Tappet adjustment

[NicBeeee]

HI,

After a recent engine rebuild due to water leak everything has ran fine, however I am a little dissapointed in the engines performance particularly uphill (please before someone mentions get a different vehicle I am comparing it to other 1.9 DG`s) it is no poorer than before rebuild but no better, now I have got a decent hill to practice on coming out of the village, after the rebuild I adjusted tappets according to Richard Atwells advice. Warm engine, 1.5 turns. However, bored and a tidy workshop I decided to play a little with the adjustments, first 1.25 turns, A little quicker up hill, second 1 turn, even a little quicker, went for 1/2 turn, rocket (over the top statement) speed. Panicked and re set to 1.5 turns as Atwells advice mentioned valve train wear if undertensioned, engine still sounded smooth. Any advice on wether to leave as is-tortoise pace or reduce tension-hare pace, and we all now how that story ended.

Cheers nic

[itchyfeet]

Really depends if you have solid or hydraulic tappets
Origionally hydraulic but one or two reconditioners use solid

[kevtherev]

1/2 a turn just gives the lifter enough preload to return the piston and fill the lifter
1 1/2 turns gives the lifter a strong return stroke

We are only talking about a difference of 1 1/2 mm here the lifter has a piston stoke of 4mm

Once the lifter is pumped up it remains in contact with the cam, it does not alter the valve timing.
A lifter thats not pumping up will affect valve timing

[NicBeeee]

1/2 a turn just gives the lifter enough preload to return the piston and fill the lifter
1 1/2 turns gives the lifter a strong return stroke

We are only talking about a difference of 1 1/2 mm here the lifter has a piston stoke of 4mm

Once the lifter is pumped up it remains in contact with the cam, it does not alter the valve timing.
A lifter thats not pumping up will affect valve timing

Cheers Kev, so adjustment only alters the strength of the lifters return stroke and not the length of the stroke of the valve`s ?

Really depends if you have solid or hydraulic tappets
Origionally hydraulic but one or two reconditioners use solid

Good point, Hydraulic

[sarran1955]

Hello,

After a recent engine rebuild due to water leak

What else did you do... barrels off... piston rings.....

Valve regrind.....

Can you do a compression test....

All the leads on right, and nice vacuum lines and flexies....

Vw flat 4's .... a lot of poetry... little magic....

Cordialement

[NicBeeee]

Hi Sarran

Yep all of the above are ok and within tolerance, changed rings as a matter of course, exhaust valves changed due to slight hairline crack, slight crack between valve seats but not too deep, engine doesnt smoke, rattle or bang, ticks over nicely. Just no oomph in 5th gear. Timing ok, fuel mix ok.

[ghost123uk]

I find your findings very interesting Nic (and good on you for having a "play" like that )

I don't have the in depth knowledge Kev has so cannot add anything useful, but I wonder (as I am sure you do) why you got those improvements. That tappet adjustment page tells you a lot but does not tell all (Kev's words explain more about the "why" rather than the "how")

[ghost123uk]

Sorry, = "back to back" post

Do you mean less Oomph in 5th than before ? I find non of the DG's have much Oomph in 5th

~~~~~~~~~~~~

If 1/2 a turn in resulted in best performance, is there a reason that Nic cannot leave it at that setting ? (he asks, risking being told "it's all in the tappets page")

[NicBeeee]

Do you mean less Oomph in 5th than before ? I find non of the DG's have much Oomph in 5th

No, its pretty much the same as before the engine rebuild, as you rightly mentioned my main concerns were what damadge could result in me leaving it at 1/2 turn and why did it give me more top end power ? After all I have lived with the lack of power since buying the van and would prefer it to run slow than to not run at all. Just be nice not to look at the queing traffic in my mirror when I get to anywhere hilly if you now what I mean. Top speed at the moment is around 65 mph,uphill lots worse, Oh and I have checked and renewed filters, pump push rod as part of engine rebuild. Just had a thought is it possible that worn parts involving the throttle cable/pedal may be hindering my fault finding. Need to get somone to hit the pedal whilst I see if I can push the throttle any further manualy.

[ghost123uk]

65 mph = Oh dear, summat is wrong. Have you had a compression test done on it ?

Mind you, that last sentence of yours definitely is worth looking into first (use a brick on the pedal ) - or "T25 cruise control" as some folk call bricks

[NicBeeee]

Have you had a compression test done on it ?

Mind you, that last sentence of yours definitely is worth looking into first (use a brick on the pedal ) - or "T25 cruise control" as some folk call bricks

Yep compression is good and balanced, the sun is shining so I am now going to find a cruise control in the garden and will report back later.

[ghost123uk]

While you are there, check that the vacuum operated "pull down" unit is opening the second choke on the carb when you apply a lot of throttle (engine running) but take care not to over rev it with it having no load on it

Kev, what is the best way to check the pull down unit, can you suck it open like you do with the dizzy vac unit ?

[kevtherev]

Remove the pipe from the carb
Suck the pipe
Pulldown should open the choke flap if the engine is cold
If you can continue to be able to suck...its shagged

[itchyfeet]

2nd choke on the carb is operated by the vacuum unit on the rear of the carb
choke pulldown is on the front
Vacuum unit for the 2nd choke will only operate once the throttle is sufficiently open by a cam arrangement
As its at the back its hard to get your mouth in a poition to suck on the pipe so you can borrow the vac plastic pipe to the dizzy to extend it

[NicBeeee]

While you are there, check that the vacuum operated "pull down" unit is opening the second choke on the carb when you apply a lot of throttle ?

Cheers for the tip, it was replaced last year but I guess this means nothing, will check Kevs way tommorow, stuck at the moment trying to change ball joint on smart car for MOT tommorow morning during a monsoon like storm. Accelerator looks ok apart from carpet, rubber mat, insulation, speaker cables all sitting under the pedal bump stop, got anouther 1/2 " of play by removing them, unfortunately it only equated to 1mph extra.