What's new
Van's Air Force

The definitive Van's Aircraft support community! Buying, building or flying an RV? Join our exclusive family of mentors and enthusiasts!

However Surefly SIMs adjust timing during engine starts, it requires a change to my hot start procedure

MauleDriver

MauleDriver

Well Known Member
I recently had to do a couple of hot starts with my dual SIM equipped IO-540. Having no luck with my normal methods I found that running the starter through 3-4 blades and then returning to the run position seemed to give me an easy, Instant start. At first I thought it was just luck but I’ve repeated it on 2 other occassions and it seems to work. It’s made me wonder what the SIMs are doing during the start with ignition timing and how that might transition to running mode. Anyone know?

On a completely unrelated note, it reminds me of how an engine with non-functioning retard breaker can be started by getting off the start button and letting then normal breakers take over for the start.
 
Where are you positioning the throttle and mixture? In our IO-360 with dual it’s throttle full forward and mixture idle cutoff.

Hit the starter usually within a blade or so the engine starts.

Go full mixture quick but not super fast then reduce throttle. Its sounds like a fast hand dance but really is a Left hand up (mixture) then left hand back (throttle).

Works great and every time
 
Last edited:
Kaos2800 said:
Where are you positioning the throttle and mixture? In our IO-360 with dual it’s throttle full forward and mixture idle cutoff.

Hit the starter usually within a blade or so the engine starts.

Go full mixture quick but not super fast then reduce throttle. Its sounds like a fast hand dance but really is a Left hand up (mixture) then left hand back (throttle).

Works great and every time
Click to expand...
My hot start on the IO540 is the same, except I have my hand on the throttle, pull it back after start, then, as you say, quickly but not super fast advance the mixture 2/3 of the way in to where it won’t quit.
To the OP: you understand that your method that works - just like releasing a retard mag back to run - risks a kickback and possible gear teeth damage? For start the EI should fire at top dead center, no advance at all. If it doesn’t work it needs to be fixed.
 
I hot start my IO360 PV (single SIM single mag) leaving the throttle and mixture at the 1000rpm ICO position I shut down at. Master ON and clear then start cranking. When it fires after 4-5 blades feed in the mixture slowly to about 1/2 travel (lean idle). No screaming start or having to mess with both throttle and mixture this way. Works fine for me.
 
Last edited:
Hey there,

Couple questions.

What RPM does your starter spin the engine at?
Some starters really spin engines good. If it’s spinning really fast it may be starting to get into the operational portion of the timing map rather than the start side. Might explain why you see it working after disengaging.

How far down does your battery voltage go with the starter engaged?
If it’s dropping too far, it might explain why you see it light as soon as you disengage the starter draw on the electrical system. Even if your batt voltage is reading okay, the voltage at the EIS might be momentarily dropping below the threshold causing it to shut off. This would likely be more apparent if you have the wrong wire gauge on the + supply side.

Hope this helps.
 
The surefly fires at TDC while starting, then above cranking speed (running) the timing software kicks in, unless you set the DIP switches to "fixed" timing. So the start procedure shouldn't be different from your old magnetos with the impulse coupling firing at TDC as they normally do. As mentioned above the surefly requires battery voltage to be above a certain threshold (9v maybe) or it won't fire. If your starter is pulling the battery down too much that would be a problem. Heavier gauge wire to the surefly might help.
 
Is it possible that your EI is grounded while your starter is engaged?

EDIT: Disregard, I missed the hot start only condition..
 
Last edited:
I have two SureFly with two ON/ OFF switches on a IO-360. As I understand it the EI retards the spark to the 0 deg point < 250 rpm.
Once > 250 rpm the normal 20 or 25 deg advance is activated (depending on DIP-switch settings).
Having trashed one starter a few years ago due to a kick back I came up with the following solution.
I have set the L-EI DIP-switch to 25 deg and the R-EI to 30 deg advance. The R-EI is clocked 5 deg after top dead center.
The R-EI is the one I use to start the engine with. Once the rpm is > 250, the timing is 25 deg on both L and R- EI.
During cranking the R-EI fires 5 deg after TDC, this way preventing a kick back.
Both EI is also set to variable timing that kicks in at altitude and reduced MP.
It works werry well.

Good luck
 
Avanza said:
I have two SureFly with two ON/ OFF switches on a IO-360. As I understand it the EI retards the spark to the 0 deg point < 250 rpm.
Once > 250 rpm the normal 20 or 25 deg advance is activated (depending on DIP-switch settings).
Having trashed one starter a few years ago due to a kick back I came up with the following solution.
I have set the L-EI DIP-switch to 25 deg and the R-EI to 30 deg advance. The R-EI is clocked 5 deg after top dead center.
The R-EI is the one I use to start the engine with. Once the rpm is > 250, the timing is 25 deg on both L and R- EI.
During cranking the R-EI fires 5 deg after TDC, this way preventing a kick back.
Both EI is also set to variable timing that kicks in at altitude and reduced MP.
It works werry well.

Good luck
Click to expand...
Interesting. I might have to look at doing the same. I've had two kick-back events, both during hot-starts and I wasn't impressed. No issue during a normal cold start or even a warm start.
 
BobTurner said:
What is your ‘normal hot start’ procedure?
Click to expand...
Two answers:

1. For immediate restart - Leave everything alone (throttle at about 1000 RPM where it was at cut-off), mixture rich just like it was when shutting down, and crank.

2. Restart after quick refuelling - Purge for a bit (APS fuel system) while getting ready to go, seatbelts on etc., then throttle at about 1000 RPM and mixture lean. Blip on the fuel pump, then crank.

If I stuff it up then it's mixture lean, throttle wide, two Hail-Mary's and do the funky chicken when it fires.
 
I also experienced kickback during hot starts. I retimed both to start at 5 deg ATDC like others have done and I've not had a kickback event since.
 
Ok, hot start.. mine (2) surefly mags had it's first kickback on hot start TODAY.. I'm a little perplexed because I checked timing and it's still at 0°TDC so how can it kick back? Sure I can retard (rotate) a little bit but I really want a technician at surefly to explain. Like others have said the DIP switches will need to be changed to accommodate the altered start position
 
sansoneservices said:
Ok, hot start.. mine (2) surefly mags had it's first kickback on hot start TODAY.. I'm a little perplexed because I checked timing and it's still at 0°TDC so how can it kick back? Sure I can retard (rotate) a little bit but I really want a technician at surefly to explain. Like others have said the DIP switches will need to be changed to accommodate the altered start position
Click to expand...
I would ask them where the rpm is set for transition from start to run. If it is 250, as suggested above, then it is possible you exceeded 250 and timing moved 25* advanced during startup and that will often cause a kickback . A hot engine will generally spin faster than a cold one. I set my transition rpm at 400 and never experienced a kickback.
 
lr172 said:
I would ask them where the rpm is set for transition from start to run. If it is 250, as suggested above, then it is possible you exceeded 250 and timing moved 25* advanced during startup and that will often cause a kickback . A hot engine will generally spin faster than a cold one. I set my transition rpm at 400 and never experienced a kickback.
Click to expand...
I don't believe SureFly has adjustable transition rpm. That would certainly solve the hot start kickback. As stated above there would be no kickback at tdc. I'm going to rotate both mags like Bcone did, then alter the DIP switches. Obviously 250 rpm transition is too low
 
sansoneservices said:
I don't believe SureFly has adjustable transition rpm. That would certainly solve the hot start kickback. As stated above there would be no kickback at tdc. I'm going to rotate both mags like Bcone did, then alter the DIP switches. Obviously 250 rpm transition is too low
Click to expand...
yes, mine is a different setup. Was just making yhe point that it could be the transition RPM. Just ask surefly what it is (believe 250 stated above may be a guess) and then observe your cranking RPM while warm.

Agree that 250 is too low. I would call surefly and discuss this issue with them. The mod will only get you to 20* advance when you get above the transition range and highly doubt that is enough to prevent a kickback. Really need to be 10* or less.

Do you have a li battery? Those can offer far more amperage to the starter and can result in higher starting RPMs. May consider going back to Pb to address issue.
 
RV7 To Go said:
I hot start my IO360 PV (single SIM single mag) leaving the throttle and mixture at the 1000rpm ICO position I shut down at. Master ON and clear then start cranking. When it fires after 4-5 blades feed in the mixture slowly to about 1/2 travel (lean idle). No screaming start or having to mess with both throttle and mixture this way. Works fine for me.
Click to expand...
That was my hot start procedure before the SIMs but it hasn't been working since the dual SIM install.
 
cmgayman said:
Hey there,

Couple questions.

What RPM does your starter spin the engine at?
Some starters really spin engines good. If it’s spinning really fast it may be starting to get into the operational portion of the timing map rather than the start side. Might explain why you see it working after disengaging.

How far down does your battery voltage go with the starter engaged?
If it’s dropping too far, it might explain why you see it light as soon as you disengage the starter draw on the electrical system. Even if your batt voltage is reading okay, the voltage at the EIS might be momentarily dropping below the threshold causing it to shut off. This would likely be more apparent if you have the wrong wire gauge on the + supply side.

Hope this helps.
Click to expand...
I can't quote the RPMs at startup but it's pretty rapid. The stock IO-540 from Vans used to come with a 'light weight' starter that was not quite up to the task. It had a slow spin-up and could be a problem. I long ago swapped it out for the 'regular' starter and my 2 battery start sped up considerably.

I did use the recommended wire gauge but the run is quite long from the batteries behind the baggage area. May be worth checking.
 
Thanks everyone for the comments and feedback! It's helped me understand things quite a bit.

I haven't experienced any kickbacks yet. My only problem currently is getting a successful hot start. And what I've discovered is that returning my ignition switch to the run position seems to allow a start (without kickbacks so far).

It occurs to me that the standard ACS keyed ignition switch, setup to ground the LH mag during start and to effectively switch to the retard breaker in the RH mag, means that during the start, only the RH SIM is firing. That is not necessarily a problem but in my particular installation, it allows me to easily test a few things with a simple procedure change.

I have (2) Odyssey 680s, powering (2) separate buses and charged by (2) separate alternators (a Z-14 design). The LH SIM is powered by the LH battery and the RH SIM by the RH battery. My normal start procedure is to have both batteries cross-linked. But I can easily start using only my LH battery. In that case, the RH battery is no longer powering the starter but is powering the RH SIM.

So doing a hot start with the batteries unlinked should test the possibility of too low a voltage on the RH SIM and also eliminate a problem with a >250RPM prop spin. It will at least give me a fresh look at my hot start situation.

I also wonder whether setting up my ignition harness and switch so that both SIMs are firing during starts might give me marginally better starts. Two should be a bit better than one.
 
You must log in or register to reply here.
Back
Top