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1977 Mk1 Polo Manila


foreststu

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Start of another car. Picked up this car recently which is in need of a bit of work to put it mildly plus in need of a lot of new parts. 1977 Polo L in Manilla Green with Tobacco interior. Here's what

Loving the Ziebart sticker, my grandad had a Cortina with the same one. It worked well, there wasn't a spot of rust on the sticker.   The rest of the car..... different story.

thats looking amazing! It's so good to get them back after paint. I wish I'd managed to get the golf back together that quickly!

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foreststu

So I painted the NOS 1.3 litre HH code 4-2-1 exhaust with some silver VHT paint and set about fitting the lot.

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Exhaust went on no problems. The old intake manifold was coolant heated so I used a spare pipe I have to bypass it in the coolant circuit, 90 deg step up diameter elbow from the smaller flange on the coolant rail to the larger one on the head. Whilst I had the coolant drained I took the opportunity to fit a new radiator. Then I ran into my first issue, I had heard some RHD cars in the past have had the SORG twin DCOE 40 setup foul on the brake master cylinder but mine fouled on the master cylinder bottle instead.

 

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I don't think I would have leaked from being inclined as the seals are deep but I was concerned about the vibration rubbing a hole in the bottle. The stock bottle is 171 611 307 with the front and rear master cylinder connections both in the middle as you would expect. I considered getting another the same and bonding them together so I could offset the holes moving the cylinder towards the strut tower. I made a trip to my local scrap yard expecting them to not even have a single Mk1 or Mk2 car these days but to my surprised they had a late-'80s Mk2 Polo bread van with the 1.3 hydraulic head engine and a great big air box. I peered under the air box and thought the master cylinder bottle was broken off as it was turned so far towards the strut tower. Then I realised this was just to make space for the huge air box, it's perfect (although very dirty)!

 

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I got it fitted up and now there is plenty of room. If anyone in the future is putting a twin 40 set up on their Mk1 Polo then the part number is 868 611 307.

 

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With that sorted the final mod after removing the old intake was to fit a standalone filter for the oil breather which had previously gone into the air box. I picked up an old K&N one for 99p and cleaned it up then fitted it in the space left between the new mater cylinder bottle and the strut tower using a 24mm stainless steel P-clip.

 

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Whilst I was at the scrap yard I also took the pull handles from the breadvan as mine had small white coat hooks that were a bit chewed-up on the ends.

 

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So now I'm waiting on some fixings for the intake. The old intake was held on with two M8 studs top middle then 6 M8 hex head bolts (15mm of thread going into the head). The SORG intake has M8 holes across the top with very little clearance to actually get in an turn the bolt (which I had head about from others). I will take the two top studs out and use four M8 20mm long round allen key head bolts. The SORG intake bottom holes are M6 with no space to get a bolt in so needing studs of just the right length. So for the bottom four holes I needed a 30mm stud 15mm M8 one end and 15mm M6 the other which were quite hard to find but I tracked some down designed to be used as 'repair studs' after a damaged M6 hole has been re-drilled to M8. I've also had to order a longer throttle cable & cable outer to reach the bottom-mounted Weber LP3000 kit so I've ordered an Audi 100 cable which has the right pedal attachment and is much longer at 1300mm with a 1000mm outer.

Wish me luck that this all fits!

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foreststu

So it’s fair to say the SORG inlet manifold isn’t designed to be ergonomic for fitting:

 

OEM top: 2x inner M8 stud & 2x outer M8 hex bolt.

SORG top: no space for a socket or spanner on a hex bolt or nut so I used 4x M8 allen head bolts (narrower round head but still needed some Dremel on the inlet to turn free) which also helped with access.

 

OEM lower: 4x M8 hex bolt

SORG: The shape of the inlet means no bolt can be lined up to go in and no socket would ever reach. The holes in the SORG are M6 not M8 therefore studs normally used to convert M8 to M6 when an M6 has been drilled and tapped to M8 as part of a repair (called repair studs) were needed. 30mm overall length with 15mm M8 seamlessly going to 15mm of M6 thread. Of the four, the inner 2 nuts are easy with a spanner but the outer 2 (even with some of the manifold grinded away) have to be done first being wound on as the manifold is moved into position - there is that little consideration of clearance. This is to the point where we had to create our own tools to do up the two outer nuts, the open spanner was shortened to miss the water pump and the ring spanner was modified to be narrow enough around the left-side outer nut to turn.

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So now the manifold was on and I set about fitting the Röhm Motorsport 90 degree trumpets to the carbs. The best trumpets to use are straight and have a section which slides into the carb between the carb body and the Auxiliary Venturi, then fixed in place with 2 small metal tabs on the 2 M6 studs. An alternative is to fit a thin tube piece between the carb body and the Auxiliary Venturi and a trumpet that fits flush with the carb face using a gasket. I have limited space in the stock engine bay and wanted easy access for the Sychrometer on each so opted for 90 degree angled, also as with 895cc performance isn’t top of the pile. These 90 degree trumpets fit flush to the face but also block the possibility of getting a nut on the top M6 stud. They came with some M6 allen head bolts but the carb body prevented these lining up to start so I removed the stock upper M6 studs and used 20mm M6 grub screws on the top with the usual M6 nylocks on the bottom. The 90 degree trumpets also block the hole (1 per carb) that allows air into the Main/Idle Jet chamber. Some people have got around this by drilling a couple of holes in the brass cap over these jets but I opted to Dremel out a scoop out of the trumpet and cut the same out of the gasket so air could enter the designed hole.

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The original throttle cable was too short to reach the Weber SP3000 bottom-fitting linkage I'd bought so I had a think about what period cars might have the same accelerator pedal connection but be longer. Golfs etc are different so I opted for an Audi 100 which I was glad to find had the right connection and was much longer with a 1300mm inner and 1000m outer so plenty to trim to size. I placed an order for a new one which had to come from Poland but worked a treat.

 

Everything was then bolted up and I “zero’d” the settings with the air bleed screws all the way in and the mixture screws 1.5 turns out (for made in Spain DCOE, if you have made in Italy start 0.5 turns out as the needle profile is different). The carbs and inlet had previously been mounted on a 1990’s Formula Vee open top single seat racer running a 1.3L VW Small Block so I’d changed some of the hard-tuning brass parts not only to match the 895cc engine but also to lower the peak power revs from 7500 to 6500:

Main venturi: 24 (taken from Weber chart and the smallest they make)

Main Jet: four times 24 so 100

Air corrector: Main+50 so 150

Idle Jet: 40F9 (smallest I could find at the time so will see what it feels like at cruise which is what this jet does regardless of the name)

Pump Jet: 30 (again smallest I could find)

Spill Jet: kept original 50 (middle option and seems pretty forgiving)

Needle Valve: kept original 150 (again seems forgiving)

Emulsion Tube: kept original F11 (another all-rounder)

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Initial idle was OK. I set the butterfly position using the Idle Speed Screw by looking though the Progression Holes on the linkage actuated carb so they were just closed then matched this on the other carb using the Balance Screw. I then opened the Mixture Screw until 1/4 turns didn’t make it any smoother. Then I used a Synchrometer to check barrels 2 & 3 and then 1&2 and 3&4. I had one difference between 1&2 which I corrected by increasing the trumpet air velocity by opening the Air Bleed Screw on the slower carb which allows the passage of additional air past that butterfly.

You will also see from the photo that I've currently retained the vacuum advance dizzy. Each barrel has a vacuum port usually capped off with a brass plug. Weber make two hose attachments for these, a 3mm opening to unable the use of a 4-way manometer tuning device and a 0.8mm opening to give a vacuum indication suitable for the vac advance dizzy. A lot of forum posts say just ignore the vac advance as its just for economy or go to electric ignition which I may do but for now I had the ports so I thought I'd use them.

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Idle seemed a bit fast but OK. I’ve got the Idle Speed screw all the way out (just touching the lever) which places the butterfly nicely blocking about 90% of the first progression hole with the 10% on the carb side not the vacuum side. I think there is a chance the standard idle air feed is a little much for the 895cc hence the slightly faster running. I’ve matched the Mixture Screws to the air flow so whilst fast it is smooth. I may try an Idle Jet that will deliver a richer mixture to the Mixture Screw which controls idle (so less air via that route) but don't want that to cause rich running at when cruising with light throttle (when the Idle Jet is in charge - better called the Low Speed Circuit Jet in some books). I've got the Mixture Screws out 3.25 turns out so which is more than the 1.5-2.5 turns out specification indicating the Idle Jet is too lean. I have an Idle Jet with the next size up fuel orifice and the same air orifice (1.00mm) (45F9) I can try or I could order a set of 40F6 which will have a smaller air orifice (0.70mm) which might be a better option.  Either way that was enough for this weekend so I just took some photos…

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To finish off the weekend I fitted the carb trumpet socks which involved opening up the two holes under each one to 65mm then stretching them over. It'll keep leaves etc out and actually sounds better on idle with them on.

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Edited by foreststu
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Lovejoy

Excellent work! Its looking great, I cannot wait to see it in person at some point 

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dvderlm

I like your Volkswagen special tool 9997 and 9998.

 

Nice work with the carbs. The RamAir socks are good kit. 

 

40 is standard smallest idle for DCOE.

40F6 might overdo the richness.

 

Lean to Rich

F3 F1 F7 F5 F2/F4 F13 F8/F11/F14 F9 F12 F6

 

45F2 are available. 

Or, perhaps you could solder up four x 40F9 and drill using a 0.35mm bit?

 

Vizard managed twin Dellortos on an 875cc imp with 40 idles and infuriatingly does not say which DHLA idle holder. With 30 chokes though as that's with large exhaust valves and big cam so torque shifted higher.

https://www.imps4ever.info/tech/875power.html

Edited by dvderlm
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foreststu
On 24/04/2021 at 11:54, dvderlm said:

Just found that Eurocarb sell 00Fx jets (for F2, F6, F8 and F9) so you can drill your own fuel hole and in theory achieve sizes that are not multiples of 5 with less variation than soldering closed.

 

https://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=291978557762

 

Thanks for the helpful comments, much appreciated.

 

I've fitted a misab soft mount kit in place of the O-rings which as you can see were cracked worse than I'd noticed before (maybe worsened by using them in anger after many years on the shelf). I'm hoping that will sort the air leak which will cause the idle speed to slow then I can reduce the fuel feed accordingly using the mixture screws. I haven't tested yet as I've zero'd everything back up ready to try balancing with different idle jets which I had hoped would arrive Saturday morning. I should have checked the o-rings more closely in the first place but this all just started as 'chucking the carbs on the 895cc for fun' - lesson learnt. The misab o-ring seems to fit sung into the circular recess on the SORG inlet manifold so that's good, will know more after running them.

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The https://www.carbparts.eu/calc/ calculator advises 30F8 Idle Jets but the smallest I could find (without buying a pack of 50 from Germany) was 35F8 so I've ordered those. The F8 is a 1.2mm air hole rather than the 1.0mm air hole on the F9 so that coupled with reducing the fuel aperture from 0.40mm to 0.35mm means it will be quite a bit leaner. I went for this as I was concerned about running rich at cruising speeds when the main fuel delivery is through the idle jet via the progression holes.

Edited by foreststu
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setch

This is why I like my DTA E48 ECU :P Select a box and change the number and done :P. Not quite as satisfying though

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foreststu

Got the engine idling much better now. I fitted the 35F8 Idle Jets and hopefully that will avoid me experiencing rich running at cruise speeds. The bigger difference was that I removed 3 out of the 4 vacuum ports from the carbs. Each vacuum port has a 0.8mm hole to give the vacuum advance on the distributor a signal via a 4mm ID vac pipe. I'd seen a build in Germany who used the same 4 port & pipe arrangement that I used but I think I was giving the distributor too much vac signal hence advancing the timing and idling fast. The original Solex just had one 0.8mm vac port on the airbox side of the butterfly. I have just retained the vac port on the carb for cylinder 4 nearest the dizzy. I set the timing with a strobe with the vac can inlet taped-up closed as the manual suggests and when I connect the vac hose afterwards it does raise the idle but not as far as before. Need to put some miles on it not and workout how it behaves in conditions other than idling in my garage. 

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foreststu
Posted (edited)

So the day of reckoning arrived and it was time for the first long-distance (3 hours each way) test run to its first show, the Early Edition Show by Edition 38. I've got a genuine VW Audi Parts & Service worksop calendar from 1977 so pulled that out for some snaps.

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First 3 hours there identified some 'opportunities for improvement' but i'll get to those later. Suffice to say we got there at around 55-60 mph and around 40 mpg which was better than expected. Also better than expected was the weather with the rain holding off most of the day. I was told on arrival at 09:00 to park down on the concrete and subsequently surrounded with much newer motors.

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As you can tell from the clouds the weather was breathing down our necks all day but I found a few less-windy periods to have the bonnet open and one of the tea-cosys off which attracted some puzzled looks.

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Towards 16:00 they announced the winners of Top 20 awards as well as two best of show. I was very happy to be awarded one of the Top 20 awards.

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So on to the 'opportunity for improvement' or 'opportunities for development' whichever works in your company:

1. I had a hesitance stumble and spit-back under low rev slight throttle aka a lean misfire. Not consistent but enough to think about.

2. I had a slight pop from the exhaust under engine braking indicating rich main jet running but given the analogue nature of the carbs I think this is not a problem.

3. My heater hot/cold adjustment knob doesn't work so I need to reach under the bonnet to adjust from hot to cold and the hot is definitely hot! Ugh taking off old plastics fills me with dread so maybe I reside myself to having to always open the bonnet to adjust the temperature.

4. I had a few water drips from rain make their way onto the parcel shelf but nothing major.

 

So my plans:

1. I'm currently running the 35F8 and cannot find 35F9 so I've ordered a replacement set of mixture screws as mine are quite deformed from past over-tightening. With the new mixture screws I'll see if the 40F9's will play ball which should richen the progression hole feed hence mitigating the lean spot between Idle and Main Circuit.

2. Live with it.

3. Undecided, not sure what I need to remove to get to the inside of the bulkhead and see where the switch cable has probably come off.

4. Nowhere has Mk1 tailgate seal but VW Heritage has Mk2 although they want £85 for it. I took some measurements and have ordered 4 meters of something I think looks the same so should work from a specialist company called edgetrims.co.uk for £14

 

Overall very happy with the performance especially as there were several hours of torrential rain and I'm running 135 tyres and postage-stamp brakes.

Edited by foreststu
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setch

well earned! 🏆

after all that effort surely won't be able to ignore the heater control?

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foreststu
On 27/05/2021 at 21:49, setch said:

well earned! 🏆

after all that effort surely won't be able to ignore the heater control?

 

Just worried about brittle plastics but yes you're right.

 

Update:

1. Mixture screws were pretty deformed but new ones made no difference.

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The 40F9 still settles at an Idle speed which is too high and that's with the Idle Speed Screw completely off so throttle plates closed (confirmed with torch and by eye before install). It does sort the transition lean spot but not sure if that's a factor of the 'resting' idle speed being so high. Swapped the 35F8 back on and idle is perfect speed and reliable but I have the hesitation stumble (lean misfire) on slight throttle as it transfers from mixture hole to progression holes (not un-drivable tho). Also, with the 35F8, if I open the Idle Speed screw even half a turn (in the direction which should increase idle speed) the engine leans out and dies.

 

Very confusing because I don't understand why the richer 40F9 (so 0.40 mm fuel and 1.00 mm air) doesn't just find a happy idle with fewer Mixture Screw turns compared to the 38F8 (so 0.35 mm fuel and 1.20 mm air). In my head richer feed with no other changes should have found a happy idle at an acceptable speed. Can fuel feed alone effect idle speed that much? Makes me feel that if I richen the Idle Jet to richen the feed to the transition holes solving the lean spot am I just going to have the same high idle speed problem. Also confused about why with the throttle plates fully closed means the vacuum is sufficiently drawing through the 35F8 to idle nicely but if I introduce some additional air under slight throttle it dies rather than just run a bit rough.

 

To richen the transition holes but not increase the fuel feed to the Mixture Screws I guess I'm looking for 35F9 (0.35 fuel 1.00 air) but it doesn't seem to be available so I'd have to buy an F9 blank and drill myself.

 

3. No progress.

 

4. Sorted for £14.

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Including cutting out space for the boot catch.

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foreststu
Posted (edited)

So I've managed to make it out to a few shows and will put my name down for Tatton Park. First up was Edition 38 Early Edition at the end of May and I was lucky enough to get a Top 20 award.

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Second show was Players Classic at the Goodwood Motor Circuit and again the standard of cars was unreal, was cool to be parked out on the track opposite the pit building and get a shot alongside another Type 86 for the first time.

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Edited by foreststu
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foreststu

Couple more shows visited although weather isn't really playing ball at the moment. I went to Tatton Park VW Show for the Club Polo stand which was good even if it did mean leaving the house at 04:00 in the morning to get to the pre-show meeting point! It rained in the morning but the sun came out after that which was nice. It also enabled me to only be a 30 minute drive (rather than 3 hours 30 minutes as it was on the way home) from some wheels I'd bought on eBay to try, more on that this winter.

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Not really made any changes on the Polo but I did pick up a NOS Votex stainless fuel filler cap to replace the black plastic one I've been using.

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Then I headed to Bristol Volksfest with my wife driving our camper. Weather during the daytime wasn't bad, the sun showed itself a few times, but there was torrential rain each night and so the grass-roads between different areas of the campsite became very damaged/muddy. Thursday afternoon arrival was no problem but even by Friday, when the linking roads were just soaked, there were a lot of modern vans with low-profile tyres that were just spinning up their wheels unable to drive along a flat field. I got up early on the Sunday to move the car from the camping field to the Show & Shine field but got an email around 07:30 saying it was cancelled due to the ground conditions and that Sunday Day-Visitors, like some friends of ours planning to come, wouldn't be let in. The 135 width tyres on the Polo and the rear-engined camper on winter tyres both had no trouble with the mud on the way out later Sunday but lots of vehicles needed assistance.

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After all that rain we had another early start on the Monday morning, 03:00 this time. That got us (at 55-60 mph) pretty much as far south-west was we could without getting wet for breakfast on the sea front in St. Ives at 08:00 shortly after which the clouds cleared and we enjoyed some good weather.

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foreststu

We visited a few more shows over the past couple of months. First up we headed to a Busfest for the day and were lucky enough to pick up second in the Watercooled Car class. First place went to this amazingly clean Mk1 Golf.

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Then we took the Polo and the Bus camping for the weekend to our most local VW-only show, Dubs at the Caste which is within the grounds of Caldicot Castle. There weren't any sub-categories for the show on Sunday, and the quality of aircooled & watercooled cars was amazing, so we were very surprised to be awarded third best in show. Second place went to a very tricked out T6 with lots of screens & speakers then first place was a beautiful patina Mango Green 1960 split screen with a gorgeous interior completed by Kens Customs and flawless cabinetry/woodwork by Richard Booth Designs.

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Then I went further afield for Westside VW Show, there was supposed to be a ZeOriginals cruise but the self-inflicted UK fuel distribution shortage put a stop to that although we still met in a petrol station that had shut due to no fuel.

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foreststu

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So after a summer of running the twin DCOE 40’s on the 895cc HA I have picked up a 1272cc HH motor from an early 80’s Polo GL Classic (Mk2 saloon) and the matching 4-speed GU gearbox.

Engine has been sat out of the donor in a garage for >10 years so plan is a partial strip-down, checks, clean and rebuild then see how it drives before considering anything more like bigger valves/more aggressive cam/6n AEX 0.5mm metal head gasket to move to CR ~9.5:1. 

The HH head is an exhaust-heated inlet type so my preference will be to reuse the head currently on the HA block which was a coolant-heated inlet. My SORG manifold doesn’t have the rabbit-ear pieces to block the exhaust ports that would have gone to the original inlet manifold and I think it will look cleaner anyway. The combustion chamber (~20ccm) and valve (34/29mm x 104mm) sizes are the same in both so on rebuild it will only be the cam that needs swapping between them. I expect to find that the HA has inner valve springs in addition to the usual outer ones as I believe they were the only Mk1 engine to come with double valve springs from factory but not sure if this was throughout production or different for early/late models. My only concern is there might also be some small coolant holes missing in the head on the HA between the chambers, feedback on the internet seems to vary but I don't think it would make much difference as they are small into the big coolant area around the cylinders and the other coolant channels in the head. I'll decide when I take the head off the HA and have a look as I could make some blanking plates for the exhaust ports on the HH head that use the existing stud thread plus tap another below if needed.

 

So for some engine comparisons:

895cc HA – Bore: 69.5mm - Stroke 59mm - CR 8.0:1 - 40 hp at 5900 RPM – 42 lbft at 3500 RPM – Cam duration Inlet: 207° & Exhaust: 225°

1272cc HH – Bore: 75mm - Stroke 72mm - CR 8.2:1 - 60 hp at 5600 RPM – 70 lbft at 3400 RPM – Cam duration Inlet: 229° & Exhaust: 227°

 

My SORG DCOE set-up originally came from a Formula Vee type race car running a 1.3 Polo engine and based on the 34mm Main Venturi (Choke) fitted probably had peak power at over 7000 RPM, the rest of its DCOE components were:

Main Venturi - 34

Aux Venturi - 4.5

Idle Valve - 45 F9

Main Jet - 125

Air Corrector - 190

Emulsion Tube - F11

Pump Jet - 40

Pump Spill Valve - 50

Float Needle Valve – 150

 

I have been running the 895 HA this summer on the below setup with the stock mechanical fuel pump with return-line. Aside from some minor spitting back at 30mph and exhaust popping on overrun deceleration it has been smooth and responsive:

Main Venturi - 24

Aux Venturi - 4.5 ( https://www.carbparts.eu/calc calculator says use 4 but I already had 4.5)

Idle Valve - 40 F9 (calculator says use 30F9 but I could find these and 30F8 gave a hesitation under initial light throttle)

Main Jet - 100

Air Corrector - 150 (calculator says use 145, don’t remember maybe 150 was smallest I could find or I was strict on the main+50 guide)

Emulsion Tube - F11

Pump Jet - 30

Pump Spill Valve - 50

Float Needle Valve - 150

 

My plans for changing the DCOE to match the 1272 HH based on https://www.carbparts.eu/calc and buying the fewest parts are:

Main Venturi – 27

Aux Venturi - 4.5

Idle Valve - 40 F9

Main Jet -110 (calculator says use 115 but I wanted to err towards the main+50 guide)

Air Corrector - 150

Emulsion Tube - F11

Pump Jet - 30 (calculator says use 35 but I’ve got the 30 so I’ll try it)

Pump Spill Valve - 50

Float Needle Valve – 150 (calculator says use 175 but I’ve got the 150 and will be changing to an electric pump & 3psi regulator (no return line))

 

So we shall see how I get on…

Edited by foreststu
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dvderlm

27mm goes well with 34mm inlet valves with 0.8 factor

 

I agree with the calculator for the main jet.

A Pierburg 2e3 with 22/26 chokes for the 1272cc with 229@1mm cammed GK uses 112.5 main jet for the 26mm secondary.

27mm choke is 7% larger cross section than 26mm which scales 112.5 to need a 116 main jet.

 

All engines are different and aux venturi dimensions and big pulses from 1 choke per cylinder may cause variation.

You could use 110 and raise the floats a tad.

 

With that cam and double valve springs you can aim higher than 5600rpm.

Edited by dvderlm
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Really glad you are getting good use of the Polo after all your hard work. Well done on the trophy haul, will be struggling for space to keep em all soon!

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foreststu
On 26/10/2021 at 20:14, foreststu said:

My SORG DCOE set-up originally came from a Formula Vee type race car running a 1.3 Polo engine

 

Just found a website with some interesting information of the performance of these engines: http://www.formel-koenig.de/de/index.html

 

Engine summary; 

"FORMEL KÖNIG", a formula for young people and beginners, is named after the man who founded and financed it in 1987, Richard König, a car and sports seat manufacturer from Baden-Württemberg. It was based on the Italian Formula Panda, the racing formula that many Italian F1 drivers went through at the beginning of their careers.

The tubular frame chassis was given its own body in Germany and was offered to young drivers as a kit or pre-built. In 1988 the first racing season was driven. The racing cars had 1000cc FIAT engines (another site says these were 70 PS).

Due to the availability of the FIAT engines in Germany, in 1989 for the 1990 season, the regulations changed to stipulate the 1272 GK VW engine from the 75 PS Polo GT with a 'mild tuning level' by companies like SORG that produced a stable 100 PS from the engine (other things I have read say that SORG also used 1272 HH engines or maybe parts of as bases). 

In 1996 Volkswagen themselves became involved in the series and the regulations were updated again. From the 1997 season the engine was changed to the Polo 1.4 16V 120 PS at 6500 rpm in stock form apart from the changes necessary to work in the formula cars. Volkswagen withdrew from their involvement in 2003 and sponsorship changed to a German importer of race car parts including those by OMP but the engine regulations have not changed.

 

Stats:

0-100 km/h in 4.1 sec
0-160 km/h in 8.5 sec

 

For interest the formula cars have a total weight (including driver) of 420 kg, use H&R suspension and 3 piece BBS wheels with Bridgestone tyres; Front: 6x13" 180/510-13 and Rear 8x13" 210/570-13.

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foreststu

@dvderlm could I please borrow some more of your brilliant Polo knowledge?

 

I want to tidy up the look of my distributor by moving to one without a vac can which I wouldn't use anyway with the twin DCOE carbs and having something a bit more stubby. An added benefit of moving away from points. That said I don't want to spend a lot on it right now, I started looking into the Webcon DCOE throttle position sensor and that's £100 alone plus everything else capable of taking the TPS signal and making it work, ugh expensive tastes!

 

A quick search brought up the below thread and a few others. I like the look of the KR dizzy and they are available new for circa £25 plus a new electric ignition coil available for less than £20.  I popped to the scrapyard near here to see what they had and got a 1986 MH engine ignition module and loom section for £10. Looked up the part number and seems that these modules are have a few OEM  numbers but are all the same in function as available new Bosch or similar ones list applications from 1.1 through to 2.0 litre).

https://www.clubpolo.co.uk/topic/328957-electronic-ignition-swap/

 

In the thread there are two people with HK engines on standard carb who are using just the above parts seemingly with acceptable performance. Is this because the centrifugal weight mechanical advance lost by using the KR dizzy makes that little difference? Is the ignition module compensating for its absence in some way? (I guess they are also going without the vac advance even though they would still have had a usable port on their manifold unlike me?!)

 

Thanks!

 

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dvderlm

I reckon the ignition amp has a good general purpose curve programmed in that uses RPM signal from Hall sender to perform advance suitable for many standard engines.

 

I don't think there's sufficient advance at idle for twin carbs (that often want 10 to 12 or even 16 degrees with big cam) so you end up with rich idle jet or high idle speed or both. You want to be careful to not exceed 37ish max or suffer knock.

 

Using the KR you could upgrade to mapped ignition like Aldon Amethyst or second hand Megajolt or Speeduino when funds allow.

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foreststu

I spent too much time reading borrowed knowledge on other ignition options over the weekend as I couldn’t stop this niggle in my head that the ignition amp module was too simple to be doing much advance-control-wise. So whilst it would certainly start/run it wouldn’t influence any advance, just a flat-line at whatever static timing the KR dizzy was bolted on at.

This thought started because although there are a lot of OEM part numbers the same Bosch (or other aftermarket) replacement part unit could be used on pretty much any of them. Whilst that could just be that irrespective of engine configuration what they need is basically the same it got me thinking that the ignition amp module in Polo system has the vac/mech advance to control the signal it gives and on the KR the ECU does this (or Diginition ECU for GK). So even if the ignition amp had the ability to vary timing it would only be doing it partially as the unit would be expecting vac/mech or ECU advance to also be happening.

I started looking into layouts and what is inside the ignition amplifier. Finding was that the ignition amp doesn’t have a map, it’s a switch to transfer a strong hall effect sensor signal to the coil. It also has a beneficial function of electrically altering the dwell angle to reduce coil saturation occurring which allows the coil to maintain high energy output in high RPM conditions where it would otherwise have dropped off due to the reducing time available between magnetic field collapses.

 

I don’t fancy having to fit a trigger wheel so I think the 123ignition system is probably the cleanest option out there but at over 500 euros it’s expensive. [https://www.123ignition.de/123-ignition-en/ignition-distributor-vw-golf-2-seat-passat-scirocco-16v-usb.aspx]

 

@dvderlm's suggested combination of the readily available KR static advance dizzy (£25) and an Aldon Amethyst (£200) I think would be second best. It appears that a few years ago they did three input options for engine load; normal inlet manifold vacuum, boost vacuum and throttle position sensor (TPS) output. As I am running a non-charged twin carb setup the first two don’t work for me so I wanted to use a Webcon DCOE TPS sensor (circa £100) but Aldon seem to have stopped selling the TPS version now, I messaged them but no response. So even cost aside that was off the table. [https://www.aldonauto.co.uk/ignition/aldon-amethyst-211/aldon-amethyst]

 

There are a number of companies doing modules that fit inside the distributor to convert from points/condenser to a ring with 4 magnets in it which slips over the 4 lobe shaft and a hall effect sensor for about £40. These are an effective means of removing the timing error that can creep in as the points gap closes from fibre block wear or contactor deposits but they don’t add anything over a correctly gapped points setup. These retain the vac/mech advance of the distributor they are put into.

 

So that brought me back to a distributor designed for electric ignition (so I could get the efficient spark generation given by an ignition amp) like the KR but with a mechanically actuated advance at mid-revs onward (and a vacuum advance at low revs disappearing at wide-open-throttle I wouldn’t have a signal for with the Webers). Borrowed knowledge again identified two donors with the same cam fitting as a mechanical head Mk1-Mk2 Polo engine which that could be used with the common ignition amp module and connecting cable from may period VW’s including Mk2 polo. The more common seems to be the Saab 900 or 99 non-turbo 2.0 litre and then there is also the Mk1 Seat Ibiza, Malaga and Ronda 1.2 or 1.5 litre.

The Saab dizzy has mounting holes for 3 bolts like the original Polo dizzy but they are offset differently so I have heard cases where they need to be elongated to allow them to be bolted in at the correct static timing.The Saab dizzy also uses a slightly oval hall sensor plug so the Mk2 Polo connector needs replacing with the one from the donor vehicle. Used Saab dizzys that I could find were pretty expensive (>£100) with more for sale located in America.

The Seat dizzy may have some differences in mech advance between 1.2 & 1.5 but I doubt there is much in it and they have the same rectangular hall sensor plug as the Mk2 Polo. The Seat dizzy only uses two bolts like the KR but they are in the right places to match with two out of the three on the cylinder head mount. Used Seat dizzys only seemed to be for sale on Spanish auto-breaker websites or Spanish eBay but cheap at €30. Bosch part numbers I have searched that have yielded results are:

 

Saab 2.0 Distributor:

0237021014

 

Seat 1.2 Distributor:

0237021050

0237021027

 

Seat 1.5 Distributor

0237021040

0237021026

 

Whilst looking I managed to find a UK company selling a NOS 0237021040 Seat 1.5 Distributor so the plan is to use this with the scrapyard Mk2 Polo ignition module (in my case 211 905 351E)/loom section cable/coil. I might rotate the dizzy 180 to hide the vacuum can and/or remove the can and put a small plate over the hole and/or not bother!

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Some useful links:

@polofin build using the Seat dizzy https://www.clubpolo.co.uk/topic/328087-polo-n-mk1-1976/?page=2

@Gaz FAQ on Electric Ignition https://www.clubpolo.co.uk/topic/6042-electronic-ignition-on-polos-without-it-faq/ 

 

Edited by foreststu
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