Oxygen sensors

I can just tell you of my experiences with Weber 48ida's on a Cleveland.

I could claim to be an expert on Webers on a "C" but that would be as ridiculous as claiming to be an expert on marriage because I am married for 38 years? Don't go there!

I have been running them since 1978.

What I have found is that virtually every engine series, i.e., Ford 289, Ford 351W, Boss 302, 428, 427, 429,Boss 429, will have a different combination, i.e., a different ratio between the fuel jet and the air jet.

In the case of the 351C, the proportion that it really works with is 135-140 fuel jet to 160 air corrector.

When you increase the size of the fuel jet, then you stay in proportion with the air corrector.

You can run the mains all the way down to 125 and all the way up to 170's.

Where the dyno will indicate the most power will depend on other factors such as the cam timing and exhaust configuration as well as the flow numbers of particularly the intake valves.

I find the most power, best cruising combination at 135f/160a.

As far as the emulsion tubes go, the two that are the most commonly used with the Fords are the F5 or F7.

Stock 48 ida's will normally be supplied with F7's. They run ok with them but some tuners like to lean out the mid-range rpm by changing to an F5. I frankly don't see the difference but a Dyno might?

I thought that the best combination of "chokes" were the 42mm. You definitely can feel additional "torque", i.e., down low power with 37's, but the 42's are MUCH better at the top of the rpm range. Depends how you drive the car or where you want the power.

Back in the day when Hall was selling the complete set up, he was using 32mm chokes. Those you need to cut out of aluminum billet.

That is where HE liked the power coming in but those really will top out at under 5,500 rpm's and the car will just hit a brick wall.

As far as the idle circuit goes, you are really stuck with what it comes with. .70/120's.

At one time the 120 idle jet holders,  (which really are a  combination of idle air jets and emulsion tubes) were all that was available. All you could do was lean the .70 idle jets down to a .65. If you went further to a .60, then the car will severely backfire through the exhaust. Severe enough to blow out mufflers and possibly break the top of the pistons above the top piston ring.

Recently there has been an availability of additional idle jet holders in sizes never before available. Some say that they have been able to reduce the idle heaviness by coming up with a new leaner combination with bigger air jet sizes? I have not played with that.

The issue with the original Weber set up is that you are idling on A/F ratios in the 12's which normally is the zone in which you want your A/F ratio under full power, so the result is that the idle leaves a black slimy residue on the exhaust pipes and the fumes just plain smart you eyes at idle.

This set up was always just intended as a "racing application" so there was never a fix for that.

Additionally, the engine generally runs on just the idle circuit up to somewhere in the 2,800 to 3,200 rpm range. It will vary depending on the atmospheric conditions A LITTLE. Often drivers will complain of a flat spot in the power curve at those rpm's. I admit that it is there with the two hole transition and mostly gone with the three hole.

This is where the third transition hole comes in. It is designed to cover as much of that flat spot as possible and generally works well or well enough to make it almost not noticible while driving.

It will not change your IDLE A/F ratio. You can't. You are stuck with it as THE compromise to run these carbs on a street car. If you are stubborn like me, you will continue to try, think what could Doug possible know,  but continued trying to lean out the idle is likely at the expense of broke pistons, piston rings and mufflers, so don't say that I didn't warn you.

The only solution really to clean up the idle is to go to an EFI setup on that intake. Then the CPU will take care of the idle issues.

And yes, I installed a oxygen sensor thirty years ago, installed an A/F gauge and gave up long ago on cleaning up the idle and went to an EFI.

What manifold is that? I don't know anyone else who is running an IR manifold with runners that long.

My exhaust system is one of the old Hall off road setups. It does not have mufflers, but rather two resonators on each side. I've had it for 45 years. I had the resonators opened up and repacked. It looks great but it's still loud

Those look like Mind Train mufflers, not Hall's.

@joules posted:

What manifold is that? I don't know anyone else who is running an IR manifold with runners that long.

I believe that is an origianl Detomaso Weber intake. The carb flanges are much thinner then Hall's so it makes the runners look longer.

They were originally painted black from Detomaso.

The intake manifold on my car is a factory DeTomaso Weber manifold, built by Holman Moody for their racing team. These manifolds were very thin and prone to break so only about 16 were made. Pantera racer, Hugh Kleinpeter, from whom this manifold was bought in 1976, indicated that only four made it to the US. He had it machined to keep it from cracking, and I've had it on and off my car for 45 years without problems. 

In checking further, I find that you are correct about the exhaust system being a Mindtrain system; I bought the car in 1979 from the first owner and at the time paid little attention to what I bought, I was so overwhelmed by having a Pantera. Later someone must have told me it was a Hall system, so I never questioned it. Yes, the exhaust has a bit of a crackle to it, but I see from an older post that a crossover pipe can solve that.

That may have some advantages, but I don't like the appearance.

I learn a lot from you all.

I don’t know if I’m qualified to comment, but I run three DCOE40s on my TVR, and have been through them a number of times.  The engine is a Triumph TR6 2.5 liter straight 6.

I found that I’ve gotten a lot better low RPM performance by running significant advanced timing, even at idle, and then limiting total timing at high RPMs.

But as Doug has pointed out, I have had people behind me, complaining that their eyes were burning after following me for a little bit!

Rocky

I run 28 degrees of advance and get the ‘stinging eyes’ complaints as  well

Hum? 28°? I've found the Boss 302 number of 16 about right for initial advance.

Webers like 40° total on a Cleveland.

I can say that often with a single Holley carb, you can't run that much initial advance without inducing "run on", i.e., the engine running after the ignition is turned off.

Also, when you switch to aluminum heads, generally you reduce the total to about 32°.

@rocky You are correct about eye watering following you at Inde Motorsport Raceway.