74 dart stumble.
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74 dart stumble.
Please help. i have been building a 93 dodge dakota 4x4 with a 74 dart 318 for years now and i have still not got it to run right. 
the truck runs with 31 tires and 3.91 gears posi front and back. i kept the transfer-case and adapted a semi electronic/mechanical 91 ram 518a tranny with oil pressure torque converter locking. i built a free 318 i got out of a friends rusting 74 dodge dart with 49,000 original miles on it. i did a bottom to top rebuild. block was cleaned, rebuilt, and bored once over. a 7qrt. oil pan, cleaned the cast rods/balanced, new speed pro pistons, 2roller timing chain, cleaned and rebuilt the cast heads/slight polished ports and chambers. headers with a two 2 1/4" into one 3"exhaust at the muffler. Edelbrock performer dual plane no emission intake-manifold with matching cam, Jacobs ignition, a 470 cfm holley truck avenger carb on a 1 inch space adapter and carter mechanical fuel pump. also the truck weighs 4200lb.
i have been trying to figure out why it has no power and the low end torque is non existent. runs ok when warmed up. fine at ideal but after awhile it stumbles while driven, and dies at a stop (got to keep some gas on it to keep it running.) it has a hard time hill climbing, sputters and gags on acceleration sometimes, back fires, runs for a second after shut off.
i think it might be the ignition being faulty or fuel delivery (carb cfm or jetting?) being wrong, gearing not enough, or the compression falling off because of the head work. but why would it run ok sometimes.
so if anyone has any suggestion on what else i could do, fix, or something i messed up on, or missing let me know. i would like all the input i can get. i really want a good truck with low end torque. Please and thank-you.
Mahalo & ALOHA
the truck runs with 31 tires and 3.91 gears posi front and back. i kept the transfer-case and adapted a semi electronic/mechanical 91 ram 518a tranny with oil pressure torque converter locking. i built a free 318 i got out of a friends rusting 74 dodge dart with 49,000 original miles on it. i did a bottom to top rebuild. block was cleaned, rebuilt, and bored once over. a 7qrt. oil pan, cleaned the cast rods/balanced, new speed pro pistons, 2roller timing chain, cleaned and rebuilt the cast heads/slight polished ports and chambers. headers with a two 2 1/4" into one 3"exhaust at the muffler. Edelbrock performer dual plane no emission intake-manifold with matching cam, Jacobs ignition, a 470 cfm holley truck avenger carb on a 1 inch space adapter and carter mechanical fuel pump. also the truck weighs 4200lb.
i have been trying to figure out why it has no power and the low end torque is non existent. runs ok when warmed up. fine at ideal but after awhile it stumbles while driven, and dies at a stop (got to keep some gas on it to keep it running.) it has a hard time hill climbing, sputters and gags on acceleration sometimes, back fires, runs for a second after shut off.
i think it might be the ignition being faulty or fuel delivery (carb cfm or jetting?) being wrong, gearing not enough, or the compression falling off because of the head work. but why would it run ok sometimes.
so if anyone has any suggestion on what else i could do, fix, or something i messed up on, or missing let me know. i would like all the input i can get. i really want a good truck with low end torque. Please and thank-you.
Mahalo & ALOHA
Last edited by maui mopar 4x4; Apr 12, 2013 at 04:28 AM.
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new update. not timing or ignition. did compression test and most of the cylinders are 120 to 130. really bad.
so i think its the compression. does not produce enough vacuum to engage the secondary. so the engine is starving for fuel.
what should i do? how can the compression be so low when i just had it rebuilt.
so i think its the compression. does not produce enough vacuum to engage the secondary. so the engine is starving for fuel.
what should i do? how can the compression be so low when i just had it rebuilt.
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I know a bit late, but your theories sound off. 120-130 psi compression sounds pretty good. Factory is ~145 psi for LA engines. You shouldn't notice a problem until <100 psi and that would be more in oil consumption, blow-by gases, and blue smoke under WOT. The vacuum secondaries aren't involved until high rpm, and they come on from "venturi vacuum", not "manifold vacuum". The former comes on at high rpm. The 470 cfm carb is a good choice and should give good driveability. I agree that your problem sounds like idling lean and you should search for a vacuum leak, or maybe just the idle screw adjustments on the carb.