Setting initial TDC before starting the engine

[IRG]

Hey guys, thats a whole load of faffing around for what is essentially a basic job ......................... do the job properly and use a dial gauge............ even the cheapo ones are fairly good for this task as you are not actually measuring anything......... just detecting when the piston has reached the top of its travel to within a thou........ then it starts to fall.

MS on the RV8 works very well indeed, however, you will get better results if you go over to using dizzyless ignition with either EDIS8 or using MS to drive the coil packs. By doing this you can get away from compromise timing and have a programmable MBT curve that is better suited to the engine..................its good to sit on the rollers and watch the torque curve as you adjust the timing vis the laptop.............

The 'must have' for tuning MS is a wideband oxygen sensor........... most of us use the Innovate LC1 ............ however, good results can be obtained by just using a standard narrow band senor, but it then become a time consuming process.



Ian

[chodjinn]

Yes i already have EDIS8 and all the gubbins, and an Innovate LC-1, although I dont know how to set that up with the MS yet (hehe, engines not in yet tho).


r.e. TDC; my engine is fully bolted together and I'm not taking it apart again, hence the spark plug approach.

[mgbv8]

I fitted two narrow band AFR's. They aint bad, but they aint fantastic.
I've checked my CO readings and when they are normal my narrow band units read in the middle of the Rich band. I assume this is ok as a reference?
I also give them a quick glance in top gear when I'm at full chat with the gas on, and they read a tad below the middle of the rich band.
I'm using this mark as my base reference.
Is this reference of good CO to AFR reading a safe way to keep an eye on the AFR's?
I have to admit, since I fitted them and use the mid rich point as my reference, the car actually seems more fuel efficient even with the bigger engine.

[IRG]

By extending the dial gauge plunger with a small piece of rod (3mm ali is ideal), you can get the required reading from the plug hole …….

With MS, is sounds as if you are good to go ……………… the benefits are well worth while, and there are plenty of us around now to give you fuel and spark maps that will get it started and running ………..


Ian

[sidecar]

By extending the dial gauge plunger with a small piece of rod (3mm ali is ideal), you can get the required reading from the plug hole …….

With MS, is sounds as if you are good to go ……………… the benefits are well worth while, and there are plenty of us around now to give you fuel and spark maps that will get it started and running ………..


Ian

I think that because the plug is at an angle the ali rod may well bend rather than move up and down with the piston.
The other problem with using a DTI is that the piston will dwell around TDC for maybe 3 or 4 degrees of crank rotation, during this period the DTI gauge will not register any change in piston height. This can mean that your cam timing could be out which will lose power or your ignition timing could be out which could cause a holed piston if you are running your motor near the ragged edge.

Using a positive stop gets round this problem as the piston hits the stop well before this dodgy area when the crank is turned in either direction.


This link explains how to find TRUE TDC, they do use a DTI gauge but not to directly read off TDC, they use it in the same way that a piston stop is used. http://www.biggles.net/cams.html They reckon that the Dwell angle is more like 10 degrees either side of TDC but this must depend on the rod/stroke ratio.


AJMHO!

Pete

[a_q]

I am in the unfortunate position of having a whopping great supercharger in the way of No1 plug (TVR 400SX).

So can I use the same method but with cylinder No.6 instead, that (I think) is coincidentally at the top of its exhaust stroke?

My marks on my damper/pulley are miles out (the pointer has been bent sometime) so it needs setting up again.

Also there's a lug on the damper in advance of the marks - how many degrees is this typically in advance of the TDC mark?

[kiwicar]

Yes set it up using number 6 if that is easier. . .
Mike

[Big woof]

Had a good look around the tank and the breather system last night and there was nothing no leaks no pressure build up on the tank made sure that all the breathers was clear and no splits any where.
Okay here what is happening now leave the car over night she starts stright up first turn off the key drive it a good few miles leave the car stood it for four hours and it will take two attempts to start once started its fine. Hot starts ain't a problem it starts stright up say if you are in a shop for ten minutes its back into life pretty much stright away it's Just if it has been stood 4 hours it will struggle to start.