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Tech Question
chad kelly, bowmanville, ON, canada, 1968 dodge dart gts 340
My father has owned a numbers matching 1968 Dodge Dart GTS since he was 18 years old. Finally, with the help of my brothers and me, we completed a ground up resto this year. It is two tone green, dark on top and light on bottom with the longitude stripe. It is a 340 4 bbl with 727 TorqueFlite and 3:9:1 gear. My question is: The engine is pretty stock except a Crane cam for low to midrange power and a 3 angle valve job. We set the timing which was recommended by the (engine guys) to 10 degrees above top dead center. Now it runs okay but it seems to lack that grunt from off the line. The carburetor is 625 Carter AVS, 1800 stall converter, and 3/8 fuel line and sending unit with high volume fuel pump. Could you possibly help a lifetime Mopar lover like my dad out with some tuning tips? Any help would be greatly appreciated.
Chad-
Obviously it's not a resto! Anyway, I'll be happy to make a few educated guesses. First, it sounds like you have installed a milder-than-stock cam, so there should be plenty of low-end torque to light 'em up, especially with that axle ratio. So, yeah, something's wrong. The most obvious is that torque converter: 1800 RPM! Jeez, stock was 2350! I have no idea why you guys did that.
Next place to look: Spark. 10 degrees initial may or may not be OK, plus, I have no idea what you mean by "above top dead center". If you meant to write "after top...." the spark is way, WAY late. But I'm betting it's really at 10 degrees BEFORE TDC, or the car would run pretty lousy all-around. Since I doubt the distributor is stock, either, we need to know how much mechanical advance, and by what RPM, is built-in. One simple way to get close is to hold the engine at 3,000 RPM (w/vacuum advance temporarily disconected) and set the timing at 35 degrees BTDC. Then see what it is at idle. If it's too retarded to idle properly, the advance mechanism needs to be reworked for your application.
You may also have the secondary air door set too loose, but, typically, it bogs bigtime or backfires if you do that.
The cam could also be installed significantly retarded, but I doubt that.
Rick
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