Engine stumbling and dropping oil pressure..

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Intense-Dakota

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Ok, I have Dart mostly dialed in, it starts and idles great, however after the engine is really warmed up (driving around for more then about 20 minutes) the oil pressure dropps from about 50-60 down to about 40 when i am stopped, and when I try to start accelerating, it seems like it has to catch up with itself for and minute. However when I put the trans in either Nuetral or Park, idle stays the same, but the oil pressure comes back up. (PS it is idling about 700-750 in both drive and nuetral).

Second problem, when driving down a road at crusing speed (idle around 1500-2000) the car seems to be stumbling/surging if I let my foot off the gas, or get into it more, it seems to be fine.

I have checked vacum and at idle I am getting a reading of about 14.5-15 steady at idle. I have been reading about adjusting the vacuum advance by using a alen wrench and going through the vacum line hole at the front of vacum advance port on distributor, but I am really not sure that will help and I want to get more info before I start messing with that. I have tried running alittle leaner and richer and that doesnt seem to make a difference. I am going to change the plugs also. I have checked the timing in park w/ e-brake set and idle around 750 (is that right, becuase some say that way and others say with the idle round 2000 in gear, but for that I will have to put the car on stands becuase I think that would pull it even with the e-brake on)

Thanks
 
Not 100% sure, and I don't know your engine size. I do my timing by ear and Vac pressure. I have both a 273 and 318 that idle about 750 RPM (carb adjustment), however my vacume at idle is about 21 PSI. Before adjusting your distributor Vac screw, I would adjust your timing to get Max Vac. Advance or retard your timing while watching your vac guage. When at max PSI, back off about 1 psi of Vac. and give it a spin around the block.
 
sounds like the carb may be lean if the timing doesnt fix it . surging can be caused by the mid range being to lean..what carb are you using?
 
Carb or timing issues..just tuning stuff. A good idle range for a street engine is 600-800. out of gear. Any higher, there's a good chance you have something wrong you're covering up, and the car will creap with most convertors.
 
I have set the timing by both ear and also vac pressure. The max pressure I can get is about 15 psi. I am not sure what carb it is other then I know it is a holley and I cannot find any numbers anywere that cross to anything. However, the Vac constantly bounces between about 14.25 and 15 psi and I cant seem to steady it out any more then that. I have a 318 on e-bay right now that I built for my 85 ramcharger, and if it does not sell I may just replace the oil pan and the pickup and swap it over into the dart for now since it is a completely new rebuild (I would rather sell it and get a 340 though). The odd thing I still cannot figure out is why it starts to stumble and drop oil pressure once it has been running for about 30-34 minutes....
 
This happens to me also, only sometimes so it's been very hard to track it down. My thoughts were electrical when the motor gets hot it interfers with the electronic ignition. I have a Mopar Performance black box stystem.
I hope someone comes along with some more insight. Peace
 
if it takes 30 minutes to act up, i agree it is most likely heat related, you may want to check your fuel line, possibly try to protect it from the heat, i have had ignition parts that were heat sensitive also, if you have new headers ,they will really put some heat into the engine bay, do you have a temp guage ? if so what is the motor running at after that long? is the engine bay getting hotter than normal?
 
The next time you feel the stumble or surge, take the vac hose off of the dist and plug it. Try it again. If this cures it you have a problem with distributor phasing. ( the reluctor isn't phased correctly with the rotor.) Some older MP distributors had this problem.

don
 
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