OK now on to Plan D 1986 Bonneville GS

Ok folks, back again with a New project,, Operation "CCC system Restoration"
I have purchased a fine survivor of a 305 ccc 4 brl 2004r G body , stashed away in a crappy 1 car garage since the sad year of 2004 , due to a non operational transmission . got it home and running in a hour or so with just filling the carb bowl through the vent and she roared to life . Sadly didnt pull in any gear. Attachment 16643 so I rebuilt the Trans, new convertor I had to replace the 4th gear pressure switch cause it was showing closed and if you applied any air at all to it it leaked around the crimp on the outside. removed the carb, cleaned it out and made sue all the air tubes where rodded out with a torch tip cleaner set. can runs flawless, CCC seems to be commanding timing because it changes to the default base setting when you unplug the 4 way to set it. Found some good videos from GM about recalibrating the carbs when they come in for a 25,000 service and explained how finely calibrated everything is including the seals for the accel pump and TPS plunger to keep out ambient air, and this is really a good system in theory and some of the cars when new had milage in the mid 20s on the highway if maintained properly. Im thinking alot of these systems got a bad rap due to lack of knowledge as to how sensitive these carbs are compared with Prior non electronic q jets. But i have regeared the rear with 3.42 gears compared to the Namesake 2.41 that is came stock with. added some New 225/70/14s on some pontiac 14x7 rallys , changed the governor gear so the speedo it within 1mph of the gps reading.Attachment 16644

Plans are to make this system work as advertised. I have a monte SS chip from a 1987 , now currently I have the stock 7169 ECM with a FFU prom. Check engine light comes on and then goes right off once you start the car and you never see it again till the next cycle. I tried swapping the SS chip in and the check engine light stays on , didnt pull the code just figured it was the mix match in years, but turned out I have head the 87s had a different ecm that was a little faster so Im wondering if I do swap to the 87 305 ECM will it work with my current 305 system?

Are the definition files the same . . . 86 Bonneville GS vs. 1987 Monte Carlo SS?

https://www.tunerpro.net/downloadBinDefs.htm#GM

I was not able to find ECM 1227169 in the link posted above.

RockAuto showed the 1227169 ECM as 1986 only.

dave w

yeah I think 86 and 87 are one year only PCMs figured they were different before looking them up seeing as how My current 86 prom is only a 3 letter code VS 4 digits for the 87 and newer
I read a few thread over on Third gen.org and several folks did the swap and said their stuff ran better, another thing that I need to check on, is I dont think Im feeling the converter lock, I tested the lock up solenoid before I reinstalled it it worked fine, so I suspect this ECM might have a problem. I havent tried to pull codes on it mainly cause I have been busy getting it road worthy. new front brake hoses, New pad, swapped out the airplane gears for normal street car gears, stuff like that, im currently installed a set of factory rally gauges and will have the Tach hooked up tomorrow and I can see if the RPMs are dropping.

I think this is the one you want... http://www.montecarloss.com/communit...Number=1027530

good thread, I went over today so I could bring the car home from the shop to my house...(Hard to drive 2 vehicles at the same time. ) and grabbed two proms I had and I was correct The one chip is for the 87 L69 ss the other was a old chi from a 90 9C1 police car I owned withe TBI LO5 so thats one isnt going to do me any good..LOL

Took the first road trip in it and the result was 21 mpg so Its close and thats with a 3.42 gear stockers where 2.41s.

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Originally Posted by Jim_Rockford

Took the first road trip in it and the result was 21 mpg so Its close and thats with a 3.42 gear stockers where 2.41s.

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At one point I played with that system in an 88 Cadillac Fleetwood with a vin 9 307. That car had a 180 hp 307, 200-4r and 2.53 gears. 27 mpg but no power on hills. Was gifted a solid main 403 out of a late 70s GMC motorhome that I helped put a 500 cadillac into. Put a set of earlier 70s olds 350 heads on that 403 along with a mondello cam and an edelbrock intake. Car would get 25 mpg and never slowed down. Was able to get it to run well without tuning the ECM although later made some small changes to that 830 ecm.

My old 83 G20 with a mechanical q-jet would often get 20-21 mpg highway. LE9 305 with flat top pistons and 601 heads and factory catless dual exhaust with factory tubular manifolds off a 1-ton 350 van that I had added a dr gas x-pipe into. Van had a 700r4 and 3.08s.

Still like my old school q-jets. Actually just finished completely rebuilding a virgin 84 305 G20 carb that came off a van nearly 20 years ago in the wrecking yard. Rebrushed the shafts, removed and resized the idle down tubes, resized the idle channel restrictions, resized the idle air bypass ports, resized the idle mixture screw holes, resized the accelerator pump holes, resized both the secondary pull over enrichment ports as well as the pull over well restrictors. Then changed the jets, metering rods and power piston spring. Finally resized the needle seat and created a new seat for it and the accelerator pump check ball. New secondary hanger cam and windup spring also installed. Removed the choke plate, shaft, and linkage but retained the thermostat and fast idle cam. Started chokeless as soon as fuel reached the fuel bowl, settled to a high idle and just ran great.

I clean my carbs in a heated ultrasonic bath. All kinds of dirt, dried gasoline, carbon and crap come out of the carb.

The one I built running on my 11:1 aluminum head, roller cam 383. Actually ran 8 minutes and 36 seconds without a load at 2,000 rpm on 1 quart of fuel.

https://youtu.be/l7XDuEvqFR4

I built an Edelbrock 1406 as well in the last couple of weeks and jetted it up enough to feed the 383. It ran for 7 minutes and 24 seconds with the last 20 seconds or so on one float bowl and on 4 cylinders. Well dialed in Q-Jet definately has better low-load fuel consumption numbers. The quadrajet had 15% longer run time on the same exact fuel volume and ran on all 8 until it stalled, something the Edelbrock did not do. That being said both carbs have great throttle response and idle manners and are seamless in throttle transitions. A couple of throttle rips on the primaries had it up to 6,000-6,200 nearly instantly.

HEI was setup to give 15° centrifical mechanical advance by playing with the center plate and weights. With medium springs from a mr gasket recurve kit, 363 center plate and 053 weights, timing curve started at 1,500 rpm and reached full advance by 3,600. Initial timing set at 16° BTDC. WOT timing is 31° @ 3,600. Vacuum advance is connected to manifold vacuum, canister starts advancing about 7 in/hg and fully in by 12°. Vacuum advance has a hei weight bushing from the mr gasket curve kit slid over the shaft into the guide channel. Limited it about 2°. Total timing at 3,600 rpm with the vacuum advance connected was 46° btdc. Idles at 650 rpm with a stable 31° of timing and nearly 18 in/hg showing on the gauge. Cam is 218/228 on a 108 LSA and 104 ICL. 0.578 lift with the 1.7 rockers. Rhoads V-Max lifters adjusted cold to the bottom of their travel with a 0.014" feeler gauge between the valve tip and rocker arm. The lifters and rockers are a little noisy but run fantastically. The rhoads lifters really tame the idle and low speed manners of the tight LSA cam.

I did the Q-Jet fuel consumption test with and without 2 chambered 40 series flowmaster knock off "rumble" mufflers. The rumble mufflers added nearly 30 seconds of run time to the q-jet and dropped off about 1 in/hg at 2,000 rpm. RPM stayed the same. I believe the mufflers kept the tri-y headers from over scavenging the chambers, allowing for some internal egr.

This is the edelbrock running with rumble mufflers.

https://youtu.be/7umnODe8nqQ

To get the edelbrock 1406 as responsive as the Q-Jet had to run the largest primary jet and thinnest metering rod in the tuning set. .101 jet and a .070 x .037 rod with the 8 in/hg step up spring. At 2,000 rpm the quadrajets small primaries and triple boosters already have the main metering flowing well. By comparison the Edelbrock is just starting to drizzle fuel from the boosters. The quadrajet has a very nice fanned out spray of metered atomized fuel flowing and the Edelbrock has big fat droplets of fuel pouring down on the throttle plates.

For reference, tried two different HEI weight and spring combinations with the same springs. Ran the same total timing but varied the initial timing to make up for the more limited centrifical mechanical advance. 383 is definately alot more responsive with more initial advance and idled better. At 1,500 rpm the new setup has a little less timing (17 vs 24 previously) but seems smoother at that rpm. With vacuum added it was 33 vs 38° respectively at 1,500. 38° at 1,500 was a bit too much and it had a skip or surge in it. At 2,500 rpm + both setups had the advance pretty close to the same values. At 2,000 rpm total advance with vacuum was about 39° now and 42° before. 38-42° at 2,000 rpm with no load is a pretty good starting place for most SBC engines. Depending on chamber/piston design, cam, compression ratio, air/fuel ratio and whether EGR is being used or not 44-52° total advance at 3,000-3,600 rpm is also in the ball park. I can tell you with a 77 jet, 48m primary rod, apt screw 2.5 turns off the bottom and 46° of timing at 3,600 rpm this 383 is dead smooth and instantly responsive to the lightest throttle movement.

Currently tested combination (used in both videos above)
(363center/053weights)
750 rpm = 0 advance
1,000 rpm = 0 advance
1,500 rpm = 1 advance
2,000 rpm = 8 advance
3,600 rpm = 15 advance
Initial set at 16° BTDC
15° vacuum advance, starts at about 7 in/hg and full in @ 12 in/hg.
Idle timing is a steady 31° with vacuum advance on manifold vacuum.

Previous combination
(369 center/41weights)
750 rpm = 0 advance
1,000 rpm = 2 advance
1,500 rpm = 15 advance
2,000 rpm = 18 advance
3,200 rpm = 23 advance
Initial set at 8° BTDC
15° vacuum advance, starts at about 7 in/hg and full in @ 12 in/hg.
Idle timing was stable at 23° BTDC with vacuum advance on manifold vacuum.

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My old 83 G20 with a mechanical q-jet would often get 20-21 mpg highway. LE9 305 with flat top pistons and 601 heads and factory catless dual exhaust with factory tubular manifolds off a 1-ton 350 van that I had added a dr gas x-pipe into. Van had a 700r4 and 3.08s.

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Lotsa flat roads in your area? I have a friend in Nebraska and another on OK that report getting very high mpg results and I believe it's the long, flat stretches. Trying to duplicate that tuning in hilly New England results in lean cruise with frequent jaunts into PE. End result is much smaller gains.

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Originally Posted by 1project2many

Lotsa flat roads in your area? I have a friend in Nebraska and another on OK that report getting very high mpg results and I believe it's the long, flat stretches. Trying to duplicate that tuning in hilly New England results in lean cruise with frequent jaunts into PE. End result is much smaller gains.

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Actually lots of rolling hills here but lots of open roads to run steady speeds on. That old 305 had enough low end grunt to pull most of the grades at 70-75 mph in overdrive even with the 3.08 gears. Had a few that it would downshift to 3rd on along the way. There were a few longer grades that were maybe 1-2 miles long that the cruise would force a 4-3 then a 3-2 downshift on and into the secondaries to hold 75 mph. Biggest killer of MPG in my area is often the 20-30+ mph winds we get. That being said my old 305 used to pull about 10-12 in/hg vacuum at 1,800 rpm at about 75 mph on fairly flat road. The factory power piston enriched at about 5-6 in/hg. Most of the time at cruising speeds even uphill the metering rods were burried into the jets. The cam I ran for the longest was a crane 274H06 and had the Q-Jet on a 7104 performer rpm. Great combination with the flat top pistons and 53cc 601 heads on a 305. After running the factory tubular manifolds for several years, I put throley tri-ys on that old van. The tri-ys woke it up even more. On level road that old G20 would run ~100 mph on the primaries and not exceed 3,000 rpm. The factory engine made peak torque at like 2,000 rpm. The intake, cam and headers pushed it up to more like 3,000-3,500 but it easily made more torque than the factory cam even down below 2,000 rpm.

This is the article years ago that made me decide to run the performer rpm on that old 305. My stock aluminum manifold started leaking and the coolant ports were heavily corroded. Chose the performer rpm over the performer which ended up with me having to later go to a Weiand 7525 when I failed smog for lack of an EGR valve. One of my customers had a few El Caminos and Monte Carlo SS 305s and suggested the 274H06. Swapped that cam in and it was like having 2 stock 305s under the hood. Little 305 really loved that little 218/218 @ 0.050, .450 lift, 106 LSA cam. Low-end power stayed pretty close to the stock power above the 1,500 rpm stall speed, but pin the throttle down and get it up to the 3,000-5,200 rpm range and it pulled like crazy for what it was. Later I played with the governor in the 700r4 and had the trans shifting 5,800ish in Drive. Old 305 didn't like that too much and after about 50K of being spun to 5,800 several times a day with that cam spun 2 rod bearings.

https://www.hotrod.com/articles/ccrp...-engine-build/

Sorry folks, Giot distracted, Finally got the 3.42s installed, and found a nice old System 2000 scanner for 50 bucks and bought the TPS and rich idle stop tools off thextons website directly for 25 bucks compaired to the 100 or so everyone wanted on E bay. Got the TPS dialed in, and the rich stop screw set and got the dwell in the 30 degree range and this thing purrs like a kitten, installed a set of hooker long tubes and a nice mandrel bent 2 1/2 dual exhaust with some thrush turbo mufflers, an X pipe crossover and installed a heated o2 in the drivers collector. car starts with just a bump of the key, decent power for what I figure is a low compression 305 . currently building a 350 for it and I will be using a 94 LT1 f body cam, and a set of ported L98 heads . so it should be a lot more fun to drive.
That being said I also had a 87 corvette Spark control module, I had tried it before getting the carb set before and I seemed to give me a check engine light so I just plugged the stock on back in. The other day I was messing around and figured now I have the check engine light at bay and everything is where it belongs I tried the corvette SCM again and the car now feels a bit peppier and no check engine light but Im not sure f the timing curve in in the module or if the Prom handles that I also noticed Im not getting any spark knock from it now either like I was with the original SCM even though I didnt change the Knock sensor, until i swap in the 350 . Anyone know if the SCM has the curve in it, or does it just take the signal from the KS and send the data to the ECM? Im thinking of trying the olds 87 ECM witheh MCSS chip again , and see if the check engine light returns on that .