Pistolpete's Mars Red Mk1 GTi restoration

jakethepeg007 said

That's mega, great work throughout and a worthy outcome!

Looking forward to reading the green resto now

Thanks Jake, the green one will be built to be driven.

So I finally got the exhaust properly sorted and sitting exactly how I want it.  Took quite a bit of messing about to get the 60mm pipe over the rear axle without hitting it.

I'm now trying to get the car running 100%, and would appreciate some advice.

To summarise the mods, car is totally standard bottom end, with stage 2 head running Schrick 276 cam and all new valves/guides/springs, tappets re-shimmed etc.  I have the Audi 2.2 throttle body  with inlet manifold ported and polished to match, uprated WUR with the allen screw adjustment exposed on the back.  K&N filter element, stainless 4-branch manifold to stainless 60mm exhaust system.  Everything is new, literally everything from fuel pump and lines, to plugs/leads/coil/dizzy cap and rotor arm etc.

The car starts fine from cold, idles ok if a little lumpy, and once warmed up idles nicely.  When you put your foot down it goes really well indeed, but when just tootling along at constant speed on light throttle (any speed, any gear) the engine is kangarooing.  It also splutters a little when picking up from low revs.

I had previously set WUR with cold control pressure at 1bar and the warm control pressure rose to 3.4bar.  System pressure is 4.9-5bar.

The timing is absolutely bang on at 6° BTDC, set with the stroboscopic timing light on No. 1 cylinder and the diamond mark on the flywheel in the middle of the gearbox hole.

I also have a Gunson Professional gas tester, and have played about with mixture from 2%-4% CO content with no real difference.

What should I do next to try and get rid of this stuttering at constant speed and light throttle?  Maybe it just needs to get set on a rolling road, if you think that's best then I'm happy to do that too.  I just want the thing to drive 100%.

What you are experiencing seems very similar to how mine feels - although I can't really open the throttle as the bottom end is all freshly rebuilt so needs some gentle running in. To me it feels as it there is a blockage (I know there isn't as like you, it's all new/very clean) but it's that kind of hesitancy. You can really notice it when it's at 2-2.5k rpm. I will be rechecking my fuel pressures, and getting it on a proper gas analyser to check the mixture. One thing I was going to try was running it with the vacuum disconnected (and plugged) from the WUR just to rule that out. But ultimately, when it's run in, I want to get it on a rolling road.

paceman said

What you are experiencing seems very similar to how mine feels - although I can't really open the throttle as the bottom end is all freshly rebuilt so needs some gentle running in. To me it feels as it there is a blockage (I know there isn't as like you, it's all new/very clean) but it's that kind of hesitancy. You can really notice it when it's at 2-2.5k rpm. I will be rechecking my fuel pressures, and getting it on a proper gas analyser to check the mixture. One thing I was going to try was running it with the vacuum disconnected (and plugged) from the WUR just to rule that out. But ultimately, when it's run in, I want to get it on a rolling road.

I did consider checking the fuel control pressure again.  I've also heard people run timing at 8deg BTDC, I'm wondering if I should try that and see if it makes a difference. It does seem to be a little less lumpy with a bit more advance on the ignition timing. 

I wonder how you work out where 8deg BTDC is on the flywheel! I'm sure there is some maths to get a measurement to make a mark, but it's pretty hard to measure when it's on the car.
Anyone got a DX flywheel that can provide the diameter (across where the timing marks are)

I can try to get you a measurement tomorrow,  my old dx is at my mums!

you can use this type of timing light to preset the flash for any timing, if I remember when you set the degrees you want it will flash at 0 once your there

https://www.ebay.co.uk/itm/Powerspark-TL200-Adjustable-Advance-Strobe-Light-Ignition-Timing-Lamp-/360513112288?mkcid=16&mkevt=1&_trksid=p2349624.m2548.l6249&mkrid=710-127635-2958-0

That's the size across the face with the timing marks

the spark plug is normal colouring mate

jakethepeg007 said

That's the size across the face with the timing marks

Great stuff!

237mm dia => circumference 744.5mm
8 degrees is 16.5mm measured on the circumference. I'll mark that out on a piece of tape and see if I can stick it on the flywheel to make a mark - all through that tiny hole in the gearbox!

Thanks for the info gents.

I decided it was worthwhile re-checking the fuel pressure settings, so rigged up the pressure gauge again to the WUR.  Bearing in mind I had already set this at 1bar cold control pressure, I was surprised to find that the cold control pressure was way down, actually sitting at around 0.3bar.



The only difference between last time and this check was that I removed the vacuum line from the WUR and plugged it both sides.



Adjusted the cold control pressure back to 1bar, and when I re-connected the electrical connector the pressure steadily rose and ended up at 3.6bar, which is correct.  System pressure is a healthy 5.2bar.



I then went through the whole process again of ignition timing and CO checks using my Gunson meter.  At 6° BTDC and CO set to around 2%, car didn't run very well at all.  Was popping and banging out of the exhaust on idle, and was spluttering when revving the engine.  A quick drive and it was very stuttering and hesitant.

I decided to tweak the timing by ear, as it seemed to run noticeably cleaner if the timing was advanced more than the 6°.  I left it so I could only just see the diamond 6° mark in the flywheel inspection port using the timing light, but don't know exactly what this equates to.  I've left it like this, with CO reading set to 2.5% and it is driving much better although still not perfect.  I'm not convinced on the accuracy of the Gunson gasmeter as you calibrate it to 2% in air, then put it in the exhaust to get a CO reading, but every time you take it out and leave it in air it never goes back to the original 2% calibrated value and needs to be adjusted again.

I have a run out tomorrow, so will see how it goes over a longer drive.

You will get there eventually Pete and great meeting you today at Titanic Dubs and congratulations again on your prize - well deserved.

Oldschoolcool said

You will get there eventually Pete and great meeting you today at Titanic Dubs and congratulations again on your prize - well deserved.

Thanks Mark, was good to meet you and put a face to the Forum name. Your Mk1 is a lovely example, a really  genuine and original looking car.

See you at the next show!

Titanic Dubs show in Belfast yesterday, cracking day for both the weather and the standard of the cars.  Was really chuffed to come away with a prize for one of the ten Best in Show.

Great setting for photos too, so I stayed behind after the crowds had left to grab some shots.

Great pic Pete, I was wondering how you had got that one - thought you had arrived early!

Little bit of an update on this Mk1.  Put another year's MOT on it at the start of the summer, and then it sat in the garage all summer.  

One thing that has always bugged me is the MFA on the car died, no doubt after car was left with no battery for so long.  It always worked perfectly when I was using the car more often before the resto.  Then the LCD screen also starting bleeding.  After unsuccessfully trying to replace the LCD with a new MFA screen from ebay, I decided to send them off to Crazyquiff's for repair.  Rich was able to replace the LCD screen, but the MFA still wouldn't function, and even the clock display was very temperamental. in the end, he had to send them back unrepaired.

Everything else works perfectly, the fuel consumption gauge and economy shift light etc all work ok.  Anyway, I thought I'd stumbled on the holy grail, a brand new old stock MFA circuit foil for Motometer clocks, still in its original packaging.  So, out came the clocks from the dashboard and off I went.



Original clocks ready for the swap







 And after a period of very careful manipulation into position, new foil installed:-


And the result……still not working!  

I've tested the MFA stalk switch and it's fine.  I've pulled the fuse and reset it etc.  The clock display eventually comes on, and it will count on with time, although I cannot actually set the correct time.

Am I missing something?  I would have thought a brand new foil circuit would have cured the issue.  Very frustrating.

I'm having similar issues with my Motometer clocks, I sent them to have a new board by the guy in Austria who is making them now, and I have a video of them working perfectly on his test rig, but since trying them in the car the MFA screen just shows 0:00 and I can't go through the MFA menu either. I've put it down to a fault on the board internally that the screen mounts onto. Luckily I have a set of VDO clocks that work in a fashion that I'm using them for the time being until I find a new or working board for the other set.

Memorextape - So did the guy in Austria not fully fix your clocks problem? 

What issues did they have before you sent them over? I'm only asking because mine had issues before the car when in for bodywork and I was considering sending them over to Austria to get fixed. 

Dano
Unfortunately I can't remember what the original problem was, it may have been the screen didn't work but it was quite some time ago since I swapped them for the VDO set.

When I sent them to him, I hadn't tested them and when he tried them it was discovered the screen had gone, which I didn't think would be a problem since you can get replacement screens now,  but it turns out the screens used in Motometer clocks are different to VDO and are unavailable. I had another set of Motometer clocks I robbed the screen and board out of and sent out to him - I tested this set and nothing worked at all but thought it was worth sending it anyway to see if he could fix it. I don't know what he did but I've got a video of them working faultlessly before he posted them back.

I can't fault his work though, the issues I'm having I'm putting down to the board internally. Communication and the finish is excellent and I know others haven't had any issue once they have got them back.

Thanks for the update. I'll wait it mine returns from the shop to see what's working - or not!! 

Cheers.?