I am in the GTA and wondering where would be the best place to tune my Dellorto Carbs. I am close to Mazdees, but would like other options as well.
Thanks.

 

Dave at Mazdees would probably be able to give you some pointers, but your best bet is an afternoon, a bunch of different jets, a lonely stretch of road and your *** dyno. You have to drive the car and only you know how you actually drive it and what it needs to be able to do. Are you using this car for racing only or is it your street car? Hand it over to someone and you may end up paying for a tune your not happy with.

 

ditto, invest in a wideband and get the manual......you'll learn a ton!

 

No need for a tuner... just learn how to jet/adjust the carb yourself. 2 Barrel carbs like the Dellorto always need a little tweaking here and there so paying someone to tune your carb for you will get old quickly.

Read everything on this site www.gruntled.com/Dellorto/ and you'll know everything you need to know about your Dellorto. You'll also know what to expect from it. The site hasn't been updated in almost 10 years but then neither has the Dellorto lol. I have a write-up on there, I'm Will.

Only problem with Dellortos is finding parts. These guys: http://www.cbperformance.com/default.asp have most of the jets/parts you'll need if you don't have a stock port 12A/13B. If you do have a stock motor, just follow the RB jetting recommended on the gruntled site and you'll most likely be ok.

 

Thank you guys...Thats what I'm going to do then, read up as much as I can and make adjustments as needed. It's being used for street at the moment.
The main problems are :

1) Does not idle properly
2)Engine turns over a few times well before it starts.
2) Stifles when I pull off from a stop position almost like its clogging.

Just does not operate smooth. The regulator is set at 4.5 and I'm running a carter P4070 fuel pump.

 

Those are typical teething problems with the Dellorto. Assuming your jetting is roughly correct for your engine, these tips should help you out.

1) What do you have your idle set at? 900-1000rpm is what you should be setting it for. Bad idle is usually either caused by poor idle mixture or flooding.

To adjust the idle mixture, turn the two top screws all the way out while the car is idling, then turn them back in (little by little, alternating between each one) until the car starts to stumble, then back them back out 1 1/2 turns.

Your regulator should be set at 4psi. You might be flooding your carb (over filling the float bowls) due to the excess pressure. That would cause bad idling. Experiment with flooding by turning the pressure up and down on your regulator... it will help you get familiar with how the carb behaves when it's flooding. Turning the regulator at a super low pressure (like 3psi) will most likely produce a great idle but you'll run out of fuel too quickly while accelerating.

2) You need to pump the gas a couple times before starting your car. That's normal for this type of carb. You also should be using the choke when the engine is cold or trying to keep the engine going is going to be hell til it warms up.

3) You're not getting enough fuel from the throttle pump. It sprays a jet of gas into the intake for a second or so when you first press the throttle. Try idling the engine and quickly snapping the throttle linkage open. Does it stumble? If it does, your throttle pump is either not adjusted properly (read my write-up) or the throttle circuit in the carb is plugged up. You need a steady stream of fuel coming from the pump... if all your getting is dribbles, it will stumble. You can see how it's working by removing the filter and looking into the barrels of the carb... the throttle pump squirts its fuel from the top of the barrel.

Is this a Racing Beat Dellorto? Because if not, you will need to modify your throttle pump gasket for rotary use.

 

"RXcetera" nice to see a fellow owner offering such comprehensive advice! I remember when I was a kid 30+ years ago my older brother 9who knew nothing about carbs, etc) would take his 240z to his mechanic for a "rally tune" when he would go on car rallys and then have him detune it the following week. To think all the guy probably did was spend 15 minutes richening the fuel and add timing then take in $$$$$ laughing about it.

 

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