In the first part of this series (Mopar Muscle, March 2002), we were surprised with what we learned from testing Holley HP carbs and Wilson Manifolds spacers on our Slick Budget Small-Block 360. That engine actually did best with the big 950 HP and four-hole spacer pairing. Regretfully, we didn't have enough time to tune the Holley HP's for optimum use. Had we tuned them, they could have easily smoked our chokeless and worked-over 750 double-pumper. So, for this adventure, we gathered up our 750 and 950 HPs, along with Wilson's open, four-hole, and four-hole tapered spacers. The old reliable '67 R/T 440 mule will be back in action, and we'll baseline with a breathed-on 850 double-pumper. This is the same 850 that won two different dragstrip carb shootouts featured in the May and September 2000 issues of High Performance Mopar.
It can really take many different size carbs and spacers to have the combo that performs and feels right in various street and strip situations. Good part-throttle drivability is important with any dual-purpose car. For example, a radical lightweight street car, under 3,000 pounds with 4.88 gears, might work well with a large carb, but that same motor in a 3,800-pound car with 3.55 gearing will need a smaller carb for decent street drivability. What works on the dyno or on our 360 and 440 dual-purpose mules is not necessarily going to behave the same in other vehicles.
Before starting, we ordered this 8 3/4 rear with 3.73 gears from Randy's Ring & Pinion in
Driving to and from the track is really living, especially in a musclecar. The ride to our happy testing grounds (Raceway Park, Englishtown, New Jersey) was pleasing enough with the sans spacer 850-cfm pot, but we hoped the day's track-bashing wouldn't cause any mechanical casualties. Can the R/T stand up to another test day beating? Happily, driving home at day's end (so far) has always given us more smiles per hour, as any effective gains are noticed when homeward bound! Testing and tuning is indeed time well spent; many tracks have testing and tuning days scheduled, so check them out.
We were welcomed with friendly weather conditions at E-Town. It was autumn (our favorite testing time of year) and in the '60s all day long. Our baseline began without a spacer and the aforementioned "tuned to our combo" 850 Holley double pumper. The 850's two years of residence on the 440 enabled it to reduce its e.t.'s by over two tenths. Normally, this would give the 850 an unfair advantage over the box stock Holley HP, but many Mopar (and brand X) buddies have been reporting e.t. reductions using the Holley HP line over the older versions. That would be the crucial value of this test.
A solid baseline would be needed for a good carb and spacer evaluation. This R/T has always given us reliable results. The 727 has a Hemi governor and shifts for itself at 5,800 rpm into Second and into Third at 6,000. A Randy's Ring & Pinion complete third member with 3.73s was dropped into the rear a week before this test. Previously, 28x9 Hoosier slicks were used for testing with the 4.10s; now equipped with 3.73s, we planned to use our 26x9 hookin' Hoosiers from the Challenger Challenge. These 26-inch slicks would help to even out the effective gear ratio, and we were content with the R/T's 11.95 baseline pass, considering it equaled its best-ever 60-foot time of 1.69. A backup two minutes later produced an 11.99, with a similar 1.69 60-footer, so we had consistent hook.