CELEBRATING 20 YEARS!

I've read through a couple different threads with the above listed 334 that had been dynoed and I would have like to seen what it would do with a better cam.

I plan too touch on it in my other thread but I had 2 issues with the ccc, never would idle correctly while the ccc was in charge and trying to maintain 14.7:1 and I could never get it to lean the a/f ratio at wot which I think was a problem with the distributor the more I think on it.

I'm not educated enough on cams and all aspects of the motor to know what was going on but the only way I could get the ccc to idle correctly is cranking on the idle air bleed to richen the mixture. Only time I could get it to idle good was when I was in the 13.2:1-13.5:1 a/f range, then the ccc wouldn't operate correctly. So I let the ccc do its thing at idle and it just never sounded or smelled healthy, always a too lean exhaust smell. I have a speed hut a/f gauge, borrowed a aem a/f, and converted over the numbers on stock narrow band from data logging and they all three were pretty much dead on, I have bungs in both collectors and I read the same in both.

Fast forward to the non ccc quadrajet, when tuning the idle circuit I never looked at a/f just the vacuum gauge, tach, and ear. Turned the screws out a little at a time until I got max vacuum, started turning back until vacuum decreased then turned back out a 1/4 turn. Looked at a/f and it was around low to mid 13's, I gave the engine what it wanted and I'm fine with it. It idles nice and smooth right at 750 r.pm.

On the wot end it would go off the chart rich on a/f and just no where near the power I thought I should feel in that range, messed with the secondary flap spring, hanger, and rods. Plugs read rich making wot runs on back road shutting down pulling both front plugs. Never could get it leaned out. Put the new distributor and carb on and I'm at low 12's a/f with more metering area through the secondary. I originally thought there might a problem with ignition but already planned the non ccc and didn't feel like messing with it or investing money.

Brent, weren't you using a custom EPROM? Did you try with the factory PROM to see if the CCC would behave properly?

I am using a PROM from ADS SuperChip that I bought in the early 1990s. When I put it into the car when all was stock, apart from the T5. The chip I bought was for a Camaro with manual transmission. I didn't really feel any difference.

However, I didn't have much trouble tuning the CCC carb when I installed the Summit K1103 cam. I did have to turn the air bleed screw several turns to set the mixture control solenoid dwell. I don't have any trouble idling. I don't have an A/F gauge, but don't experience any rich/lean smell at idle. My throttle response is very good.

Yes, tried both eproms. I did not get away from ccc because of the issues, it's what I wanted to do all along. The ccc and everything that goes with it is nicely packed in a box up on a shelf. What I posted above is just an uneducated guess on my part, you could set the dwell in the correct place the engine didn't like it and the the ccc would fight it. It is what it is. All I know is that now the engine is what I thought it should be from the get go and I'm very happy with it.

Did you tried enlarging the idle downtubes in the E4ME? In stock form the idle circuits are very close to lean in E4ME. In a Motortrend article, Sean Murphy drilled the downtubes from stock .032 to .034. He also enlarged the accel pump discharge ports in the airhorn from .026 to .029. Another factor too is that anytime you use a bigger camshaft you usually need to run more ignition base time to restore idle quality. The ZZ4 chip is supposed to be able to handle hotter cams than the stock L69 chip. I don't know how much hotter but its what the 3rd Gen guys say.

Also read that with some hotter setups, its better to adjust the idle mixture needles first until you get s smooth idle. Then adjust the IAB for 30 degree dwell.

I’ve been using Performance Trends EA since 1992 and it’s proved to be fairly accurate over the years. Back around 1998 a friend wanted me to see what I thought about the DD version at that time and it was all over the place. I ran four or five known combos through it and back then most came close on the peak numbers but the rest of the curve would be way off. Part of that was because of the limited parameters that you could change (most were drop downs). In Brent’s case with those heads being on a 305 bore (tested on a 4.00 bore) you need to drop the published flow numbers a little. Still that wouldn’t account for the huge HP difference between the EA simulation and publishes results of similar combinations.

Yep, there was a good bit of power left on the table with that cam. Much better profiles out there and needs more lift. I think he picked one with a CARB exemption - still can’t help but believe they’re better exempt cams. I know a lot of those CA guys maxing out the TPIs are running XFI cams. Now whether they’re legal or not they are passing emissions with them.

I pulled flow data from the 175 heads from a 305 bore.

Performance Trends EA Software...............I still have the 3.5" floppy some of us in the office were asked to review and comment on when first produced. Little did we know where it would go some 30 some years later.
Their software/services are used by many in the industry today.

I looked for that and couldn't find it. Does it show what the numbers are at different lifts? If so, I'd like to see how far off my estimates were (based on the only flow data I could find based on a 4.03" bore).

Here is the flow chart Travis is referencing in the thread above for anyone that is interested.

I'm diagnosing myself as having early onset Alzheimer's.

Thanks Travis, after clicking the link to 3rdGen, I remember seeing that post. Looking at the data I input for the head flow on the simulation runs for Brent, it looks like I just pulled 1 or 2 CFM off some lift points of the 3.766 bore flow numbers to "adjust" for his standard bore.

Probably too late of a reply to help you but it may help others. Generally with the stock LG4 or L69 PROM chips you want to keep .050 duration below 220 degrees. The ZZ4 PROM chip is purported to handle more cam duration than the stock L69 chips.

As I posted before, stock E4ME idle circuits are setup very close to lean for a stock cam. Most bone stock Qjets have rather lean idle circuits while most aftermarket have really rich idle circuits to run on nearly anything. So its possible the idle tubes and other parts of the idle circuit may require slight enlarging. Furthermore, the idle tubes can also easily become clogged from ethanol. During a rebuild, at a minimum .030 wire should be jammed down the idle tubes to help ensure they are clear. But its best but tricky to pull the idle tubes for proper cleaning of both the tubes and the underlying passageways. Many rebuilders fail to properly clean the idle tubes including so called professionals.

As for WOT, the ECM defaults to full rich command and the E4ME effectively becomes a regular mechanical carburetor. The ECM only operates the primary side during idle and part throttle crusie. The ZZ4 PROM has a more agressive ignition advance curve than the stock L69 PROM, I can say it makes a big difference. Also the 7 pin HEI ignition modules that CCC systems use can flow more amps than the 4 pin ignition module in mechanical advance HEI.

Its also not uncommon for the secondary air flap plastic cam to be cracked and cause issues.

In short, I think the issues 88ssbert had are undersized, clogged, or both idle circuits and not enough of a ignition advance curve.

I'm not going to go back and forth with you but if you will reread what I put above you will realize that your assumptions are wrong on the idle circuit.

I reread whaf you posted and it fits with my hypothesis. If the idle circuit is too small, then the computer can't cycle the solenoid in the proper range to provide enough fuel for the engine. Ie you adjusting thr dwell rich to get a stable idle and the engine and computer seemingly fighting each other at idle is a sign of this. As I posted already, my last post was meant to help other readers who may come upon similar issues, not to help or apply to you, which I don't mean as an insult. Nor am I trying to start any argument and I am sorry if you feel that way. The computer simply can't compenisate for a undersized or clogged idle circuit for upgraded heads and cams. All Qjets are sensitive to vacuum changes and designed for individual applications.

The engine produces the most vacuum at idle on the non ccc quadrajet and ccc quadrajet at around 13.5 a/f ratio. The engine likes 13.5 a/f ratio at idle, I have no trouble at all getting the ccc to richen to even mid 12's a/f ratio . The engine likes 13.5 afr , the ccc wants it at 14.7 afr but the engine does not like 14.7 afr it likes 13.5 afr. We can modify the idle circuit all we want but the engine is still going to want 13.5 afr and the ccc is always going to make it try to go to 14.7 based off what it is reading at the narrow band. If I could not get the carb to richen then yes the idle circuit would need to be modified but I have never had that issue, the issue is ccc tries to maintain 14.7. My cam is just 210/218 @ .050" on a 113 lsa and I was using the zz4 chip when I removed it.

Not wanting to enter the fray but make a comment that will hopefully help - agreed that one thing is the carb's ability to supply any desired A/F, another is the A/F that makes the engine run best. Here's a fairly helpful article: https://tmfcycles.com/blogs/tech-tips/cams-explained

Both sides of the equation need to be addressed.

Y'all probably know this but just in case you don't - basically, the bigger the overlap triangle, the more one needs to fatten supplied A/F to counteract intake charge dilution. One also needs more ignition advance to counteract the slower-burning characteristics of that diluted intake charge. The article gets this right and touches on many of the same things David Vizard and Gerry Clark at GM told me about designing good cams.
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About the Q-Jet, I tried a couple and could never get them to work right, no doubt due to my lack of competence in working with their inherent fussiness from my perspective. Today, I'd throw it in the garbage and head straight for EFI. But again, that's me.

HTH,
MAP

Thank you Mark. I can say that at this point I'm really happy with the quadrajet and the hei distributor. I'm not that good at understanding cams but after a quick glance at the article it might lead me in the right direction, thank for that. What I'm seeing with the vacuum gauge is what you are describing. Right now I'm around 13.5 a/f and 12 ° initial, it really likes 14° initial better but that puts my initial plus mechanical at 38° so I plan to mess with that as time permits.

You're welcome. If it works, then at the end of the day, that's all that matters - great! That last EAP simulation run shows 58% engine torque bandwidth, which I'd say is consistent with the duration of the cam you have with this 305. In this case, I believe the wide LSA is helping you somewhat with respect to the idle region. So can increasing idle rpm within reason.

That is a handy link MAP. Qjets are highly application specific carbs, especially the idle circuits which were sized borderline lean for stock applications. Put a Qjet on a different application engine and the headaches will begin. That is not considering how many rebuilt Qjets these days are often Frankenstein together from mismatching cores and sup par parts. `

At the risk of fanning the flames, here is a link to a article of Sean Murphy, one of the big Qjet gurus modifying a CCC Qjet for a 305 with Trick Flow heads and a hotter cam, similar to the OP's modified 305 here. BTW my cammed 305 with CCC is 210/216 @.50, both are cams are under the 220 limit of even stock chips.
https://www.smicarburetor.com/ecom/download/Chevy_Hi_Po_Elec._Qjet_9-07.1.pdf

The idle adjustments only adjust the ratio mixture, not the total volume per se. You can adjust the mixture rich to slightly increase fuel volume but its not the best way to do it. The better way to increase volume is to increase the clearances in the internal idle circuits for more fuel volume flow at the desired mixture ratio rather than run it rich for the desired flow. I doubt the Lars carb has stock size idle circuit for its original application. Qjet adjustments are like the Overton window, if you modify the engine so the ideal setting is out of the adjustment window, then you need to move the window. Modifying the circuits helps to move the window. Afterall, posters here have used CCC system on big blocks and over on Thirdgen some of the F body guys even used CCC on top of blowers successfully. This isn't meant as a slam against anyone, just trying to dispel the myth that CCC is some sort of HP shackle, at least for anything under 500 HP.

Rather than further spaming Bert's thread here any further I will create a how to thread for modifying CCC systems to handle higher HP as it seems to fast becoming a lost art.

H

It seems we're really on the same page with our cars. Mine only has 28k on it and I couldn't justify changing short blocks, at least for the time being. Just ordered the same Trick Flow heads and a slightly bigger Lunati flat tappet cam (10120702). I'll be reading your whole build later today. Looks like it's going great!

Yep, I'm completely happy now with 305, it's quite a little beast.

Picture of my now upgraded serpentine engine bay!

That factory clean look is where it's at! Awesome job and attention to detail.