carb jetting - who knows their stuff?

[dugcati]

Hey all,
I am trying to find out how you calculate which jets would suit an engine...

I have twin single ICT34's on my tank and have just re-jetted as per someone's suggestion.

After re sync'ing/balancing and re-setting up the timing to around 2d ATDC (it was at TDC) the van starts up, ticks over and generally runs better but blimey charlie it drinks fuel now! I think I might have gone to high with the jet sizes however mixture's are OK etc but am unsure what I would change.

I am told the ICT's use the idle jet for upto 2500/3000 rpm (around 80% driving use!) but I don't know which jet is the likely culprit and also which emulsion tube size to go with etc etc

details are:-
Engine - 1776cc CT with an engle 110 CAM
carbs- ICT single 34's


Current setup is:-
Idle jet 55
Main jet 170
Air corrector 150
Emulsion tube f78


Old setup was:-
Idle jet 52
Main jet 160
Air corrector 130
Emulsion tube f78


thanks in advance...

Doug

[kevtherev]

Doug
After hours of fiddling and guessing I took an engine I had to rolling road tuner
Best way in my opinion, cost fifty quid

[jason k]

rolling road is the only way to sort it, your bus will come from there with better mpg and better bhp.

if you dont get it jetted you run the risk of burning valves pistons etc if running lean

i always use http://www.raceshack.co.uk" onclick="window.open(this.href);return false;

[dugcati]

point taken guys thanks

Anyone know of a decent rolling road outfit in Derby/Notts?

[kevtherev]

point taken guys thanks

Anyone know of a decent rolling road outfit in Derby/Notts?

these guys are good.. not sure what they charge though

http://www.noblemotorsportltd.co.uk/rol ... uning.html" onclick="window.open(this.href);return false;

any good?

[dugcati]

aye - Chesterfield is about 35 miles away from me so not that far - only prob is it'll prbably cost me 50 quid in fuel the at it seems to be burning it at the mo!

Tuning/ Fault Finding
If your car is pinking, has flat spots, loss of power, has had modifications made or is just not running right, then we can put your vehicle on the Rolling Road and run a diagnostic check to ascertain the problem. We book most tuning sessions in 2-hour time slots. In this time we will be able to rectify your problem using our dyno tune method or give you the reason as to why the car isn't running properly. A 2-hour slot costs £120.00 plus VAT.

[Adrian244]

Agree with all thats said. Find someone that really understands carbs (not many left now) and pay the money.

I spent ages trying to get a twin choke weber carb working on a golf driver last year. After weeks of fiddling with emulsion tubes and jets finally found a setting that worked throughout the rev range and under different load conditions. The std suggested tubes/jets didn't do it for my car.

Sold it then

[dugcati]

I'd still like to know how the jet sizes are worked out based on CC etc - does anyone know of any web links that supply info on this so I can background learn a bit....

[VWCamperfan]

Try here. >>>>>http://www.Aircooled.net/gnrlsite/resou ... etting.htm

One of the sites I used to jet my 40 IDFs. (amongst others!)
Gives you a fair idea though.