Need Help With 318 Build

Toolman X2

Careful selection of parts is very critical. It is easy to over-carb and over-cam a 318, especially with stock compression and a stock rear axle gear ratio. Stock heads stop increasing flow rate at around 5500 rpm. Recommend a cam that starts its torque band before 2000 rpm for a street car. Also recommend using the search function to look for other threads for 318 builds. There have been a few in the last year.

Here's what I did on the 318 street motor I built for the Demon. I bought the car without an engine. The goal was to build a fun street engine that makes respectable power, stays above 12 mpg, and is easy to drive (not too cold natured). I selected components so that the cam power band and the cylinder head airflow would come to a stop at 5500 rpm. Just to keep things honest, I installed an orange box electronic ignition that shuts down the fun at 6000 rpm.

The block is a 1968, with 302 heads from a Diplomat. Block was power washed with the freeze plugs out, honed, new bearings. The heads were given a mild clean up in the combustion chamber, new springs and seals fitted.

Pistons are cast for the 67-70 318. These were chosen for cost and because these years sit highest in the cylinder at the top of the stroke. I went for moly rings.

The cam is a flat tappet Summit special (Crane Fireball) 218º/228º @.050 .441"/.441". I got a set of SSI springs from PAW that are good to .500" Sadly PAW no longer deals in anything other than Gen 1 Hemis.

On the intake I used an Eddy Performer and a 625 Carter AFB. The Performer has the small ports that complement the small ports on nearly all 318 heads (exception if the 4 bbl cop car engine). I had a 3855 AFB (625 cfm) on my 66 Dart GT, so I figured it would work here.

Transmission is a 904 with a TransGo TF1 shift kit. I didn't want the hardness of a race shift. I used a kickdown kit from Bouchillon Performance. If you want more of a custom/hot rod look, Lokar has a sturdy kickdown you could use. The car originally had drum brakes, so when I did the BBP disk brake swap in front, I put in a BBP 7¼ rear (2.93:1) in it. I wouldn't recommend a 7¼, but I needed to be able to move the car. I'm in the process of piecing together a 8.75" that will have a 3.55:1 gear ratio.