E-mail your tech questions to us at carcraft@primedia.com (include the words "What's Your Problem?" in the subject line) or fax them to 323/782-2223. All correspondence must be signed with the sender's real name (not a nickname or a screen name) and include the sender's hometown and state or province. While mail cannot be answered personally, Car Craft will publish as many letters and replies as space permits. Photos are welcome, but no materials will be returned.
II Times FiveI have a '33 Ford Coupe with a Mustang II front suspension, which uses four-lug brake rotors. I'd like to convert it to a five-lug pattern, but I'm not sure what hubs to use. Any suggestions?John Hanna Aberdeen, MS
The simplest way to get to a five-lug pattern would be to swap your brake rotors, since the hubs and rotors are integral on the Mustang II setup. Stock 911/44-inch vented Mustang II (M-II) rotors are available new with either the traditional Ford 5-on-411/42-inch bolt pattern or GM's 5-on-431/44-inch pattern from a variety of street rod parts suppliers, including Speedway Motors. At $34.95 apiece, the price is right, too. These are brand-new rotors that are only drilled with the desired bolt pattern, not converted from four-lug to five. Order up a set of fresh wheel bearings and you'll be ready for five-lug wheels inside of an hour. Speedway also offers Mustang II "Super Rotors," which are the same size but are cross-drilled and zinc-washed.
However, while you're at it, you may want to take the opportunity to upgrade your braking, particularly since the stock Mustang II brakes are small, and were originally intended for four- and six-cylinder Pinto-based M-II models, even though V-8s were later offered. A fairly common upgrade involves using Granada 11-inch rotors, which use the same wheel-bearing dimensions so they bolt right up to the Mustang II spindles. This requires custom caliper brackets, and most of these swaps are offered in kit form using GM "metric" calipers (third-gen F-body and '78-'88 A/G body) with the required adapter brackets.
Master Power Brakes offers a kit that upgrades the M-II front spindles to 11-inch brakes, but it uses separate hubs to mount the rotors, and the hubs and rotors are both drilled to accept studs for either 411/42-inch or 431/44-inch bolt pattern. This kit also uses the "big" GM-style calipers found on many '70s-era GM cars, as opposed to the later metric GM calipers. According to Master Power, the larger calipers are good for an additional 65 percent clamping force. Another stated benefit of this kit is that it does not widen the vehicle's track width-the wheels remain in the same position relative to the vehicle.
If you still want more braking for your Mustang II-equipped vehicle, Master Power also offers a Deluxe M-II brake kit, featuring 12-inch cross-drilled and slotted rotors and late-model Corvette-style PBR aluminum calipers. The kit uses aluminum hubs and comes with stainless-braided brake hoses, and while it also does not widen the vehicle's track width, it does require the use of at least 16-inch wheels.
Proper HeaderingIn your Sept. '03 issue, you featured a set of Ford GT-40P iron cylinder heads on an engine buildup. My question is, what would happen if you bolted a set of these heads onto a 5.0L Mustang? Would the angled spark plugs clear the headers, and if not, are there shorty headers to make this work without requiring a custom-made set of tubes?Ramon DuvernayHyattsville, MD
The spark plug location used on the GT-40P heads isn't significantly different than traditional small-block Ford cylinder heads, but the angle of the plugs is, as you point out. This does create header fitment conflicts in some situations. From the feedback we've collected, there are some headers that just happen to fit the "P" heads, and some that don't; Internet sites seem to be a good source of information on this. Rumor has it that stock 5.0L Mustang tube headers will clear, but we haven't actually tried this ourselves. There are application-specific headers for this swap, however, available from Ford Racing and from MAC Products. We bolted a set of P heads to a '93 Mustang a couple years back, and tried both sets of shorty headers, and though the designs are different, both fit just fine. The car currently runs the Ford Racing tubes, though these are not smog-certified. Incidentally, the GT-40P heads were worth 30 hp over the stock '93 E7TE heads when used in conjunction with a Cobra intake manifold and 65mm throttle-body on an otherwise stock Mustang.
Russian Roulette, Ford StyleI have a Ford 302, casting number C8OE-6015-A, that I sent to the machine shop to be inspected and overbored. When I got it back, the crank was not the same one I had sent. The crank I got back has a casting number of 2MAE, which is an '82-'90 crank. Now I'm wondering if I can use my old flywheel and balancer. My flywheel is casting number C4AE-6375-B, though I'm not sure of the original application. I already know that the late-model balancer is a four-bolt unit while my original is a three-bolt type. I don't want to mix-match parts without being sure they are compatible, so could you tell me if these pieces can be used together, and if not, what parts I need to make this work?Thomas HollowellVicksburg, MS
The problem you're going to have is with the balancing of these engines. The Ford small-block engines are externally balanced, meaning that an imbalance in the rotating assembly is corrected with weights on the external rotating parts, specifically the harmonic balancer and the flywheel/flexplate. The early 302 and all 351W Ford engines used a 28.2-ounce/inch imbalance while later 302s, from '80-on, used a 50-ounce/inch imbalance. These parts can't be mixed and matched; they must be used in the appropriate application. The simple answer would seem to be for you to install the 50-ounce balancer and corresponding flywheel/flexplate from a later engine, but as you've noticed, Ford changed from a three-bolt pulley arrangement to a four-bolt pulley in the early '70s. This leaves you with the option of switching to a later accessory drive or using a conversion balancer. Ford engine swap specialists Total Performance offers the proper 50-oz-in three-bolt balancer, and Professional Products offers high-performance Ford small-block balancers that are drilled for both three- and four-bolt pulley patterns, plus they are available with spacers to match any of the Ford accessory-drive placements.
Fourth-Gen FattiesI have an '02 Trans Am with the WS-6 Ram Air package, and I'd like to step up to 18-inch wheels and tires. I have a complete Hotchkis suspension system on the car right now, which lowered it about an inch.
I want to use 18x9.5-inch wheels in the front with 275/35 tires and 18x10.5-inch wheels out back with 315/30s. Will this combo work? Is there any chance of fitting an 18x12 with a 335/30 tire? I'm trying to have the fourth-gen F-car with the fattest shoes. This car is really only used on weekends on good roads, so sidewall height isn't much of an issue.Kyle SundbergLake Butler, FL
Your proposed wheel/tire combo is pushing the limits, but should work, provided you order the wheels with the proper backspacing/offset. We've seen 275/35-18s on the front of fourth-gens before, so that shouldn't be a problem, though they're usually mounted on a 9-inch wheel. Still, if you're determined to have a 9.5-incher, sources say it can be made to fit. The 10.5-inch rear wheel is also on the edge-a 10-inch rear wheel is more common for upgraded F-cars of this vintage, but again, sources say it should fit, though depending on the wheel manufacturer, that 315/30 tire may be stretched a bit to span the rim width. Definitely consult with the wheel-maker prior to ordering. Some fourth-gen Camaro SS owners like to use 11-inch ZR1 wheels on the rear of their cars, but if you've ever seen this, you know that they usually hang out under the wheel lip, and even a touch beyond it in some cases (usually with 335/30 tires). That said, it's a safe bet that you won't get 12-inch wheels in there. Since you have the Hotchkis suspension with its rigid trailing arms and panhard bar along with stiff urethane bushings, you can afford to run the rubber fairly close to the inner fenderwells (you need a minimum of 11/42-31/44 inch of clearance at rest), but if you were still running the stock stamped-steel/rubber pieces, the flex would require more clearance, and therefore would likely not permit the use of a 10-inch wheel or bigger.
By the way, fourth-gen F-cars that left the factory with 17-inch wheels have a spacer between the rubber jounce bumper and the frame over the rear axle. Your car should already have these (and you may be able to spot them by looking through the wheel openings), but for those upgrading from 16-inch rollers, these should probably be added to limit the axle travel, providing a bit of insurance between the tires and quarter-panels. You can get them from SLP.
Oldsmo-BuickI am planning on rebuilding my Olds 425, which is out of a '65 98. I want to bore it 0.030 over, and I am trying to decide on pistons. My question is, will 0.030-over Olds 455 pistons work for me? I am almost positive that the 425 and 455 share the same block. I am planning on putting this motor in my '69 Buick Skylark along with a TH400 trans. I know it will be tough to do, considering I will need a new trans crossmember and the Olds block sits an inch higher than a Buick big-block would. But time is not a concern for a 19-year-old college guy who is sick of my generation driving Kia Rios mod'ed with aluminum wings and coffee cans for mufflers. Any advice you can give me is great.John Gerrity Mokena, IL
The 425 and the 455 Olds do use basically the same block-that is, both engines use a 4.125-inch bore and 3-inch main journals. However, if you check into the factory specs a little deeper, you'll find that the 425 uses 6.998-inch connecting rods while the 455 uses 6.735-inch rods, and the stock pistons in a 425 have a 1.615-inch compression height while the 455 pistons have a 1.74-inch compression height. So, pistons are not interchangeable between engines.
As far as the engine swap, it really shouldn't be difficult at all. First, your Skylark is basically the same chassis as a similar-era Olds Cutlass, which was offered with a 455 in '68 and '69 (in Hurst/Olds models), and then as an option for the standard Cutlass from '70-'72. Since the 350 and 455 Olds use the same engine mounts, even a set from a 350 Cutlass should work to mount the 455 in your Skylark. The proper frame mounting holes are probably already drilled in your engine crossmember as well. You also mentioned the need for a new transmission crossmember, probably because you figure this will be necessary to mount the TH400. However, on most A-body GM cars of that era, the same transmission crossmember is used with all transmissions-it's just slid back for the larger trans. Again, the holes in the frame to mount the trans crossmember in the TH400 position should already be there, since some Skylarks-like the GS 400-could be had with the larger Hydramatic box. Some Buick/Olds/Pontiac applications from that era used transmission crossmembers that had rubber isolators on the ends to dampen vibrations transferred to the chassis, and if your car has this, you may want to find the one-piece Chevelle-style tubular crossmember that does not have isolators. After 30-some-odd years, the rubber bushings may not deal well with the monster torque of a 455 and a heavy foot. Note also that you will need a shorter driveshaft that uses the larger TH400-style slip yoke; your existing shaft could be modified by a competent shop to work.
Pontiac Big-Block?From what I was told a while ago, the Pontiac V-8s are all the same block from the 350 to the 455. Yet I keep seeing listings on eBay claiming the 400 is a big-block. Which is correct?Carl McCoyVia the Internet
You were right the first time, Carl. The Pontiac V-8 that was first introduced for the '55 model year has come to be known as the "traditional" Pontiac V-8 among enthusiasts, to differentiate it from "corporate" V-8s (read: Chevy) found in many Pontiac vehicles, a GM practice that began in the late '70s. All traditional Pontiac V-8s are based on the same block design, from the 326 up to the 455. This is not to say that all of these engines actually use the same block-they don't. They do, however, share external dimensions. The 421/428/455 versions are called "large-main" engines, referring to the 3.25-inch main journals these engines have as opposed to the 3-inch mains of the 400 and smaller engines.
Engine swapping is fairly easy among Pontiac vehicles, with one primary obstacle in the motor-mount bosses-early motors have two holes per side while '70-later have five, a move made to accommodate the second-generation Firebird's engine positioning. Some oddball engines circa '73-'74 seem to have three holes, as the other two bosses were not drilled for some reason. Nunzi's Automotive in Brooklyn, New York, offers adapter brackets for those wishing to mount a pre-'70 engine in a later Firebird under part number 8070.
Score Or Scrap?I have a set of SBC heads with the casting number 10125320. How do these stack up against the Vortec heads? What size combustion chambers do these have?Greg GortonWillis, TX
The casting number you listed is for a set of '94-'96 LT1 cast-iron heads. These would have been used on the 260hp version of the 5.7L LT1 found in the Caprice, Impala SS, Buick Roadmaster, and rear-drive Cadillac. As far as the port design, the Vortec's ports were based on the Gen II LT1 design, so they are very similar. Most LT1 heads have 64cc combustion chambers used in conjunction with the flat-top pistons in the 5.7L short-block.
However, since the LT1 heads are part of the Gen II small-block design, they cannot be swapped onto an earlier small-block. Physically, you might be able to make it happen as the dimensions are roughly the same, but the main difference is in the cooling passages, since the Gen II used a reverse-flow cooling system that feeds coolant to the heads first, then the block, which is the inverse of most traditional V-8s. Even if these could be modified to work on a traditional small-block, it wouldn't be worth the effort, since so many excellent heads are available to bolt directly to the small-block at reasonable cost.
Axle AskingI recently bought a disc-brake Posi-traction rearend to replace the drum brake open rear in my '84 Camaro. It's a Borg Warner rear that I believe came out of an '87 Pontiac. It had a metal tag on the cover with 2.77 stamped on it. I understand rear-disc F-cars came with Moraine-type calipers. Does this rear have the same type? I know I'll need a new proportioning valve. Could I use one of those adjustable valves alone, or do I need to use it in conjunction with a stock valve? Also, the parts place has the same parts numbers for both disc and drum master cylinders. Could I use mine? Is this rearend worth it? I only paid $100 for it.Jeff MedineViolet, LA
The rearend you've acquired is what most third-gen enthusiasts refer to as the Australian axle, as that's where it was built. It's also referred to as the 9-bolt, because of the number of bolts holding the rear cover in place. It may well be a Borg-Warner design, but it's not one that was used on any other GM car here in the states. The 2.77 refers to the axle ratio, and this unit was also offered with 3.27:1, 3.45:1, and 3.70:1 gearsets. The '87 model year was the first time this axle was used, replacing the puny GM-built 7.5-inch axle used on all third-gen F-cars previously. The strength of this unit was a definite improvement over the 7.5, though that's not to say it's actually strong by musclecar standards. For a mild street car it should be fine, as long as repeated drag launches with sticky tires aren't part of your plan.
The brakes that would have come with that axle are the Delco-Moraine type, which can be identified by the cast-iron calipers-in '89, GM switched to aluminum PBR-sourced rear calipers. This change was reportedly precipitated by reliability issues with the iron calipers. The main problem is that the calipers "freeze," which seems to be linked to the parking brake mechanism.
But if your calipers check out OK, this rear axle assembly should be an improvement over your stock '84 unit, though you may be losing some axle ratio depending on what you have now. The rear brakes should bolt right up, and some sources tell us that the drum-brake proportioning actually works well with the rear discs in this particular application. As you seem to be aware, normally a disc-to-drum swap would require a proportioning change and a differently sized master cylinder. In this case, retaining the drum-brake proportioning would limit the effectiveness of the rear discs, if anything. It is possible that the master cylinder is the same for both applications in this instance. But anytime non-factory brake system changes are made, it is critical to verify that the system still works properly under all conditions. That means you need to find out if the rear brakes will under- or over-brake in heavy braking situations, including wet pavement. If the brake proportioning isn't correct, you could use an aftermarket manual-adjustable proportioning valve. To be most effective, these are usually used without the factory proportioning valve; if the manual unit is installed after the factory unit, all it can do is further limit the rear braking.
Little EnginesI've decided what I would like to do to my 283. I would like to start by using a 327 crank. I have read that some 283 blocks are not compatible with 327 cranks. Is there any truth to this? And if so, how can I go about determining if I have the right 283 block?Josh ShanksWillard, MO
What you're talking about building, Josh, is a 307. From 1968 through 1973, Chevy placed 3.25-inch stroke crankshafts (the same stroke as a 327) in a 283 block to create, in essence, a "stroker" 283 since the original stroke on a 283 is 3.00 inches. You are also correct that there are two different types of 327 crankshafts. All early small-blocks used small journal crankshafts employing a 2.30-inch main journal and 2.00-inch rod journals. Beginning in 1968, Chevy increased the journal diameters to 2.45 for the mains and 2.100 for the rods. The cheapest way to go is to find an early, small journal 327 crank for your 283 block. All 327 cranks were forged steel. All 307 cranks are large journal-that won't work unless you're willing to pay to have the mains cut down, which is expensive.
To answer your question of whether you have the right 283 block, the real point is that if you use an early, small-journal 327 crank, it will drop right in. Be aware that you will have to also use 307-style pistons because the added 0.250-inch stroke (3.25 vs. 3.00 for the 283) will require a 307-style compression height piston while still using a 283-style bore. This might be a little more expensive since 307 engines are not nearly as popular as the 327 or the 283. It would be wise to price it all out first.
For best power, the ideal combination is the 302, which is a larger 4.00-inch bore 327 block with a short 3.00-inch stroke 283 crank. This offers a larger bore for better cylinder head breathing and virtually the same displacement.
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