Crossflow ignition systems

[Crazy2287 1,886]

how "High comp" is high comp and whats your timing set to?

 

the 7 series are higher power so make sure you, as others have said, run a coil recommended by MSD. This will ensure the primary winding has been designed with the correct size and inductance to take the power without cooking.

 

Forget about cylinder dwell at this stage IMO, it will over complicate the system for, most likely, very little gain. That's future Mixalis's if he has one.

 

You should be able to tell if you need to change plug temp by looking at the plugs. Cold plugs will run filthy and hot ones will run way too clean/white or damage the insulator. Similar issues can be cause by incorrectly set timing too.

[slydog 7,873]

Id actually question camshaft v's compression on the iron head.Once you go to a alloy head you can run more comp safer if the chambers are shaped accordingly.

 

As for the run on.if it's auto turn it off in gear and same as manual with clutch out enough to put some load on and kill it when key is switched off.

[Mixalis 266]

Cheers for the replies. I had thrown the numbers into a calculator and cringe thinking about it, but let's just say it's flat tops with an iron head that I have not cc'd, and motor was rebuilt twice, once in my possession so I'm guessing two minor deck mills on the block, but pretty sure it's not zero decked or anything. Unfortunately don't have this info on me, but when I had plugged the numbers years ago into te calculator assuming standard cc iron heads and I had gotten something around the 12:1 mark. And from memory that was with certain parameters like deck and gasket thickness to my favour. But this was a few years ago I may have made a mistake with the numbers but it sure behaves like a high comp. coupled with a tiny 14892 crow cam with little overlap just spelt disaster. But you live and learn I guess and I know this now for next time

 

ATM I run around 8 degrees on idle not sure what the all in timing is tho it's the same dizzy when j bought the car all those years ago so I had never got it graphed. Can't wait for MSD to fix that. Also looking forward to getting this alloy head built to help make it safer on compression and hopefully get a larger chamber done over what I have now assuming it can be done

 

So turns out I know have access to an MSD 8261 HVC coil, 2 amp output, and an MSD tech has said it can be run on the street might re confirm it cause I found his post from 2012. Thanks for the help and for that explanation mr.crazy always good to grasp the concept from a technical stand point.

 

Individual cylinder timing, yeh maybe down the track haha so many little things I need to sort out with it to make it what I want it to be

 

 

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[Mixalis 266]

I kno there's a lot of 'unknowns' in my setup and guesswork is never good lol but they were the joys assembling your first engine as a young p plater hahaha, will be much better when round two comes along one day

 

 

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[slydog 7,873]

Good thing about the MSD is you pump in heaps and heaps of timing in for idle and just above then dump it all and start your curve. By doing this you can have clean plugs and a even smooth idling car like a EFI set up doe's then go for a conventional curve for the rest of it's needs.People are scared to give em timing but they love and need it on carbied engines around idle but they never had enough control to do so.Your MSD allows you too now. Even a local dyno shop tried to start my car on 14 degree's. Ummmm nope it wants waaaaay more there turbo.

 

So for your alloy head CC it and tweak it to your needed comp,get a 4-5 angle valve seat job,proper springs retainers and stuff and watch your enjoyment level rise

[Mixalis 266]

Awesome then honestly can't wait to get stuck into this, got everything at home and loom is almost set up now, just missing the all important dizzy! I'm anticipating a massive difference in economy, starting and of course HP especially over the top. It's done well for the standard inductive set up and it's been begging for an ignition set up for a while.

 

Interesting with your timing set up I think I had noticed it when you uploaded your ignition retard graph in your thread the other week. So what do you run as cranking ignition timing can I ask?

 

 

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[slydog 7,873]

Oh cranking it see's 22 I think ? Big thing to remember is at idle there's no load so running alot of timing is OK but it cannot be lean of have a bad tune cos it will do damage just like if at RPM. But if tunes good and sorted once past idle timing is back down to your 24 or wherever you want to start your base at and your gunna put all in by 3000rpm. After that it's tune by EGT's (VE's would be awesome but you don't get on a chassis dyno) and plugs. 

[ando76 4,354]

12:1 and a baby cam. Hmmm. Well it's not going to like too mutch timing with that iron head. I'd be sneaking up on the tune on this one and using really good fuel.

[Mixalis 266]

Yep points taken fellas looking forward to seeing how close I can get it at home first as always. Yeh ando have been battling with it for the last few years now not fun, BP 98 with 7 point octane booster (100 octane) on warmer days with low timing... AFR was around the low mid 11 mark tho on WOT when I had it on chassis dyno keeping it as much on the safe side as j could. Will keep you all updated as it comes along

 

 

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[gerg 10,871]

I'll help ya dial it in Michael, when we doing a cruise again?

 

Weren't you going to throw an alloy head on it? You can take some ccs out of the chamber pretty easily on them, and being alloy will handle an extra point in comp

[Mixalis 266]

Cheers Greg mate keen for a cruise whenever we gotta get the Nsw section happening. And yep ended up getting that motor with the alloy head, got a C1A head now that's next on the list once the MSD is in. ATM the head is sitting on the beach just waiting!

 

 

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[Crazy2287 1,886]

Yep points taken fellas looking forward to seeing how close I can get it at home first as always. Yeh ando have been battling with it for the last few years now not fun, BP 98 with 7 point octane booster (100 octane) on warmer days with low timing... AFR was around the low mid 11 mark tho on WOT when I had it on chassis dyno keeping it as much on the safe side as j could. Will keep you all updated as it comes along

 

 

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Stop fkn around and run it on E85.

[ando76 4,354]

Corn fuel for the win. That would solve it

[Mixalis 266]

Ok so this is the distributor I picked up today, am I correct in saying these have no mechanical advance built into them? All computer controlled from factory?

 

 

Cheers fellas

 

 

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[slydog 7,873]

Yes correct. All timing will be put in on the crank and timing will be cut via retard curve on the Digital 7. So I'd suggest set dizzy to your maximum idle timing which TBH should be a few over max run timing then after 1300 or so drop to start your curve.

 

Make sense ?

[Mixalis 266]

Yes correct. All timing will be put in on the crank and timing will be cut via retard curve on the Digital 7. So I'd suggest set dizzy to your maximum idle timing which TBH should be a few over max run timing then after 1300 or so drop to start your curve.

 

Make sense ?

 

Yep sounds spot on to me cheers Rob. Might need to get my hands on an adjustable timing light to try and dial the timing at the crank cause i can only see up to the 14 degrees on the tab. Thinking of putting around 32 or so at the crank so min. timing should be 7 degrees after MSD retard. Keen to try your theory with big advance on idle and a bit (I might start my curve at around 1000rpm cause my idle is around 800-850rpm quite a bit lower than yours) and see how the thing behaves. Exciting times ahead

 

Also can't forget to throw on the hardened dizzy gear on the new dizzy

 

Michael

[broken-wheel 659]

Yep sounds spot on to me cheers Rob. Might need to get my hands on an adjustable timing light to try and dial the timing at the crank cause i can only see up to the 14 degrees on the tab. Thinking of putting around 32 or so at the crank so min. timing should be 7 degrees after MSD retard. Keen to try your theory with big advance on idle and a bit (I might start my curve at around 1000rpm cause my idle is around 800-850rpm quite a bit lower than yours) and see how the thing behaves. Exciting times ahead

 

Also can't forget to throw on the hardened dizzy gear on the new dizzy

 

Michael

 

you don't need a adjustable timing light!

 

Find your TDC and mark your harmonic balance, you an buy a tape with degrees for this, one you got your TDC marked on the harmonic balancer to 0 then it's all easy. The dizzy is locked and set your programable ignition to 0

 

1. Start car and give it about 15degrees of timing whit the timing light on it
2. Wait for it to warm up
3. take the revs to about 5.000 RPM and set timing to 40 degree
4. stop car and lock down the distributor 

Now you go into our MSD and plot a curve, say you want 20 degrees of timing at 2000 RPM? simple take 20 from 40 total and you're left with 20 degrees, you pull 20 degrees on the graph and put a dot there.

 

The MSD only retards timing it does not add it. If you set your dizzy to 40 degrees and it's locked your engine will see 40 degrees of timing. What the MSD does it retards that timing so if you want 10 degree of timing you heard it by 30 degrees and if you want 40 degrees of timing you don't retard it at all.

 

The idle timing is best done just above idle, say if you're idle is 900RPM then bring raves 300rpm higher and look at the MSD screen where you can see the vacuum or get a vacuum gauge. Idle will be rough on most big cams xflows but 300 RPM higher than the cam is the sweet spot for advanced timing at idle. Think about it you blip the throttle and there is lag for the air/fuel to get to the heads by the time they get there you're already in the better timing zone.

 

I had it idle at about 1100 to 1200 on 10 degrees then 28 degrees by 1500 then pull back to 25 degrees until 2500 then ramp it up all the way to max timing at 6800 then take 5 degrees out from max timing to to 7200

 

also pull all the timing out if the vacuum is strong (closed throttle) so you get mad crackle/pop

[XPT 673]

Stop fkn around and run it on E85.

E85 would be great but would add some expense with changing the fuel system etc.I wonder if a 10% Toluene mix might do the trick as an octane booster. At about $80 for 20L or $4 a litre, it's not cheap but neither is bottled octane booster. Just until the Alloy head gets sorted.

[broken-wheel 659]

cheaper to get a alloy head and spend 2 hours with a die grinder on it

[ando76 4,354]

32 degrees total on a high comp iron head on 98..... Hmmm me thinks not. If it takes more than 26-28 total with that small of a camshaft I'd be very very surprised. Thing is high static compression and no bleed off due to small cam equals very high cylinder pressure. You ever done a compression test on this engine.

 

Come to think of it if it takes 24-25 I'd be really surprised

[broken-wheel 659]

he'll come to his senses and get an alloy head in there soon, even stock with good seats the alloy head will be faster due to the weight alone methinks 

[ando76 4,354]

Those old iron heads are seriously heavy. Like a 2 person lift to get them off in the car. Just way heavy.

[Mixalis 266]

cheers boys, the reasoning behind the 32 degrees was cause i didn't think i would need any less than 7 degrees advanced so the 32 was just so i get the full spectrum of adjustability from the MSD, but yeh i guess i could dial in the crank timing at maybe 28 but restrain myself to something lower like 23 give take after testing will leaving a few degrees of headroom if i need for any reason. 

 

once again broken wheel i understand the reasoning behind the alloy head thats why i have one here, I'm just doing these bits as time and funds permit, MSD is what i want to do in the immediate feature and once thats done the alloy head will start getting attention

[Mixalis 266]

Well I finished this up a few weeks back, haven't had time to drive the car more than a couple of laps, but thought I'd post the update and pics. Once again thanks for the help guys, special thanks to Greg for the message bouncing back and forth. Overall, completely different motor as expected. Most notably, there is no comparison below 2500rpm drivability due to the multi spark, every stumbling issue is pretty much gone. Secondly, motor no longer breaks down at 4800rpm, now just goes straight to the 5500rpm limiter like nothing, direct result of CDI & big coil vs 'standard' inductive & coil. Cranking retard means car starts easy plus the million other features I'm yet to use on the box but will be for sure.

 

Will be creating two maps for now (hot and cold conditions) until i wire up a switch and load the 'hot' map under the nitrous retard function. The All in timing atm is at 27 degree @ 5000rpm (cold conditions) and still no pinging, but i think thats where ill leave it for now as I have a feeling its probably just about to approach the peak where gains are little and detonation is next. Now its just up to setting up the rest of the curve from idle below maximum timing and get the entire mid range torque right up as its still on the 'get it going' timing map. Also put it all together in a way that the tuning is done from the passenger seat so no need to pop the bonnet anymore! Definitely a worthwhile upgrade as everyone here has stated, even if its just a simple street fire setup, the CDI box with a decent coil changes the whole engine up and I was lucky to get the equipment here at a price i couldn't refuse. Enjoy the pics! 

 

 

 

[slydog 7,873]

Well done bud and yes the bigger the spark the better the power output but also every other aspect of it improves. Starts better,gets better milage,revs better,makes more HP there is no downside.