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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Forgive me if this has been answered before, I did a quick search search but didn't find much. I also searched the web in general too.
I am wondering to what extent the CCC engines did actual timing control?
I am putting an older Holley HP Avenger system in my friends vehicle and the engine came out of an 85 C10 pickup, stock with a CCC. The distributor has a vacuum advance cam and spring/weight setup. I was just going to throw an older HEI big cap distributor in there just because it was "easy" and I had one lying around. BUT doing timing control with the Holley is nice and I had it working when I had the system in my car before with a small cap TPI distributor.
I know I can keep the big cap in there and I know I can put a small cap HEI, but this is VERY budget build for him and if I can use the CCC distributor to do timing control that would be great. I know I would basically ditch the vacuum can and I can lock out the weight and spring setup, but will the stock module in the distributor ACTUALLY work to do timing control? From the limited info I can find it looks like the CCC setup from the truck just pulled timing if the setup detected knock?
Is that all? Can I use this or is it futile? Thanks for any info.
Electronic spark timing was standard on SOME Chevy V-8s as early as 1981. If there is an EST bypass connector (disconnect to set base timing) present, the distributor had EST as some point.
There is an "ignition module bypass output", circuit 424 on the diagram.
Everything was hacked on this when I got it, but I don't see a connector like the TPI had to set the base timing. None of the vacuum circuits were hooked up right. We had swapped my non CCC onto it a while ago and it still ran like crap, little did I realize all the vacuum hoses were wrong until I started tearing into it for this
The "old" method for base timing adjustment was to disconnect the 4-wire EST connector from the distributor. The diagram you provided clearly shows an EST (right at the top) with the tan/blk wire marked as circuit 424.
There is an advance curve table in the CALPAK plugged into the ECM, but altering that in the older CCC ECMs is not easy - The software to access the memory map is not readily available AKAIK. If you can live with the factory advance, it should at least make it run respectably once you sort out all the pther problems. If the Holley system mimics the factory ECM outputs, it should work. You can verify its operation with a timing light by reconnecting the EST connnector at the distributor after setting base timing once the engine is at temperature.
Maybe I wasn't clear, I am only looking to use the distributor (if possible) with a Holley HP setup. I am not looking to keep using the CCC ECM.
Again, I know I can get a small cap dizzy or keep the normal vacuum and weight advance HEI, I was just wondering if I can use CCC dizzy for advance without the weight system or vacuum
The CCC dist will give no advance whatsoever under any circumstances without an ECM and all the appropriate connections, sensors, programming (tuning), etc. In any "computer controlled" system the dist provides a "reference pulse" only, which the ECM then performs its calculations, lookups, etc. on, to decide the appropriate time for the next spark. Without an ECM the ignition timing will remain at the "static" setting at all times no matter what. It will be BEYOND merely unsatisfactory.
No idea whether the Holley system you're wanting to use has this capability. Obviously all of their EFI setups do; don't know about that one though. If it doesn't, then you'll need a straight-up mechanical old skool dist. If it does, then you can use the one from the CCC setup to generate the reference pulses it needs.
No idea whether the Holley system you're wanting to use has this capability. Obviously all of their EFI setups do; don't know about that one though. If it doesn't, then you'll need a straight-up mechanical old skool dist. If it does, then you can use the one from the CCC setup to generate the reference pulses it needs.
Yes, the Holley HP is capable of running almost any engine out there if it has the right sensors or if those can be added somehow. It will run TPI, TBI, LS, LT, Ford, Chrysler, etc engines with the correct harness and configuration. It will even run an engine with sensors from a different engine if configured correctly. My friend runs an SBC with a crank trigger and runs LS coil on plug on his 2nd gen Camaro.
I just wasn't sure whether the CCC distributor did anything other than pull timing if the CCC ECM detected knock.
The CCC distributor does ABSOLUTELY NOTHING WHATSOEVER on its own other than provide reference pulses. Doesn't "pull timing" or any of that. Other things in that system do all that other stuff. Exactly the same as the small-cap later type in every way except its physical layout.
So yeah, I'm pretty sure then, based on that, that it will work fine for what you're doing.
Thanks. I wanted to get some feedback from people that have actually given good/correct advice rather then some random thread on another board that had replies from people i have never interacted with before I am on some of the Third gen Facebook forums and some of the replies are bad/wrong/dangerous and I want to punch babies because it's so wrong. I am in another 30 day ban though so I can't reply to any of them, lol
OP, you mention that the ccc distributor you have has a vacuum connection and weights/springs. That sounds like someone swapped the ccc distributor to a standard non-computer distributor at some point. The ccc distributor should be the same type as on the fuel injected motors. There shouldn’t be any vacuum advance, weights or springs. It would just have an electronic pickup and an ignition module. All of the igniton advance would be done by the ecm.
OP, you mention that the ccc distributor you have has a vacuum connection and weights/springs. That sounds like someone swapped the ccc distributor to a standard non-computer distributor at some point. The ccc distributor should be the same type as on the fuel injected motors. There shouldn’t be any vacuum advance, weights or springs. It would just have an electronic pickup and an ignition module. All of the igniton advance would be done by the ecm.
When I look on Rock Auto for an 84 TA 305 (just reference) it shows as both the vacuum advance and non vacuum distributors with the non vacuum dizzy as the one not as much of a choice. That doesn't mean much, but this engine came out of a truck and the limited stuff I could find said that the ECM was only pulling timing when it heard knock. So I am guessing for the trucks GM put in the weighted and vacuum advance dizzy because it was cheaper than putting in a different distributor or redesigning
When I look on Rock Auto for an 84 TA 305 (just reference) it shows as both the vacuum advance and non vacuum distributors with the non vacuum dizzy as the one not as much of a choice. That doesn't mean much, but this engine came out of a truck and the limited stuff I could find said that the ECM was only pulling timing when it heard knock. So I am guessing for the trucks GM put in the weighted and vacuum advance dizzy because it was cheaper than putting in a different distributor or redesigning
I don’t know if the trucks were different than the cars. Could have been. My 86’ Camaro with an LG4 had no vacuum advance or weights/springs in the distributor.
I assume you know that the GM EFI distributor can be converted to a two-wire distributor for aftermarket timing control. Is this how you connected your small cap setup? Otherwise I'm not sure what you're trying to accomplish. Opening up that dist on the truck should provide the answers you need (I can't really answer a truck related question in this context). It either has an ICM and the proper pick up, or it does not.
Otherwise I may be confused as to the goal here, but I am curious as to the outcome.
The Weatherpak in the big cap dist has 4 terminals: gnd (blk/red), amplified pickup coil pulse (purple/white) which is shielded at least partway through the rest of the harness, bypass control (tan), and spark pulse input (white). The ECM and ESC module combine to take the (amplified) pulse from the pickup coil, and return the spark command to the high-power amplifier part of the ICM. Bypass is usually active only in Start; when in that mode, the pulse from the pickup goes directly to the output amplifier, i.e. "static" timing with no further control. The rest of the time, the ECM controls it. When that connector is unplugged the ICM goes into bypass mode.
AFAIK there is no difference whatsoever between the truck and car implementations of this design.
bypass should also be active at loss of signal from ECM (when connector is unplugged to set base timing for example). in this mode I have observed the dist to provide rudimentary timing advance, a jump in timing at maybe 1200-1500 rpm (I use 'maybe' because it's been so long since the observations). this is the 'limp home' advance built into the ICM. Observations were for an 87 LG4 and cannot be assumed to be a universal truth.
in the end though these discussions of the GM EST may be academic, although interesting. I'm in the process of converting an MSD small cap to a two wire connection for use with fitech. i"ll lose spark knock as the fitech does not have that capability. Does the Holley? and is that why you're pursuing continued use of the ICM?
Good info, though a lot of it is above my understanding/comprehension.
Originally Posted by naf
I assume you know that the GM EFI distributor can be converted to a two-wire distributor for aftermarket timing control. Is this how you connected your small cap setup? Otherwise I'm not sure what you're trying to accomplish. Opening up that dist on the truck should provide the answers you need (I can't really answer a truck related question in this context). It either has an ICM and the proper pick up, or it does not.
You assume too much When I had the HP setup in my 2nd gen with the BBC I used my expensive MSD small cap distributor and just bought the requisite connector from Holley to connect the module to the HP TBI harness. Now that it's ~7 years later and I know more I can make my own connector to the CCC dizzy and not have to send 10's of dollars on something that will cost me a couple bucks in terminals at most. This is a real budget build for my friend and I am trying to get him the most benefit for the smallest amount of money. I know the weight/vacuum distributor is probably good enough but, now that I have the info, this isn't much more work so I might as well just use it. Eventually this will go on top another BBC for him when he has more funds and I have less projects.
Originally Posted by naf
Otherwise I may be confused as to the goal here, but I am curious as to the outcome.
The goal is to use the parts I already have to allow the HP to do timing control instead of the springs, weights and vacuum canister. Since the distributor that came in the engine was for a CCC and can allow the HP to do it, I would rather use it since I know it already works
this may be what you're looking for. there is an adapter available somewhere for the GM small cap.
I'm not sure why you linked that since it applies to the small cap HEI distributor. I am looking to use the CCC distributor I already have, and know functions so I can do timing control with the Holley HP ECM. I don't want to spend more money for me or for my friend. I have a couple small cap distributors, but that would require me to then wire up a different ignition coil, fab a bracket, mounting it, getting a wire to go from the coil to the small cap dizzy. I could also just drop in a NON CCC HEI distributor but why not just use the CCC and get electronic timing control?
sofakingdom explained that it will do what I need since it really only is sending pulses for the ECM. So the CCC dizzy should work with the HP ECM so I can do electronic timing control and NOT do vacuum/weighted advance.
Originally Posted by sofakingdom
The CCC distributor does ABSOLUTELY NOTHING WHATSOEVER on its own other than provide reference pulses.
All I have to do is take a 4 cavity Weatherpack connector, which I already have (many), Weatherpak terminals I already have and then terminate on the other end the Metripak 150 on the other end to match the HP harness, et voila, timing control ignition system. I can do this in my garage on the bench in 10 minutes and plug in two connections and not have to break my back bending over the fender for 30-60 minutes changing the distributor, coil, wiring in car.
Yup, I'm pretty sure that's all you need to do. Seems straightforward enough.
The ICM is required... it does 3 critical things: (1) takes the pickup coil signal and turns it into a nice squared-off pule with fast rise & fall times for the rest of the system; (2) accepts the pulse from the ECM that triggers the spark, and amplifies it to the level needed to drive the coil; and (3) switches to "bypass" mode when deprived of the signal from the ECM, such as when unplugging it to set the static timing. Can't live without it.
I just need to line up the descriptions in the schematic from the Holley HP system to what the descriptions say in the 85 drawing. But I think it's simple since I actually have the intermediate harness for the small cap HEI, so I can compare the wiring and use the link naf provided to make sure I connect the right terminals
the fitech requires a two wire connection directly to the dist. it handles all of the ICM control functions and the ICM is no longer needed. it may be the same with your system. and the large cap could be modified the same way as the small cap. Again I've not yet done this with mine, but have spent some time in research.
if your large cap has a vac can on it, it should be mechanical and not computer controlled. If so I'd hook it back up (or leave it in place) for timing control-at least until after you get the new EFI system running. one less thing to trouble shoot. you can later go to computer control of the timing.
if you need any pieces parts (or a used small cap dist and coil) I'd be able to send you them at the cost of shipping. You just have to keep us updated on your progress and results.
the fitech requires a two wire connection directly to the dist. it handles all of the ICM control functions and the ICM is no longer needed. it may be the same with your system. and the large cap could be modified the same way as the small cap. Again I've not yet done this with mine, but have spent some time in research.
If the Holley HP can do this, I am not sure. I could go on the Holley board and research, but I don't really care to at this point, I want to stick with the big coil cap. I really don't want to change more stuff.
Originally Posted by naf
if your large cap has a vac can on it, it should be mechanical and not computer controlled. If so I'd hook it back up (or leave it in place) for timing control-at least until after you get the new EFI system running. one less thing to trouble shoot. you can later go to computer control of the timing.
It has a 7 pin module in it even though it has the vacuum and weight system, I found a few internet responses that said the CCC in the truck was ONLY pulling timing when it detected knock. I can't leave it in and not hook it up, it won't work at all then, so the ECM is still part of the equation as we found out before I started this endeavor, We left it unhooked accidentally and the truck wouldn't start. I either have to use the HP and do control or swap out for a plain jane HEI distributor (which I have and can do I just don't want to if I can help it)
Originally Posted by naf
if you need any pieces parts (or a used small cap dist and coil) I'd be able to send you them at the cost of shipping. You just have to keep us updated on your progress and results.
let us know what you've got and how it works.
Thanks, but I have several small cap and large cap HEI lying around from other cars
This is from the Holley Avenger setup I am putting in the vehicle with the irrelevant connections blacked out. Link here if you would like to see it
I think the 424 Ignition module bypass output is supposed to go to A22 Purple Cam input (dig & IPU)/Bypass.
And from the diagram I linked at the beginning shows 453 Distrib Ref Pulse Lo Input should go to ground since it is connected to the body of the distributor on the drawing and in the distributor, so I would connect that to A14 Green IPU Ground
11-13-2020, 10:01 PM
I am on some of the Third gen Facebook forums and some of the replies are bad/wrong/dangerous and I want to punch babies because it's so wrong. I am in another 30 day ban though so I can't reply to any of them, lol 
When I had the HP setup in my 2nd gen with the BBC I used my expensive MSD small cap distributor and just bought the requisite connector from Holley to connect the module to the HP TBI harness. Now that it's ~7 years later and I know more I can make my own connector to the CCC dizzy and not have to send 10's of dollars on something that will cost me a couple bucks in terminals at most. This is a real budget build for my friend and I am trying to get him the most benefit for the smallest amount of money. I know the weight/vacuum distributor is probably good enough but, now that I have the info, this isn't much more work so I might as well just use it. Eventually this will go on top another BBC for him when he has more funds and I have less projects.
