Weber overhaul and set up advice please

[mycar]

What type of ignition does your car have Captain ? Simple points and coil (Kettering) or CDI (capacitive discharge) ?

Points and coil.

This is me picking my way through an MSD install in my 911, have a read.

viewtopic.php?f=27&t=32218&hi

[Captaintremendous]

Oh and by the way. You are right. Road testing in rural France is a hoot!!!

[Captaintremendous]

What type of ignition does your car have Captain ? Simple points and coil (Kettering) or CDI (capacitive discharge) ?

Points and coil.

This is me picking my way through an MSD install in my 911, have a read.

viewtopic.php?f=27&t=32218&hi

An interesting read there mycar. Sadly i am at the mercy of the FFSA and their almost fanatical insistence on period correctness and originality, so anything visually not in keeping gets the red card. What they can't see however, won't hurt them

[mycar]

Ah, I completely missed the bit where you said you wanted to be FFSA compliant.

[fetuhoe]

The Dog Leg First 901/911 box does, of course, have a synchro on 1st gear but it is a fairly weak Baulk Ring design that does struggle.

Using very slippy GL-5 Transmission oils doesn't help and the increase lubricity of this type of oil slows down speed matching and make gear shifting even slower.

I would tend to use an older type GL-4 Oil such as Redline MT90 which works well in these older boxes.

You still need to be careful as the design of the 901/911 allows them to snap the end off the mainshaft in 1st gear if you apply too much torque but if your speed is low enough and you use some care it should be OK.

You should still, however, be able to pull away in 2nd and it shouldn't really bog down.

[Jonny Hart]

What they can't see however, won't hurt them

Nothing to see here, move along...



Just dont open the lid!

[Captaintremendous]

The Dog Leg First 901/911 box does, of course, have a synchro on 1st gear but it is a fairly weak Baulk Ring design that does struggle.

Using very slippy GL-5 Transmission oils doesn't help and the increase lubricity of this type of oil slows down speed matching and make gear shifting even slower.

I would tend to use an older type GL-4 Oil such as Redline MT90 which works well in these older boxes.

You still need to be careful as the design of the 901/911 allows them to snap the end off the mainshaft in 1st gear if you apply too much torque but if your speed is low enough and you use some care it should be OK.

You should still, however, be able to pull away in 2nd and it shouldn't really bog down.

I use Castrol B373 in the box as i find it works well with the LSD. Slipping into first at anything other than a standstill is out of the question however.

[Captaintremendous]

What they can't see however, won't hurt them

Nothing to see here, move along...



Just dont open the lid!

Hmmmmmmm............Nope, I ain't seen nuffink guv'nor.......

[Captaintremendous]

Thought i would post an update on the ongoing Weber saga. I have now recieved the 32mm venturis, plus a few other nik naks from PMO and have rejetted the carbs to near S spec. Today was my first attempt at tuning them in and was an unmitigated nightmare. I started with PMO's reccommended starting point. Idle screws half a turn in, mixture screws two turns out and idle air correction screws eighth of a turn out. The car fired up and ran like a bag of spanners, popping, banging and farting and would only tick over, even when fully warm, if i had it held at about two thousand revs. Despite trying to carefully wind in each mixture screw individually with the linkage between the two carbs disconnected so that one could not affect the other, i could not achieve the desired drop off in revs to indicate lean best idle.Even when i managed to get it ticking over at around 1100 RPM it still wouldn't happen. The synchrometer did indicate that everything was sucking pretty evenly, but any success with the mixture screws was impossible to achieve.i ended up with the thing surging, dying on me, picking up revs of its own accord and generally seeming to do its own thing as if it had a life of its own and i ended up going back to the basic PMO starting point and starting over from scratch several times to no avail. i am now pursuing the "stick feet up, glug bottle of wine, sulk and curse" approach, whilst i wait and hope one of you learned gentlemen can suggest anything else more constructive.
Here endeth the rant.

[911hillclimber]

I have PMOs on my 3.2 race engine, and self tuned them in 30 mins!

Critical is that you have no air leaks at all.
I had one I was not aware of and it murdered me sorting the one choke that was a real pain, pops bangs and big farts etc.
Found it by spraying carb cleaner on all the gasket interfaces with the engine running.
The rouge cylinder literally changes the exhaust note.

The PMO instructions are spot on.
I set the mixture once all 6 were balanced side to side and individually using a humble Colour Tune from my dark old days of SU carbs on my Triumphs.

Hunt for air leaks esp the gaskets on both sides of the heat insulators.

[Captaintremendous]

Colortune is my next my step once i've peeled myself off the ceiling! a more frustrating day you would be hard pushed to imagine!

[mycar]

I your first post you mention O rings.

Just to check, have a look at your idle jet holders.



Weber used earlier and later idle jet holders, the upper/later jet here needs the O ring, the lower/earlier does not.

Which do you have. Are they all the same ?

After that check that the idle air bleed holes are not blocked. These are the brass 'pills' that are pressed into the top of the main throttle bodies. Sometimes the gasket can be dislodged to cover it or not be punched correctly.

Number 74 here.




So many thing to check... might as well make a start somewhere.

[911hillclimber]

I have assumed your carbs are in good condition and jetting etc are all as PMO.
The PMO carbs are not exactly the same as Webers but function the same, hence the PMO set up procedure will guide you IMHO.
If your engine is one that had injectors then unless you have the right gaskets you might have what I had and that was a long very thin gap in the gasket mating faces that added up to about 30mm x 0.25mm. This let in a huge level of additional air.
Fixing that transformed the engine and ease of set up.

A 1/4 turn of any screw makes all the difference.

Hope the wine works and you can crack it over the weekend.

[mycar]

What Hillclimber means by injectors is the high speed enrichment circuit squirters on top of the carbs pointing down into each throat..

Only the IDS carbs came with the enrichment circuit, not the IDA.

Worth a check to see if you have them though.

[Captaintremendous]

Accelerator pumps i call em. Yes i do have them, all renewed along with a complete overhaul and refurb of the carbs which i have just completed. I have just purchased a colour tune kit from Gunson online, so once that turns up i will have at it again, in the meantime i am not going to blunder around in the dark chasing my own tail as i did yesterday as i will probably end up doing more harm than good. It is going to be a long process of verifying dwell, timing, carbs, then back to dwell and timing until it is all good i guess. Can anyone recommend some good over the counter sedatives ?