Carbs and an 2.7 RS spec engine

[red-beard]

Already is....

[araine901]

LOL, That was good.

[red-beard]

Bosch dist is dead again. I switched back to the Marelli. Unfortunately, it is rev limited to 6500 rpm. The Bosch may have an advance curve issue. I played with the dist timing and the car runs much better. Now I need to fix the exhaust leak (Thanks Bert ) and I may still need to replace the clutch. I think it's running well enough to get it inspected for registration in Texas.

James

[jluetjen]

Redbeard, I doubt the car will even run (past idle)without the venturi since there won't be any pressure drop to pull the fuel out through the main jets. I'd say that for the money, getting (borrowing?) a set of 36 mm venturi and trying them out would be a reasonable solution. You'll most likely need to change the other jetting to match.

Here's an out-of the box solution. Switch to a mappable ignition system. You should then be able to start advancing the ignition timing as the venturi start to choke off the intakes. Basically you'll be increasing the cylinder pressures with the ignition timing to offset the drop in pressure resulting from the venturi. It's a thought, but not particularly cheap nor potentially legal in some rule books.

[red-beard]

It will run without the vents. The velocity will just be lower.

It is running, but testing is being put aside until I can get this Bosch dist working right. I need to get a new set of. For some reason, this set will ground for no appearent reason.

[araine901]

Red beard, I think you are wise to wait until you get your dizy sorted out first. Your carb set up seems appropriate (ie: venturies, jets etc) I wonder if that distributor is not causing some or all of the fall off in power. Baring something mechanicly wrong with your carbs, the set up you have should not cuase the power drop off. Let us know what happens with the distributor.

[red-beard]

There is something funky about the point. I'm going to pickup a set this weekend.

[araine901]

If you are still running points, you seriously need to look at getting a pertronix ingnior or somthing similar. I use one to trigger my MSD but I can say that I will never go back to points.

[jluetjen]

Definitely -- Ditch the points!!!

[red-beard]

OK, bringing this back to life.

Update. I spent about 3 hours balancing the carbs to smooth the engine out and set the idle screws. From idle up to 5500 RPM the cars runs great. Around 5500 RPM the engine starts to miss. It is not the dist, as I can push it to 6500 and have it cut out on the rotor.

I'm looking at the Air Corrector. 1.80's are installed. I'm thinking about putting in my 1.70's, to richen the mixture. Thoghts?

[dimps8]

Red beard, a problem i found when replacing the two piece points on the bosch distributor, the metal piece on the bigger halve will touch the side of the dist where the screw passes through the body for terminal one. You may need an extra piece of insulation.

[araine901]

It sounds like you have confirmed that the miss is lean condition induced. If thatis the case it wont hurt to drop the airs down. But in my experiance the mains have more more impact cleaning up a lean condition. Also I have found that larger air's makes my power hit later rather than sooner. I am running 160 mains 205 airs and 65 idles on a 2.2 with solex cams. It pulls good from 1900rpms to 6000. But 3-6 is the sweet spot. But at 6 there is a big kick in the pants and it wants to go pulls super hard but I shut it off at 7K with the rev limiter. It would pull higher but I wont let it.

[RoninLB]

Originally posted by jluetjen

. Switch to a mappable ignition system.
Basically you'll be increasing the cylinder pressures

I'm with you on this for consideration, but there's more than one way to attack this... assuming carbs are ok for the task.

[red-beard]

Originally posted by dimps8
Red beard, a problem i found when replacing the two piece points on the bosch distributor, the metal piece on the bigger halve will touch the side of the dist where the screw passes through the body for terminal one. You may need an extra piece of insulation.

Presently running a Marelli Dist. The Bosch will be after I fix the carbs.

The lean condition seems to be near the top which is why I was considering smaller air correctors. But you have a good point, upping the mains slightly may be better at first.

[RoninLB]

fwiw.. Grady posted this on another thread.

"If it is OK with you (hijack), I would propose a data acquisition preference.
1) Head temperatures at the intake and exhaust on all six heads.
2) Exhaust gas temperatures for each cylinder.
3) Intake air temperature, humidity, and pressure.
4) Exhaust gas CO and O2 measurements.
5) Fuel flow.
6) RPM
7) Ignition timing.
8) Throttle position.
9) Acceleration.
XX) What more?
There is a lot to be gained with good data acquisition. These days it is widely available and relatively inexpensive. "

[red-beard]

OK, I have a set of 135's and a reamer. I'll move them up to 150 and see how it does.

[red-beard]

Originally posted by RoninLB
fwiw.. Grady posted this on another thread.

"If it is OK with you (hijack), I would propose a data acquisition preference.
1) Head temperatures at the intake and exhaust on all six heads.
2) Exhaust gas temperatures for each cylinder.
3) Intake air temperature, humidity, and pressure.
4) Exhaust gas CO and O2 measurements.
5) Fuel flow.
6) RPM
7) Ignition timing.
8) Throttle position.
9) Acceleration.
XX) What more?
There is a lot to be gained with good data acquisition. These days it is widely available and relatively inexpensive. "

Head temps have hit the middle of the range. No markings.
EGT - ?
Fuel flow ?
I told you the RPM - It's missing/cutting out at 5500 rpm.
Timing 27 deg BTDC @ 6000 RPM
TP - ?


This is a 1970 with CARBS. I could buy PMOs for the cost of installing/buying the sensors. I am installing O2 sensors and A/F ratio meter for each side. This will take a few days to get a muffler shop to drill and weld the bosses in.

[dimps8]

Redbeard is 27 deg btdc enough advance?

[red-beard]

Sorry, 35 degrees at 6000 rpm

[jluetjen]

red-beard;
So what is the latest condition of the car and problem. How's it running now?