E-Mail: Hotrod@Primedia.Com * Mail: Hot Rod Pit Stop, 6420 Wilshire Blvd., Los Angeles, CA 90048 * Fax: 323/782-2223 * Message Board: HOTROD.Com
Street rod, musclecar, race car-whatever you drive, if you are reading HOT ROD, it means you just can't resist the urge to make it stronger, faster, and better. But unlike a typical government contract, you'd like to get the job done on time and within budget. To that end, Pit Stop is here to help resolve your technical problems. Whether it's theory, resolving a thorny driveability problem, recommending the best combination, or helping to locate a hard-to-find part, we'll answer as many questions in these pages as space permits. When e-mailing, don't forget to include "Pit Stop" in the subject line, as well as your real full name and hometown or military unit, base, or ship in the message. If you have quality digital photos of the car or problem, and if they're at least 300 dpi at 4x4 inches or larger in size (bigger is always better), send 'em in too.-Marlan Davis
L88 vs ZL1
What's the difference between a stock L88 and a stock ZL1? My roommate and I are fighting. Please help calm things over here at Central Washington University.
Garrett Lee
Ellensburg, WA
About 150 pounds. The Chevy L88 heavy-duty 427 big-block was factory-installed in '67-'69 models, while the original all-aluminum 427ci ZL1 was an option only in late '69s, so the differences depend on which model-year L88 you're talking about. Essentially, the late-'69 second-design L88 was basically the same engine as a ZL1, except on the L88 the block was still cast-iron, the cam was slightly milder, and the ZL1's high-volume oil pump was not installed. For detailed differences, see the spec chart. Note you can still buy an improved, bare ZL1 block today under GM PN 12370850. Just because those engines were nasty doesn't mean you guys gotta be too-go stand in opposite corners and take a time-out.
Where Do I Getrestoration catalogs for a '7011/42 Ford Falcon, as well as a disc-brake swap kit for the front?
Jeremy Sasser
Pensacola, FL
Dearborn Classics (Bend, OR; 800/252-7427 or 541/318-7471; www.dearbornclassics.com) is a good comprehensive restoration parts dealer. Stainless Steel Brakes (Clarence, NY; 800/448-7722 or 716/759-8666; www.ssbrakes.com) is one source for disc-brake conversion kits.an intake manifold for a '73 Buick Apollo with a Buick 350?
Mike Meloshinsky
Hope, BC, Canada
You have your choice of the Stage 1 350 Buick intake (PN TA 1235) from TA Performance Products (Scottsdale, AZ; 480/922-6807; www.taperformance.com) or the Poston Enterprises (Atmore, AL; 800/635-9781; www.postonbuick.com) intake (PN B350).
...a good software program for engine building/designing?
Arcangelo Limanni
Toronto, ON, Canada
ProRacing Sim LLC (Memphis, TN; 901/259-2355; www.proracingsim.com) offers a wide range of engine and vehicle-dynamics simulation software ranging from the entry-level DeskTop Software series all the way through the professional-level Dynomation Advanced Pro.
two SPAL 10-inch puller fans for the '89 S-10 with a 350 that I'm building?
Scott Foster
Bluffton, IN
SPAL USA (Des Moines, IA; 800/704-8067; www.spal-usa.com) sells direct.
...license-plate-light housings for '91-'92 Camaros?Ben Allgeier
Louisville, KY
There is both a lefthand and a righthand assembly. GM has discontinued them, but Year One (Braselton, GA; 800/932-7663 or 706/658-2140; www.yearone.com) still lists the driver-side "tag-light housing" under PN B34LH. For used assemblies, try Jimmy's Bowtie Supply (Shelbyville, TN; 800/414-JIMS or 931/695-5204; www.jimmysbowtie.com).
...a torque-arm mounting bracket for installing a Ford 9-inch rearend in a '95 F-body Camaro?
R. Bentson
Wall, SD
A weld-on bracket (PN CE-7009) is available from Currie Enterprises Inc. (Anaheim, CA; 714/528-6957; www.currieenterprises.com).
Drag Radials: To Screw Or Not To Screw
I've been having trouble the last two years with my rear drag radials moving on the rims. I have used the BFGoodrich and now have a set of Mickey Thompson drag radials. I have had a tire place say they could stop it by putting this black sticky stuff on the rim beads before they mount the tire. They did this but it did not help. The tires move 2-3 inches every time I go to the track.
When I drive home I have to go back to the tire store and have them rebalanced. I have been told by some of the racers at the track to go ahead and screw the tires to the rims, but the manufacturers say not to screw these tubeless tires.
The car I'm running is nothing really fast. It runs 12.15 quarters with 1.68-second 60-foot times. Is it possible that I just need to keep balancing them until they take a set on the rims?
Greg Drew
Durand, MI
According to Mickey Thompson sources, generally radials can tolerate more rim movement than old-school bias-belted tires, primarily due to difference in sidewall configuration. Radials with their more flexible sidewalls move more than bias tires, which have stiffer sidewalls. That said, from 11/44 to 11/42-inch rim movement is considered normal with drag radials; more than 1-inch movement is asking for trouble. You can verify movement by marking a line on the tires and rim.
In the event of excessive movement, first check the wheel condition-it should be round overall, and the seal-bead surface should be smooth and free of crud and corrosion. Over the years the bead surface tends to get beat up. If the rim checks out, then it's OK to screw the tire to the rim using 16 mounting screws per side. Thompson says air leakage should not be a problem, so there's no need to add an inner tube. Finally, cars running faster than 150 mph should consider using a bead-lock wheel.
Irs Antisway Bars
Having read your excellent article on the Corvette IRS ("Taxing the IRS," Feb '05), as well as the article about the early Mustang with an IRS in the same issue ("The Blender"), I was wondering why independent rear suspensions don't use antisway bars?
Ernst Hoard
Waverly, VA
Never say never, but it is a general truism that a rear antisway bar usually does not aid the handling characteristics of an independent rear suspension (IRS) as it would on a conventional solid-axle car. A rear antisway bar is basically a tuning device. If a car understeers, you need to either up rear spring rate or use a bigger rear bar. An IRS has less unsprung weight than a solid rear axle, which makes it more sensitive to antisway-bar changes. Adding a big bar out back tends to make the IRS car twitchy and create power oversteer. Instead, most Corvette tuners prefer to set up the IRS with the correct spring rate and shock-absorber valving using little or no rear bar. Another factor is that because a big rear bar effectively ties the right and left wheels together, it makes the IRS behave more like a solid axle, which kind of negates the reason for having an IRS in the first place. Also remember that antisway bars are primarily for cars that go around corners in a handling application. While the IRS beef-up mods mentioned in February's story can benefit any Corvette rearend subject to abuse, the complete suspension package is specifically designed for straight-line drag-racing, where antisway bars are not normally used even on a solid-rear-axle combination.
Shorty vs. Long-tube headers
I have a '78 Chevy 3500 truck with a 400 small-block. I have always used tri-Y headers but I have recently found shorty headers for my truck. I was wondering if the shorties work as well as the long-tube headers. The shorty headers I have found are 14-gauge steel with 111/44-inch primaries, 211/42-inch collectors, and 31/48-inch-thick flanges.
David Preston
Buena Park, CA
If the shorty primary tube diameter really is 111/44 inches, that's too small. The tubes need to be at least 151/48 inches. That said, short, unequal-length tubes may be an improvement over stock cast-iron exhaust manifolds, but they won't have the scavenging effects of properly designed equal-length tubes. Off-the-shelf tri-Ys are generally thought to make more low-end torque than full-length four-into-one designs but at the expense of some top-end power, however, it totally depends on the overall combination. The ultimate, no-compromise configuration for high-perf street operation would be a full-length tri-Y, with the Y merge-point occurring at the end of the full-length primary tubes. But proper exhaust phasing and ultimate scavenging can't be achieved by pairing adjacent cylinders. Ideally, the pairing should be set so that when one cylinder is in overlap, the other is firing. On a Chevy V-8 with its 1-8-4-3-6-5-7-2 firing order, the pairs should be 1-5, 8-6, 4-2, and 3-7. This requires a 180-degree design. You won't find mass-produced headers like this due to cost and complexity.
Short of the complex 180-degree design, what can you do to make a given set of headers more effective? Start by extending the collector by 8 to 10 inches before reducing it down to the exhaust-pipe diameter. Similar to the effect of adding more plenum volume to an intake manifold, extending the collector tends to broaden the torque band. Invest in a good, true dual-exhaust system; 2.5-inch duals are about right for your application. Add an H-shaped crossover between the pipes installed as close to the header-collector ends as possible. In lieu of the superior 180-degree header configuration, the crossover helps balance the exhaust system and relieve overpressure when adjacent cylinders fire on the same bank through the same collector. And make sure to use good aftermarket mufflers.
Ford Mexican Blocks
I live in Southern California and own a '94 Mustang GT. I was planning to rebuild the engine this spring to give the pony a little more kick. I've heard about 302ci Mexican production blocks. Where can I find one? Are they really stronger than a standard 302? I plan to stroke it to 347 ci and run forged internals, AFR 185 heads, and a 150hp shot of laughing gas.
Abel Martinez
Palmdale, CA
Compared to a late-model 302 U.S. block, mid-'70s Mexican blocks have thicker main caps like those on a '65 289 block and are supposedly cast with a higher nickel content. According to various Ford sources, Mexican blocks do not have thicker cylinder walls than standard blocks. They also lack provisions for mounting the late-model hydraulic-roller-lifter retainers. Identify a Mexican block by the "Hecho en Mexico" cast into the lifter valley area, as well as additional unmachined bosses on the front of the block below the deck surface, one each on the driver and passenger side. Your late-model 302 roller-cam-block casting is good through about 450 hp. Beyond that level, I wouldn't go out of my way to find a rare Mexican block; instead, consider a truly superior casting, such as those available from Ford Racing, Dart, or World Products.
Chevy 283 Induction
I am overhauling my '63 283 Chevy for moderate performance in a '59 Chevy on 87-octane pump gas. I know a 350 would be a better choice but I already have the 283. It has 0.060-over flattops and Power Pack heads with 1.72/1.50-inch valves. I think a 266 Crane cam will be a suitable choice with a compression ratio not to exceed 9.25:1. I have a 260hp target with this combo using mild porting and headers. Which intake and carb should I use: a Q-Jet and a factory manifold (casting No. 3905393, originally on '67 275hp 327s and 295hp 350s), or a '63 250hp 327 manifold (casting No. 3783244) with a 500- or 600-cfm carb? I have measured the height and width (ignoring the corner fillets) of the intake ports in the Power Pack heads and both manifolds. The early manifold runners are about 1.63 square inches, the later ones are about 2.06 square inches, and the head has about 2.05 square inches at the manifold, tapering to 1.72 square inches 2.25 inches down from the inlet flange. That looks like a lot of neck-down to me; will low and midrange performance suffer in spite of the small Q-Jet primaries with the bigger manifold due to the runner velocity being too slow?
John Zins
Thief River Falls, MN
The Power Pack head's inlet-port neck-down boosts air/fuel charge velocity, and though crude by modern standards, it helps low and midrange power, which is badly needed in the small 283. With the choke-point in the head, the larger-runner '67 intake should work OK, but it's machined for the WCFB Carter or early Rochester 4GC carb. Parts are hard to find for the old carbs, and in terms of driveability and performance, they aren't as good as the superior Quadrajet. So, assuming you are limited to the choice of those two stock manifolds, I'd pick the '67 intake with a dialed-in Q-Jet.
As to your combo and goals, old 283 GM factory power ratings are inflated, so your 260hp expectation with 87-octane gas, mildly ported Power Pack heads, and a 212-degree duration (at 0.050-inch lift) hydraulic cam is optimistic. More likely you're looking at around 220-250 hp. To make a 283 run, you have to rev it.
Here's a better combo: Instead of a hydraulic cam that poops out at 5,500 rpm, get a solid cam with about 230 degrees duration at 0.050 that'll run to 7,000. Get some heads off a later 305 engine. They have larger inlet valves (1.84 compared to the 283's 1.72), better ports, and a superior combustion-chamber shape than Power Pack heads. The No. 416 casting, used '80-'86, is one of the better 305 heads and it uses perimeter-style valve-cover bolts. An Edelbrock Performer 2101 intake has dual large/small runners that generate dual torque peaks for a broad torque band, and on a 283 it's worth at least 12 hp upstairs over any stock intake. On a small 283, the standard Performer 2101 acts like a Performer RPM does on a 350.
If you are willing to move away from the classic look in search of far better driveability and performance, take a hard look at mid- to late-'90s 350 Vortech heads (casting Nos. 906 or 062). To retain compression in a 283, you'll have to mill the heads to reduce the 64cc chambers down to 58 cc. A 350-style head gasket will be needed because a 283 gasket will overhang the chamber contours. GM head gasket PN 10105117 better conforms to 4.0-inch and smaller bores compared to typical oversize aftermarket gaskets. The Vortech heads are so good that you can probably get away with a cam with 220 degrees at 0.050 and still meet your performance goals. Because of the different inlet-manifold bolt pattern, you'll need to use an Edelbrock Performer Vortec manifold (PN 2116). Vortech heads are machined for late-style center-bolt valve covers, but GM has an adapter (PN 24502540) that permits installing early perimeter-bolt covers on the late heads.
