Ignition curve for 2270 9:1cr motor web86 dual 44's

[Orange72changeover]

Hi
After initial run-in I decided to push the bus this weekend, 80miles each way to the apex festival. The bus ran well ( constant 66-70mph at 3-3.5k rpm ) but on return, a quick check over and I fould the engine had been running hot, very hot, the inlet manifolds for the 44idfs were hot to the point that I could hear the fuel popping & bubbling in the carbs, however no metallic heat smell and oil was clean ( not boiling )
One thing I did notice was some fairly loud induction noise at 3-3.5k rpm but when pushed to 4-5k engine response was crisp and induction noise seemed quieter and all together a more tuned result ( fuel consumption was also fairly good, considering the 44's )
Co2 level good to slightly rich staying constant at all rpm
Which brings me back to the ignition timing,
I have now bought the stealth black box to play with the spark & timing, as I know the 009 is not a favorite of the type 4, I have also found a plot/graph by volks bolts.com which if correct could also explain the heating issue ( obviously I realise the 2270, 9:1 motor will run hotter anyway )
Any advise on the correct curve plot for such a motor as mine

[Jadewombat]

9:1 is fine, it shouldn't run hotter than a stock 8:1 motor.

I switched my bug to EDIS wasted-spark and it ran much better and cooler. Detonation doesn't kick in until 9.3 or 9.4 to 1, but if you worried about it for the short term then run a higher octane gas to keep it from popping. Take a look at this:

viewtopic.php?f=63&t=139125&p=1113707&h ... t#p1113707

Megajolt, Megasquirt, Electromotive, Weber Redline, there's a lot of aftermarket crank-trigger ignition systems out there to choose from.

viewtopic.php?f=65&t=114309

It doesn't matter which system you add to a distributor system, if you're still dealing with timing scatter and poor spark control in only 2 dimensions (engine speeds up, spark system gives more sparky). But ask yourself this, is 3,000 rpms the same revving the engine in neutral, cruising down the highway, or going up a hill? Of course not. The manifold air pressure sensor can determine what the engine needs much better at these different rpms.

A distributor is linking three moving components at different angles to spin a rotor shaft, meaning there is some amount of play and you can see timing scatter when you put a timing light on the crank. Crank-trigger systems don't do this. They burn much, much more efficiently, not just hotter spark.

[Orange72changeover]

Hi
Thanks for the info
Will defo try the 97 Oct fuel anyway
Don't know much about crank trigger systems for the type 4 motor, especially as I am still running the stock fan & housing so not sure where the wheel & trigger would fit
Also don't forget I am running carbs, one thing I may try is a vac advance distributer, lock out the mechanical advance leaving the vac advance, but still fit the stealth black box to control the fixed rpm timing at least the engine will respond better to load requirements when accelerating hard etc
Still need that advice on the timing curve itself if anybody can help
Next outing stonor park

[Jadewombat]

The ignition settings would have to be waaay out to be backfiring in the carbs. Go back to stock settings, get comfortable with this black box setup (sorry, I don't quite know what system you are talking about) then trial and error of gradually dialing in more timing.

It sounds like your carbs. are out of sync. if it's backfiring in the runners. Check the usual stuff also, valves, bad plug wires, etc.

Mario makes a hidden sensor for use on T4s, he'll probably chime in here.