Dellorto Nightmare
Discussion
Hello, my name is Chris.
I'll try to keep it short because i would need 10 pages to describe what i run into after buying a car.
The car is a Toyota Starlet '82, RWD, with a 7K-e motor which is 1800cc. The injection was thrown away and the engine was equiped with dellorto DHLA 40F carburetors. Sounds good right ?
All this from the previous (incapable of doing anything) owner an i am being polite.
I had no previous experience with carbs. All my friends were insisting to go to a carbs expert and give 20 euros to sync and tune them but i wanted to do it on my own. So i started studying...
The car was running with torque at low rpm but as the rpm went up it was like restraining. The progression was neither good nor bad and it couldnt hold idle whenever i stopped to a red light. Also it was spitting gasoline from the venturis to the engine bay on hard acceleration.
Long story short... 15 degrees advance istead of 8-10 stock, floats set (figure of speech) 9mm and 11mm, the rear carb had rocks of mud and gasoline inside, some jets were a little clogged.
I rebuilt them first without taking the manifold out (big mistake, i sould have seen it coming) and now i have to fix the vacuum leak that i have from there.
Now here is my question. I know that it cant be answered with certainty from a forum, but i need some feedback. I have 55 idle jets. According to paper i would need 50 for 1800cc. After several sessions of attemps to tune them i found out that the engine settles in 7-8,5 turns from fully closed !!! SO i need bigger idle jets. I found out that these carbs when put on another engine need bigger idle jets instead of smaller.
What should be the number of the idle jet ?? An ''expert'' told me to go to a 65. (the man put in the idle jet holder a 130 main jet and tried to tune it........)
What is your opinion on this ?
Thanks
(Really sorry for the long post)
I'll try to keep it short because i would need 10 pages to describe what i run into after buying a car.
The car is a Toyota Starlet '82, RWD, with a 7K-e motor which is 1800cc. The injection was thrown away and the engine was equiped with dellorto DHLA 40F carburetors. Sounds good right ?
All this from the previous (incapable of doing anything) owner an i am being polite.
I had no previous experience with carbs. All my friends were insisting to go to a carbs expert and give 20 euros to sync and tune them but i wanted to do it on my own. So i started studying...
The car was running with torque at low rpm but as the rpm went up it was like restraining. The progression was neither good nor bad and it couldnt hold idle whenever i stopped to a red light. Also it was spitting gasoline from the venturis to the engine bay on hard acceleration.
Long story short... 15 degrees advance istead of 8-10 stock, floats set (figure of speech) 9mm and 11mm, the rear carb had rocks of mud and gasoline inside, some jets were a little clogged.
I rebuilt them first without taking the manifold out (big mistake, i sould have seen it coming) and now i have to fix the vacuum leak that i have from there.
Now here is my question. I know that it cant be answered with certainty from a forum, but i need some feedback. I have 55 idle jets. According to paper i would need 50 for 1800cc. After several sessions of attemps to tune them i found out that the engine settles in 7-8,5 turns from fully closed !!! SO i need bigger idle jets. I found out that these carbs when put on another engine need bigger idle jets instead of smaller.
What should be the number of the idle jet ?? An ''expert'' told me to go to a 65. (the man put in the idle jet holder a 130 main jet and tried to tune it........)
What is your opinion on this ?
Thanks
(Really sorry for the long post)
Edited by chrisvam on Tuesday 29th April 13:16
packman10_4 said:
Take it to a dyno if they know there stuff it should run like any injection equipped car ....
My 2 ltr Pinto ran like a Swiss watch running a pair of 48's with 90 mm trumpets
A Dyno is only a tuning tool, it means nothing about the operator there.My 2 ltr Pinto ran like a Swiss watch running a pair of 48's with 90 mm trumpets
And many of these "modern" dyno's havent a damn clue about carburettors ( and sometimes engines or tuning ), as they've popped up in recent years
And then finding a dyno with Dellorto experience, and one with access to jets etc to try....well, they'll be very few on the ground
Yes Steve your right you might have all the kit to hand but if u have no experience or jets and tubes chokes ect ect its usless ....
I was merely saying get it on a dyno and check out the mixture levels at different points ... We hardly kept any Dellorto stuff on the shelf more Webber even then we ordered stuff from Webcon or popped down to the Carb Centre (Nothampton Motorsport)now.
Check your Misab spacers are to tight and the carbs have movement up and down if not the fuel with froth with bubbles this causes all sorts of problems.
If they have been sitting with fuel in it might be worth stripping them and dropping them in a ultrasonic cleaner just to get them clean then go from there.
I presume there is a specially fabricated inlet manifold on the car, I can't see any other way of fitting a pair of Delortos to an injection engine. (I also presume it's a pair!) I would check out the manifold very carefully first in case there is warping or an air leak. Is there any possibility that a damaged valve might be causing the fuel to spit back into the engine bay?
Hi Chris
You need to sort the air leak/s first.Make sure all the jets are screwed in tight, loose jets/chokes can cause missfire on acceleration/under load.Make sure the accelerator pumps dump fuel in when you floor the throttle. Assuming all the chokes/jets etc are the same sizes for each barrel, wind the idle jets out the same number of turns, if it is 6 or 7 it is 6 or 7. Using some thin tube such as windscreen washer tube listen for the hiss at the entrance of each carb, alter the balance screws between the carbs until the hiss is the same. Screw the idle screws in or out the same amount to get the fastest idle. Drop idle speed down to say 8-1000 rpm. Next step really involves afr monitoring to read afr under hard acceleration to select suitable main jets/air correctors also selection of idle jets/air correctors for cruising and pick up at low rpms.
I hope this helps.
Peter
You need to sort the air leak/s first.Make sure all the jets are screwed in tight, loose jets/chokes can cause missfire on acceleration/under load.Make sure the accelerator pumps dump fuel in when you floor the throttle. Assuming all the chokes/jets etc are the same sizes for each barrel, wind the idle jets out the same number of turns, if it is 6 or 7 it is 6 or 7. Using some thin tube such as windscreen washer tube listen for the hiss at the entrance of each carb, alter the balance screws between the carbs until the hiss is the same. Screw the idle screws in or out the same amount to get the fastest idle. Drop idle speed down to say 8-1000 rpm. Next step really involves afr monitoring to read afr under hard acceleration to select suitable main jets/air correctors also selection of idle jets/air correctors for cruising and pick up at low rpms.
I hope this helps.
Peter
As you do not know if the engine ever ran properly with these carbs fitted you might have a difficult task. As other posters have said, you need to start from square one and double check everything.
Firstly are you sure the fuel in your tank is not stale or dirty and the fuel pump is delivering the correct pressure, the fuel pump will not be the original high pressure injection pump so needs checking carefully for pressure and delivery.
Next you should clean out and check each carb, you don't know how old they are or where they came from, ultrasonic cleaning would be good.
Also make sure that other parts of the motor are working properly, check compressions, spark,connections,cam timing etc. Do not assume that anything is OK until it has been checked.
The engine might not run properly even when everything is ok as the engine was not designed for carbs, injection is far more forgiving of wild cams etc.it will never idle as smoothly as an injected engine.
If this were mine I would not spend lots of cash to try and sort it, without the proper expensive to hire rolling road dyno and someone who knows these carbs you will never get it right. What I would do is remove the Dellortos and sell them then use part of the cash to buy and refit an original injection system. I feel this will be cheaper less hassle and more successful than trying to fix a pair of hard to tune carbs.
Firstly are you sure the fuel in your tank is not stale or dirty and the fuel pump is delivering the correct pressure, the fuel pump will not be the original high pressure injection pump so needs checking carefully for pressure and delivery.
Next you should clean out and check each carb, you don't know how old they are or where they came from, ultrasonic cleaning would be good.
Also make sure that other parts of the motor are working properly, check compressions, spark,connections,cam timing etc. Do not assume that anything is OK until it has been checked.
The engine might not run properly even when everything is ok as the engine was not designed for carbs, injection is far more forgiving of wild cams etc.it will never idle as smoothly as an injected engine.
If this were mine I would not spend lots of cash to try and sort it, without the proper expensive to hire rolling road dyno and someone who knows these carbs you will never get it right. What I would do is remove the Dellortos and sell them then use part of the cash to buy and refit an original injection system. I feel this will be cheaper less hassle and more successful than trying to fix a pair of hard to tune carbs.
kev b said:
the fuel pump will not be the original high pressure injection pump so needs checking carefully for pressure and delivery.
If this were mine I would not spend lots of cash to try and sort it, without the proper expensive to hire rolling road dyno and someone who knows these carbs you will never get it right. What I would do is remove the Dellortos and sell them then use part of the cash to buy and refit an original injection system. I feel this will be cheaper less hassle and more successful than trying to fix a pair of hard to tune carbs.
Whilst I agree on other counts. The fuel pump could easily be the injection pump, as as it was already fitted would make perfect sense to use it.If this were mine I would not spend lots of cash to try and sort it, without the proper expensive to hire rolling road dyno and someone who knows these carbs you will never get it right. What I would do is remove the Dellortos and sell them then use part of the cash to buy and refit an original injection system. I feel this will be cheaper less hassle and more successful than trying to fix a pair of hard to tune carbs.
As for dyno time, it would be insane to book dyno time until it is running half sensibly and the carbs are known to be functioning, so any dyno time wouldnt be wasted.
But totally agree, if a quick, cost effective simple solution cannot be found, refit the original injection system.
Other than noise, I doubt the Dellortos will offer much anyway.
kev b said:
So the original pump runs at 60/80 psi and carbs need 3psi, the original pump is a bit over specced I would say.
I'll bet this is a typical over ambitious abandoned/unfinished project that will require large amounts of know how or cash to finish to a reasonable standard.
The original pump only makes whatever pressure the regulator demands from it. What pressure the pump is capable of in another setting is largely irrelevantI'll bet this is a typical over ambitious abandoned/unfinished project that will require large amounts of know how or cash to finish to a reasonable standard.
The original pump will be reliable, it will flow plenty of fuel, all tank, wiring and fuel lines are in place. So really it would be crazy to use anything else.
First of all i want to thank you all for your replies.
What i 've done do far.
I have set the timing at 10 degrees. I took the carbs out, cleaned and rebuilt them with the oem kits. Everything is screwed tight with caution. I set the floats to 17mm because i have the 10 grams floats, not the 8.5. The carbs are a bit angled because of the manifold so i left the setting at 17mm. No more spitting gas. I did a compression check, the engine is like new. It does not have the oem electric pump on it but a mechanical one from an older K engine.
I tryied emailing eurocarb for some help. No help.
I do have some vacuum leak on the second cylinder that i am about to fix the following week.
GASKET or GASKET MAKER ???? for example the products of permatex ?
What i 've done do far.
I have set the timing at 10 degrees. I took the carbs out, cleaned and rebuilt them with the oem kits. Everything is screwed tight with caution. I set the floats to 17mm because i have the 10 grams floats, not the 8.5. The carbs are a bit angled because of the manifold so i left the setting at 17mm. No more spitting gas. I did a compression check, the engine is like new. It does not have the oem electric pump on it but a mechanical one from an older K engine.
I tryied emailing eurocarb for some help. No help.
I do have some vacuum leak on the second cylinder that i am about to fix the following week.
GASKET or GASKET MAKER ???? for example the products of permatex ?
Read this.
http://www.s262612653.websitehome.co.uk/DVAndrews/...
Then this.
https://web.archive.org/web/20110809041756/http://...
If the engine is stock with only 80 - 100 bhp or so then 28mm chokes would do ok. If the chokes currently fitted are far too big then you'll never get it running right or with any sort of fuel economy.
http://www.s262612653.websitehome.co.uk/DVAndrews/...
Then this.
https://web.archive.org/web/20110809041756/http://...
If the engine is stock with only 80 - 100 bhp or so then 28mm chokes would do ok. If the chokes currently fitted are far too big then you'll never get it running right or with any sort of fuel economy.
I have read the second one. According to that at 1800cc with peak power at around 5500 the main venturi size should be 32. My carbs are stock alfa romeo. They have 32 on them.
Also it suggests to begin with a 50 idle jet, and i have 55's and it needs bigger. Dellorto according to the book of Des hammil sould settle the engine from 3.5 to 5 turns from the fully closed position and mine settles at 8. This means that the idle jets are too small.
Am i right ?
Also it suggests to begin with a 50 idle jet, and i have 55's and it needs bigger. Dellorto according to the book of Des hammil sould settle the engine from 3.5 to 5 turns from the fully closed position and mine settles at 8. This means that the idle jets are too small.
Am i right ?
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