440 Engine Issues

[BlueSS454]

I'm looking for some insight on a few problems I'm having with the 440 in the Charger, I hope this is the right place to post this in.  I'm used to playing around with Chevy and Oldsmobile engines, so fiddling with a Mopar RB engine is a little new to me so please bear with me here.  I had the engine running fairly well, except for a misfire that I have not been able to track down yet.  The thing is, it seems to disappear when the RPM's are up over 2000.  I had intended to deal with that issue after a show I took the car too last Sunday, and now there is a new problem with it.  It no longer will stay idling.  It stalls out unless the gas pedal is feathered to keep it running.  I have already checked for vacuum leaks, can't find any.  I thought it may have been starving for fuel, but I checked all the float levels and everything appears to be ok with the carbureator.  I did rebuild it, Holley 3310.  I set the base timing where it should be by the specs I read which were 32 degrees at 2600 RPM.  I checked some voltage readings at the coil and they were 10 volts on the positive side of the coil and 5 volts at the negetive side which 5 volts seems a tad too low.  It does have an electronic ignition conversion on it.  It also has a serious vacuum problem or lack thereof I should say.  I took a reading on it and it's only coming up with 10 psi of vacuum.  It also has a serious blowby problem which I'm sure is due to the lack of vacuum.  Unfortunately, I did not assemble the engine or have anything to do with the build of it, the previous owner had already rebuilt it but never gave me any specs on it so I don't know what pistons or cam are in it.  It also seems to be making an excessive amount of valve train noise.  I'm kind of hoping that this is an electrical issue more than anything.  I'm open to any and all suggestions.

[firefighter3931]

I would start by bumping up the timing....shoot for 15* at idle and 36* total in by 2600-3000. Low engine vacuum readings result from insufficient base timing.....that cam is asking for more spark lead. 

Also, make sure the carb base gasket isn't interfering with the butterflies. If it's slow to return to idle after a blip of the throttle....the blades may be hanging open momentarily.


Ron

[BlueSS454]

Ok, so I figured out why it wouldn't stay running.  There was a piece of old carb. gasket that got stuck in the primary jets so I took the Holley all the way apart again, cleaned it, flushed it, and blew it out, put it back together and it seems to be ok now.

Now, I went to set the timing again and it seems to like running at 36 degrees at 3,000 RPM's, vacuum was ok at that RPM, but as soon as I backed the idle down to 1000 RPM, the blowby came back right away, the vacuum reading dropped to 10, and it still is running rich.  I checked the timing at idle and it was reading 25 advanced.  I think there is something wrong with the distributor itself.  Just for laughs, I connected the vacuum advance and it retarded the timing so something is not right there.  I don't know where the distributor came from as it was already installed when I got the car.  I did order a new distributor from NAPA, should be here on Monday.  Any other ideas or suggestions here??  I'm about at a loss here 

[firefighter3931]

Tom,

The distributor has only 10* of mechanical advance from what you are describing....someone must have modified the advance plates. The newer MP distributors have and adjustable advance mechanism....how old is this MP conversion kit ?

If it's still burning rich the jetting could be too fat or it's idling too high and running on the main circuit and not the idle circuit. If you adjust the idle mixture screws and there is no change in idle quality then you are using the main circuit. 

Another issue could be the ignition box....if you are using the MP orange box then that could be a problem (weak spark). Pull a plugwire and ground it while cranking the engine over....you should see a bright blue/white spark. If the spark is a dull orange you have a weak ignition system.

It's also important to use the correct heat range plugs for your build.



Ron

[BlueSS454]

The distributor is just a stock one from I don't know what.  The electronic control box looks like a generic Echlin one.  I did have the coil wire off earlier and it seems to have a pretty healthy spark.   As far as the carb is concerned.....I don't have a real tach hooked up to it, I was using a volt meter that doubles as a tach to read the RPM's.  It may be off for all I know, but I do know that it won't stay running if I lower the RPMs under 1000 going by the meter I was using.  For the spark plugs, I just got the ones that the book called for...AC Delco# R43S, which did seem a little too cold to me.
The guy that had the car before me had completly butchered and rigged up the engine wiring/ignition system.  All I did was get a new engine harness that was already wired for electronic iginition from Year One and hook everything up that is suppose to.
I'm also considering getting an MSD 6AL box to run the iginition system and see if it helps any.

[BlueSS454]

Update......

I put a new distributor in, helped it a little more to get the timing right, but still had a lean condition.  I decided to check a few other items that I may have overlooked and sure enough.....I tightened a few of the intake bolts.  They weren't loose, but weren't as tight as they should be, then low and behold, I checked the little intake vacuum fitting in the back of the intake and what do ya know, it was loose.  Not sure how I overlooked that, but it happens I guess.  I put alittle liquid thread sealer on it and cranked it down and it's running much better now.  Not 100%, but better than it was.  Now I can go play with the timing and hope it straightens everything out.

[charger_mike75]

By the sounds of it you may not have a rebuilt engine if it's got a lot of blowby. As far as distributers go the ones from the local parts store are not very good from my own experience as well as the experience of my friends. I've changed many because of bad vacuum canisters on my '73 truck as well as my charger. As far as the carb I have not had much luck with Holley carbs on mopar engines. I had one once, and after rebuilding it cuz it kept messing up I switched to an Edelbrock carb and never had a problem. The current distributer I have came with a conversion kit. For some reason my engine likes 40 degrees total timing which I'm not impressed with cuz it seems to effect the top end. I'll probably put my old point distributor back in with a conversion kit under the cap, It ran great with that. That's my   

[firefighter3931]

Update......

I put a new distributor in, helped it a little more to get the timing right, but still had a lean condition.  I decided to check a few other items that I may have overlooked and sure enough.....I tightened a few of the intake bolts.  They weren't loose, but weren't as tight as they should be, then low and behold, I checked the little intake vacuum fitting in the back of the intake and what do ya know, it was loose.  Not sure how I overlooked that, but it happens I guess.  I put alittle liquid thread sealer on it and cranked it down and it's running much better now.  Not 100%, but better than it was.  Now I can go play with the timing and hope it straightens everything out.

That sounds much better.  Chasing vacuum leaks is no fun.  Time to throw some timing at it and wake the big dog up ! 


Ron

[rt green]

didnt you mention that you had 10 volts at the pos coil? shouldnt you have 12 volts?

[Chryco Psycho]

make sure there is no leak in the power brake booster as well , it will lean out #6&7 cylinder & cause a misfire