440 problems!!! HELP!!!

[MusclecarsDK]

I have a problem with my 440. It has a nice idle but if I rev the engine it wont go all the way back to idle again. It's take 5-15 seconds before it's back to normal idle speed. It drops to 1200-1400 rpm first and then drops to 800 rpm. If we reduces the airflow to the carb when it wont go back, we can force it down to idle and it stays there. It's runs a little hard and "knocking" when accelerating. When reading the timing, it's varies something like 5 degrees. Maybe a worn timing chain. We tried alot of thing we thought might solve the problem or at least give us some pointers of which part to change but without any luck. Here are some fact on the engine and what we tried so far:

Facts on engine:
-440 cui.
-915 closed chamber heads
-unknown mech cam
-cast iron HP intake
-Edelbock 750 carb.
-Older Mopar performance electronic ignition

What we tried already with no luck:
-Changed the intake gasket (The big aluminum one)
-Tried a couple of different gaskets between intake and carb.
-Tried another carburator (Holley 750 vac.)
-sprayed around the intake and carb.
-checked all hoses for leaks
-set the timing

Any suggestions what to try next???

[Bearcuda]

That IS a tricky one. I was going to suggest intake or carb leak, but you've checked and replaced all that. And no leaky hoses huh? I'm sure one of these gurus on here can help. I'm stumped at the moment.

[MusclecarsDK]

Yeah that sure is tricky!

I'm sure there's some logic to this problem but maybe it needs a fresh pair of eyes looking at it. My first guess would be that it's air related but I think I replaced or testet everything that could be leaking.

[MEK-Dangerfield]

If it's not a vacuum leak, does your throttle return spring have enough tension on it?


  Mike

[MusclecarsDK]

Yeah the return spring is pretty strong. To make sure that wasn't the problem, we also checked it was all the way back when not going back to idle but it was.

Can it be ignition related? Maybe some failure in the distributor???

[loco440]

Ok lets try these ones ,every hand helps,disconect EVERY vacume line and plug including brake booster if you have one(will some times suck air thru if faulty)get a can of engine start and spray around the base of carb,if no result spray on each manifold to head runner,if there are any leaks you will notice a rise in revs,also you can screw the idle needles all the way in on your carb and see if it still idles and check carb float levels,hope this helps.

[Bullitt-]

What about sticky advance in the distributor... I have no experience with this problem but have heard of similar issues.

[MusclecarsDK]

There's no booster on. The only hose i have on the carb. is from the big stud in the front (on the Edelbrock) to the pcv valve on the valve cover in the drivers side. All other studs are blocked. we also tried to take the hose of the pcv valve and block it but no difference. We also tried to put the hose from the carb to the distributor advance on.

We tried 2 different carburators so it would be very strange if both had the same leak.

I tried to spray around carb base and along the manifold runners. The only place i haven't sprayed is on the underside of the manifold. That was the only place left there could be a leak so that's why i changed the gasket but it's still the same.

My friend who knows about adjusting carbs wasn't too familiar with the Edelbrock so that's why we tried with the Holley.

[MusclecarsDK]

What about sticky advance in the distributor... I have no experience with this problem but have heard of similar issues.

How do i check for sticky advance??? We tried with and without the vacum hose on the distributor but maybe it could be an issue anyway.

[Bullitt-]

How do i check for sticky advance??? We tried with and without the vacum hose on the distributor but maybe it could be an issue anyway.

There is mechanical advance that comes from centrifugal force. How to check I'm not sure but there are springs that pull the mechanism back as the rpms decrease soooo maybe make sure everything is moving smoooooth.

[MusclecarsDK]

Thanks, I will try that! If anyone has some good advices on how to test the distributor I would like to hear it. I'm trying to locate another distributor to check if that was the problem but that's not too easy over here. They're not laying around 

[Bearcuda]

Actually the distributor may very well be the issue. I had to take mine out of my old Cuda twice and polish the main shaft of imperfections and lube it. Take the cap off and twist the advance by hand. If it doesn't snap back then you need to due this. THere could be some corrosion or crap on the main shaft. Is it an original distributor?

[MusclecarsDK]

Actually the distributor may very well be the issue. I had to take mine out of my old Cuda twice and polish the main shaft of imperfections and lube it. Take the cap off and twist the advance by hand. If it doesn't snap back then you need to due this. THere could be some corrosion or crap on the main shaft. Is it an original distributor?

I will try that and see if it snaps right back.

I think it part of an old conversion kit from Mopar Performance because it doesn't look new but i'm far from sure. There's a little plate on it with a number on. I will try to post a pic of it when i get home.

If I could just borrow another to check if that would work I could elimate that part or even better locate the problem )

[PlumCraZRT]

Not sure how much money you got, but I got a rebuilt distributor for $20 or so from a local car parts store.  It was your basic run of the mill rebuild by some major manufacturer.  We actually asked the parts guy for some points and a condenser, and then finally asked how much a whole new distributor costs... turns out the distributor was cheaper.     For $20 you can afford to have an extra lying around for whatever you may need it for... like troubleshooting?

[MusclecarsDK]

Yesterday we took the distributor apart and cleaned everything and made sure everthing worked okay and run smoothly. Mounted it and set the timing but i still won't go back to idle right away... 

I'm thinking about giving up and drive it to a shop and hope they can fix it without getting ruined.