A friend's Imperial with '69 440HP from a B-body is running a little rough, and it's MUCH slower in the top end than it should be - in a rolling start "drag race", it has been handed it's [Edited by Moparts - Family Friendly Site - Keep it clean] by a turbodiesel Renault Latitude...

It seems to me that the problem can be in the vacuum advance regulation - the engine runs too rich, but get it any leaner and it starts to run rough. Maybe some problem in the vacuum lines? Guys who put the thing together have never seen a Mopar engine before, so they could just mismatch something, maybe?

Here are some pictures - maybe someone can see something wrong there?

https://picasaweb.google.com/115646732410106877156/20110915?authkey=Gv1sRgCMHO8LGtganhxwE

One thing I see is the kick down linkage isn't setup right. It looks like it's missing a spring or has a mismatch of parts from a 2 barrel setup. The slot in arm should be tight against the carb stud, not in the middle as it is.

Looks like you are on manifold vacuum adv.
I would ditch that and put some light springs in the dist. Then time it up at high rpm for 38 degrees. That will eliminate ignition issues and leave you with just your carb problem( Carter )

is this a new problem that just developed?

Its not the vacuum advance. Simply put....the engine doesnt produce vacuum(or at least much more than maybe 1 inch) at full throttle. So any high rpm, full throttle issues wont be related to vac advance, because vac advance isnt in the mix or doing anything at all under full throttle.

Vac advance only works at idle/part throttle where the engine produces vacuum.

If its a new prob, Id be looking elsewhere

By the way - is it possible that car starts running rough when the air cleaner is removed and installed back? It seems to me that the seal between the cleaner and the carb is not what it should be, but can it really make a difference?

Start at the beginning. Want vac adv connected to the front pass nipple (carter) which'll b ported. pull the vac adv hose off & plug it w a golf tee & set the initial at 10BTDC (stock cam) 15 (wild cam) then run the rpm up until it will not adv any more & post what you have. If no dialback or timing tape 2&1/4" is 35.5 degrees. And if (10) or (15) makes it ping or if it pushe sit way past 38 total back that off. If it is not pinging you're good until you get it spot on & any pinging you can hear is way too much & you're racing it so not sure if you can hear it. take off the dist cap & see what springs you have, stock is a heavy spring with a long loop on one end and a light spring. may need to alter the dist slot length to get initial/total correct but start w initial & post what total you have now. Stock '69 carter AVS? What eng mods, what cam/what idle speed. rich at idle? smells like gas? The more info the better

Here is what you do to sort the timing.

First and foremost....unhook the vac advance completely and plug its port on the carb so that you dont have a vacuum leak.

Get a timing light and check initial timing at idle. For any performance engine, at least 10 degrees timing should be there at idle. Higher is not out of the question. Give the motor what it wants. Go up in 2 degree increments at a time just to see how she responds.

Then...I always put the absolute lightest advance springs in as possible and check total timing(that way your not under the hood with the engine spinning 4000 rpm or something....the quicker the timing comes in, the safer it "feels" checking total).

Anywhere from 34-40 degrees total is common depending on various factors. I always first find an initial value that it likes.

See where it idles best, and where it starts easiest and quickest(check after warmed up also to make sure it wont kick back on you or roll over or anytihng).

Then...find total timing. Start at 34 and go up 2 degrees at a time with some full throttle runs. Wherever it feels best, make note.

Say for example it likes 14 initial best, and 38 total best. With that in mind, you need 24 degrees of mechanical advance. This is where it gets fun, and recurving comes into play to adjust advance to 24 degrees mechanical so that you can have that 14/38. If you dont wanna play with it, compromise as best as possible.

Say your distributor only has 20 degrees as is. Set initial at 16 and you'll have 36 total. decent compromise.

Hook the vac advance back up to full manifold. If it adds too much adance and you experience pinging at part throttle...tweak the vac advance to limit how much advance it adds. Real real simple to add a stop plate to a non adjustable vac advance to limit how much timing it adds.

Some simple stuff.....check for full throttle! Dont assume your linkage is spot on. If your only opening the butterflies 80%....that would explain a loss in upper rpm power.

Then we get into carb tuning. The list goes on and on

440 in the Imperial running weird ....

DID you get a feets-guy tune-up ?

THAT would 'splain it ! ...

And what about that air cleaner seal? It seems strange to me that after taking off and refitting the air cleaner, the car starts running better or worse, depending on how you put it in there... There's quite a high seal under the cleaner - maybe the problem is there? What about throwing the seal away? I had air cleaner without any seal on many cars and it worked just right...

ANOTHER European Imperial! My god man... they're taking over the place...

Anyways, if the engine is a recent transplant, how do you know its a good one? Has it run well in this car before, ever? How about in the last car? If it was rebuilt are you sure they built it right? I ask because you say the people that did it didn't know Mopars... There are a lot ov ways a build could go wrong long before it hits the car.

How about a pic ov the car itself... Hmmm...???

breather should make no difference unless it is touching the accelerator pump or pinching the fuel line??
anyway tuning brocedure is always done vacuum line off and pluged at the carb. set total to 36 deg and drive setting up carb and seeing if it pings then maybe go up to 38?? later you can try and add vacuum in. if you are using vacuum to hold up idle it will drop off and run like crap. also at WOT there is no vacuum so it drops away and no power.

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That has to be the best looking Mc Donalds I have ever seen, very classy.
Nice Imperial too.

You may want to look at that carburetor also. Re-adjust fuel mixture screws. It may be running too rich. Also the rod in the acc. pump should be in the middle hole for the AVS's. Anyone agree? You say it is a carb. from the smog era! Does that mean it is jetted on the lean side? Get timing fixed first then work on carburetion! The engine running smoother after you take the air cleaner off means that you are getting more air thru the carb. and it is leaning out the carburetor which sounds to me like it may be running too rich at idle!