help IDA jetting for 1776

[Ninho/DKM]

Hello to everybody.
I had just ended my first project car.
I am i trouble with my Italian 48 IDA's jetting, engine is a
1776cc
sport heads valves in 39mm, out 35,5mm
compression ratio 8.2
camme engle 100

My actual carb setting is 48 IDA:
3rd hole
venturis 37mm
idle air f120
idle fuel 60
main jet 160
emulsion tube F7
short manifolds 

Car does not goes so smooth, have a hole in power at very low speed in first gear and do not get all power at higher RPM.
Can someone suggest other jet settings?
many thanks in advance.

[lawrence]

Here is something that will get you close. 135 main jet, 170 air corrector and 60 idle fuel jet. Try the 120 idle air jet, but it may cause the idle circuit to run lean before transition into the main jets. If this happens a 110 idle air may be necessary. Make only one change at a time and keep good notes of the changes. Do a search of this forum, there is a lot of information to be found. Good luck.

[Diederick/DVK]

just wondering but...
with that engine, won't you be better off with smaller venturis? they are still available.
or perhaps a smaller idle jet like 50 ?

[Ninho/DKM]

Thanks, Infact i am waiting for 55 idle jets to arrive.
Lawrence probably you're right couse actually i have 190 air corretor.
Will try your configuration and will see. Many thanks.

[Peter Shattock]

I'm not in a position to say in terms of the high end jetting as the 1776cc engine I ran was a different sort of combination of compression cam and heads, relative to yours, but I had a very similar sounding low end problem. Although is sounds wrong, I ended up with a 65 idle jet and it cured the problem for my combination and made for much better street driving.

Hope this helps.

Peter

[TexasTom]

I've never run IDAs on an engine that small, but considering the cam will probably only allow the engine to rev out to 5, maybe 5500 rpm, I agree the venturis may be WAY too big. Those 37s are sized for a 1776 to rev out to over 7500 on paper ...
I'd neck them down to a 32 or so to get better drivability, better airspeed ...
TxT

[Ninho/DKM]

TexasTom, the engine was assembled not for street use only but for strip use with some street rounds. My want is to have hi rpm and a lot of torque with that cam.

[TexasTom]

Atom,
Am I mistaken, or is the cam you're using an Engle W100?
TxT

[Type1/DVK]

W100 won't go that high in rpm, as Tom says.

[Ninho/DKM]

Actually with 190 air, 175 main, 65 idle and 37 vents the engine with 100 engle cam raise till 6000 Rpm like a monster but mixture is terible rich. So i am trying to lean it out step by step to mantain that range of Rpm abtaining a compromising setting.

[TexasTom]

The deal is a 1776 will rev to 6000 with a 33 or 34mm vent ... then your starter jetting is something like 55 idles, 140/45 mains and a 180 air.
The carbs will work better because airspeed is better, response would be much improved; only needs fine tuning.
If you want more rpm you could try some 1.25:1 rockers.
Sounds like an interesting project ...
Have fun!
TxT

[Ninho/DKM]

Texas, today i tried few configuration, 200 air, 175 main 65 idle, 37 vents 120 idle air. the car went so fast, max Rpm 6500 but a very little hole at very low speed around 1000-1500 Rpm. It seems a good configuration for strip performance........and sorry for mistake, Cam is Engle 110!

[stealth67vw]

My old daily driver 1776 with ported 40 x 35.5 044s, 1 5/8 exhaust, Engle W125 w/ 1.25 rockers and 8.9:1 CR used 37 vents, F7 E-tubes, 135 mains, 190 airs and 60 idles with 120 idle air. It ran great besides the stumble at transition nobody could tune out of it. It would pull to 7,000 fairly easy.

[Cheesepanzer]

You haven't said what type of spark plugs you're running.  With that mild set up I'd recommend the stock heat range.  I've run IDA's on a couple of small engines and with low compression, 280-ish duration cams, a colder plug ran like shit and fouled easy with the fat fuel mixture.

I ended up finding a set of 32mm vents, tossed in 125 mains, 55 idles and something like 160 airs and the engines ran bitchin!  Pulled to 6500 no problem - making power - not just reving.  Chrisp throttle response and a cute IDA bark.

Smaller engines like this are a hoot!  They allow you to try stuff and not break anything.  You learn and tune, and figure out what works and what doesn't, so when you step up to a bigger, badder set up, you're smarter and prepared.