MegaJolt on an a different type 3

[Ravivos]

Hi all,
i am currently building an engine for my T34, and decided to go with MegaJolt.
i know that there is a thread about trigger wheels for the T3, but i have a different problem.
my engine have an additional pulley for an air conditioner, this pulley will not allow me to use the big trigger wheel that bolts on the the T3 aluminum fan.

i know that one can drill the flywheel and use it as a TW, but this is something i would like to avoid.
so, my problem is that i cant use any TW that bolts to the fan and i cant use a thick TW that will bolt to the AC pulley since it will rub against the steel shroud.

any ideas or thought on how to get a decent signal to the EDIS? (36-1 wheel)?
can the Megajolt work with a different system beside the EDIS?

any input will be much welcomed.
Thanks
Ravivos.

[Jadewombat]

How much extra threading do you have on the pulley bolt? What is the outer diameter of the A/C pulley?

One idea is to mount the trigger wheel to the outside of the A/C pulley. Most any machine shop should be able to drill mounting screws to mount the trigger wheel to the A/C pulley. The most important thing is having the mounting holes centered so there will not be a lot of run-out on the trigger wheel rotation. There are several different sized trigger wheels out there on the market. Some listed here:

viewtopic.php?f=63&t=139125&hilit=notes+on+megajolt

There is not much science to mounting the VR sensor though. Just make sure you have a sturdy bracket so the VR sensor will not move around too much from vibration, I would mount it inside the pulley area so if the belt breaks the chances are less that it will damage the VR sensor, and just make sure the mounting screws for the sensor have some adjustment range.

[Max Welton]

Man, that pulley sure looks like it would interfere with flow into the fan.

Max

[Ravivos]

Hi Jade,
Thanks for the ideas,
i actually fabricated a new mounting for the fan and pulley, you can see in the pictures below... this means that i can change the bolt to whatever length needed.
the A/C pulley outer diameter is approx 113mm (4.5").
so i guess there is no escape but mounting the trigger wheel to that area... was thinking of a small wheel (2-2.5" ?) that will not interfere with the air flowing through the A/C pulley.

Hi Max.
Actually, this is an original VW type 3 A/C pulley that was available as an upgrade to the T3 line through the dealership, manage to get my hands on one of these, so i guess if VW offered it, it should be o.k.

Thanks a lot for the helpful advices, keep em coming, brainstorming away

[Jadewombat]

I would mount the VR sensor here in the attached photo. If the belt breaks there is less chance it will hit the sensor and damage it.

It's up to you the diameter of the trigger wheel, but it probably depends upon the amount of space you have on to mount the VR sensor between the pulleys and the rear engine tin.

[Ravivos]

Hi Jade,
That is a good idea, but dont forget that there are two belts there, one for the A/C compressor (which can be seen in the picture you marked) and another one for the alternator,
so there are two belts at approx 90 degrees to each other, in a V shape across the engine's rear.
also need to consider mounting the belts without the need to disassemble halve the engine.
will take some pictures with the rear engine's tin, it shows how close the AC pulley is.
if i mount the VS sensor to the rear tin, it will enable me to mount the belts with an easy access to the VR sensor's bolts.
i guess serviceability is also a consideration.

Thanks.

[gearheadgreg]

Why not mount it on the Flywheel side?

[Ravivos]

Hi Greg,
I thought about it, but this means i will have to re-balance my flywheel after drilling 36 holes at 10deg spacing.
main problem is that, here in Israel, it is almost impossible to find a any shop that can balance these parts.
this, actually, is my biggest problem when building a hi-performance engine, not having the ability to properly balance my rotating assembly.

i saw the flywheel idea and really liked it, but it seems rather difficult to do it myself.
although i really love doing these things, and pretty much knows my way around my workshop.

i wonder, any picture of a DIY flywheel drilled (procedure, already saw the final result pics) for 36-1 system?

Thanks.
Raviv.

[gearheadgreg]

Although I wouldn't usually recommend it, if you drill 36 holes, spaced correctly, it *shouldn't* change the balance and you should get away with it. Unless some of the material you drilled out was heavier/lighter than other material, or closer to the center or further out. There HAS to be a decent machine shop that can balance.

OR - you could make a rig to balance the flywheel yourself like motorcycle guys do with wheels. Years ago I used a setup like this for my Motorcycle wheels -

I would think you could use it or something similar to do the flywheel - only have to make and adapter for the center hub part?

[Ravivos]

He Greg,
Basically, you are right, as long as the holes are drilled correctly (i.e same depth, same size, same radius) is shouldn't affect the flywheel's balance.
but... (there is always a but)... we both know that it is impossible to do that without proper machining, CNC and all.

As for the static balancing, i am actually very familiar with the entire balancing procedure, as i used to fly RC jet planes, and did some of the turbine balancing myself.
Due to that, i started building a dynamic balancer (based on a piezoelectric device and a led stroboscope) for the engine parts, but it got a bit side-tracked, could really use it of it was operational.

guess i am kinda stuck...

any other thoughts and ideas will be much appreciated.

Thanks man.
Raviv.

[gearheadgreg]

Hmm - I see.

Is there a way to make EDIS/Megajolt work with a different number of input signals? Could you mount the VR sensor to read off the 'bumps' on the OD of the cooling fan? That, or use the distributor signal solution (of course that means the slopiness of the distributor isn't really avoided).

http://www.peachparts.com/shopforum/per ... ystem.html

Maybe something like this:

viewtopic.php?f=63&t=143194

viewtopic.php?f=63&t=143282

[Ravivos]

eventually , got it mounted like that -
after some tinkering, manage to get the engine running on MJ (it was easier than i thought it would be) and hooked up my innovate AFR meter to the auxiliary input, so now i have all the information i need - RPM, Ignition timing and AFR.





i have a problem/question - the engine is currently on a test stand.
i am running twin HPMX40 carbs with 32mm vents on 2021cc engine,
i hooked both of the vacuum ports of the carbs to the MJ MAP sensor (using a T connector) but it seems the MAP sensor shows a minimum of 80 KPa (idle is at approx 100).
is that correct? shouldn't the engine have a higher vacuum?
i am going to use the following ignition table and would love to have some input about it...
thanks a lot.

[Steve Arndt]

You need manifold vacuum for the megajolt map sensor, not ported vacuum from the carbs. Which ports did you use?
It is best to drill all four manifolds and run lines to a small plenum then tie the sensor there. It smooths out the fluctuation.

[Ravivos]

i used the one circled in red...
connected both sides to the MJ...
these are suppose to work for vacuum advance, and i really would like to avoid drilling my manifolds.

[Steve Arndt]

That is ported vacuum. The lower two named "vacuum ports" towards the middle are manifold vacuum which is measured below the throttle plate.

The advance port is only seeing vacuum once the throttle is slightly open. When throttle closed at idle they see no vacuum (by design for a distributor).