Flat Spot on Accelerating

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boardman411
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Flat Spot on Accelerating

Post by boardman411 »

Hi All,

I've noticed that I have a flat spot when pulling away in first and second, it sort of has no response and then kicks back into life - 3rd & 4th when cruising is fine. After some random research I came across this interesting piece from http://http://www.vw-resource.com - which covers my issue & I have a 009 distributor, non vacuum.

"The 009 distributor sometimes causes an acceleration "flat spot" (hesitation, stumbling, the Dreaded Bog!), as it does not have the vacuum advance adjustment of the original distributor. These can usually be overcome by ensuring that the accelerator pump is adjusted for it's maximum stroke, and installing a richer main jet in the carburetor (one size up should do it)"

What does this mean and how do I check "that the accelerator pump is adjusted for it's maximum stroke" ? Not sure about this.

I was also wondering has anyone done the above mod. I currently have a Solex PICT 34 Carb and was going to perform a refurb, so my thinking is, if the above is a know resolution to this problem, then I might as well source a slightly bigger main jet (need to work out what size I have today) My other question is, would changing from points to electronic ignition help, as I know this seems to be a good mod as well..

Any Advice appreciated
Thanks,
Shaun.
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boardman411
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Re: Flat Spot on Accelerating

Post by boardman411 »

As this seems to be a common setup, I would thought someone would have some views on this... Don't want to post same on FB - as I will get all sorts of answers..

Shaun


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Banger
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Re: Flat Spot on Accelerating

Post by Banger »

If you Google "solex 34 pict 3", look for a page entitled "what really burns me about the...." It's a pdf showing a step by step guide to making a 34 pict 3 work with a 009.

It should be mentioned that AFAIK VW never offered the 009 in any a/c road vehicles. They all had distributors that had the advance controlled either by vacuum only or a combination of vac and centrifugal. The 009 is a centrifugal only type. The type & model varies depending on the carb used, so you need to know the carb/distributor match. VW were forever updating and amending this compatability to try and keep up to date with the changing emissions regs in the 60s and 70s.

I would initially check the jetting is correct for your engine (I'm assuming it's a stock 1600tp), and get a distributor that matches the carb - it should be an SVDA. These are easy to get new (try Autospark), and even come with an electronic option. Set the timing as per stock and you should be good to go.
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Re: Flat Spot on Accelerating

Post by boardman411 »

Thanks Banger
This is useful stuff, I think I remember reading that the 009 was not a standard offering and is only used as it's a cheap alternative.. I've also read that replacing for a vacuum advance alternative will possibly resolve the flat stop as well..

I will look for the PDF and check what dizzy matches my carb..

Thanks for the useful information.
Shaun.


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Re: Flat Spot on Accelerating

Post by flatbeat »

Originally 009's were not used on stock engines but rather 'performance' engines where they work very well at the top end of the revs.....a flat spot in 1st and 2nd not really an issue when screaming balls out :lol:
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boardman411
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Re: Flat Spot on Accelerating

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Here's the link to the article - If anyone is interested in making the modification to a Solex 34 PICT 3 carb and increase the size of the main jet as well. I will probably disgest the article and consider this as an option, once I've checked the timing and a few other things first..

http://www.flaktfolket.se/tips%20o%20tr ... %20009.pdf

I will update the post with any further updates...

:cheers:
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Re: Flat Spot on Accelerating

Post by BJ1 »

All the above is interesting but have you checked that the accelerator pump is working properly? These symptoms point towards either a split diaphragm and/or a blocked drilling on that circuit inside the carb. Both easy to fix.
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boardman411
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Re: Flat Spot on Accelerating

Post by boardman411 »

There's a good reference on the following page on how to check/adjust the accelerator pump, I will of course check this first.



http://www.vw-resource.com/accelerator_pump.html



There's also a note to people who are using the SOLEX 34 PIC 3 carb and a 009 dizzy...



"To compensate for the flat spot inherent in the 009 distributor (but ONLY this distributor), adjust the accelerator pump injection quantity to the maximum; i.e., move the adjusting segment counterclockwise as far as it will go"



I suppose this is a good workaround for the time being, but my current thoughts are, that I'm running a cheap incompatible non vacuum dizzy, when I should have a SVDA compatible dizzy that matches the carb for better performance and to eliminate hesitation.



I'll keep on investigating in the meantime - but my current thought is to purchase a Pertonix Ignitor 1 Distributor - instead of changing jet size, adjusting accelerator pump etc,etc.. Also I would like to ditch my current chrome aftermarket air filter and change back to original type.. Which I'm yet to determine what that is, so if anyone reading this can tell me what the correct air filter is for that carb that would be helpful.



Thanks,

Shaun




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Re: Flat Spot on Accelerating

Post by Banger »

Accuspark do an electronic SVDA for £65, or a points version for £40. They also do a kit with dizzy, coil, leads and plugs for £100. I used an Accuspark 009 for 6 years with no problems at all.

Airfilter, I suppose you could get a standard oil bath type (you might need to check you still have the mount in place on the "roof" of the engine compartment). You'll need to get the hose (Scofields carry them), plus the two ends of the hose. You will have to be a bit creative on the "U bend" that goes on to the carb, as I think the throat diameter is bigger on a 34 pict 3. You will then be able to connect the oil breather hose from the alternator/dynamo stand to the air cleaner. Make sure the air cleaner inlet trumpet has the flap and bob weight included and attached. You could also look at the carb pre heat, which combined with properly fitted thermostat flaps and a thermostat will mean that things work as VW intended.

If you are stripping the carb, make sure that the jet sizes are commensurate with a 1600TP.
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Re: Flat Spot on Accelerating

Post by boardman411 »

Thanks Banger for the info on the air filter.. I'll add that to my list of ever growing research..

Had a look at the Accuspark SVDA distributor, looks like a bargain for the price compared to the Pertronix version. I'm sure there's some differences between the two, might be cheaper components or something like that, but without a side by side comparison of the two you will never know - and a recommendation is always better than some article on a website..

Shaun.


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Re: Flat Spot on Accelerating

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Went for the plunge & purchased the Accuspark SVDA with electronic points after speaking to their customer services team, who were very helpful and knowledgeable.. Let you all know how that works out once received and fitted.


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Re: Flat Spot on Accelerating

Post by Gunnsie »

Hi... sorry to highjack your thread.

I am having flat spots in 1st and 2nd in my 1500 SP with Vacuum advance dizzy.... does anyone have any advise they could give me as to overcome this?
I have had some recommendations of buying the above mentioned AccuSpark Kit, but others saying that they aren't that good and sometimes decide to just stop working.
I've also had recommendations to go for the Pertronix ignitor 1 ignition system for vacuum advance.

The price difference is quite a bit, but is it really worth spending out that bit more?? Would it mean more reliability etc?

I use my bus for weddings, so I don't do loads of mileage, but I do need it to start and run correctly each time and ensure I get to the weddings etc.

Cheers.

Chris
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Re: Flat Spot on Accelerating

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Re: Flat Spot on Accelerating

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No problems about high jacking the thread as long as, it's in relation to current issue.. The more information out there, that can help others the better..

I also looked at the Pertronix dizzy as well, but when you compare the price and quality of both components, I couldn't justify the higher cost. After speaking to the manufacturers of Accuspark, they've also heard of failures for Pertronix and people have swapped to there components instead. To be honest there are probably stores of failures of both components, it's just that you don't here much about the good stories..

I've not fitted the Accuspark yet, still sitting in the box at home.

You don't mention exactly what carb you have or the make of dizzy, which will be helpful.


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Re: Flat Spot on Accelerating

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After ordering the Accuspark a month or so ago, I eventually got round to replacing the dreaded 009.

First I checked the timing with my timing gun and made sure everything was running as expected before removing the old dizzy.. Then I removed the old & replaced with the new Accuspark SVDA - thought I'd see if you could static time this, but my test light was always on.. so I guess that is a 'No' then ..

Once replaced, I tried firing up the bus, no joy.. so turned the dizzy a bit at a time and eventually fired up.. Once running - set the timing to 7.5 degrees with timing gun, then checked the advance all looked spot on.. Tighten the dizzy and attached the vacuum advance hose to carb..

Then went for a cruise..... A lot smoother and the dreaded flat spot had gone.. So far so good, let's see how these goes over the coming months.

Shaun.




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