Pinto powered Robin Hood on the road

[capri_turbo]

I am having great difficulty finding a starter map for my pinto powered Capri that uses a MAP sensor... all the ignition maps I have found so far are TPS... I'd be interested to know how you get on, as I am going MJLJ very soon... just awaiting parts now...

[niduncan]

I am using Matt Dearden's "Pinto 3D base 6k" map which I downloaded from http://www.cate1.co.uk/megajolt/mapping.php.
This was for TPS but I replaced the TPS settings for pressure settings:
0 to 10
36 to 20
51 to 30
65 to 40
80 to 50
94 to 60
108 to 70
123 to 80
137 to 90
152 to 100

on the assumption that 0 on TPS is FOT and 152 is idle.

I have also changed the 1200 rpm to 800 and tweaked the advance as I idle at this rpm.

Good luck with the build. The hardest part I found was mounting the circuit board in a case! - I did not use the recommended one, just bought a plastic one from Farnell.

[capri_turbo]

I'm using the proper case etc. You couldn't e mail me a photo of the crank sensor location and bracket? [email protected] I have a "spare" engine to work it all out on... how did you mount the trigger wheel? I have a sierra CVH one that I was going to weld to the front pulley.

I have those maps on my system... will have to have a play around when I get the unit installed.

[capri_turbo]

surely "152" is WOT (e.g. 100kPa ish.)as this is where the advance is less, and "0" is fully closed throttle 20kPa ish.) and the advance is cranked up like the vacuum advance capsule would do on a standard dizzy.

Can someone confirm this?

I'll email Matt Dearden to see if he can help us.

Edited: Got the kPa readings the wrong way round... 100kPa will surely be WOT.

[MartinM]

I always have the map with low pressures eg 20 kPa and low revs eg 800 rpm at the top left of corner ie revs increase as you move across left to right and pressure increases as you move down.

In general, advance increases as pressure drops (it is traditionally called 'vacuum advance' on distributors, after all!) so the advance bins on (a map set up as above) the top rows have bigger values than the bottom rows (...but with diminishing differences above 3500rpm or so!)

[niduncan]

I have discovered that on the Weber 32/36DGV the vacuum takoff is on the air side of the butterfly, hence at idle I am getting roughly atmospheric pressure (100kPa). I assume that most people take the vacuum from the inlet manifold which at idle will be 20-30kPa. I now understand why my readings are back to front.

Capri_turbo,

I will send you some picture of my trigger wheel and sensor installation.

Nigel.

[MartinM]

...on the Weber 32/36DGV the vacuum takoff is on the air side of the butterfly...

Really? So how does it change on throttle opening - venturi effect? And i guess that this take-off would be no good for a brake servo then?

I'm intrigued....

[capri_turbo]

They will help me a huge amount. Which vacuum take off point are you using? I'm getting a bit confused with the figures now... I'll hook up a vacuum gauge to my 2.1's 38DGAS and see what I get tomorrow.

[capri_turbo]

They will be a big help. Thinking about the figures you are seeing... 100kPa is atmospheric pressure, so you should see this at full throttle... the thing to remember is that the MJLJ map sensor is absolute... so 100kPa on this would read 0inHg on my vacuum gauge.

I'll hook up my gauge tomorrow and see what my 38DGAS pulls at idle. Obviously it'll be in inHg and i'll have to convert that to an absolute reading of kPa. Maths isn't my strong point though lol.

[capri_turbo]

I take it you are using the vacuum pipe that originally linked the carb to the dizzy... Now, as you say, this vacuum point is above the throttle plates, and therefore is not seeing the same vacuum levels as the manifold...

I'd suggest taking the vacuum input to the MJLJ directly from the manifold and NOT from the carburettor, as I think that the original vacuum advance system was not supposed to see full manifold vacuum.

[capri_turbo]

on the 32/36DGAV and the 38DGAS... but only by a couple of millimeters or so... the reason for this is the original vacuum advance mechanism is not supposed to see any vacuum at idle, but when running at higher revs there is vacuum there at light and closed throttle conditions. I have measured the vacuum advance effect on my Capri and there is very little vacuum at idle through this fitting on the carburettor. For the MJLJ install, you'll have to fit a vacuum take off on the manifold itself. I'd suggest somewhere near the brake servo take off point. I am going to use the original take off point for the crankcase breather as I have removed the original breather system. Just gotta get something made up to fit.

[niduncan]

Hi Colin,
I had not thought of connecting up to the original breather take off point, I currently have this blocked off. I shall try it tomorrow evening.

Nigel.

[niduncan]

Submitted by niduncan on Sat, 04/22/2006 - 20:00.
I moved the vacuum pipe from the carb to a takeoff on the manifold and the car drives a lot better now, it is smoother and more responsive. Watching the runtime display shows that the MAP is 40kPa at idle and the tracker now moves down and to the right as revs increase.
Thank you guys - look's like it is now working properly.

Lesson learnt - DO NOT USE VACUUM TAKEOFF ON A WEBER 32/36DGV

[niduncan]

Today my Robin Hood Series 3 made it onto the road with a self built Megajolt. The engine is a Ford 2lt SOHC Pinto with a Weber 32/36DGV carb. I am using the vacuum takeoff on the carb to feed the MAP sensor. The pressure readings I am getting are not what I expected, at idle about 100kPa and at FOT about 20kPa, other posts on this forum state that idle is 20-30kPa and FOT 100kPa - why are my readings back to front? Are these dependant on the type of carb and where the vacuum is taken from?
Initial driving impressions are good, idle is very steady but above 4000 rpm the rev response feels a bit slow. I suspect the map I am using is not correct, time to start experimenting.
Many thanks Brent for an exellent bit of kit.