setting tdc

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2005lyndon

New Member
Posts
50
Location
stafford
is there an idiot proof way of setting tdc,
ive been trying to get the engine going in my mgb v8 for a few weeks now,
(as if owning a p38 wasnt enough of a challenge)
its an sd1 endine with a range rover v8 flapper efi system fitted, ive gone through the efi testing manual written by ramone, and everyting checks out, its got new plugs and a new coil, theres a good spark, and fuel, the injectors are pulsing ikt still doesnt start
ive set tdc three or four times times eventually ignoring the tdc marker on the pulley, and done it with a pencil down no1<, i even jury rigged an old plug with a rubber tube and a latex glove secured to the end to indicate, when inflated to its largest when highest compression was or as i thought tdc, and all it would do is pop a little through the exhaust, ive retimed it again suspecting i was 180 degrees out, and it blew the afm clear across the room, ive had the rocker cover off and waited for both arms to sit level, coincideing with tdc as confirmed by pencil, and this roughly aligned with the "after" script on pulley.
ive also tried swinging the dizzy while a freind cranked the engine,to no avail, just want to be 100% sure its correctly timed
also if the plugs are wet, correction very wet, will popping them in the rayburn while the mother in law isnt looking dry them out, or should i buiy another set to be sure
 
little bit technical....:eek:

But from memory you need to find out from the org manufacturer how many degree BTDC the ignition needs to take place. it won't happen at TDC something like 10deg before.
when you say no1 cylinder it may not be you cars front cylinder could be like no5 or 2. i would realign the manufacurers mark and check the cylinder that is at TDC it will be your first cylinder then go from there.
 
First point - Rv8's HATE fouled plugs,so wont start with them.In the past with flapper engines I've taken out all the plugs and left overnight,then fit 4 new and 4 old plugs to fire it up.The old plugs usually chime in afer a few seconds.Second point,disconnect the ninth injector on the plenum chamber,this is not needed.
Third point,it sounds like the spark may be at the right time,but is the tip of the rotor pointing at the correct terminal in the dizzy cap - many RR's I have been to where the body of the dizzy has been turned around to "get the timing right",resulting in the spark not making it back out of the dizzy.I think you need to totally redo the instillation of the dizzy,following the manual to the letter.
Lastly, a Rv8 will start and run,(Albeit badly) with the timing just about anywhere in the parish so dont fret to much about getting it accurate to the last degree,I think there is something a mile out for it not to fire up.
 
thanks for that, will rework the manual procedure, and fit four new plugs, as a double check if i disconnect all plug leads,then plug no1 lead to a spare plug earthed to the block switch ignition on, and crank engine by hand, with no1 plug removed (front right when looking at engine from front of car), i should be able to get a spark, that will coincide with the pencil approximation of tdc,
but i confess to moving dizzy to making it align to no1 firing
is there a way of measuring the quality of spark, the more i think about it, its not a brioght blue loverly spark its more an orangey brown
 
use a strobe light to set ignition timing dynamically is always best mark crank pulley with white marker first it not unusual to get weaker spark on v8 compared to 4cyl coil has do to twice as much later engines use multiple coil packs if you can find some one with an old krypton tuner it will tell you everything you need to know
 
You should have a nice blue spark,I forgot to mention that Rv8's dont like cheap ignition components - cap,rotor and leads all need to be LR or Lucas - even so-called OEM stuff often wont work.For plugs you wont go far wrong with NGK BPR6ES.
 
its a bosch coil, but the cap looks cheap(and was) and the leads are very original, ie old ones that came with the motor.
it helps that i didnt take the stuupid pill this morning, and rest timing 6 deg BEFORE top dead centre, not after, spark is very weak, when turning over, with an occisional strong one, when i go through the haynes test manual for the amplifier it identifies that is faulty, giving a voltage at the coil neg when ignition is switched off, have one on order so will be fitting when it arrives, was thinking of upgrading to magnecor leads are they an improvement over standard/ genuine parts?
 
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