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Daragh

Correct spark advance for RV8 3.5

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Hello,

This may be a 'how long is a piece of  string question', but I am trying to figure out the correct timing for my RV8 3.5.

Details: 1995 3.5 RV8 standard (no tuning or fancy cams) running MS1 and edis

The general concensus is 10 degree BTDC but I have read a few posts that suggest 8 and one that said 7.

So, my question is how do I know what is the best settting for mine? I read about adjusting it till torque flattens but I have no way of measureing that in my driveway. Is there a more DIY way of figuring what is best or is it just seat of pants?

Thanks

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Static timing is 3 BDTC but it can handle up to 10 BDTC static timing if you are confident on fuel quality or use higher octane fuels.

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Are you talking about setting the base timing, or after a spark map?

If you are running a distributor, normally you set the base timing up to whatever the book says - so at idle it's running at (eg.) 3 BTDC, normally by twisting the dizzy (with vac advance disconnected). A bit more twist changes the whole timing curve advanced or retarded.

On the MS - you should lock the timing to a fixed value, then check that the mechanical timing with a light and make sure that the two match - so if MS 'thinks' it's running at 3 BTDC, mechanically that's correct. Then you set up your spark curve/map in software.

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Oh, and if you are going to that end, making up a piston stop and checking that the timing marks on the pulley are in the correct place would be very wise! They have often found to be out...

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Thanks guys,

As per Garry, it can be between 3 and 10, but is there a way of telling what is the best degrees for mine? I'm running regular pump fue of RON 95l.

Jon, to clarify, it is an MS1 with EDIS so no distributor. So, based on my understanding of your advice, I keep changing the timing in tunerstudio till it matches the mechanical TDC timing based on strobe i.e. set TS fixed angle to zero and alter trim angle until the timing gun reads TDC on the pully and then this tells me what degrees BTDC it should be? I'm not sure I have this correct as this would surly mean my timing, if based on TDC would be zero advance. Perhaps this was a bad example. Maybe what will happen in reality is that I keep trimming the angle until it shows TDC on pully and this will correspond to a positive BTDC figure eg 3 or 10 or whatever which will then tell me my correct timing? So, have I got the mechanics of your advice correct?

Bowie69, identifying actual TDC might be a good idea aswell, it just the thought of taking off the belts here is -1 is not appealing to day :) 

Thanks guys,

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Hi Jon,

Sorry,  I missed your initial comment - Are you talking about setting the base timing, or after a spark map?

To be honest, I'm a bit of a novice so not sure how to answer the above. The engine is being run by the MS1 and therefore I would presume the map will be involved. So I guess to answer your question, I presume I am setting it after map..... but I dont know how else to do it. How do you set base timing without ECU? 

Is base timing the timing at idle and using the map is checking timing under load ie up the rev range?

Tks again.

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33 minutes ago, Daragh said:

Is base timing the timing at idle and using the map is checking timing under load ie up the rev range

No. "Static timing" isn't really a relevant concept with efi. The important bit is that the measured timing matches what the ecu thinks its setting the advance to. In normal operation, the ecu will adjust the timing based on rpm and load according to what's in the spark advance table - including idle.

For setup, you can specify a "fixed timing" angle, which ignores the table and locks into that. Its useful as it gives you time to check with a timing light and see that what you're measuring matches what you've set and adjust the trigger wheel accordingly. If you're going to do this, a good value would be anywhere 0-10 degrees. You can also cheat with edis and disconnect the SAW wire. If its not sent a Spark Advance Word, edis defaults to 10° btdc. The MS still gets an RPM signal from the PIP wire so long as you don't disconnect that. 

If you're new to it, I'd suggest reading the msextra manual thoroughly! 

As Bowie points out, some way of verifying that the mark on the pulley matches TDC is very wise on an RV8. Yes it's a pain. 

As far as tuning advance goes, aim for having it run the nicest and getting max rpm for a given amount of throttle is about as close as you'll get to a poor man's measure of reaching max torque. If it's pinging, you've gone too far, though! I'd suggest you have a pretty good understanding before getting stuck into that, however. If it's a decent MS kit, the spark table that came with the ecu should be fine to get you up and running. 

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1 hour ago, Daragh said:

Bowie69, identifying actual TDC might be a good idea aswell, it just the thought of taking off the belts here is -1 is not appealing to day :) 

Why do you need to take the belts off?

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2 hours ago, Daragh said:

To be honest, I'm a bit of a novice so not sure how to answer the above. The engine is being run by the MS1 and therefore I would presume the map will be involved. So I guess to answer your question, I presume I am setting it after map..... but I dont know how else to do it. How do you set base timing without ECU? 

 Is base timing the timing at idle and using the map is checking timing under load ie up the rev range?

OK - if the landy is starting and running and is reasonably drivable, then you probably have a spark map of some kind already :)

First thing is to check that the MS and the physical hardware are reasonably in collusion with each other - in Tunerstudio go into Ignition Options, and there should be an option called 'fixed advance' - with a choice of 'table' (which will use the spark map in one of the 'ignition table' sections'), or 'fixed timing'. (I'm reading off an MS2E map, so the options may be slightly different)

If you choose 'fixed timing', one of the other fields will ungrey itself (timing for fixed advance) and you can force the MS to spark on whatever value you put in there - so pick a value that lines up with one of the timing marks on the pulley. Then start her up, put the timing light on and check that whatever value is in MS lines up with what the pulley marks say. If they don't line up, you can adjust 'Trigger Angle Offset (deg)' up or down until they match up (so 10 BTDC in the MS lines up with the 10 BDTC mark on the pulley).

Once you've done that, set Ignition Options / Fixed Advance back to 'use table' and check that the timing isn't still stuck at 10 (or whatever you set it at) and assuming your ignition map isn't all the same value, that the timing changes if you blip the throttle :)

Now if you go back to tunerstudio, if you open up 'ignition table 1' - you should have a little circle hovering somewhere round the table - where is dependant on the current revs and vacuum, which moves around as you rev / drive / whatever - the point under that marker is whatever the timing is at that point. The table is probably something around 10ish bottom left hand corner, dropping as you go vertically and rising as you go horizontally. 

If you paste a pic of that table one of the grown ups who properly understand how to tune spark maps will be able to help :)

 

 

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5 hours ago, lo-fi said:

As far as tuning advance goes, aim for having it run the nicest and getting max rpm for a given amount of throttle is about as close as you'll get to a poor man's measure of reaching max torque. If it's pinging, you've gone too far, though! I'd suggest you have a pretty good understanding before getting stuck into that, however. If it's a decent MS kit, the spark table that came with the ecu should be fine to get you up and running. 

Hi Guys,

Hi-Lo,

Thank you for the clear and informative reply. I have actually read up a lot and each time I re-read I seem to learn a little bit more. The general information out there will tell you that you are looking for 10 degrees BTDC and will explain how to do it, but it ddoes not tell you how to check if this setting is specifically suitable for your individual engine. Your advise above is great and a simple way to test, just what I was looking for.

Jon,

Again, thank you for your clear and informative comments. My Landie is in fact up and running and the map is directly from Nigle and unchanged, so I would guess that it is fairly robust. It appears generally down on power accross the board and so I am making sure the basics are sound before changing anything else. I am actually running MS1, so our screens differ (I have come accross some examples of MS2 interface). However, from your comments I understand where you are going with it and I will therefore apply accordingly to my own screens. Strangly, in this regard I have actually found varying advice as to weather I should alter the 'Trim Angle (Deg)' or the  'Triggger angle (Deg)' to alter timing! I think MS2 simplifies this.

Bowie,

I am guessing from your comment that I have this wrong :) I presumed that I should remove belts before attempting to manually turn the engine. I guess you are about to tell me I don't?

 

Thanks guys for all the help. I am hoping to have a go at this tomorrow. I actually bought an AccuSpark timing gun (as they were meant to be good and reasonably priced) to learn and try more but it will not pick up a signal from the new coil leads, although it does work on my other cars. I have borrowed one from my mechanic so hopefully that will work. 

Anyway, I will have a play tomorrow and see how I get on.

Thanks again.

 

 

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33 minutes ago, Daragh said:

am guessing from your comment that I have this wrong :) I presumed that I should remove belts before attempting to manually turn the engine. I guess you are about to tell me I don't?

Correct, just a big socket on the crank :)

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That's what makes it such a great forum :)

 

Timing guns can struggle to trigger off wasted spark setups like EDIS that are firing two plugs at a time with a common coil. Mileage may vary and you may get lucky, though. Be very careful if you use one of the posh timing lights that has an RPM readout and a dial to correct a btdc spark event to coincide with a tdc marker: as is hopefully clear, each plug gets fired twice as many times as it would in a "normal" setup so indicated rpm and advance will be double unless it has a "two stroke" setting. The cheap "dumb" lights are actually a much safer bet here if you can get one to trigger. One cheat I've seen and used is to get a spare spark plug to open the gap up on and swap out for whichever plug is paired with no. 1 (I forget which on edis 8). This biases the spark to the shorter gap on no. 1, hopefully enough to trigger the light. 

Lacking power, if its running "OK" (not overly lean or rich) otherwise is usually lack of advance. The equivalent of having the static timing retarded on a dizzy. You can correct this in the table or with trims, of course, but as you're doing, it's better to know where you're starting from. 

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7 hours ago, lo-fi said:

As Bowie points out, some way of verifying that the mark on the pulley matches TDC is very wise on an RV8. Yes it's a pain.

This is very important - I have a 4.6 which has no timing pointer or marks on the harmonic balancer - I set up a pointer and marks after determining TDC via measuring No1 piston position - I then had the engine running on Edis in default mode so supposedly 10 BTDC but when I put the timing light on it it was showing 15 BTDC - so I have doubt in my mind that the marks are correct - or does Edis actually deliver 10 BDTC - I dont know.

I am going to try again to measure TDC in the engine and if necessary readjust the marks but the engine is now in the vehicle so will be hard to do because No 1 cylinder is up near body work.

So with any MS system you need to have TDC measured correctly - with MS you still want about 3-10BTDC (I would go 10 on 95RON) at idle (800rpm) - adjust the trigger wheel pick up to get the idle timing you want, and then of course as you increase revs MS should then advance the timing (there are preferred timing vs revs graphs available on line) but generally you will advance up to somewhere around 30/35 BTDC depending on what you want.  Of course MS should also change timing also based on load (MAP sensor) but that is hard to measure when setting up in the garage.

I went with MS3 so can use my knock sensors to adjust timing if things get too advanced in some circumstances so in theory I can use MS3 to keep the engine as advanced as possible for any circumstance - I say in theory as I have not got my MS connected up yet and have been running on LPG with Edis in default mode and no electronic control of the gas.  At 10 degrees (maybe 15) the engine starts fine and runs fine at all load conditions all at fixed timing - when I thought it would start to suffer with retarded ignition at higher revs - but didn't seem to happen.

Garry

 

 

 

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10 hours ago, Bowie69 said:

Correct, just a big socket on the crank :)

😏   doh! You live and learn, makes sense I suppose. tks

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11 hours ago, garrycol said:

 I then had the engine running on Edis in default mode so supposedly 10 BTDC but when I put the timing light on it it was showing 15 BTDC - so I have doubt in my mind that the marks are correct - or does Edis actually deliver 10 BDTC - I dont know.

EDIS with no SAW connected will be rock solid 10btdc.

Also, with ref to the original post;

In the MS settings the "fixed angle" can be set to various things OR "-10" to use the spark map, but there's also the trim angle to be taken into account... TBH it's a bit confusing, so what I do to set the timing is save my settings, then make the bottom corner of the spark map (where it idles) all 10's so I know that the true overall advance (as seen by the engine) should be 10deg, and I can then check & adjust the trim angle, or the pointer, or draw a new marking (again, 4.6 has no markings).

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27 minutes ago, FridgeFreezer said:

EDIS with no SAW connected will be rock solid 10btdc.

 

Yes - I guess I was just waiting for someone to tell me.

I think I will just adjust the trigger wheel sensor and maybe the trigger wheel if necessary so that the timing reads 10BTDC via Edis rather than going through the whole process of finding TDC again.

Cheers

Garry

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Hi Guys,

Didn't get to it today so will be the weekend.

6 hours ago, FridgeFreezer said:

EDIS with no SAW connected will be rock solid 10btdc.

Also, with ref to the original post;

In the MS settings the "fixed angle" can be set to various things OR "-10" to use the spark map, but there's also the trim angle to be taken into account... TBH it's a bit confusing, so what I do to set the timing is save my settings, then make the bottom corner of the spark map (where it idles) all 10's so I know that the true overall advance (as seen by the engine) should be 10deg, and I can then check & adjust the trim angle, or the pointer, or draw a new marking (again, 4.6 has no markings).

Thanks for confirm on SAW and interesting way of making sure it is fixed at 10 deg with the spark table, although mine is idling at 900 rpm and 70kpa so I would have to change nearer the top corner :) ! I've been reading up on that as well, but that is the next challenge. Basics first and one step at a time.

Tks

Daragh

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I'd expect it to be lower at idle, maybe 45kpa or so. There's nothing badly wrong, just the tuning could be better. You'll find as you improve it that the rpm will rise - you're making more power - so you'll wind the throttle stop down to bring the idle down again. As I said above, I think you're probably running a bit retarded (pardon the expression), so you'll probably find it's a bit more lively as you get that sorted. I'll be interested to see what you find when you get a timing light to it. 

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8 hours ago, lo-fi said:

I'd expect it to be lower at idle, maybe 45kpa or so. There's nothing badly wrong, just the tuning could be better. You'll find as you improve it that the rpm will rise - you're making more power - so you'll wind the throttle stop down to bring the idle down again. As I said above, I think you're probably running a bit retarded (pardon the expression), so you'll probably find it's a bit more lively as you get that sorted. I'll be interested to see what you find when you get a timing light to it. 

Yep, I have read that it should be at circa 45kpa and also that its not a biggy. I will update as soon as I get a chance to have a go at it and let you know how I succeed or fail miserably ;)

 

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As LoFi says you will find a lot of times you change one setting and it makes the engine run differently, so then you have to go back and tweak something else... that's why you really want to get the solid basics right first before spending lots of time and effort on tuning. Also, ignition first THEN fuel map.

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9 hours ago, FridgeFreezer said:

As LoFi says you will find a lot of times you change one setting and it makes the engine run differently, so then you have to go back and tweak something else... that's why you really want to get the solid basics right first before spending lots of time and effort on tuning. Also, ignition first THEN fuel map.

Yep and new lambda arrived today so ready for step 2 when I get the timing right........

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So, a little update......Good news, bad news!

I did the timing on Saturday. The good news is that I checked the TDC on cylinder one and it appears to be correct and matched the TDC marker on the pulley. The second good news is that the timing appears to be set at 10 degrees BTDC so that is good. So the timing seems to be correct, I was secretly hoping that it might have been wrong.

Now the bad/strange part. I am running MS1 and as per above you should be able to alter the timing with the Trigger Angle or the Trim Angle but when I changed them and burned each change, there was no change to the timing. No ,matter what I did it stayed on 10 degrees! Maybe I am missing something ;) However, when I change the Fixed Angle to any positive number it is reflected at the pulley. And when back at -10 it matches whatever I put in spark table. Anyway,  timing appears to be correct so I guess I don't need to worry about it but would love to know if I am getting something wrong.

To give you all a laugh, my lambda arrived so I took off exhaust to clean up a tiny leak in weld on lambda bung but dropped some weld onto the threads...... no sensor going in there for the moment :(.  I was sooo close to getting a tuning drive. Ah well, there is always next week.

Thanks guys

 

 

 

 

  • Thanks 1

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Ah no, what a shame about the welded thread! 

I remember having the same problem with the trim angle; I believe it was a bug "feature" that it didn't do quite what you might expect. Great to know its bang on, though! 

Given your lack of fuel pressure I'm not surprised it's not been running very well   - it will have been very lean. The old V8 is very tolerant, but has its limits. Any progress on the fuel pressure?

You've got a decent timing map and verified timing to build on, so once you get that lambda going it won't take long to get it running really nicely. What lambda did you go for? 

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I'm not 100% sure but I suspect trigger angle doesn't apply to EDIS as the EDIS has a fixed trigger angle (it expects the VR sensor to be in a particular place).

As for trim angle, that's a tad odd, dunno.

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20 hours ago, lo-fi said:

Given your lack of fuel pressure I'm not surprised it's not been running very well   - it will have been very lean. The old V8 is very tolerant, but has its limits. Any progress on the fuel pressure?

Hi Lo-fi, 

Great to hear that it is not just me that 'features' don't do what they should. I think I missed something there, how did you identify I have low fuel pressure? What should it be? I actually have one filling a swirl pot and then a second new one feeding the engine. 

Fridge F

I suppose that would make sense re the trigger angle and I might have another play with trim angle at another stage. Some of the videos I have found online as for Miatas, megasquirt seems popular in that world, so maybe it is different for them.

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