Hey guys, With the help of all of you, I pulled and rebuilt the carbs. Previously, when I got on the throttle the car would just stall out. I assumed an accelerator pump issue, as it didn't look like they were firing. So I have everything rebuilt with 55 idle, 135 mains, and 200 ACs. Unfortunately, I'm running into the same issue. She idles bang on 1,000 rpm and sounds smooth. When I gradually increase throttle, it will pull all the way up as high as I care to run; however, whenever I suddenly increase throttle, the car immediately dies. The car starts immediately. I'm wondering if I have the setup correct. I followed Birdman's sync tutorial and it seems like everything is as it should be. The one thing I'm not sure about is if they're pulling too much air, as all the throats seem to be above 10 kg/hr, maybe even more around 14 kg/hr or so: Image Unavailable, Please Login The interesting thing is that it's idling great, but I'm wondering if this amount of airflow is bringing me past an intermediate circuit in the carb or something else? How should I diagnose this issue? Also, possibly related, it seems like my microswitch might have been out of position through the messing with the carbs. AFAIK, this switch should be set to be closed JUUUUUST off the throttle. Is that correct? Could that be causing my issue? While I have just done a coolant flush, new alternator, new starter, belt service, tensioners, transmission fluid, oil change, fuel filter, I have not messed with the ignition system at all. Could that be an issue that I'm overlooking?
Ignition - I doubt it but worth checking anyway Micro switch (cold start) - Disconnect it. Normal tick over flow rate is around 4kg/hr so you are way off with those settings, you need to go back to basic settings and restart in my opinion. Best Tony
Okay, guys, I will re-evaluate and try setting up again. I am suspicious of the linkage. I am now wondering if the lower linkage to the throttle is way too short, causing high idle and throwing everything off.
At rest, the linkage should be a bit loose. Do not have the linkage touching the ball. Ideally, both linkages should be the same length and when you pull the throttle cable both linkages should move at the same time and activate all the throttle butterflies at the same time. Adjustment is done by lengthening or shortening one linkage. Obviously one of the locknuts on the linkage shaft is a left hand thread.
Hey everyone, Happy Thanksgiving! I finally acquired the correct spark plug tool and have run into a bit of a dead-end getting this old girl back going. First, a quick summary. The symptoms that kicked off this project are: The alternator wasn't charging. When I floored it, the car would stall. Time for a belt change. Also, I've got a build/project diary going here. I assumed that the stalling issue was being caused by the carbs not being set up correctly or busted accelerator pumps, etc. They've never been apart under my ownership, so I thought it would be a fun project to rebuild them. I sent the alternator for rebuild, installed a high twist starter, did all the fluids, filters, plugs timing belts, and rebuilt the carbs. Now I'm stuck Immediately post rebuild, I was able to get the car to start and idle, but WAY too high. additionally, there was way too much air being pulled in. That the linkage was WAY off the dampner, I suspected that the old setup was incorrect. I redid the linkage and now I cannot get the car to fire at all. With that being said, I'm almost positive the linkage is now "correct". The little stop just kisses the dampner, I'm holding the butterflies open with throttle adjustment screw as expected, etc etc. I adjusted the mixture out a 1/4 turn at a time from 0 all the way to 6 turns. Towards the end, I would get a couple of fires, but nothing running. I'm now beginning to suspect ignition. Could the stalling have been electrical all along? Should I pull the dizzys and send them off for a rebuild? Additionally, there's oil in the plug sockets, so I assume I need to replace the valve cover gaskets, which has not been done under my ownership either. I assume adjusting the valves would be part of this. I'm just wondering what my next move should be to get this girl back on the road? What are my next troubleshooting steps? Thank you everyone for all your insight and for helping me along this process. This is so much fun!
after the carbs are on the idle screws you need to loosen the throttle cable. In other words the idle is set with the cable first then touch the 2 idle screws to just touch. I use a piece of paper for this. Then loosen the throttle cable to have slack. Also be sure the thermo spring is not in contact with the linkage. Also be sure you didnt flood the plugs.
Sorry to hear about your troubles. You've probably done all this but here goes. My California setup for 78 GTS Idle jets 60 (Stock 55) Main 130 (Stock 125) Emul F36 Air Corr 200 Accelerator pump nozzles one size richer (can't remember the number) It ran fine with the stock jetting just not a well. Idle screws between 4 and 5 turns. (There are apparently different idle screws which will change adj) Air flow at idle (1000 RPM) 4 - 4,2 Kg. Ing Timing with r1 and r2 points 7 degrees after TDC at 1000 rpm,. 34 degrees at 5000 RPM Ing Timing with Pertronix 9 degrees BTD (no retard points) at idle and 34 degrees at 5000 RPM. Had a little trouble getting it to idle down to 1000 without the retard points in fact had to add extra sprint but now hot idle is 1050 with AC off and 970 with AC on. These things will run, although not well, with things wayyyy out of kilter. They will even run and are drivable with only one bank's ignition working. So. 1. Do you have fuel at the carbs. If so are all 4 squinters (accelerator pumps working). I bypass the seat belt switch under the driver seat so the fuel pump runs whenever the key is on, not just when someone is in the drivers seat. If you have fuel at the carbs and the squinters are working it will start so long as you pump the gas. If the pump is running and no gas at the carbs check the filter. (Both the canister and the sock in the tank). You can check the sock by slowly pulling the feed fuel line off the tank. (Have container to catch fuel as it really runs out. Also have the fuel pump off so no possibility of electrical spark). 2. If you have gas at the carbs it pretty much has to be ign. Make sure you have spark at both banks (assuming you have duel dizzys). The stock spark is fairly weak so don't be alarmed but make sure you have full voltage at coils. I personally would adjust the retard micro switch so it is closed all the time until I got it running. The way I adjust my carb linkage (cold) and I've messed with it a lot. 1. Rotate fast idle cam to insure it's not holding carbs open. Or back off fast idle screw until it no longer contacts the cam. While adjusting linkage make sure the fast idle screw is not holding carbs open. 2. Loosen linkage rods by backing off jam nuts. 3. Back off throttle cable until definite slack when carbs closed. 3. Close throttle idle speed adjusting screws until carbs are all the way closed. (rotate linkage rods to insure a little "slop"), On mine I insure there is no built in tension in the throttle linkage. I can rotate either rod about 1/8 turn without moving the carbs. 4. Adjust carb connector so passenger side carbs are all the way closed. Watch to insure you don't inadvertently open the drivers side carb while adjusting. 5.Open both drivers side carbs just a smidge. Mine are almost completely closed due to the lack of ignition retard at idle. 6. Idle mixture screws set at 4 1/2 turns out. 7. Set fast idle cam screw about 2 turns in with cam in cold position. (You can adjust it as you go along but with it backed all the way off it will really want to die at cold idle.) 8. Adjust throttle cable to insure full throttle and a little slack when at idle. I can move the gas peddle about 1/4 inch before it starts opening the carbs. As far as syncing the carbs go after rebuilding I close all the air bypass screws and set the idle at 1000 rpm cold for the initial setup. I do an initial air flow check just to make sure all eight barrels are flowing air and are reasonably close (3 to 7 kg). Then I adjust the idle mixture by richening each carb until noticeable slow down then lean until noticeable slow down then 1/4 turn richer. keep in mind this is only for initial setup. When syncing the carbs you need to pay attention to air flow for both carbs when adjusting the carb connection as closing the passenger carb will open the driver side carb if the passenger carb is all the way closed. I also adjust the air bypass screws at this time if necessary. Only one of my carbs requires any adjustment and its only 1/4 turn otherwise they are all closed. At this point I get serious about syncing resetting the idle as necessary as it will change, generally speed up, while adjusting. After all seems good I take it out for a hard test run to insure all the temps are equalized. Then without shutting it off I readjust the idle mixture as above (it generally will be leaner) and double check the syn. Easy peasy!!! Since I work by myself I do the following so I can manage it. 1. bypass the fuel pump seat switch. 2. Have remote starter connection so I can start it from the engine. 3. Have "hot" terminal in engine compartment so I can mess with it with ignition off and power timing light and such without comprising ignition voltage and put battery tender on it if I not going to drive it for more than a couple of weeks . Cold start assuming the accelerator pumps are working. Fuel pump on for 15 sec to fill carbs. Pump gas 4 times to prime engine. Its been my experience it takes quite a bit of pumping if its been sitting a while. Like a couple of weeks. Hold carbs about 1/8th open. Start I generally don't use the choke however have found it useful during very cold weather. (I don't activate the choke until after I've started the engine. Hot start (sitting less than an hour) Fuel pump on for 15 sec to fill carbs. Will generally start without pumping or cracking the throttle. Otherwise a couple of pumps and about 1/8 throttle. Quick question. When you said it dies when you open the throttle quickly does it pop back through the carbs or just quits. A lot of times if the accelerator pumps are not working correctly it will pop back through the carbs due to lean condition when opening the carbs quickly. I was convinced I had a vacuum leak somewhere due to the trouble I had getting it to idle down with the Pertronix ign so I built a "smoke machine" and proved myself wrong but that is a definite possibly if it really wont idle down. I was only looking for about 150 rpm. If it really won't idle down with the carbs mechanically closed I would certainly look at the vacuum system. I was particularly concerned that the power brake booster line was leaking as it is original but its fine. When right the car is a pleasure to drive with no hesitation anywhere in the normal rpm range. Even when idling at 970 RPM with the AC on it just pulls like a tractor when pulling away from a stop and will RPM way past what I'm comfortable with. (one cylinder head still has the sodium filled exhaust valves). Anyway just keep at it Barry
Barry, thank you so much for the detailed response. This is absolutely wonderful and a template I will follow to get the car back and running again! Thank you, E
Your welcome. For me the thing to remember is if it has spark, gas and the timing is anywhere close it will run. The internet is my bible for figuring things out. For example if you think you have a bad coil just search on checking auto coils or something like that an you'll see how to check coils or almost anything else for that matter. Also Ferrarichat has been a god send for me. The guys here really know their stuff. FYI if your going to adjust the valves because you have to pull the cam covers the Fiat club in Ventura Ca. offers a free shim exchange program which saved me a bunch. Barry
Hey Guys, I finally got a chance to go up to the house and do a little more work on the 308. To recap: The car was cutting out when flooring it and the alternator was all over the place. Replaced alternator and starter with a high torque model. Works great. To address the load issue, decided to rebuild the carbs. Reinstalled the carbs and was able to start the car, and run around the neighborhood, my mixture/airflow was way way too far out. Came back the next day to continue to tune, but the car won't start at all. The next culprit was thought to be the distributor. I had the distributors rebuilt and timed by David North. He said they needed a rebuild, but they weren't so far out that the car wouldn't run. I removed the R2 points at this time. I reinstalled the dizzy's this weekend and verified that there is a spark; however, the car simply won't fire. Not even run bad, just no fire at all. I am now suspecting that maybe the fuel pressure isn't high enough? I've got a little inline fuel pressure gauge to install and will report back with results. I can hear the fuel pump running... Are there any other rookie checks that I should do to troubleshoot? I know we're in the suck/squish/bang/blow phase here, but I'm perplexed as to my issue. Any other guesses? Thanks, E
I only changed the idle jet to 65 and kept all the others per owners manual. I opened the idle mixture screws 3.75 turns. Passed smog and runs great on my 78 308gts. I also have my rear distributor modified to run the timing advance for front and rear distributor. Make sure you have same airflow through all carbs.
Have you checked the distributors were reinstalled correctly per the WSM? The carbs work off the fuel in the float bowl so the fuel pump only needs enough pressure to refill the bowl. I believe Webers use between 3-4psi. The WSM has a test for fuel delivery volume if you wish to eliminate that. Sent from my iPhone using FerrariChat
Your idle set-up (as shown in post #1) is way, way off -- indicating that you have some cylinders that are not actually running at idle. Each carb barrel should have an airflow of about 3~3.5 Kg/hr with an R1 only set-up at 7 deg BTDC when at 1000 RPM idle.
Car ran. You removed carbs and 'rebuilt' them, car ran poorly and then didn't start. The likelihood that you developed a non-start issue from the distributor while working on the carbs was slim, and generally whatever a person touched last is responsible for a new problem. Since you've now removed and 'rebuilt' and reinstalled the distributors, you've complicated the project. You need to make absolute sure that you've got the static timing set properly to remove the distributor work from the non-start troubleshooting. Is everything on the timing marks? Are the distributors set to fire the right cylinders? Then check the plugs. When "my mixture/airflow was way way too far out." was it too rich? if so, that could have clogged your plugs enough so that the car doesn't start. Pull the plugs and examine them (maybe post photos here for others to look over your shoulder).
Hey guys, I'll post a bunch more pictures as soon as I get back up to the house next weekend. Thank you for all the pointers!
Hey guys, I finally got a chance to work on the car and I have some interesting findings. I installed a little fuel pressure gauge on the main line coming into the carbs. I turned on the car, the fuel pump clicked on, and I got this: Image Unavailable, Please Login Under 3psi. According to all my research, that's pretty low. I checked the fuel filter and that all looked good. I used one of my fuel line clams to close off the return: Image Unavailable, Please Login Which made the fuel gauge jump up to ~12 psi. That seems way too high! Image Unavailable, Please Login But, I guess higher is better than lower, so I put the mixture screws all the way back in, pulled them out three full turns, and... the car starts again! It's not running wonderful by any stretch, but at least I can get it to fire! So, with this new information at hand, I'm wondering what the best course of action is? The fuel pump is certainly some kind of replacement. It looks like the check-value is not functioning. Should I get a fuel pump with a regulator and cap off the return line? Should I get a standard fuel pressure regulator and put it on the return line instead of the check valve? Any recommendations here? Thank you for all your help! E
I think this could well be your issue. My car demonstrated a similar amount of way off air flow, as well idling but stalling when the accelerator was pressed. It sounded as if it was idling quite happily - turned out an entire bank of cylinders wasn’t running on account of knocking a wire off one of the coils when changing the front bank spark plugs.
I think you are chasing too many leads... The factory specs for fuel pressure is 4.25 psi with the fuel return line open. Closing it off just makes he pump dead-head and fuel pressure jumps up. Back up a little bit. If it were my car, I would ... 1. Do a compression test to see if all cylinders are good. 2. Remove and inspect or replace the spark plugs. 3. Measure all spark plug wires to see if they are good 4. Inspect plug extenders 5. Inspect distributor caps, points and condensors. Get rid of the R2 set up if you have it. It makes life a lot simpler. 6. Go back and check carb rebuild work to make sure it was all done correctly. Adjust the floats and valves. 7. Set the fuel pressure at the inlet to the carbs to be 4 psi. (You can experiment with this by loosening the clamp on the return line until the fuel pressure gauge reads 4 psi) If the car does not start, I would spray some starter fluid into the carbs. That will tell me if it's a fuel problem or ignition problem. Fix that problem and then proceed to balance the carbs.
