308 running crappy

I have a 76 carb 308. Have had a few problems, but not as many as you are having.

One problem I did have sounds somewhat similar to some of your stumbling problems: One of the cam belts had slipped by one tooth. No idea how that happened, although I hypothesize that it was actually installed wrong to begin with.

Anyway, as soon as the belt was installed correctly, the car was completely different. No flat spots, no weird stumbling and less backfiring. Before correcting the problem, I was also getting a nice red glow on the muffler. Definitely not a good thing.

Still had to do some carb tuning, especially the left rear carb that has the power brake unit connected. Once that one was rebalanced, the car ran perfectly.

Good luck,
Mark

 

I am tending to lean with Mark on this one.

Sounds timing or ignition related to me.

How are the coils? extenders? Distributors, points, rotors?

Have you upgraded to a crane system or is it still stock?

 

I don't think you are ever going to get rid of the stumbling in hard turns. I think this is a problem with all carb'd 308s. My 1978 does the same thing, the remedy is to never let off the gas and keep it floored through the turn!!!! : )

When I first bought my car, it too ran like crap. It exhibited much of the same symptoms you are describing. I put in a pertronix ignition system and then had a local mechanic set the timing, sync the carbs, replace the belts, do a valve adjustment, and I assume, he checked to see that the cams were "timed" properly when he did the belts/valve adjustment. After all that, the car runs great, all the way to 8k rpm. I will get some popping on deceleration, but, I also have a home made almost straight through exhaust system. Speaking of which, do your slow down lights ever come on? I wonder if one or both of your cats could be blown apart and causing you some problems? When I removed my original exhaust system, one cat was totally blown apart inside. Maybe you could check that.

 

Walawdogon't mean to hijack thread, but when you installed Petronix, what did you do about advance? Removing one set of points cuts advance by 6 degrees. I'm pondering doing the same to my 78 but I'm concerned about total advance.
Rcraig- have you gone through the distributors/timing yet? It would make sense to start there before messing with carb jets. Also, make sure the jets are close to stock for a starting poiint. NGK 8's are way colder than 6's and I can't imagine them helping a poor running problem. Plugs too cold foul and will run poorly, too hot will cook the motor but run OK.
Tom

 

For what its worth, my 77 carb 308 has never run well on anything other than standard type plugs. I have tried the Platinums and they foul. This might be because I have a stock ignition. The only things I have done is remove the set of points that are actuated by the micro switch and installed higher output coils. I don't have ignition problems since that was done many moons ago.

Regarding fuel starvation on corners in a 308 - everyone I have done track events in has had the problem. Add to that the fact that oil pressure goes away in hard corners too. If you see videos of cars that don't have fuel starvation its probably because the corner didn't provide a significant enough direction change, or the driver wasn't going fast enough.

With the problems you have described it would be difficult to not want to confirm the cam timing. I wouldn't get into carbs and jets until the cam timing and ignition are solid. Again, fwiw. Good luck.

 

Wow, I was about to get pissed off knowing that my 308 was one of the only ones that does the stumbling in corners....luckily, I have some company and I am not the only one, I feel better now!!! : ) I know you can adjust the float level (or at least make sure it is 100% correct) and that might help the stumbling a bit, but, can never make it go away completely. Like I said, just keep if floored. On the pertronix set up, I made a mistake when I got mine. I should have had the two pertronix pick ups put into the ONE distributor and only relied on the one distributor for advance. If I were to do it again, this is what I would have done. I must point out that I have never had two sets of points in my car. The previous owner must have done away with the other set. I thought as pointed out above, that the one set of points was for starting (maybe retard timing by 6 degrees) and didn't effect warmed up timing. As far as I know, nothing was done, or needed to be done, to get the timing right on my car other than to set max advance and call it good.

 

I have a '79 308GT4, and mine stumbles a little bit in the corners. I do mostly "around town" driving, though, and have yet to be able to run her wide open through a nice wide curve at someplace like Laguna Seca or Sears Point. In short, that's not *too* abnormal of a problem.

When I first purchased her, I was also experiencing some of the same symptoms as you (though not as serious)... Two things I did that dramatically improved my car's fully-warm performance (because cold operation was never an issue - just once it got hot) was, 1) replace new cats with hollowed-out, OEM cats, and 2) remove belt from airpump.

Living in CA, my car's carbs were set up by the seller's mechanic prior to sale to pass emmissions - not to run at tip-top condition. I *do* happen to have a PermaTune ignition, though, instead of the original points system. Just about every person I talked to about my symptoms would say, "Do you still have the points hooked up?" That suggests to me that they are a dead-ringer for something that "needs to be updated" on any carbed 308. I'm still considering a further upgrade to an MSD or Crane unit, but only after I get the other "have-to-do's" done.

At any rate, hang in there... I can sympathize with you. There's hardly anything worse than achieving the goal of Ferrari ownership, only to mentally torment yourself day-by-day over whether or not you made a gigantic mistake. Just stick with it - it'll be worth it.

Best -

Aaron

 

Have you tried to put a timing light on it, just to see what your timing is doing? That would be something simple you could do yourself, just to at least see what's going on. Again, hang in there, once it's running right, you'll love it.

 

I know a lot of you guys hate points, thats great, but you also probably just either dont know how to set them or hate maintainence. That said, they arent the be all and end all of running trouble. These cars ran fine when they were new, and every magazine of the day sang praise after praise of these cars, not how awful they stumbled on acceleration, how doggy they accelerated, or how they bogged out in turns. If points are set even halfassed right, they work, no questions asked. Yeah, maybe some light high RPM miss stuff, not the ultimate in performance by todays standards, but they worked fine in the 70's for FERRARI.

Now I am surprised no one else picked up on this, but white spark plugs? Light tan to white????? Come on, thats really lean. Check float level to spec, and check main jet sizes on ALL FOUR CARBS, both main jets, all eight of them and make sure they all match.

First thing is basic engine mechanics, make sure points are set to gap with a feeler guage, or if you know what your doing, use a dwell meter. Get em as close as you can. Then time it with a timing light, both banks, close as you can get to right on, but MATCH both as absolutely close as you can, so they are as equal as possible. Lots of fiddling but hey, its not a Pinto, its a FERRARI, so SMILE!

Next, warm it up a bit, or its probably already warm, and with timing light pointing at the flywheel, slowly rev it to 5000 rpm and watch the flywheel to see how the advance moves, and to see where it stops. Should be the 34 degree mark on the flywheel at 5000 RPM, and should move up there smoothly. Tells you how your advance is working. If works okay, timing is on, you checked jets, you checked float level, you changed the fuel filter (we know you did), you didnt fiddle with the idle mix screws, and you didnt monkey with the sync of the carbs right? Take it for a spin and report back.

 

rcraig,
I met you at the meet up at Algar ferrari a few weeks ago. I had the dirty 308.
It sucks to hear about the problems that you've been having. I hope you are able to sort them out without going for broke.
When I bought my car, the timing was set wrong, and I thought it seemed to be running pretty good too. I found out the timing was wrong because I went to synch the carbs, and I was getting a fuel mist out of the front back of carbs when I would advance the idle.
I had the cam timing corrected (it was off one tooth on the front bank) and the carbs synched, and the car runs great. I'm running a little rich at idle (.60 idle jets) but other than that I have no problems.
Does your idle float at all? Does it backfire slightly during idle? Does it diesel during shutdown?

 

Bob,
Everyone has their opinion here, but it is certainly only one of two things:

1. Timing
2. Fuel

You know you are getting a spark, so you need to check if its coming at the right time (advance). If Algar says it's OK, then on to the next thing. Unfortunately you also may need to confirm that the cams are timed right, but I would leave that until last because the cam covers will have to come off.

Your issues sound classic carb-related to me. If the cats were removed and the thing wasn't re-jetted, this is a big problem. (You would be surprised how many people know that you need to rejet when you put on a less restrictive exhaust, but don't do it anyway because they don't know how.) Remember that the 308 was set to run as lean as it could to pass emissions. Change the exhaust and all hell breaks loose. Now they should be jetted to run right. You will amost certainly find that it needs richer idle jets (maybe main jets too) and a carb synch. It's very easy to do yourself. It will only take an afternoon. The jets are cheap. Check out my tutorials on carb synch and float height setting:

http://www.birdmanferrari.com

If you weren't so far away, I would be happy to show you how to do it in person. Drive the car to Boston this summer and we'll fix it up. I'm only 6 hours away.

Best,

Birdman

P.S. With a points ignition, I would stick with the 6 plugs.

 

This is absolutly true. When I changed my exhaust, I started getting 8 MPG! Even at full lean on the carbs the plugs were fouling. When you change one thing on a carb car, you have frequently change a whole lot of other stuff as well.

Question: can he just lower the float heights or do Webers require new jets?

Ken

 

Carbs dont have brains, that is in the brain box of the person working on the car. Point gap/dwell angles, then timing, then carb adjustmenst, in THAT order. Always check max advance, its more important than idle advance. Never make any carb adjustments until you are absolutely sure the ignition is spot on. Never never never!!! If you arent absolutely sure in your mind how your car is timed, you could be damaging it. More reason to do your own work sorting it out.

Float height worked on the cars when new, set it to spec and look elsewhere to make it run better. Save minor tinkering with stuff like that when you have your problems sorted out and when you know what your doing looking for an edge in performance. Seriously, you can listen to the carb throats with a hose in your ear, moving from carb to carb at idle, and hear if they are synced close enough to drive the car or not.

White plug electrodes indicate a dangerously lean running condition that could burn an exhaust valve or melt off a valve head on any engine ever made, it don't have to be a Ferrari.

 

So you're saying float height adjustments are minor and just for an edge as opposed to changing choke size? I never realized that.

I'm a little confused on the dynamics of a less restrictive exhaust. On one hand, the engine is pumping air faster, so you need more fuel to keep up or you'll burn an eahaust valve as you say. That would suggest a richer setting/ larger jets. OTOH, on a CD carb like mine at least, the increased air flow will pull more fuel through the jet and you need to go leaner. Granted Webers are completely different; which effect will a less restrictive exhaust have on them?

Ken

 

I wont pretend to know why they do what they do, I just simply know that they do. Open up your exhaust, the mixture goes lean, its that simple.

As far as float setting, you dont have a lot of leeway from high to low, and either end can cause trouble. Jets set the mixture, and thats how you should adjust it, before you start playing with things that have little effect and outside standard specs. But in any event you first need to have knowledge of the ignition before you play with the mixture.

In the end we may well find this car has a timing belt thats off its mark or something, but I am guessing its just simply to lean or to far advanced, and if its NOT corrected, someone is going to burn a valve or a piston.

 

Paul is right that one should check the timing first, not only because it's important, but because it's pretty easy to check as well (with a timing light). But I was under the impression from the thread that Bill has had the timing checked by a dealer and they said it was fine. That leaves the carbs (unless the cams are off, but that's harder to check than the carbs, so why not check the carbs first?) Paul, you yourself said that the white plugs indicates a lean condition, so this is a good place to check.

Carb adjustment is not a black art. Carbs are pretty simple devices. I do not profess to be an expert on carbs, but adjusting the carbs on a 308 is really not that hard and does not need to be done in a laboratory or anything. I do not think that I could do it the way Paul can do it with a stethoscope to listen to the throats, but I know I can do it with a flowmeter in about 2 hours, taking my time and doing a good job.

Getting the idle mixture "just right" requires an exhaust analyzer, but getting it in the ballpark is generally plenty good and can be done without one, plus a little experience. Most of these carbed 308sare SO far out of adjustment at this point that it isn't funny, and getting them in the ballpark makes a huge improvement.

As for the float level, I have never heard of tweaking a carb with the float level. Maybe that's not a Weber thing. With Webers, you set them so the floats are right and that's that. Float height DOES affect how the carbs work, which is why if the float heights are off on a Weber, things don't work well. I'm not enough of an expert that I would have any idea what I could accomplish by tweaking the float height.

As for jetting, I have often wondered why a less restrictive exhaust or a less restrictive intake should require different jetting. In THEORY, the increased flow of such a system should cause more vacuum in the venturi and therefore pull more fuel through the jets. I have always assumed that in reality, the devices are only linear over a narrow range, and when you move the whole curve up or down with changes in the system, the jet change keeps the carb operating in the linear part of the curve. Someday I would love to sit down with a true carb guru and learn about that.

In the meantime, many Fchatters here have done the carb thing (like Russ) and really know what works. I have learned from following their adventures with jetting and discovered where my car likes to be jetted. All I can say is that the right jetting and the right carb synch makes a HUGE HUGE difference in how the car runs. There will always be the idiosyncrasies of carbed 308s (fuel starvation in hard corners, for example) but there is no reason the car should not run well and be very driveable. Mine was awful. Now it is fantastic. The previous owner changed the exhaust system from the stock thermoreactor muffler to an Ansa system, and never changed jetting. Then I went and removed the restriction from the airbox (thanks Russ!) and made it breathe even better. It REALLY needed a rejet. What a difference.

Bill, I will be very happy to help you with the car if you can get it up here this summer. And Verell will probably be easy to convince to come over as well. You will have the guru and me to figure it out.

Best,
Birdman

 

This was a great post, thanks! One issue to make clear: the ignition timing is one thing and I was under the impression that the dealer checked that. Again, easy to do yourself to be sure. An issue brought up was the valvetrain timing as well. If it's off 1 tooth, the car will run, but crappy, right? Do the valves hit the pistons in a 308 if you're off one tooth? Hopefully not!

Checking this means some additional work, so it makes sense to check the carb jetting first as it will need that anyway, regardless of it's the source of your problem.

Ken

 

The valves will not touch the pistons if off one tooth.
I drove my car for 5,000 miles that way.

 

I dont know how many teeth off you could be, but I would imagine even two or three wouldnt damage anything, but you would want to experiment with it not running to find out for sure. I also would not think being off one tooth on one bank, is going to make the other bank run lean, unless whomever worked on it screwed up both banks the same amount. I also don't feel valve timing would lean out the mixture, but I wouldnt know. But I do know an engine can be rediculously screwed up and still run. I would imagine if one cam or two were one tooth off you might not even be able to tell. Depends on which way off it was, and which cam.