Type 3 - variant 1971 - low rpm, stalling, before engine warms up

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sima112
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Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by sima112 » 8th January 2020 - 1:50am

Hi guys, greetings from Colombia,
I have a problem with type 3 variant 71.double carb. Its starts ok but when trying to head off, chokes ,stalls, i need to use a lot of gas pedal to get it moving . Overall drives very bad. Rpm around 500 (there is a gauge added, so if i can trust it) All the problems goes away when engine gets warm and drive ok more or less. Rpm goes up to 900.
Here the temperature never goes under 10 degrees and it does in in hot or colder days.
Its a car of my father in law but i like to drive it and would like to get it in shape. As the car drives normally i dont want to create more mess, so I need advice where to start. Ive tried googling a lot also have a manual from Bentley. Which is ok but has fuel system info only for FI.However i could not find out any info how the system works during heating up.

1.Ive tried only check the vacuum with a gauge, connected between left carb and distributor, no reading at all. When i unplug it from carb and suck in the engine showed a response. Looks like the vacuum advance in distributor works. Unplugging the vacuum house while engine running doesn't have any effect.

2.When I took of the air filter unit i notice there is a hissing coming from straight from the left carb. I used a hose to check around and couldn't find anything around the carb, the hissing sucking sound is coming from the throttle body.

3.While searching with the hose i found out that there is sucking sound coming from where all 4 spark plugs are fitted in. Is this normal? I found out that there was missing the round seals on the ignition leads. Definitely good to have them on as I read, otherwise the engine is not cooling properly

4.With engine running i unplugged the cables from cut off jets, the left shut the engine right off, as it supposed to, right kept on running it was struggling but going

5. Just interesting, i found a round air filter inside of the air case, shouldnt be there only oil? Is it a normal upgrade or is it completely off idea?


Thank you for any tips, explanations, ides and where to start
Sima
Last edited by sima112 on 22nd January 2020 - 12:50am, edited 1 time in total.

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purplepeter
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by purplepeter » 9th January 2020 - 7:25pm

I would suggest the first thing to do, is give it a good service- Valve clearances, clean/replace plugs (& fit them tightly), check points gap, check that both cut off valves are screwed in properly, check the connections to the balance pipe & just lightly nip up all of the screws in the carb tops to see if that eliminates the sucking noise in your second point.

Do you still have/ did you ever receive the email I sent you a couple of years ago, with the Haynes manual scans?

sima112
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by sima112 » 10th January 2020 - 3:15pm

Hi Peter, thank you for your answer, i will start doing all the checking as you advise. It will take some time, but i will get beck with what I discovered.
And yes i got the email from you and honestly I thought that i answered to you with thanks and gratitude. Weird if i didn't, i aways do especially when im grateful for something. Im very sorry and thank you!! I refurbished old fuel pump using the manual and fixed the starting problem. Thank you Sima

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broady_6
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by broady_6 » 12th January 2020 - 9:10pm

Hello,

As peter says, give the system a proper service and set up as per the factory settings. This is full guide on how to set up the carbs.

https://www.thesamba.com/vw/archives/ma ... /index.php

It would be interesting to see some photos of the airfilter please. Might be that someone has modified it?

Looking forward to hearing how the engine is once you've been over the basics.
The sultan of swing

sima112
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by sima112 » 22nd January 2020 - 1:04am

Image

Image

The filter outer diameter is 23.5 cm and inner 18,5 cm. Ive never seen the original oil system so i cannot say if it has been modified.

As for the engine, im learning basic of tuning to be absolutely sure what im doing. It has electronic distributor points. The distributor its not original, don't know which type.

Image


I tried static timing but the light never went off when turning distributor so i guess this type can be only tuned by stroboscopic light which i have to get first. Or Im doing something wrong. Would be interesting to know how come some of the electronic distributors can be tuned statically and some not.???
The original distributor has number 311 905 205 T on it. I think its still functional and was replaced just for to get electronic points. Wondering if they are not modules which fits into these old types of distributors?
I will try to get the number of current one which is probably hidden behind generator. If im correct it will help me while timing.

Im still a bit unsure about the timing with strobo light. If I understand well, first I will heat up the engine, then disconnect the vacuum hose from the distributor end and plug it. Then install timing light and aim on TDC notch while rpm are at 850. So far so good.
How about the advance at 3000rpm? Do i first make a mark on 28-32 before top TDC and at this rpm it must align as well? How do I know what degree to measure (28-32 or different) does this depend on the distributor I have?

As I understood its much accurate doing timing with a strobo light. As I like the engine i will get one. Any suggestions which one is just sufficient. Dont need anything fancy. Quite enough what will the job well every 5000 miles.
Thank you Sima

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broady_6
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by broady_6 » 26th January 2020 - 4:31am

I agree, that doesnt look like it has been modified. Im not familiare with the couth american cars. But that doesnt look like the traditional bosch distributor. If you are using a strobe light, you will need the engine running in order to use it for setting the ignition timing. they cant be used to set the static timing. Which is often tricky to set with electronic ignition.

Your original distributor sounds like the correct part number. There are lots of kits available to covert it to electronic ignition if that is what you want. Petronix sell a popular kit.

You are following the correct timing procedure, if you have a modern style timing light, it will have a dial on which you can set the advance. And use the TDC mark on the pulley. this means you dont have to do any calulations to mark the pulley at 30 degrees.

But in order to calculate the marks. Measure the circumference of the pulley and then divide by 12. That will give you 30 degrees before TDC.

For example if the pulley is 45cm circumference.
45cm/360degrees=0.125cm
0.125cm x 30degrees = 3.75cm

Because 360/30=12. All you need to do is measure the Circumference and divide by 12 to get the distance you need for 30 degrees.

45/12=3.75cm

I hope this helps
The sultan of swing

sima112
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by sima112 » 28th January 2020 - 12:55am

Thank you for confirmation of the process and explanation. I sort of have an idea about how to measure the degree. My main concern was if the degrees are changing with different types of distributors or if its still 30 degrees no matter which distributor i have? Im sorry if its sometimes difficult to understand exactly what im trying to say. The knowledge of the language is missing now and then.
The distributor with the number I stated will be original bosh and ist on a shelf in garage. The one on the car (foto) has number 67974F2 (not sure if its whole and if its 6). I will try to find out which distributor it is, but if its always 30 degrees with every distributor it really does not matter.

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broady_6
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by broady_6 » 28th January 2020 - 9:18pm

Dont worry about the language, your english is far better than my spannish.

There are slight differences depending on which Distributor you are using. If you are using 311 905 205 T the main thing to check is that it is at 7.5 BTDC at idle. Rather than focusing on the upper advance limit. I would expect to see it around 30-35 BTDC at 3000+RPM. If the distributor is working properly then it simply needs setting at idle and then it will follow its own inbuilt curve.

I dont recoginise the distributor which you have installed, and I cant find any information from the part number 67974F2 on google.
The sultan of swing

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purplepeter
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by purplepeter » 28th January 2020 - 10:38pm

That's a relief to hear someone say that.. I've never in my life taken an unloaded engine up to that kind of revs just to check the advance limits. I don't think I've seen it written down anywhere either
I would check the 205T over thoroughly though, suck on the vac to check that it moves & stick a squirt of oil down into the internals

When You swap the dissy's over Sima, turn the engine to tdc on no1 before removing the existing dissy, then when You put the 205T in, turn it til the rotor arm points to the mark on it's rim & be prepared to have to hit it to get it fully into the engine case. DO NOT turn the engine over without a distributor installed, as the drive inside the case can lift & cause nasty problems!

sima112
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by sima112 » 29th January 2020 - 5:18am

broady_6 wrote:
28th January 2020 - 9:18pm
If you are using 311 905 205 T the main thing to check is that it is at 7.5 BTDC at idle.
I thought i should be on TDC at idle 850rpm. Bentley says
68-71 = 0 before TDC
72-73 = 5 before TDC
I also saw table here on forum which states different timing points depending on engine number. What is more important engine number or distributor?
I will shortly meet the guy who was working on the car so i will ask about the type of distributor which is on the car. I guess it might be some Brazilian.
The 205T was not on the car for some time, i just found it in garage and Im not planing to put it in, however thank you guys for very valuable information.
About the advance timing, Ive been reading a lot on samba and here and it was mentioned a few times. Maybe its just double check. I probably missed why its been done. I will do it just on idle then.

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broady_6
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by broady_6 » 29th January 2020 - 7:39am

purplepeter wrote:
28th January 2020 - 10:38pm
That's a relief to hear someone say that.. I've never in my life taken an unloaded engine up to that kind of revs just to check the advance limits. I don't think I've seen it written down anywhere either
For stock engines there isnt a need really, but for anyone who fits a 009 its required as timing is set using maximum advance for 30 degrees at 3000rpm. I never found a 009 that was any good for general road use as you have to over fuel in order to compensate for the lack of vacuum adance. So we can ignore this, as far as this thread is concerned.

sima112

It is more important to time the distributor. The information given in the bentley is for a completely standard engine as a general overview. As you have a different distributor installed we need to find out what it is, then we can find out what its advance curve looks like and hopefully find the correct timing setting for you.
The sultan of swing

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Editor
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Re: Type 3 - variant 1971 - low rpm, stalling, before engine warms up

Post by Editor » 1st March 2020 - 12:52pm

205T is a twin vac unit, correct for a 1971 twin carb engine. The diaphragm is prone to failure, but mine is still fine (AFAIK!). The info on our technical page should be right for timing it, but if it has a fault, maybe that's why it was changed.
Dave.

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