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Original Message
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| You want a Traction-lok, not an Equa Lock. |
| By Dave Shoe - 05/12/2002 9:17:19 PM; IP 216.243.191.33 |
Equa Lock is the limited slip rear used in 8" and 9" differentialed cars through midyear 1968, Traction-lok was used from mid-1968-on. (Note that the 8.8" Traction-lok is based on the same engineering concepts as the 8"/9" but is a completely different product).
Equa Lock offered a constant friction differential between the rear wheels. It was a bit much on slippery corners and not quite enough on hard dragstrip starts.
Traction-lok is different in that it varies the friction coupling between the rear wheels based on how much torque is being delivered by the driveshaft. On slippery corners when minimal throttle will be used the coupling is low, allowing the rear wheels to spin easily a different speeds and thus preventing slip. On hard, straight drag starts, the coupling between rear wheels is at a maximum.
Traction-lok's reduced coupling at low driveshaft torques is achieved by the use of a small coil spring which applies only a small force to the clutchpack. This will offer slight coupling in sand and snow when the traction conditions only allow slight traction from each wheel anyway. At high driveshaft torques the spider gears inside the differential provide a ramming effect against the axlegear, and the axle gear presses on the clutchpack, forcing a hard lockup.
Fuel injection would be a good idea, but a Royce mentioned, this is an area where you need prior knowledge if you expect good results. Most FE folk opt for carburetion because it's cheap and easy to dial in. You can make more power with a properly installed fuel injection system, but only if the whole engine is properly wired and only if the right type of fuel injection is selected and if job is done just right.
One thing you'll want to determine is the casting number on the heads. Most likely they are the C6AE-U or C7AE-A castings which are "full emissions" castings with exhaust ports positioned lower on the head than 1958-65 heads and smaller "velocity-type" intake runners than the 1958-65 heads. There's about a 30% chance you've got C6AE-R head castings which are a "transition emissions" design. By "transition", I mean it contains some features of pre-emissions head castings and also has some features from the emissions era. C6AE-R was only available on about 1/3 of the FEs and only in 1966-67, and the engines appear to be selected at random.
"Full emissions" and "transition emissions" heads do not use the same type of header. In some cases you'll want to use different intake manifolds, so you'll need to pay attention to details here. Both types of heads will make 400 flywheel horsepower with little effort, but the transition head will tend to breath better as the RPMs climb and horsepower moves beyond 450. If horsepower moves beyond 450, you're going to have a high-revving hot-cammed engine with mediocre gas mileage. Since you're looking for fuel efficiency, 450HP is likely not a target and either head type will likely work well for you.
If you are looking for extra horsepower without driveability or mileage issues, you may want to look at the expense of a mild roller cam. It'd probably be cheaper horsepower than fuel injection, and the efficiency of a modern-profile roller cam would make sense if you went the fuel-injection route. Since a roller cam is probably not in the budget, I won't go into many details - not that I know all that many details anyway.
Most likely, you'll want an Edelbrock Performer RPM intake. This is ideally suited to a 390 with either type of head. Don't even think of buying a "performer" or "performer 390" intake - they're not performance intakes.
Hooker headers will only work with C6AE-R heads (and 427 and CJ and 1965-earlier heads) because the Hooker header flange is designed to match the high-positioned exhaust port. FPA makes a tri-Y design in two styles, one fits the high-positioned exhaust port, the other fits the low-positioned exhaust port. Note they semi-erroneously call the "low positioned" header the 390GT header. It's true it'll work on all 390GT heads, but if you have an FE with C6AE-R castings you really should get the 427/428CJ headers from FPA (www.fordpowertrain.com). FPA headers fit great and are reputed to be particularly high in quality. They're not cheap, but cheap FE headers disappeared 15 years ago.
The stock connecting rods are fine performance pieces. They become great street performance pieces when ARP bolts are installed, and are then resized to match the higher clamping force the new bolts provide. The cranks are a famously strong nodular iron design. The blocks should be sonic-mapped prior to boring, just to be sure you've got minimal core shift. If anybody tells you the C6, C7, or C8 casting number which might be on the side of the block means it's a 428 block, thell them they're full of it. This was an incorrect rumor started long ago and popularized in more recent books.
This scratches the surface. Hope it helps.
Shoe. |
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