86LG4Bird

iTrader: (1)

This discussion started at Post #84 in another thread:
https://www.thirdgen.org/forums/carb...305-tbi-2.html

We're ending the thread hijack over there and starting a new thread here.

Here's the goal: simple adjustments (ie. lazy-man's method) to an E4ME carb to overcome the shortage of idle circuit fuel supply when dealing with the lower vacuum of a higher overlap cam. We're not talking extreme cams here. The one being discussed is a ZZ3 (208/221/112) cam in a Vortec 350.
I know these carbs can be reworked to accomodate almost any cam specs imaginable, but want to explore the simple tricks/methods, without removing or disassembling the carb, to accomodate mild cams such as the one mentioned that are just barely beyond the design limits of the factory carb.

Here's one of the last posts from over there to get started:

Quote:

Originally Posted by 86LG4Bird

I had that exact thought about biasing the TPS base mV reading higher and was about to add that when I saw your last post ring in
Do you think it would affect the MCS (needle height in the jets) at all at such a low TPS %? I've never seen the tables to know where TPS starts to affect commanded AFR.

Yes, I agree the idle feed is inadequate for the lower vacuum of the ZZ3 cam. I have the baseplate screws backed all the way out.

I wondered if adjusting the lean stop of the MCS would have any effect at all; I doubt it since it's operating on the idle circuit.

.

Fast355

iTrader: (2)

Here is a good article from Hemmings on the CCC Q-Jet and how it worked.

http://www.hemmings.com/hcc/stories/...hmn_tips2.html

Have you hooked a dwell meter to it and tried to close off the air bleed for a richer mixture? Might be able to richen the mixture some by closing the air bleed and then might be able to fine tune it with the idle mixture screws.

Damon

The CC-Qjet system should eat a cam like that, no problem, if the system is functioning properly. Over 220* @ .050 and tighter 110* or less LSA is where they begin to falter in my experience. I got a NEAR STOCK steup running beautiful on a 434 small block with a super mild cam. Then they stabbed in a big-ol 236* cam and.... well, it didn't work so well.

Before we dig into the exotic, how about we check the simple? Is the basic system working properly? When you say you have the idle mix screws "backed out all the way" how many turns from lightly seated are you talking about? ~4 is stock, you can go up to 7(!!) on some CC-QJets. The threads are much finer than on earlier non-CC Qjets.

The IAB should be the only thing you need to adjust for some basic control of idle and off-idle mixture if the rich and lean stops (on the primary rods) are in proper range and you've already backed out the idle mixture screws as far as you dare. The IAB is, essentially, an adjustable idle air bleed, opened and closed using the same "duty cycle" principle as the primary rods (since it moves up and down with them by way of the MC solenoid).

The primary rods on a CC-QJet are definitely NOT capable of blocking off the jets, no matter how far down you adjust the lean stop. Typical cc primary rods are about .052-.054" metering diameter on the lean step (the larger diameter step). Primary jets are typically around .076" orifice dimateter.

Fast355

iTrader: (2)

I guess I should have said that a little differently. Its not an interference fit, but compared to a standard Q-Jet the metering rod area of a CCC Q-Jet is substantially less than the APT allows on a traditional Q-Jet. If I remember from running my standard Q-Jet I was running a 50M rod about 2.5 turns out on the APT and a 76 or 78 jet. The CCC Q-Jet from the cadillac had a .056" metering rod and 70 or 72 jet. The monte ss I had apart and put a ZZ4 cammed 350 Vortec under had around a 74 jet. I went behind someones shoddy rebuild on one once and it was missing the spring that returned the metering rods to the up position. The car had ZERO throttle response even off-idle.

That being said the ZZ4 prom had a fairly aggressive timing map in it and the EGR spark and fuel compensations disabled.

Ozz1967

iTrader: (4)

I'm running a Lunati 60121 Cam with a 219/227 Int/exh @ .050 and other than the basics (Dwell, IAB and other small adjustments) and mine runs fine.

86LG4Bird

iTrader: (1)

I would have expected that. And that's my point with this post.
I've already adjusted the IAB and idle screws to get it as good as I can. It idles as smooth as a stock cam. I'm convinced that there's just something minor I'm missing. Maybe I didn't word my original post correctly; I know there's not an overall fuel supply issue. Other than the bucking when fully warmed up with the TCC locked and at VERY light or NO throttle, the car runs PERFECTLY. The computer is just trying to run it ever so slightly on the lean side at that particular operating point in closed loop. If I lean on the throttle ever so slightly, it smooths right out and accelerates cleanly with the TCC locked. I haven't messed around enough to figure out what tool I can make / how to limit the MCS lean stop. Too much work and other projects going on!

Maybe I'm just being too picky. I suppose I could put a manual switch in to keep the TCC disengaged under 40 mph. I'm not going to invest in programming/burning a chip for this thing just to overcome this one minor open item.

Fast355

iTrader: (2)

If you could dig up one of the old Jet lockup delay harnesses it would probably make you happy. That or an old Hypertech or ADS Superchip with the lockup delayed.

makaveli09

It is possible to use the CCC carb on bigger motors and make good power with them.
I talk to a guy that used one on a powerful 427 BBC. Not sure if he still using it or if he swamped carbs by now.

Ozz1967

iTrader: (4)

Since the carb runs mainly on vacuum signal for idle I was having issues. So when cliff Ruggles did the overall rebuild on my carb, he set my TPS to run slighly rich, mostly because I had off-idle issues with it. He also enlarged some of the idle tubes (not finding the right word for it) to ive the carb a better vacuum signal at idle. I can't speak to why the ECM wants to run lean, but perhaps thats why he set the TPS to a richer initial setting?

86LG4Bird

iTrader: (1)

No fair! You got the "Ruggles" treatment; you did it right!
I met Cliff a few years ago at the Pontiac Nationals; he had Q-jets on customer cars there running NINE's! And we're not talking lightweight 3rd Gen's
What you say makes perfect sense about the vacuum/idle circuit. I haven't driven the car in a few weeks but my next move is to see if setting the TPS to a higher mV level at idle helps.

86LG4Bird

iTrader: (1)

I tried adjusting the idle TPS voltage setting (it's currently about 340 mV), but with my makeshift tool I can't even get the voltage to move, even holding the throttle open to take the pressure off while trying to turn the screw. I'd sure like to find the tool set to adjust this carb! I don't even know what the TPS screw head looks like down inside that recess.

On another note: took the car on a 520 mile round trip last weekend and averaged 26.5 mpg! Just 3 short trips/cold startups involved; the rest was a 50/50 mix between 65-70mph interstate crusing and 60mph 2-lane highways with very few stops.

You would think the ZZ3 cam with it's fairly early exhaust opening wouldn't be a great mileage cam, but I'm running it in my pickup also, and with tuning it has surpassed the best the truck ever saw with the stock L31 cam.

naf

iTrader: (7)

the most easily accessible TPS adjustment tool is an appropriately sized roll pin lightly tapped over the screw head.

86LG4Bird

iTrader: (1)

I was trying to use a hollow plastic rod (same principle), but can't seem to get any movement.
I don't know how fragile the screw and mating threads/support structure are, so I'm leery of trying to drive some metal part over the screw head.

naf

iTrader: (7)

probably got a little rust on it. spray it and try the roll pin.

Ozz1967

iTrader: (4)

Good lord! I get 18.5 on a good run in mine...mild build 355.