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Discussion Starter #1
What is the correct procedure on 16v twin TB’s?

Do you unwind them and then wind them until they just touch and then screw in a further ½ turn?

Or do you do as above but where they just touch do you use feeler gauges at a set amount and adjust until it just grabs and then turn by a set amount?

I have read that it can be done by putting feeler gauges, of a set thickness, down the inside of the TB’s and butterfly.
 

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hello Mate,
do you have the alfa 33 16v workshop manual?

on pages 1116 or section "04 D" onwards it describes how to set these up... its a bit tricky by the looks of it, and you need a manometer according to the book.

if you have not moved the air bypass screws from factory settings i dont think you would go too far wrong by disconnecting the linkages that link the two throttle bodies, then let of the screw that adjusts the throttle postion, so they are completely closed, (on both throttles) then try screwing both screws in so they contact the lever and then by say one turn both sides. then reconnect the cross linkage and make sur that there is equal " slack" in bothe sides so that the two trottles are opened at the same time.,, the trick is balance everything

thats a bit of a starting point i think rather than a definitive guide, as i say the workshop manual explains exactly how to do it but u need a manometer ( £50 ish quid if you get really stuck )
 

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Discussion Starter #4
Hey Kam,
yes i have looked at the manual but dont have a manometer and no one was able to tell me what the "K" or "N" scale would be on a synchrometer :(
Thanks for your reply though.
 

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hi, yeah thats tricky as the syncometer measure flow rate, the manometer measures a vacuum,.. sure the two are linked but not actually the same...
 

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Discussion Starter #6
OK guys i got advised the following, thought i'd pass it on incase anyone else wanted to know
1k - 1.5k feeler gauges down the side of the butterfly, if tick over is too much wind out the throttle stop screws "2.5mm allenkey grub and 8mm nut to lock them off" equal amounts on both sides.
 

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Discussion Starter #7
anyone know how to set idle speed as in making sure the throttle stops are correct?
Do you get it to running temp close all bypass screws and disconnect the IAC or take it off and block the hole?
 

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Discussion Starter #8
Well i had a go today.
I used feeler gauges .010 = 3 turns on the throttle stops, the TPS would only allow 1.5 turns = to .004. The idle was at 1.5k so i adjusted to 1 turn, the idle is a little high but might be due to the bypass screws needing adjusting????
I think i have to bite the bullet and whip them off and find someone with a proper alfa manometer and get them set up off the car. My thinking is that if there is an air leak somewhere and you try to set them up on the car you are compensating for the air leak.
 

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Discussion Starter #9
Well I just went for a drive, started from cold no prob, idle was no prob, I will see how it is when freezing/v cold. Think i will still get them setup off car and ask them to note down the number of turns.
 

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hello mate,

if you take them off the car it might be harder to get them set up, as who ever doe sit will need a flow bench kit to " suck " thru them and read of the vacuum readings,...

if it were me i would be tempted to leave them on the car and bring the car to a decent alfa specialist, AHM or the like to get them balanced.. hope you get it fixed either way
 

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Discussion Starter #11
Hey Kam
I am popping into one of my local alfa specialists tomorrow, i am lucky, I have a choice of 3, I think they have the proper alfa tool.
All is good though, one of the throttle stops was loose when i went to adjust it.
MY problem was that when very cold the car would idle at 500 rpm and take about 2 mins to slowly get to 900 rpm, tried everything, only had fuel pressure and TB's left, fuel pressure regulator might be faulty or there might not be enough vacuum on idle to bring down fuel pressure. This is why i want to get the TB's set off car "on the bench"
 

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Discussion Starter #12
I popped into my local alfa garage, they have a manometer but no flow meter, so will have a go setting them up on the car, i didnt realise that the water would have to be drained ect ect. I did play around with the idle bypass screws when i balanced them up with a synchrometer.
The engine has always been fluffy/wooly since i owned it when slowly increasing the revs from idle.
 

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Discussion Starter #14
I didn't have time today, hopefully next week, on a good note car idles quickly to 900 prm when cold now.
 

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Discussion Starter #15
Still waiting to get the car in lol
I now know my FPR is working and there is not enough vacuum being produced. I said before "1k - 1.5k feeler gauges down the side of the butterfly" I confirmed this and was told they should be almost closed to produce vacuum and be controlled by IACV, 10 thou, not 1 thou :eek: my bad. I will try again and see
 

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Discussion Starter #16
I set the TB butterfly stop screws to 1/4 turn "10 thou" it mad no difference to the vacuum produced on the pipe to the FPR.
I disconnected the IAC, no difference to the vacuum produced on the pipe to the FPR.
I checked all the vacuum pipes from the plastic spider.

There is only enough vacuum to just move the skin on the tip of my finger and the pipe will not say there by itself.
When i connected a vacuum pipe to the FPR and monitored the fuel pressure, i needed to suck about the same as when sucking a milkshake through a straw

What else could cause not enough vacuum on the pipe to the FPR, the pipe to the brake master cylinder, which has a 1 way valve?
 

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I set the TB butterfly stop screws to 1/4 turn "10 thou" it mad no difference to the vacuum produced on the pipe to the FPR.
I disconnected the IAC, no difference to the vacuum produced on the pipe to the FPR.
I checked all the vacuum pipes from the plastic spider.

There is only enough vacuum to just move the skin on the tip of my finger and the pipe will not say there by itself.
When i connected a vacuum pipe to the FPR and monitored the fuel pressure, i needed to suck about the same as when sucking a milkshake through a straw

What else could cause not enough vacuum on the pipe to the FPR, the pipe to the brake master cylinder, which has a 1 way valve?
sorry for old thread waking up, but this story the same as mine. vacuum very low. no leaks.
any news about it?
if i open TB plates a bit too much, when cold idle starts at ~2200 rpm, after a minute slows to normal, if i close a bit, idle starts not so high, but acceleration from stop is a bit worse..
maybe idle air bypass is faulty..
 

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Discussion Starter #18 (Edited)
Hi Niaugi,
I replaced the throttle body bakelight Alfa Pages :: View topic - 16v throttle-body insulator prob solved. to eliminate air leaks from there. I did have some cracks but it didn't make any difference to the low vacuum problem.
I tried another idle bypass valve, it operated the same as the other one and made no difference.

did you look at the vid in this post? http://www.alfaowner.com/Forum/alfa...-running-rough-rich-low-revs.html#post4702725

I have since fitted a race engine running trumpets and omex ecu.
 
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