Is there a carb doctor in the audience? Was cleaning up the engine, wanted to repaint the box and after removing the cover this was wat I encountered: One of the carb is a bit black down the bottom it is OK, the same colour as the rest. What can it be, and does it hurt? Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
One thing that you should check is that there is no net airflow in the line marked with the red arrow -- i.e., whatever that line is hooked to needs to be a completely "closed" system airflow-wise. On a stock '78-'79 that line runs the airbox flap mechanism (which is a closed system). If that cyl #8 vacuum port is now being used as the vacuum source for the charcoal canister, that would not be ideal. Image Unavailable, Please Login
Ricky x, Not to hijack the thread, but have you determined the ohm value for your new wires from the cap to the extensions?...I haven't seen a reply from my last post on this issue.
Hello Mike, Don´t mind the hijacking, I am getting new plug extensions on monday. Wanted to do the whole thing at once. the extensions come with a resistor and my actual plugs are also of the resistor type. Do you know if this can harm?
(I know I'm slowly losing my 308 memories , but) If the fitting is tapped into the side of the #8 intake manifold runner, it can't be a water line -- there are no water passages inside of the 308 intake manifolds. Where does the other end of that line go?
Ricky, I would stay with the original type extensions, don't know if yours were resistor or not, but if they were resistor I would stay with them. Using resistor plugs won't hurt but you may want to use a slightly hotter plug (if your using resistor plugs especially since you're carbed).. Also..91 TR do you know the ohm value from the inside of the distributor cap, to the extension?..what I'm trying to do is direct Ricky to the correct ohm value when he pierces the new wires..any comment?
Rickyx, Do not sweat it. You have an issue, but not a serious one. The blackness is caused by "backfiring" through the carbs. This is a misfire almost always caused by running lean. (Can also be an ignition issue, but this is not as common). When one carb throat is doing is like yours, the culprit is usually one of three things: 1. vacuum leak 2. bad synch 3. clogged idle jet or idle circuit in the carb First question. Does the car "cough" through the carbs? If not, this may have been fixed in the past and the darkened carb throat is left over from then. You can clean it with some carb cleaner and a toothbrush if you want it to be pretty again. If the car still coughs, you need to figure out why. The first thing to do to troubleshoot is be sure you have no vacuum leaks. I would start by plugging both vacuum lines into that manifold. Steve is right, that big hose is a vacuum line. I do not have a '78, so on mine that line is capped at the intake manifold. I'm 99% sure that vacuum line is used for the flapper in the airbox. There is a similar one on cylinder #4 (Diagonally across the engine, driver's side rear) that provides vacuum assist to the brakes. I would pull that hose and plug the nipple it attaches to in the manifold with a rubber cork or something for a test. (You will also need to manually hold the flapper in the airbox open since you won't have a vacuum to do it). Also, there is a small vacuum line connected between cylinder 7 and 8 at the manifold, which runs to the charcoal cannister for the evaporative emissions system. Plug that one too. See if this helps. If it does, you can now narrow down the source of the leak. Finally, it's very unlikely, but you can have a vacuum leak at the interface of the carb/manifold, or the manifold/block. Gently squirt a tiny bit of carb cleaner or starter fluid around those areas and see if the engine reacts. If there is a leak, it will get sucked through the hole and the engine will either go faster or slower in response. Pull the idle jet on that barrel and clean/inspect. Blow compressed air through the hole where the jet goes. Pull the idle mixture screw out entirely and blow air through there. Put the jet back in with a new o-ring. (Never hurts to pull and clean ALL the jets.) Now synch the carbs. For a procedure, go here: http://www.birdmanferrari.com Hope this helps Birdman
Rickyx- I didn't realize it was a GT4. I thought it was a GTB/GTS. You don't have a flapper in the airbox. Ignore that. Here's what to do to see if you have a vacuum leak in the brake line. Start the car, rev a little to get a good vacuum in the line. Now turn the car off. On that brake vacuum line there will be a one way valve in the hose. Pull the hose off of the forward part of the one way valve and you should hear a pop like a cork or just a quick inhalation of air as the vacuum goes away. If you get that, it's holding a vacuum and probably not your issue. If the carbs aren't popping, you don't have an issue anyway. Birdman
Yes, this sounds more familiar. I will check it this afternoon. Could it be that the in between valve was mounted reverse? Thanks Birdman, I am getting addicted to this site. It is great!!
First, that is really weird that your brake-booster hose is hooked up there, as on every other 308 I've seen, it's always attached to the #4 intake port. I can assume this hose of yours then travels together with the A/C hoses, along the passenger's side, correct? '75 GT4's never had the vacuum-controlled air-flap, so you're not missing any parts.
I have never realized that, but it has been like that from the day a bought it, 8 years ago. I wonder if it is unique, or if there are more GT4 with this set-up? (GT4 drivers and connaisseurs your input please) By the way the brake booster hose goes along the driver´s side, and NOT with the A/C hoses (that would never fit anyway, 3 hoses). It comes from the driver´s side, than passes neatly below the fuel line at the back of the car against the firewall. In the middle you will find the one-way valve. Peter, I pressume that it doesn't matter that it enters at #8 instead of 4#. The engine looks "cleaner" with that hose being placed at the back. Ricky
That's weird. Since I have never worked on a GT4, I just assumed that was normal that the brake booster was on #8 instead of #4. The same intake manifold seems to be used on both banks. My '77 GTB has a threaded port on #8 that is plugged, which would be on #4 if it were on the rear bank. I wonder if maybe someone rebuilt the engine at some point and swapped manifolds by accident? Once installed in the car, they just ran the hose to #8 since that's where the port ended up? Anyway, it shouldn't make any difference. Ricky, did you test the vacuum? Birdman
Not yet, Birdman! thanks for asking! I have been trying to buy a new fuseblock!, but everytime I am filling in the credit card payment form it tells me that the time has expired and that I have to try again! Can that be avoided with paypal (where do I sign up)? Ricky
Is there anything that prevents someone from inadvertently swapping the 1-4 intake with the 5-8 intake during engine assembly (and then correcting it by rerouting the brake booster line when they realize the error)? -- just a thought...
Could be, but I still do not know the official intake for the GT4 if it is #4 or #8, or that it has been done randomly, or with certain serial numbers.
The info you are entering is with Paypal. For some reason, some people have a timeout error and I have no been able to figure out why. It's an issue with Paypal. What browser are you using? It will usually work on a different browser or computer. Sorry for the hassle. About 1 in 10 people have this issue. Paypal sucks. When will Google introduce a better service and blow them out of the water?? Birdman
Birdman, that's what it looks like. Must have been one of those: "oh man, I just finished putting this f---ing thing on and it's backwards... Hope he doesn't notice..." Although they use different part numbers, they are both the same part. I'll have to look closely the next time I'm down in the garage, but I think the "other" manifold has an aluminum plug in place of the hose barb. No, there should be no problem running this way.
I could not make any progress on this subject due that I was waiting for parts. A little resume: The car had suffered from a trip under heavy rain and four of the plugs refused to do their work properly. Changed the plugs Changed the plug extensions Changed the cables For that I had to remove the airbox, and then is when I discovered the blackened carb. you helped me look for the problem. It wasn't the vacuum, although the airhose was connected on #8 instead of #4. Why, I do not know. It couldn't have been a sloppy mecanic, because in order to switch it, you need extra lenght of hose to get to #8. I cleaned the carb, and IMO the reason is/was that car has not been running much for the last years. So today was the big day to start the engine! It started after 4 times, and run very smoothly (yes!!!) even with the airbox of the sound was very smooth, only I heared a spluttering sound. I thought that would be carb #8, but it was to soft for a backfire noise. I stopped the engine and discovered that one side the exhaust had coughed up water & carbon dust (it was not greasy). My question to you guys; is this still due to the heavy rain fall I suffered, that water could have got in. It has never done this before. Looking forward to your opinions. Ricky Image Unavailable, Please Login Image Unavailable, Please Login
