got this yesterday...seller didnt say alot about its history but its either new or been refurbed to like new , spot less everywhere and no signs of nuts on the studs etc , cam has been turned over , dunno maybe it was taken off a brand new engine ?

I was just looking at one of these this morning. It still had VW Audi sticker on it. 

oh for sale ?

the "new" head came with this unused looking cam , can anyone i.d it 

 

was a chart around at one time showing the lift /spec...almost a shame not to use it sinse its like new 

3 hours ago, steveo3002 said:

can anyone i.d it  was a chart around at one time showing the lift /spec

 

The chart is in this post https://www.clubpolo.co.uk/topic/235735-polo-8v-camshaft-identification/

 

randomly browsing the net as you do....wonder if it could be this ?  didnt really know any better but this new head the valve guides have zero slop , the old head they have noticable play

 

Worn guides can likewise pass air. “Unmetered” air pulled through the intake ports past the guides produces an effect comparable to worn throttle shafts on a carburetor. The additional air decreases intake vacuum and distorts the air/fuel calibration of the engine at idle. The consequence can be a lean misfire challenge and rough idle.

22inHg vacuum, 170psi compression 

 

On mechy head I think the valve guide is allowed an incredible 1mm of play.

 

Thought the valve stem seals would stop air leak down the guides.

But if the valves occasionally aren't seating well, yes, havoc. 

 

yeah most likley a wild stab in the dark

 

id guess my head has 1mm or so play yet never burned any oil or smoked at all...wonder if they add to the engine noise ?

watching the vids again ...block 4 , box 3  the timings dont really match up to gaz's  although he has an aftermarket cam

 

thing is i dont know if its the timing moving = bad idle ...or is the timing jumping around trying hard to keep it running 

Digifant setting (watch out for American Digi II)

http://www.shoebox-electronix.com/assets/VW_Digifant_Manual.pdf

 

How Idle stabilisation works(with Haltech)

http://forums.haltech.com/viewtopic.php?t=6543

 

VW SSP 87 Digifant in G40

http://www.volkspage.net/technik/ssp/ssp/SSP_87.PDF

 

suggests to me that there's ignition controlled and throttle plate controlled idle stabilising systems  A PWM modulation of throttle angle lets more air in to speed up, and more ignition advance below 750ish  speeds up. 

Throttle position base setting looks important, buzzing control unit on the throttle body too. Ecu earthing points matter.

 

Hope that helps.

 

head is off

 

bores look fine no scoring etc 

valves all look the same but sooty ..to be expected with it having been so rich  (oily marks are spills from where its stood on its side )

 

only thing i can fault is inlet has oil or petrol residue in it again?  which i dont understand as theres no where for it to come from 

Edited 9 October, 20187 yr by steveo3002

Be interesting to see the other side of the valves.

 

Digifant injectors are not sequential firing, they pulse once every 2 crankshaft revolutions simultaneously, so in theory the fuel could pool/condense when inlet manifold cool.

Leaking injector?

 

I found somewhere else that ABD is specified as 6 degrees +or-1 BTDC static advance.

valve insides look sooty too..will grab a pic another day

 

thing is the pooled fuel /oil is in the rear most part of the manifold , nothing in the runners and the inj are right at the very end nearest the head , no signs its been dribbling from the fpr vac hose  

Right. So possibly carbon stopping good flow or seal along with valve guide play. Hot soot can pre-ignite too.

 

There's one throttle plate, surely the fuel and air mixture bounces around the inlet manifold when a valve closes for the inlet runner it is heading down,  joining in rest of mixture that might still be there from 1 to 3 to 4 to 2 suction strokes before the next injection pulse. Perhaps there are more pulses while cranking.

 

Suspect that's why direct cylinder injection is holy grail.

yeah well sit tight lets see what happens 

 

doubt theres fuel bouncing around in the manifold...while its not direct inj it pretty much points straight into the head port 

 

got a feeling the head wasnt the issue

right - getting somewhere now 

 

new /refurb head is on , confirmed it is the gt cam too

 

exh sounds smooth now with an untouched afm ...havent tested the emissions yet but should be better

 

somethings up with the timing for now, set it by ear earlier in the day , starts and ran ok , went out by torchlight and set it properly and it wouldnt hot start , so turn the dizzy a bit and its running again , will re investigate that again in daylight

"Properly".

is that 6 degrees BTDC for ABD? 

Or 5 degrees for 3F?

 

Use the vac gauge to set timing first, then lean it out.

by properly i mean disconect the blue temp sender when hot , rev to 3000 x3 then set timing at 2250  

 

ive been going for 5-6 degs which shoudlnt be far off....5 deg +/- 1 for a 3f

For 3F with engine warm to at least 80C and big electric consumers off and fan not cutting in during procedure and idle speed adjust  I  agree.

 

Spec is 6 +or-1 for ABD. If you get high HC again increase from 5.

3F Idle speed adjust for 900 +or-50 rpm. CO at idle 1.2% +or- 0.2%, then replace Blue temp sender.

 

14.11:1 to 13.98:1 AFR 

Edited 16 October, 20187 yr by dvderlm

i will see how i go ...didnt have hot start probs with the old head so maybe ive fluffed it up

 

1 deg isnt going to make or break the way an engine runs 

got the wideband on today 

 

set it to 13.9-1   - 14.1-1 which should equal just over 1% co or so

 

re set the timing , drives well but very jump at small throttle openings , not good enough but will play with the mixture and timing and see if i can tune it out

 

at least it stays running at mot'able emmisions so ive certainly got somewhere

 

exhaust still sounds a bit funny 

Sounds like progress.

So valve seat/wiped cam lobe/coked up in original head?

 

Might there still be water/moisture in exhaust?

still using the 3f cam ...the new head came with some random cam so didnt fit it

 

i think i will try and get some miles on it and work out any niggles , its not had any use all year really

 

oil might be a bit fuely too

 

might cobble the wideband up so i can run it for a while , check cruise /wot is suitable

On ‎16‎/‎10‎/‎2018 at 19:51, steveo3002 said:

, confirmed it is the gt cam too

So the 030d marked is a random cam, not gt cam.

😕

https://www.clubpolo.co.uk/topic/263739-what-camshaft-is-this/?do=findComment&comment=2190701

says HZ, ACM or AAK

 

https://www.clubpolo.co.uk/topic/235735-polo-8v-camshaft-identification/?do=findComment&comment=2508610

196 duration @ 1mm lift

Edited 17 October, 20187 yr by dvderlm