaros to work in conjunction with their specific traction device.

Sources: calvertracing.com, hotchkis.net

Plenty of Fuel

Q: My ’70 Chevelle SS has a ZZ502, an 850-cfm Demon carb, Hookers, a Hughes Turbo 400 with a GM25 converter, and a stock 3.31 posi. I spoke to Demon because I have installed bigger jets several times, currently 88 primaries and 93 secondaries, and the plugs are just barely starting to show a bit of tan color. The guy at Demon said if I have to put jets that big into that carb then it is starving for fuel. The fuel system is a stock tank pick-up and 18 inches of 1/2-inch rubber hose, a Holley HP125 pump, 24 inches of 1/2-inch hose with a Jeg’s screen filter in the middle. Then I go back to stock steel 3/8-inch line up the frame to engine compartment then 1/2-inch rubber hose to both inlets on carb. The Demon tech said I need a bigger pick-up tube in the tank and also change the stock steel 3/8-inch line on the frame to 1/2 inch. I can’t find anyone who makes a tank unit with a bigger pickup tube. Help!

Tim Raubinger
Wasilla, AK

A: Hey, Tim, you and George hang out at the same dragstrip in Alaska? What a coincidence. We rarely hear from you guys from up north! Your 502 will live just fine with the 3/8-inch pickup and fuel line. Let’s talk.

We’ve run a 502/502 in a ’72 Chevelle with a Carter electric pump at the tank and full 3/8-inch line and factory Holley-type fuel distribution lines at the carburetor. This Chevelle ran great on the dragstrip, handling challenges, and braking. We built this Chevelle for Flowmaster for the Hot Rod Power Tour. It was Richard Small’s and it was used by several magazines for many performance challenges.

Back to reading your spark plugs. With unleaded fuel, the center electrodes will be perfectly white when the engine is fueled correctly. We run our 524 in our roadster on the rich side. With our Racepak data logger recording the wideband O2 sensor, the air/fuel ranges between 11.9 and 12.2 from the starting line to the finish. We keep it on the rich side to make it less sensitive to atmospheric changes and to help prevent detonation. When we check out the plugs in this engine after 50 dragstrip passes they are still perfectly white! You will never see color on the center electrode that you would with leaded-type fuels. The only true way to set the jetting on your Chevelle is either through performance testing to the highest mph on the dragstrip, or with a wideband O2—the O2 is the easy way to go.

If you really want to convert your Chevelle to full ½-inch fuel line, you’ll need to fabricate a pick-up through your sending unit in the tank. You could also add a pick-up to the bottom of the tank, but that’s not very clean for a street-driving car. Great for race cars, but can be problematic on regularly street-driven vehicles.

Clueless

Q: Can you help me identify my big-block Chevy? The engine code is T05217BJ; the block is 3963512 dated E14-9. I can’t find this in any books. I Googled it and found another guy with a BJ engine code. It’s in my ’67 Camaro RS/SS, but it’s not the original engine for the car. The seller told me it was a 427. The heads on it are 3964291 dated K28-9. Please help.

Garrett Ikeda
Honolulu, HI

A: We can give you some help, but your letter codes don’t make any sense. It was not uncommon for GM to use odd letter designations for crate service engines, however, your ID does look to be a production identification. The engine ID T05217BJ identifies that your engine came from the Tonawanda engine plant, and was built May 21. This is where it gets a little weird. You have an extra number. We tried to find a three-letter code in the 427/454 engine identifications with the final two digits BJ. The only time any big-block used the last two digits BJ was in 1984 on a 454 in a truck. Based on the casting dates of the block and cylinder heads, the engine assembly date must be May 21, 1970. That pretty much knocks out the ’84 model year.

All the information you gave us points to an L-71 425hp 427. The engine block casting number 3963512 was used from 1969 for 427s, and 1970-76 for both production 454s and crate engines. The date code E14-9 represents May 14, 1969. These blocks were produced in either two-or four-bolt mains. The easiest way to identify the block as a four-bolt is to check for the 3/4 pipe threaded ports right above the oil filter pad. These threaded oil galleries were for external oil coolers in racing applications. The cylinder heads are a rectangular-intake-port, closed-chamber 109 cc that was used on 396/402/427 and 454 engines. They were used on crate engines after the ’70 model year. The date code K28-9 represents November 28, 1969. The last 427s were assembled for production use in 1969. The model year change for production falls in September and October.

One final thing, you didn’t mention if next to the engine identification code on the deck of the block there was a partial VIN number. All production engines have the final eight characters of the VIN number from the vehicle the engine was installed in. None of the crate engines have VIN numbers on the deck.

If your engine is an L-71 427 big-block crate replacement it would have 11:1 forged TRW pistons, 7/16-inch rod bolt “Dot” rods, a forged steel crankshaft, a mechanical flat-tappet camshaft, an aluminum high-rise inlet manifold with a Holley square-bore flange. Finally, check out the harmonic damper on the engine; 454 engines have a counterweight cast into the inner ring of the damper. The 427s were neutral balanced, and the 454s had this counterweight on the damper, and also on the flexplate/flywheel. We hope this has gotten you closer to identifying your big-block. Enjoy your SS, and happy cruising. Aloha!

Resto Tech

Q: I would like some info on my resto build. I have a cam and lifter set with 218 degrees at 0.050-inch tappet lift, 0.460-inch max lift, ground on 110 centers. I also have a set of heads with a recent valve job, casting number 462624, and an aluminum Edelbrock intake (PN 2101) for a Q-jet. If I put this on my ’65 Chevy 283 short-block, what kind of power do you think I would get? Can I use my stock rocker arms with this cam? Thanks, I love this magazine.

Bob Holland
Via email

A: Your resto build plan has a couple of problems. Mainly it’s your cylinder head selection. These were originally used on both 350- and 400-cid small-blocks with 76cc combustion chambers. The chambers would overhang the small bore (3.875 inches) of the 283, and the large combustion chambers would kill the compression ratio of your Mouse. With the small displacement and low compression, it would kill any slow-speed power your little engine thought it would have.

Most 283 offerings from Chevrolet came with 60cc combustion chambers. This pegged the compression in the mid-9:1 range with flat-top pistons. Unfortunately, the aftermarket never stepped up to the small-bore engines. There were S/R 305s offered by World Products many years ago. We couldn’t even find information online on these very rare heads. The best bet would be to pick up a set of Power Pack casting from an original 283 and have them freshened for your mini Mouse. A couple of casting numbers you can look for are 3817680 and 3795896. Contact Tony Knight at Cylinder Head Exchange in Sylmar, California. He has a deep inventory of these early castings and we bet he has a set on the shelf, ready to go.

A set of fresh cylinder heads with the Performer manifold would give you 270-280 hp and around 300 lb-ft of torque. Also, you can use your stock rocker arms with 0.460 inch of max lift. Good luck.

Source: cylinderheadexchange.com

Not a Chance

Q: I was wondering if Chevy ever made a ‘90 SS 350 truck. If they did, any information on it would be helpful. Thanks.

Adam Beckmann
Via email

A: Nope! They only produced the SS 454 trucks from 1990-93. These were equipped with L-19 TBI 454s, which didn’t really deserve the SS moniker. Sorry we couldn’t help with your quest for a 350 SS pickup. If they did build one in those model year ranges, the L0-5 TBI 350s were even worse! CHP

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