Dino still misfires

Just had valve adjustment, new points, new clutch, new alternator belt, and carb adjustment done.

The mechanic was able to tune away half of the popping and some exhaust smell after all.

Questions:

1. The engine often stumbles/bogs during stop and go. if I kick down the throttle hard(>70%) at low rpm(800-2000rpm). Normal?

2. The engine hesitates/burbles slightly when I cruise at a constant speed holding steady rpm between 2000-3500rpm. I can sometimes heard 1 or 2 pops from the exhaust. Acceptable?

3. The exhaust pops worst under deceleration, perhas one pop every 1 to 2 seconds. Acceptable?

Thanks
Raymond

 

post the results of your gas analyser tune up after the vlave adjustment ray, then we may be able to help you.

need to know CO, HC and O2 and CO2. Confirm static timing and max advance settings at which rpm?, and air flow read from manometer at idle and just off idle.

 

Ray.

Run out with your video camer and make a video with sound, of what you car sounds like with the popping noise.

Then email it to a couple of us. you've got my email, and I can forward it as necessary. Try to keep the file small. Or record it and make a wav file.

Some popping/burbling is normal. We've covered that. If it's backfiring, that's a different subject.

After significant tuning and tweaking, we've just about got mine completely under control.

A close inspection of the carbs and of the fuel pump indicated there were some jets we needed to replace, as they had corroded some from the 30 years they had been in the carbs.

 

Phil> the mechanic only tune by feel, no proper equipment.

Dave> I suspect something is broken, now that you mention the carb, I think that could be the problem, I will bring it up to the mechanic.

 

!!

It's fair to say a good mechanic can get it really close by feel, but when you have this kind of problem, you really need all the gear.

I hope he's cheap!!

 

My modern car mechanic had a look at my Dino today and spoted some fuel stain under the middle carb, what seems to be a leak in the carb bottom gasket. He's surprised that my Dino mechanic didn't take care of the leak before the tune up, or maybe he didn't think it was a problem.

What would happen if one of the carb is leaking?

Raymond

 

Eventually you burn up.

NO leaking fuel is acceptable!!!! That last mechanic either caused the leak or didn't see it. Either way it's a huge mistake for him not to deal with it.

Ken

 

Ray.

I hope you have a fire extinguisher nearby.

Fuel, vaporizing on a header or some other hot car part is an invitation to disaster.

That needs to be addressed right now. Can you see fresh fuel leaking?

Time to maybe smack your Dino mechanic over the head a bit.

Have you asked your modern car mechanic if he can work on the dino, or if he knows of anyone who can?

I'm not sure of this, but it could also cause those cylinders to run lean, or require an over rich setting to compensate for fuel leaking or air infiltrating the carb at that point.

DM

 

Ok, the stain seem sticky and brown, and seem still moist. There's some on the left carb, a lot on the middle carb, and a little bit on the right carb. I hope it's just WD-40, maybe he needed to lossen up the controls... I will try to stick my finger in there to sample it later.

Raymond

 

brought the car to the garage this morning, he said that's fuel stain, gas sipping out of the gaskets, but he assured me it is not going to burn up my car.
For the misfiring and the engine hesitation, he said it is most likely caused by worn valve guide/seat, not the carb.

 

Have you tried going up a size on idle jets? A lot of 308's are jetted a little lean for modern fuels and benefit from going up one size in idle jet. It made a WORLD of difference on my 308. I know NOTHING about Dinos, but it's worth a try. The idle jets are cheap as dirt.

Birdman

 

Ken - my Dino has a thick, brownish stain on the base of each of the carbs that I suppose is a result of gas seepage. I suspect this is the "...evidence of seepage..." that Ray's wrench is referring to. I would not lose sleep over it, and have not lost a moment of sleep during the past 25 years that I have been aware of it on my carbs. Then again, it may catch fire tomorrow, although, statistical, anecdotal, and experiential evidence speaks against it. Wet gas is another issue.

Jim S.

 

I'm banking on a carb. problem. If there is a fuel stain there may be a base not flat enough to seal out air. This is exactly the problem I had with a 250GT. After sanding the carb base perfectly flat and re-adjusting the carbs it made a huge difference. I now only have slight popping, and I do think that is valve related.

 

Well, if this is typical of Webers it's news to me but I don't have Webers so I really don't know. With my Strombergs I'm very paranoid about leaking fuel; they have that well deserved reputation.

It seems to me if gas can seep out, air can seep in. This may be part of the tuning problems 246 owners seem to have? Perhaps the mounting on a 246 is not so good compared to other designs? If I had a 246, I'd be disatisfied at the seepage being "normal". Common perhaps, but not normal.

Ken

 

The webbers on my Lola have no such stain. The gaskets don't seep. The motor don't stumble, it pulls from 2K to 7.5K. It don't pop. There are a ton of Webber tricks and a lot of good books that tell you how to rebuild them, tune them and modify them to fix all of these issues. Rebuild kits, jets, shafts, butterflys, seals, and gaskets are available and no big deal. If the floats are gummed up they can overflo in a heartbeat and cause a fire.
Hey if we could get the Lucas Mech. FI in 0846 to start without priming and run on the street you can find someone who can sort these carbs.

 

Lola Webbers.
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