Need some help on my old dodge 360 motor. I have done all of the standard tuning, I will list it. NEW: Cap, Rotor, points adjusted "matchbook top thickness" plugs, wires, plugs gapped to 35, pcv valve, air filter, fuel filter, holley 2 barrel rebuilt. Now for the behavior: It is really cold blooded, and when a vacuum leak is intentionally introduced, runs better. I checked compression via a wet and dry test, the differences were nothing between the wet and dry tests, this was also performed on a hot motor, I have compression losses on all but three cyl, and the other five either have low compression, or the valves have let it out "bad valve seal?" before the tester can read it. What can I do aside from completely rebuilding the heads? I was thinking along the lines of piston to TDC, then remove valve springs, and replace the stem seals and check guide clearances, in case I do need to rebuild, and use an electric drill to try and re-seat the valves. thanks, Kevin P.S. Yes, I am aware that the 360 and 318 are essentially the same motor.
Couple of questions. How did you intentionally introduce vac leak? Removing the vac line to the distributor? If so, it sounds like a timing problem. Please also define "cold blooded". Also, the compression gage should have a check-valve on it, so it can hold the reading. If it's leaking out, the check-valve is bad...which is common.
I remove the vac line from the PCV valve. The check valve is fine, I initially thought so as well, so I checked it, replaced the o-ring and tested again. thanks, Kevin
If you got really bad/low compression readings, valves seals are not going to cure nothing.If the guides are wore out, lapping in the valves with a drill won't work either. How many miles on this engine? Any history on it?? If you are inducing a more air mixture by pulling off the vavuum line, and it runs smoother, it indicates your running to rich.Might be a internal carb. problem. Did you have this problem before the carb. was rebuilt. How good was the rebuild?? Ken
Hmmm. Any heavy blow-by? Air pressure coming out the oil-breather/filler tube/dipstick hole? Could need more than head work. If not, maybe the valves are so loose in the guides, that the valves just aren't sealing well. In which case, the heads need to come off and get reworked. Don't want you doing that though before you've eliminated other causes. I'm coming up with nothing else though. Bad gaskets maybe? Look down the neck of the radiator when it's running, and look for bubbles in the coolant. Be careful, don't get splashed/burned.
do you have a known good carb to try out? How much cranking of the idle speed adjustment take? if a bunch, suspect your timing chain- even if the timing's on the chain would cause a late cam. i'd pull the front cover to check slop in the timing chain. where are you hearing all the air go with the hose on in the plug hole? valve cover, tailpipe, or intake? rick
HA! I've run into this problem time and time again with SB mopars with carburetors. It took a while for us to find the reason for this problem when I worked for our local city shop..[we had dozens of dodge pickups] .it was the same thing everytime. Engine ran great in the summer....runs like shit in the cold weather. If you'll pull the intake manifold off I'll bet 34 million dollars the exhaust crossover in the intake under the carb is plugged tight with black, nasty "coke"...they're famous for this. When that passage gets plugged there is no heat for the carb base...runs terrible...stumbles, pops back through the carb, jerks the car/truck back and forth etc...in really extreme cases the intake and the heads both will be packed fulla this black shit. The on ly cure is to chip it out with a chizel or old screwdriver....laquer thinner helps desolve it. If this is your problem, no amount of carb adjustment will fix it...gotta come apart and be cleaned out to run right... You're welcome.....Rocky
I like this! If the crossover is plugged there might also be no heat source for the automatic choke, assuming it doesn't have an electric choke thermostat. The choke stays closed too long making the mixture stay too rich for too long. Creating a vacuum leak helps to lean the mixture out and makes it run better. Make sure the heat riser valve is free and working properly also. Even if it's got an electric choke stat make sure it's working as well. And check the choke pull-off too.
Miles unknown, It was originally purchased in V.A., and driven across country to it's current location so at least that many miles.ODO says 15300. I believe that this engine was in a b300, and the transmission is from the same van. The 727 3-speed is original and has never been rebuilt. The muffler was exploded previously and had to be replaced "like Elmer Fudd's gun after bugs shoves a carrot in it" This was not me, but I received it like this. I had wore running issues prior to rebuilding the carb, which is why I did it. My very first rebuild, but it was an official Holley kit and had all the right stuff. I also thought that it was running rich, "gassy exhaust smell" and the same thing tipped me off. The float level is good, "plastic/foam float" I checked it twice. I tried adjusting the fuel screws at the metering block when all of the way in it will still idle. The carb looked god, and cleaned really easy "boiled in white vinegar and distilled water. Replaced everything and followed instructions to a tee. The car also stalls at idle "stop" or when in gear, timing is set at 8deg adv and ~850 rpms. Has a noticeable miss, both before and after carb rebuild. It is better now and is drivable but constant throttle modulation is necessary of the choke as well. The venturis are always wet and you can actually hear it gargling fuel inside t idle. runs strong when you give it gas though. 4.10 dually gears=slow but torquey. I tried to find a good rebuilt one online "same please" but summit wants 240+ for a holley 2210 2-barrel. I want to go to Pomona next time to see what they have lyin around, missed it this weekend.
sometimes there is indeed heavy blowby, but only when it isn't runnin right, when it runs well, no/little blowby. "this is on the pass. side valve cover" I'll check for bubbles, these old 360's are known for cracked heads due to cooling adequacy problems.
I'm tellin ya...plugged exhaust cross over in the intake....seen it many, many times and repaired it many many times...
sure don't, wish I hadda gone to Pomona this weekend. I'll pull the mani and the plugs and check for TDC and cam chain slop when I do my valve adjustment, or would you also suggest physically checking the chain? I'll listen in to see what I can hear. Machineguns took most of that from me though. "the hearing, that is"
no electric choke, and it don't work worth a damn anyhow, I guess this is probably the culprit. The spring works well and doesn't hang, I did wonder why the choke was just so late in opening. thanks, Kevin
Thanks Rocky, I'll check this first, I surmise that the combustion chambers, pistons, valves, seals are also covered with this crap. What is it? how to prevent in the future. Any easy way to remove it,? I'll try some laquer first.
May not be the end all fix, but it would be good to be sure. You can eyeball it by turning the crank and seeing how many degrees it moves until you get action on the distributor rotor. The idea about the coked up heat crossover is a very good theory as well-could quite well be the main deal right there. As for the machine guns, the only thing i'm able to offer is a big thank you for your service and sacrifice. rick
Sorry, no fix for this problem as it happens from a little oil burning in the chambers from wear...the only true fix is a rebuild but the good news is it takes many miles to get all "coked up" again... just clean it out as best you can. A big problem with our dodges was the number of hours they sat idling all day..our police cars with 318s also had this problem...we got good at doing the job but it still took a good day to do it..
Another thing to check while you have the carburetor off the manifold, look down in the manifold for cracks that develop under the carb mounting flange. I've had them crack and create a vacuum leak.
I'll check for cracks, I am thinking of doing an old trick someone told me about cleaning old diesel manifolds. Use a propane torch, and some compressed air. Heat the carbon buildup until embers form, and simply use the air to "stoke" the fire, and burn all of the old crud out. Let it air cool afterwards to prevent cracking. I'll be sure to keep some nickel rod handy if it cracks at all. will this be to harsh on the manifold? the heat is being absorbed by all of the crud mostly and not the manifold so I think it will be a quick, albeit "fun" way to remove this debris. What do you think?
One comment...as has been commented on by others in other Threads, PCV valves are controlled vacuum leaks. By pulling off the hose you're not causing a vacuum leak, you're sealing one off. Therefore it sounds like you have a leak somewhere else that needs plugging.
as mentioned above the two achilles heels of a stock 360 or 318 mopar Timing chain - get rid of the stock chain with nylon toothed top gear and put in a double roller Intake manifold heat crossover - plugged solid Try these first, total rebuild after that.
I just had a flash back if what you're working with is the stock Holley 22XX. These were largely fuel-mileage, "emissions" carburetors and tended to usually be running right on the edge of being too lean. They didn't completely suck but they could be a bit tempermental. The bowl covers tended to warp if they weren't tightened properly or if the air cleaner was overtightened. This caused an internal vacuum leak and as a result the idle mixture screws couldn't be adjusted out far enough to richen the idle mixture. Chrysler at one time offered a "bridge kit", I believe it was called, to reinforce the bowl cover if it wasn't already too badly distorted. These carbs also had a very weak, lean accelerator pump shot. If you study the linkage you'll see that opening the throttle didn't directly depress the accelerator pump plunger, but merely allowed the spring above the pump to push the plunger downward. And the spring tended to be fairly weak. If you feel like experimenting you could try using a stronger spring in place of the stock unit. You could also try stretching the stock spring a little bit to give it more tension, but be careful not to overstretch it. The other trick I used a few times was to remove the pump plunger and stretch the spring a bit. Then with the bowl cover inverted, look for the cavity where the spring is normally seated. In that cavity, stack about 4 or 5 flat washers (5/16" I think?) until they're flush with the gasket surface and reassemble the pump plunger into the bowl cover. The washers have to fit into the cavity and the hole has to be big enough for the pump shaft to move freely. Doing this gave the pump spring a little more preload, fattened up the pump shot and seemed to cure about 90% or more of the off-idle lean stumble. If you're a glutton for punishment, here's a link to more than you ever wanted to know about some of the quirks of the Holley 22XX carburetors. http://www.ihonlynorth.com/forums/carb-tech/511-holley-22xx-series-carb-stuff.html
From my experience, the first thing to look at, is plugged internal crossover passages in that intake manifold, as others have identified. These plug up regularly and a lot of the cause is failure to keep that auto choke working properly. The choke sequence should be like this.....engine cold, stepping on the accelerator the choke should slam shut. Pushing the accelerator pedal hard on the floor, the choke should open about 1/4" **. When the engine starts, the choke pull off should immediately open the choke 1/4". A heater inside the choke actuator (down on the intake) should immediately start to heat the element in there to decrease the force trying to keep the choke closed. That choke heater operates similar to the anticipator in your wall thermostat controlling your home furnace. The choke heater is controlled by a timer, it is on the carburetor and looks like a thick dime cylinder mounted on a tab. ** You should be able to insert a 1/4" drill between the choke butterfly and the carburetor's horn. That choke heater works in conjunction with heat from the intake to release the choke, but...........with no heat (caused by plugged passages) the engine gets choked much too long, contributing to the carbon in the already (or soon to be) plugged passages. This stuff is all from memory, if you wish, I can find the actual info, with some digging.
For all the plugged up heat crossover guys- while I don't doubt that this could be a serious problem in other parts of the country, the OP is in 29 Palms, CA. It should run just fine without the crossover, because it should rarely ever need the choke to begin with. Even with the crossover plugged, the engine will still warm up completely in a few minutes time and the choke will come off. The crossover on the 2v intake that was on the 318 I still drive daily was plugged up solid (like it wasn't even there), and I never had any issues starting it, or driving it after a few minutes of warm up. The holley 2v that's was referenced is an emission version of a not particularly great carb to begin with. As it was pointed out, it should run pretty lean if its operating correctly. If its running so rich that the venturi's are always wet and the idle screws can be run all the way in or out with no effect, the carb has a serious internal issue. Also, the constant miss and stalling tells me that this isn't just an issue on start up. I would waste zero time with the 2v carbs that came on these engines. If you're going to buy a new carb, convert it to a 4v. A 600cfm 4v will work killer on a mild 360, a plain old edelbrock performer intake will work great. The carb will cost almost the same as a new 2v, and the intakes are pretty easily found for $100-$150 used. If you're really in a bind for a carb, I have a Carter 2v that came off of a running '70's 318. No promises on its longevity, but it was on a daily driver long enough for me to say it has less issues than the carb you've got. Shoot me a PM if you want it, a few bucks and shipping and its yours.
Nice tech info dudes, Rocky, sounds like you got the number on those MoPars. More good vibes for the cure on this problemo!Cool! ~sololobo~
When I swapped engines in my van I had to spend a bit of time chipping the carbon out of those passages on the four barrel intake that was on the original engine and got swapped to the replacement. On your other engine problems, valve seals have no effect one way or the other on compression. They only control the amount of oil that gets into the valve guide. If it has a lot of blowby the rings are suspect at the least.
I agree the choke crossover clogged up sounds suspect. This can be checked easily. Start the engine cold, let it run a few minutes then touch the cast iron well on the intake where the choke spring sets. If this does not burn your fingers , the crossover is plugged. While cleaning the intake crossover,also remove the carb, there is a floor jet in the intake manifold (small hole) that travels to the crossover, this is usually plugged up also.
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