strikerguy
|
| posted on 27/7/13 at 10:54 AM |
|
|
Crossflow tdc mark on pulley
Need some advice on this very strange issue.
(I am dutch, so there could be some translation faults in this topic :-) )
I recently bought a 1990 Sylva Striker with a Vulcan 1360 cc crossflow engine with bcf2 cam. This Sylva did not run for several years. So besides
obvious issues with that, i have troubles getting the ignition sorted.
It looks like the mark on the crankshaft pulley is 45 degrees advanced with reference to the TDC mark on the block.
I am used to set the ignition by ear on idle. If i do that, then it runs ok and likes to rev. As adviced by Vulcan the best figures for this setup are
16 degrees at idle and 34 degrees at 4000 rpm.
When i use the stroboscope and the settings on the pulley and block with these figures, the results are terrible. It idles like sh... and immediately
runs hot. Clear signs for a retarded ignition !
I will use some methods found on this forum to determine the real TDC, but i am still curious if you recognize this behaviour.
Regards
Dirk strikwerda
The Netherlands
|
|
|
|
|
theconrodkid
|
| posted on 27/7/13 at 11:38 AM |
|
|
welkom bij het ​​gekkenhuis 
best to start from the begining,remove NO 1 spark plug and find TDC with a screwdriver down the hole.
the marks on the pulleys may or may not be in the right place 
who cares who wins
pass the pork pies
|
|
|
britishtrident
|
| posted on 27/7/13 at 12:02 PM |
|
|
As above is good enough for ignition timing, old time mechanics were taught to use a pencil down the plug but these days I use a plastic rod cut
from a plastic coat hanger. i
At the true tdc you can rock the crank back an forth a tiny amount and piston will not move any discernible amount, in other words there is a dead
zone with virtually no movement of the piston. Mark the TDC on the pulley in the middle of the dead area. Old time mechanics used to refer to
describe it as TDC being on the rock of the crankshaft. You can of course by special tools quite cheaply off ebay.
*****As the engine has not been in use for some years one thing to check is the that the mechanical advance in the distributor is free and not
sticking, it requires a tiny drop of oil ****
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
strikerguy
|
| posted on 27/7/13 at 12:58 PM |
|
|
Ok, now it is getting weird...
I checked the TDC mark with piston 1. Spot on !!!! WTF !!!!
previously i completely replaced the ignition part of the engine with Lucas sports coil, new leads and plugs and new dizzy with Accuspark.
What is going on here ? Stroboscope down the drain... ?
|
|
|
Dick Axtell
|
| posted on 27/7/13 at 02:29 PM |
|
|
Have you checked the spark + TDC combination? Just to verify that the distributor is in correct position. From recall, the dizzie drive has an offset
key arrangement on the Xflow engine, so should not be possible to get the dreaded 180 degree out problem. Hopefully!
Work-in-Progress: Changed to Zetec + T9. Still trying!!
|
|
|
theconrodkid
|
| posted on 27/7/13 at 03:53 PM |
|
|
dizzy drive is helical gear,you are suposed to have the rotor arm pointing to NO 1 inlet port when it,s at tdc/firing on NO 1.
has your strobe got advance on it or is it just a flashing light ?,unlikley the strobe is broken.
if nothing else works,just do it by ear
who cares who wins
pass the pork pies
|
|
|
rusty nuts
|
| posted on 27/7/13 at 04:48 PM |
|
|
Probably auto advance not working as it should, distributor may benefit from stripping and freeing off , make sure the cam is free to move on the
distributor main shaft. Common problem especially on engines that have not been used for a long time.
|
|
|
strikerguy
|
| posted on 28/7/13 at 12:11 PM |
|
|
quote:
Originally posted by Dick Axtell
Have you checked the spark + TDC combination? Just to verify that the distributor is in correct position. From recall, the dizzie drive has an offset
key arrangement on the Xflow engine, so should not be possible to get the dreaded 180 degree out problem. Hopefully!
That thought crossed my mind, but then it is a non-runner i suppose ? And it runs....
|
|
|
strikerguy
|
| posted on 28/7/13 at 12:20 PM |
|
|
quote:
Originally posted by theconrodkid
dizzy drive is helical gear,you are suposed to have the rotor arm pointing to NO 1 inlet port when it,s at tdc/firing on NO 1.
has your strobe got advance on it or is it just a flashing light ?,unlikley the strobe is broken.
if nothing else works,just do it by ear
I checked if the rotor arm was pointing towards cylinder 1 on tdc. And it was....
My strobe has got an advance knob. With some racy cams it is best to set the ignition timing at high revs. Whatever it will end up at idle. So you
need such a strobe because them stupid manufacturers only provided a dial from 4 - 12 degrees on the engine .....
[Edited on 28/7/13 by strikerguy]
|
|
|
strikerguy
|
| posted on 28/7/13 at 12:23 PM |
|
|
quote:
Originally posted by rusty nuts
Probably auto advance not working as it should, distributor may benefit from stripping and freeing off , make sure the cam is free to move on the
distributor main shaft. Common problem especially on engines that have not been used for a long time.
I completely replaced the ignition with new stuff, so i doubt that's the case....
|
|
|
rusty nuts
|
| posted on 28/7/13 at 02:02 PM |
|
|
quote:
Originally posted by strikerguy
quote:
Originally posted by rusty nuts
Probably auto advance not working as it should, distributor may benefit from stripping and freeing off , make sure the cam is free to move on the
distributor main shaft. Common problem especially on engines that have not been used for a long time.
I completely replaced the ignition with new stuff, so i doubt that's the case....
If it runs OK at fast idle when set by ear but runs poorly at idle or runs OK at idle when set with a strobe but runs poorly at fast idle then it
sounds like the advance curve on the distributor isn't what's required
|
|
|
strikerguy
|
| posted on 31/8/13 at 11:55 AM |
|
|
I found another post on this forum describing exactly the same problem. Unfortunately the post stopped and there is no real solution noted.
But, it is suggested that the timing of the camshaft could be an issue. If e.g. the timing chain is one tooth below or above on the camshaft sprocket,
this could explain the ignition timing issue.
But if that's the case, what effect would the wrong camshaft timing have on the behaviour of the engine ? Cold start with one push on the
button. Warm start needs a longer push and sometimes the engine kicks back. Idles like a bag of spanners and no of revs is very unreliable, somewhere
between almost stalling and 1500 rpm. Above 2000 rpm ok, accelerates ok but at around 5000 rpm it slightly splutters and coughs. Liftoff at higher
revs gives some bangs in the exhaust, but nothing like entering the soundbarriere or so.
I visually checked the valves in relation to the TDC. In the same post it was said that at TDC the valves on cylinder 4 should be rocking. And they
do.
Is there another way to check without having to remove the gearbox, sump and timing cover ? The Burton catalogue also describes a method but then i
need to fetch a timing disc and gauge first...
[Edited on 31/8/13 by strikerguy]
|
|
|
.jpg)
