318 running rough and losing vacuum when in gear.

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Str8up

Str8up

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I'm sure this has been discussed many times but here's my issue. 1971 dodge dart 318 2bbl cast intake. electronic ignition. 727 auto. only mod. is the elec ign. was running fine with it.
first started when cruising home and I would be running at a certain RPM. car would start to run like it was running out of gas or missing. if I gave it a little gas or let off on the gas it worked fine. came to a stop sign and the rpm died right off and car was shaking and hunting. noticed my power brakes were not working. idles not bad but if you gently apply the throttle it has a spot at low rpm where it bogs, runs rough and no power. give it a little more throttle and it picks right up. at idle if you apply brakes or put in gear the car almost shakes apart and runs super rough and rich. thought power booster leak? nope ! here is everything I have done since to try and fix it. booster plugged still does it in gear.
plugged power brake vacuum port.
did complete vacuum leak check several times with spray can, propane you name it. no leaks
new dissy, cap, rotor, wires, plugs. to verify (bought second set of wires, cap,rotor, plugs)
new coil and ballast
complete carb rebuild
new egr and cleaned port. no luck. plugged egr port.
new PCV and tried plugging
set timing several times. has to be very advanced to idle fairly smooth.
got feed up. installed new aluminum intake and 4bbl. looked at cam lobes, lifters and rockers.
new fuel lines and filter, gas tank vent. even remove gas gap to ensure vented. fuel pump has good pressure.
nothing helped at all.
I am positive no vacuum leaks, timing is correct, firing order is correct, operating temp. is good. oil level is good. had someone else verify timing and firing order and check for vacuum leaks encase I missed something.
I have a tranny leak but I keep the fluid up. Only other thing is besides leak is when I put car on stand I cannot turn the back wheels by hand unless I have it in neutral. but it was like that before the engine started acting up. tranny seems to be shifting fine.
I know it was long. just trying to avoid having a long thread of questions that I should have included myself. thanks
Keep er STR8UP and between the ditches!!!!!!
 
how many miles on this engine? I'm thinking valve train failing - seal(s), lifter(s), cracked head or bad head gasket(s)? ...maybe
 
I would Start with a compression test. Seems like you have looked at the basic problem areas. At first I thought the coil but I reread your thread. Next would take off a valve cover and look to see if any valve train is bent or broken.
 
the 318 was just put in last year with supposable 77000 miles on it. long story behind this car. my sister had it, was a 340 but brother inlaw spin a crank bearing. he kept the 340 for another project. so the story goes, he say's the 318 has the 340 flex plate and torque converter on it. I have wondered if that makes the engine unbalanced because it feels like the driveshaft vibrated over 60mph. hence the tranny leak. I have been mulling the fact that the torque converter may be the entire issue with the engine also.
 
Mike 340 said:
I would Start with a compression test. Seems like you have looked at the basic problem areas. At first I thought the coil but I reread your thread. Next would take off a valve cover and look to see if any valve train is bent or broken.
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Yeah I did all that when I swapped intakes yesterday. all plugs were nice and golden just like mcdonald's fries. so don't think compression is the issue put will check it. thanks
 
Str8up said:
the 318 was just put in last year with supposable 77000 miles on it. long story behind this car. my sister had it, was a 340 but brother inlaw spin a crank bearing. he kept the 340 for another project. so the story goes, he say's the 318 has the 340 flex plate and torque converter on it. I have wondered if that makes the engine unbalanced because it feels like the driveshaft vibrated over 60mph. hence the tranny leak. I have been mulling the fact that the torque converter may be the entire issue with the engine also.
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fairly sure 318/340 are same same - 360 is different
 
F@0 brother in laws!
Does he still have the original engine?
 
You said the timing has to be very advanced in order for it to idle. Did you check to see if it jumped time or not?
 
Mike 340 said:
F@0 brother in laws!
Does he still have the original engine?
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yes, he is using it to rebuild for another car he is doing. wouldn't part with it. I traded a 1971 buick skylark to him for the dart. I"m not into GMs I only bought it because it was a good deal. I like Mopar. I have a 66 2dr polara and a 55 dodge pickup also.
 
Jax340Dart said:
You said the timing has to be very advanced in order for it to idle. Did you check to see if it jumped time or not?
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no, I didn't want to get into removing everything from front yet if I didn't have to. I guess when I has valve covers off I could have checked valve position at TDC #1
 
Str8up said:
yes, he is using it to rebuild for another car he is doing. wouldn't part with it. I traded a 1971 buick skylark to him for the dart. I"m not into GMs I only bought it because it was a good deal. I like Mopar. I have a 66 2dr polara and a 55 dodge pickup also.
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if it were out on mechanical timing would it smooth out with increasing rpm?
 
I think I found the issue.
Remember I said I could not rotate rear wheels by hand on jack stands.
disconnected driveshaft. tires turn free.
started engine not nearly as bad idle but still boggy when I put in drive. then when I went to shift into park it would not go just made that clattering noise like when u go in reverse by mistake. doesn't catch. turned engine off went in park. repeated process to be sure. so I am 99% sure torque converter???
 
when you put it in gear with the drive shaft was off the tail shaft would spin then you jammed it in park that's the noise its like driving 30mph and jamming it into park .
 
jimjimjimmy said:
when you put it in gear with the drive shaft was off the tail shaft would spin then you jammed it in park that's the noise its like driving 30mph and jamming it into park .
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yeap . now to get the trannyoff and figureout if it's the converter or lockup valve in tranny.
is there anyway to unlock it with removing tranny?
 
Jax340Dart said:
You said the timing has to be very advanced in order for it to idle. Did you check to see if it jumped time or not?
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This x2 sounds like it jumped a tooth. From my experience they tend to jump upon shut down. I believe 318 is an interference engine so if it jumps a few teeth valves will clash. Also I don't believe 340 uses the same balance on the converters if it was a cast crank. Pull your plugs, pull distributor cap, socket and breaker bar on the crank nut , turn it over forward and pull it back and observe rotor. It will tell you if you have excessive slack in the chain. Don't keep starting it and shutting it off. The lack of vacuum also indicates this.
 
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the 318 and 340 are both internally balanced except the 73 cast crank 340 and maybe a few 72's were external balance .what makes you think your tc is the problem ?
 
jimjimjimmy said:
the 318 and 340 are both internally balanced except the 73 cast crank 340 and maybe a few 72's were external balance .what makes you think your tc is the problem ?
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think tc because when I started the car without the driveshaft connected the tail shaft was spinning while in park. there is no internal engine issue. 120psi compression across all 8 within 2 psi of each other. don't think that u would have that with timing jumped. as mentioned above . have inspected internals
thanks for the tc balance info. I'm going to get it apart this week.
 
that just tells me your park lock is striped or out of adjustment not a bad torque .
 
so my engine is a 1971 318. today I pulled the tranny (727) non-lock up. (Spline to the end of shaft). and the torque convert has weights on it. I searched the numbers on the converter (03193) only close thing I could find with that # is it may be for a magnum engine. anyways I think 318 torque converts do not have weights as they are internal balanced. this would explain the bad vibs . the bother inlaw I got the car from kept telling me the driveshaft was out of balance. with that convertor # can anyone tell me if it was a lockup converter.
thanks
 
I can't tell you if it's a lockup or not but you can just knock the weights off and run it . that would explain the bad vibs .
 
Careful, you may be exactly right. However, some converters have weights to balance the CONVERTER to itself, but they are not necessarily the counter weights for a 360. The weights that balance the converter to itself are usually small. The 360 weights are much longer. Just be sure before you knock of weights. But this being said, it could very well be you found your problem
 
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