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Easy Performance TipsEngine-Building Tricks Proven on the Trail From the February, 2009 issue of Jp
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 The overall top tip is an...  The overall top tip is an improved air filter. Earl Rahder of the Victor Valley Four Wheelers has a foam covering over a K&N filter element, all to improve airflow and keep out the dust on the trail. Earl also leaves the hood of his trail-worn 1968 CJ-6 at home so he can better see the trail, but we figure it also helps the engine breathe and keep cool on hot summer trail rides.  An interesting theory on cooling...  An interesting theory on cooling was provided by Bud Miller, who found that eliminating the thermal clutch on the fan and using a spacer instead made more power. The idea of a fan clutch is, however, to lessen the drag of the fan at highway speeds, creating better fuel economy. Bud feels that the slow speed associated with trail riding creates extra heat, which robs power, so his AMC 360 sports a spacer instead of a clutch.  A proper combination is what...  A proper combination is what Steve Allison of Norco, California, runs on his Jeep. The 1984 CJ-7 has the factory 258, but Steve hopped up the spark with a Jacobs ignition system. The Jacobs wires, coil, and Mileagemaster control box sparks the fuel coming from the replacement Weber two barrel. Steve says that along with a Cagle fuel regulator for hillclimbs and altitude changes, the whole system runs about 50 percent better than stock.  When you&8217re stuck with...  When you&8217re stuck with the Prestolite ignition Jeep used in 1976-1978, anything is better. Peter Smyth yanked the bogus sparker out of his 1978 Wagoneer with the AMC 401 and went to a points-style distributor. The 1974 model distributor fits right in and features a one-wire hookup, and, says Peter, it has never run so well since he swapped the distributor.  Back in his sand-running days,...  Back in his sand-running days, Ray Lueuschner ran paddle tires on his 1970 CJ-5, and the 225 Buick V-6 was built to handle it. The little V-6 sports a mild Isky cam and an Offenhauser intake topped by a Holley 465 with vacuum secondaries. Ray says he does more rockcrawling these days, and the same setup works great, just at a lower rpm. The Mallory dual-point distributor is a holdover from the high rpm sand-dune days, when point float could be a problem.  The emissions laws in California...  The emissions laws in California are a bit tough, but Tom Kane of Valencia, California, wanted more power for his 1977 AMC 360-powered J-10 truck. The Edelbrock Performer manifold is legal, as is the Holley replacement-style four-barrel carb since the factory had a 4-bbl carb offered that year. Tom says the combo is much more driveable than the old Ford-style carb, and has plenty of power for the old beast.  Electronically controlled...  Electronically controlled two-barrel Carter carbs on 258 sixes have wires sticking out the back, and are found on CJs and YJs from 1982 until fuel injection was introduced. The throttle shafts wear out and suck in air at idle, causing the mixture to lean out. The lean condition is automatically compensated for by the computer, causing the idle to be erratic. A proper rebuild of these carbs entails reaming the carb base and installing bushings to cure the air leak.  More often than not, we opened...  More often than not, we opened hoods and were faced with what many owners thought was the ultimate Jeep engine upgrade: a swapped-in small-block Chevy. Mike Smith acquired this 1953 M38A1 with the GM mill already inside, but it sported a Holley carb. After trying vainly to get the Holley to work in the rough, Mike swapped on a Quadrajet carb. He feels injection is nice, but knows that the Q-jet will continue to run without electrical power, and if it’s set up correctly, it won&8217t spooge fuel like a Holley can.  Doug Reynolds keeps the air...  Doug Reynolds keeps the air coming in clean with a K&N filter, but protects the front of it with a cover so water won&8217t splash in as easily. A closed-element housing is better protection, but the increased airflow of an open design helps the 225 V-6 gulp in air. Doug also runs the stock Rochester two-barrel carb and an Isky cam in his 1969 CJ-5, which is also fitted with headers from J.C. Whitney.  A Weber carburetor conversion...  A Weber carburetor conversion to replace ailing stock carbs is available for four- and six-cylinder Jeep engines. It may not be smog-legal in all states, but proven performance gains and better throttle response are real benefits. Even with all the factory vacuum hoses hooked up, the little Weber can really perform. Bench racing is a lot like bench Jeeping: mostly it's a lot of bull. And the same can be said of many of the products designed to improve the performance of your Jeep engine. But truth be told, practical experience with on-the-trail testing is one of the best ways to see what really works and what should be left behind. On a recent trail ride, we decided to ask a few Jeep owners about their modifications and how well they worked over the long run. As always, internal engine mods such as cams and trick internals usually produced good results, but for the most part, those we surveyed thought that simple items worked best. Top on their list of improvements was better breathing through specialized air filters and headers that rid the rig of spent gasses. But many a carb style and modification was also noted, with a healthy dose of ignition products to spark the mixtures. And when all the mods are properly mixed, significant improvements can be had. Check out some of the ideas we found, and see if you can use them on your own engine. Though some of the parts are vintage, junkyard shopping for that special part is half the fun. And since most of the parts are available from your local Jeep specialty shop or mail-order house, you too can benefit from what trail riders have found.
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