The Dodge Challenger Message Board

I know we done this topic many times before, but I want your advice on what I think is my 440 still running too rich. It stinks inside at anything over a very light throtle and stills bogs when I try to accelerate hard. In fact after a spot of full throttle action the smell makes my eyes water. The car drives loveky on a light pedal tho', smooth, torquey, clean idle, sounds real crispy too.
I've recently rebuilt the Eddy Perf 750 and very carefully set the float heights and drop, the choke rod adj and the idle setting. New needles and seats, gaskets and just over 5lbs of fuel pressure. Timing is set to Daves well proven method, got an FBO advance plate and ign module, the electronic dist is set to 20deg initial, 34deg at 3000, no vacuum used and at idle my Mityvac reads about 8" from the fulltime manifold port on the carb.
Just to recap I got 452 heads with very mild work, headers, HP iron intake, Xtreme Energy 284/296, .507.510 lift cam, KB quench pistons, about 10.5 c.r. and a 4 speed with 3.55 gears, nothing radical there.
Got hold of an Eddy jet and rod kit and swapped in a set of 1 stage leaner metering rods, a small improvement was made, have'nt made a jet change yet, need to take the car to a dyno really don't I ?

How come you dont have a vacum advance Adrian? I too have Don's re-curved distributor with 20 initial, 14 mechanical and 12 deg. vacum advance using Constant Manifold Vacum. My engine makes 12" at 900 RPM's,(idle). Your Cam specs are very similar to my 440 SixPack's cam spec. What do your sparkplugs look like? At operating Temp. Does it re-start easily after shutting it down? Have you looked into the throttle bores at idle? No raw fuel dripping down especially after shutting it down. My Center carby was leaking horribly until I had to have it fixed.

How come you dont have a vacum advance Adrian? I too have Don's re-curved distributor with 20 initial, 14 mechanical and 12 deg. vacum advance using Constant Manifold Vacum. My engine makes 12" at 900 RPM's,(idle). Your Cam specs are very similar to my 440 SixPack's cam spec. What do your sparkplugs look like? My situation was a little different but my plugs were dry black,,way too rich!! At operating Temp. Does it re-start easily after shutting it down? Have you looked into the throttle bores at idle? No raw fuel dripping down especially after shutting it down. My Center carby was leaking horribly until I had to fix it.

You don't need a rolling road. You just need an air/fuel ratio monitor. Your timing is fine for that application. You just need to tune the carb.

Actually I never bothered with the vac Eddie cos I thought at 20 deg I'd already got as much advance as the motor could take without any damage, and I'd seen Dave run a similar set up with great success. Don't have any kick back on starting, even at full temp, motor will start on the key without any gas and settle down to a clean idle. I don't think my vac advance can works cos when I put the Mityvac on it earlier and tried to draw some up with a tube attatched to the can it would'nt display any vacuum, let alone make the ign increase the engine speed. Do you think I need more advance then? always worried about damaging the motor with detonation though Ed.
The plugs always look a light tan colour, like a digestive biscuit

Just see that Daveman .......going to carry on and try the metering rods, springs and then start on the primary and secondary jets. I thought that timing was good, pleased I got something right

An air/fuel monitor will make the carb tuning really easy as you can see how big a jump you need to make to the jets straight away (one you see how much difference a step makes).

Have you got the correct springs fitted to the metering rods? You need to match those to your manifold vacuum first before you start.

The stock springs are in, they work at 5", in the jet kit there are springs that go to muck kigher values. If I had too little vacuum, say 4" or 5", I could understand the rods lifting and causing the enrichment, but at a fairly high reading I would expect the rods too stay down. In fact I'd put a stronger spring in to combat that.
Gonna call in to a mate of mines parts shop amd see if he's got an A/F meter, does that require a sensor installed into the header or collector?

The better wideband ones work best if you weld a bung for the oxygen sensor the meters come with. They often come with the bung so uou just need to drill a hole and weld it on. Easy peasy.

It makes life a lot easier if you can actually see what the mixture is doing in real time.
Something like this...

http://www.innovatemotorsports.com/products/MTXL.php

We got threaded unions for that job in stock, don't even need welding, we use 'em for temp probes in commercial boilers and combustion chambers. I'll check these out mate, looks like you can read every bit of data at all times, any load, any revs etc, ta

The old LM-1 is what I use Adrian. It's very easy to use but you need a bung in the collector for the wide band sensor. As Dave stated, it's really the easiest way to determine what is going on in the induction system. Some guys use Vac. adv. some guys dont. But if you dont have it you wont be burning everything in the chamber during light load, decel, idling. Whenever the throttle is mashed it doesnt come into play, but most of the time cruising, it should be used. On fuel injected engines it's not uncommon to have 60-65 degrees,(total) during decel and very light loads or idling. This is why they can go thousands of miles and no tune-up and the chambers look pretty clean even after 100k miles.

Well, I've spoke to a customer of mine who tunes rice burners, he's lending me a meter that uses probes up the tailpipes, he says its very accurate, reckons it owes him a £1000 , better be good at that money.
Secondly and most importantly, I took the vac can off of the 440 at work, checked it with my Mityvac, installed it and............works wonders super responsive engine, lovely idle still, but hardly any smell. Was very late when I finished so it did'nt see tarmac yet, will do that Saturday. My question is what did I have wrong in the first instance? That set up should have worked fine, Daves used that method for a while and so have plenty of others. Was it just a case of this particular engine needing more advance, could I have dialed in more initial and used less mechanical?
Still got to tackle the metering rods and jets, but I look to have a more suitable starting point.

I had to get up to 24 degrees to clean my burn up. But the engine was still starting fine at that so no need for the vac advance.

If it works stick with it mate. No two engines are the same.

Got out in the sun on Sunday and fired up the car for a run around the block to see how the motor ran with the vac can hooked up. I can see an improvement in the part throttle, the exhaust does'nt smell half so bad, wound it open a couple of times only to be presented with the pungent aroma of frying clutch plate, so hard to tell the whole outcome, gonna get a new dia. kit and try it again