Alfa Pages

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

hmmm appears that the static idle of 9/10 was too much.

Was in heavy traffic last night and accelerating fast hearing pinging above 3000 rpm again.

Got home, lowered it back to 8. Was a bit sluggish off acceleration. Crying or Very sad

This is proving to be tricky.
I hope is not the secondary spring that needs replacing.
I believe its the sum of both of them that control the advance at higher revs.
So if I put a thicker primary spring in then it should lower the total advance.

I was reading this article with interest. He's basically using only 1 spring, second one used as a stop.
He says this produces a more linear curve.

I have a secondary spring that is very thick and would act a stop almost.

Distributor advance
_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

Considering sending my old bosch dizzy to H&H for a total rebuild and re-mapping service.

I need to find a donor dizzy.

Been offered one locally but its from a very early boxer (82 - unknown so far) and it has points.

I have an electronic version, 2 wire output.

How easy is it to get a points dizzy hooked up to my current set up?

What do I need to know about the old dizzy?
Hopefully will just be a donor for a couple of months.

1.3 and 1.5 boxers they come from.
Trying to get some serial numbers from him.

Electronic to points anyone?
Easy connection?
_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

Problem solved I think. Found myself a dizzy in uk. Will send it to h&h for a complete service and remap.
Also found a 16v oil pump. Better flow so I might be able to use a thinner oil and still have good op at hot idle.
Now just got to get them sent down here! !!
_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

Better late than never.

Finally got hold of the reconditioned dizzy from H&H.
Has a very smooth action and linear curve.

They did underestimate how bad the petrol is here so I had to add a couple of bushings on the centrifugal weight end stops as it was pinging around 3000 rpm even with a low timing at BTDC.

With the bushings I can run it at 9 degrees BTDC and full power up to 6000 rpm without any pinging.

Also eliminated a flat spot I had below 2000 rpm.

Nice work guys!!

Now I was laid off yesterday I can enjoy it a bit during the summer school vacations here until March!!

Shocked

_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

ZeNiTh-PbArM · Posted: Fri Jan 10, 2014 11:16 pm Post subject:

Hi Brit,

Glad to hear you solved the issue with the ignition.
By the way, are you now happy with your hydraulic lifters? Have been reading your story with the INA replacements and am not sure how it ended up...
Been fiddling with lifters lately and this gave me quite a number of nightmares as well.

Regards,
zp

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

ZeNiTh-PbArM · Posted: Sun Jan 12, 2014 5:37 pm Post subject:

Hi Brit,

A while ago I changed the tappets and been using some VW model I had in stock which looked like it was going to fit. Unfortunately the car sounded like a sewing machine since the first ~1mm or so of the lifter stroke would always stay soft. I did two full heat cycles, tried bleeding the lifters by keeping the RPMs high for quite a time, no luck.
I ended up tearing everything apart again to replace the lifters with some NOS items I had. I was quite angry that I had to do the job twice and ended up replacing the lifters in 3hrs40min all included!
What's the part number you used and how did you put a stop to the intermittent ticking and cold start clacking you reported?

regards,
zp

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

ZeNiTh-PbArM · Posted: Sun Jan 12, 2014 9:54 pm Post subject:

Hi,

I had installed 038 109 309. Measurements are just the same including piston height of the lifter. But obviously not quite the same spec !
The cams were really in good shape and the lifters did not show any particular mark of scuffing or wear before replacement. Only they were quite noisy on startup and with engine hot, therefore the internal leakage rate must have been too high due to wear.
There is no issue in using NOS lifters, I only wanted to test a different part number because NOS items are getting quite scarce these days.

Regards,
zp

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

What are people using as their static idle advance setting?

I've got mine at just above 8 degrees. Think I can push it to 9 or 10 for a cooler idle.
When would it start to kickback on starting?
_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

Now I have the detonation sorted and right dizzy curve I have refitted the msd unit.
_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

mg907 · Alfasud Joined: 12 Dec 2011 Posts: 38 Location: Italy

Hi
in my 33 the static advance is set at the correspondence of the I mark on the flywheel ...

https://picasaweb.google.com/110916262030376023265/33?authkey=Gv1sRgCI7_tP6byfz15QE#5945665869236784306

...with the arrow on the crankcase rear cover.

I do not know how many degree of static advance I've got with a similar setting, but I notice no kickback on starting neither pinging on uphills.

(the second issue is very unlikely in my case because my engine usually runs with LPG that has an extremely high octane ratio).

Just a question, which method are you using to calculate 8,9 or 10 degrees?

Mario

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

I was measuring by eye only using the timing light. A couple of mms at a time from the 8 degree mark on the flywheel.

Anyway I found it to be too advanced yesterday.
I set it back at the standard 8 degrees.
_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

mg907 · Alfasud Joined: 12 Dec 2011 Posts: 38 Location: Italy

Thanks for your clarification!

I was only wondering if you where struggling against any (approximate) trigonometric formula like:

sin(AdvanceDeegre)*FlywheelRadius

Smile

Mario

(anyway, if someone is still interested in maths I can provide the measure of the flywheel radius because I've got a dismounted spare engine)

ZeNiTh-PbArM · Posted: Tue Jan 28, 2014 12:22 pm Post subject:

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

Hi zp

I am sure there is a thread about hydraulic tappets here.

Would be good to add your findings to that.

Shame the tappets aren't easier to change and experiment.
_________________
S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

Bobkelso · Posted: Fri Jan 31, 2014 7:58 pm Post subject:

Nice drawing.

Really not sure but It seam to me that the way the two
coils work together wouldn't generate backlash,
maybeonly a softer transition, like a small damper,
to reduce pressure on cams during initial opening
(at a cost of valves opening less a minimal fraction of mm)

..maybe I'm wrong and it depends also
on where are put the lateral holes
for oil pressure to arrive in the internal parts.

Ps.: should it be present also a small
coil acting on the sphere?
http://www.cuorialfisti.com/tecnica/punterie.htm
_________________
Alfa 33

ZeNiTh-PbArM · Posted: Sun Feb 02, 2014 9:52 pm Post subject:

Hi,

You are right there is a small cup and coil on the ball. I omitted this for clarity.
The way the back spring generates backlash is, before the hydraulic element expands the backspring expands a little and this generates some slack.
Ive measures this backlash to be consistently around 0.4 - 0.5 mm and this is puzzling.
If I remove the back spring and pump in oil the backlash gets away.
Go figure...

regards,
zp

RFlower · Posted: Mon Feb 03, 2014 11:47 am Post subject:

Interesting that the 4-5mm backlash you measure is about what is specified on our Sprint engine, which has solid tappets.

Maybe the reason is that, on startup, without any backlash, the hydraulic element is expanded by oil pressure to take up all the clearance, and as the valve heats up its length increases, preventing it from closing completely.

I have always thought that this is a disadvantage of hydraulic lifters.

The small backlash will ensure that the valve always closes tightly, at the expense of a slight increase in tappet noise, which I find pleasant anyway Very Happy

Edit: The oil trapped where the small spring is situated will have to be pushed back through the feed hole, which will stop the backlash being taken up too suddenly, and reduce the noise created.

ZeNiTh-PbArM · Posted: Tue Feb 04, 2014 12:06 am Post subject:

Hi

I must say the noise generated is most unpleasant and quite more significant than the noise you get with solid lifters. Maybe this is due to the cam profile being different.
At the same time you don't want the valve hitting the seat too hard in order to avoid damage to the seat and to the valve.

Heat-up phase with hydraulic lifters is quite interesting as the valve expands quicker than the head does but the leak-down rate of the hydraulic element is supposed to compensate for that. Of course this is dependent on the oil viscosity (one of the reasons why recommended oil grades are important!)

regards,
zp

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

ZeNiTh-PbArM · Posted: Thu Feb 06, 2014 12:02 am Post subject:

Hi Brit,

I sure will !
Not sure how you ended up selecting normal against lightweight lifters though...
I'm just trying to get a little bit wiser by understanding how stuff works and how to improve reliability and operation of the engines I work on.
It's impressive how little people (including myself) know about engineering details of most parts of an engine.

regards,
zp

Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665