Add 10 Horsepower with an Intake and Carb Spacer

Words and photos by Chris Holley

The Dart with the driver weights just over 3070 lbs. The 340 leaves the starting line at 3500 rpm, and it pulls through the speed traps at about 6500 rpm. The assessment of the manifolds and carburetors spacers proved to be a good series of tests to fine tune the 340 combination. There is horsepower to be found in testing parts in a systematic fashion. Do not get sucked into the hype about a part or the “flavor of the week”. Test, test, and test until you find a part that works for you. This photo is just before the 1/8-mile marker with the 340 at full song breaking into the 7.0s in the 1/8-mile for the first time with the open plenum carburetor spacer. The open spacer proved to be the best spacer for this 340; your results may vary.

When it comes to a drag car, there is an old adage that in the constant pursuit of a quicker elapsed time (ET), a faster mph, or a more consistent part that ultimately brings about a win light, evaluating parts never seems to end. In our quest to continually improve, MoparMax selected a new Edelbrock Performer RPM Air-Gap intake manifold to track test with three different 1-inch carburetor spacers on a warmed over 340 in a 1969 Dodge Dart.

Edelbrock’s Performer RPM Air-Gap (part no. ELD-7576) was the focus of the testing on a modified 340 engine. Three 1-inch carburetor spacers were tested in conjunction with the Performer RPM Air-Gap. The spacers are a CSR tapered 4-hole spacer, a CSR open plenum spacer, and an Edelbrock divided plenum spacer.

The testing would be limited to only 1-inch maximum spacer thicknesses due to concerns of restricted under hood clearance of the fiberglass six-pack hood scoop. Two of the three spacers are CSR units. One of the CSR spacers is a tapered 4-hole spacer, and the second is an open plenum spacer. The third spacer to be tested is an Edelbrock divided plenum spacer.