Dellorto DHLA40s

[JonB]

What are these holes for?

[William2]

Have a look at previous posts on Dellortos, particularly the replies from Tim Engel. He is a master of all things in this area and gave me a lot of help and advice in setting up my 40Es. I used both a Colourtune and a Syncrometer airflow meter and found them to be very useful bits of kit although a 4 branch manometer is the best tool. As has already been said if you check that all jets, emulsion tubes and air correctors are as per the Lotus manual and latest bulletin sheet then that will be pretty close to ideal. Float height is also important as is ignition timing and spark plugs.
Once the carbs are balanced take the car out for a decent run and try accelerating slowly through the rev range. If there is no flat spot above about 3200rpm which is when the jets switch from idle to mains then that is a good sign. I would also suggest whipping the plugs out immediately after a drive above 2500rpm say and check their colour. Should be greyish brown. Checking mpg is also a good indicator of correct jetting, etc. Have fun!!

[jeff jackson]

This is what you want...after you get now O rings, new Thackary washers, plain washers and Nyloc nuts.
Morgan Carbtune.
Easy peasy to use.
http://www.carbtune.com/

Jeff 72 +2

[vincereynard]

What are these holes for?

The attachment InkedIMG_4323_LI.jpg is no longer available

You are obviously bored and looking for things to do.

Be very careful with these they are easily stripped.

[JonB]

I thought they migh be the idle bypass screws, only there are no screws visible, unless they are wound right in.

[jono]

Mine are the same - the air bleed bosses are there but there are no adjusters (I think the bosses are plugged or otherwise blanked off at the factory).

The is a feature of the earlier Dellortos which are not adjustable for flow barrel to barrel (unfortunately)

I also recommend the Morgan Carbtune - an excellent bit of kit

[William2]

Dellorto DHLA40 carbs don't have air bypass screws. 40E carbs do.

[alan.barker]

+1 Just put a Morgan Carbtune on Santa's list
Alan

[vincereynard]

Dellorto DHLA40 carbs don't have air bypass screws. 40E carbs do.

There you go. Looks like you cannot do anything about it, so one less worry.

[john.p.clegg]

"Make the suspension adjustable and they will adjust it wrong ...... look what they can do to a carburetor in just a few moments of stupidity with a screwdriver." - Colin Chapman "


John

[JonB]

"Make the suspension adjustable and they will adjust it wrong ...... look what they can do to a carburetor in just a few moments of stupidity with a screwdriver." - Colin Chapman "


John

Thanks for that, Colin.

As to stupidity, well, that's why I started this thread - to avoid it.

[Fredtech]

Guys.

Just a add-on here. We recently fitted a pair of Dell?s on my early Sprint. Original carbs are Weber 40DCOE31?s which I could never get balanced correctly.

Fitting the Dell?s, albeit with the original Alpha Jetting and Chokes (32-s instead of 33-s for Elan), the car started and after the usual faf-around, with the Hand-Held Flow Meter on the Inlets, we thought it ran ok-ish?.

Then occurred to me to use a Vacuum Gauge set that I had from an old friend who used to run 4-pot Honda & Kawasaki Bikes. The Dell?s have a Vacuum Bleed-Blank on each side that can be removed and a brass tube fitted, then connected to the gauges, the thin brass tubes in the picture were a perfect thread-fit for the Dell?s as well.

I was sceptical at first as to how much vacuum can be achieved here, boy was I wrong. Gauges fitted and it was then obvious we were miles out with the hand-held flow tool. Balancing the carbs on these new gauges and boy what a difference. I can actual get a twincam to run very smoothly at 500-600 RPM which I was never able to do with the Webers.

For those with deep-ish pockets, might be worth an investment. Keep an eye out for them on Flea-Bay, as they seem to come up occasionally on the Bikers-Sections.

[alan.barker]

Imho it's easier with the 4 column Morgan Carbtune which has the 4 vertical columns all next to each other.
Easier to compare the 4 levels at the same time
Sorry but the non calibrated numbers on dial gauges mean very little.
Alan

[vincereynard]

Dellorto DHLA40 carbs don't have air bypass screws. 40E carbs do.

Presumable you could get away with only connecting cylinders 2 & 3 as they have no individual bypass screws.

I've heard about twisting the spindle to balance both barrels in an individual carbs but cannot see me trying it.

It would be interesting to swap connections between the columns and see how accurate they are!

[alan.barker]

That's just it with 4 columns you can see if there are balance problems between the chokes in the same carb
Alan