More problems with the Cortina.

[73GreenMachine]

Now that the engine actually runs, its time to sort out mixture\timing issues. I have got a Bosch electronic recurved for the motor, but I am having real trouble jetting the 34ADM on the 250 pre crossflow. Starting it up in the morning leaves the motor backfiring thru the carby and only JUST running, but gets better as it warms up. The next problem I have is now the motor won't rev cleanly. It stutters badly as you try to rev it and backfires thru the carby repeatedly as it runs. I have no idea what is causing the problem. It has gotten to the point where I can barely drive the car.
I checked out the ignition because I thought it was misfiring. The sparkplugs were BLACK. The problem was still there after cleaning the plugs.
I am somewhat frustrated with the car atm because it never runs.
Can anyone help???

 

[addo]

Have you checked the spark from the coil lead? What about the rotor and dizzy cap condition? Nobody's swapped your leads 3 places?

If all that's OK, and compression's all right then blame the carby. What if you cobbled up a plate to mount an XA 250 carb on it temporarily?

 

[73GreenMachine]

I had a play with the car today and got it alive again. I got some upper cylinder lubricant\cleaner and pretty much poured it in the carby at 3000 rpm. I held it there for a minute or so and that helped clean out all the deposits in the combustion chamber. It idled remarkably smoothly afterwards. I also advanced the timing from 7 degrees up to about 10 or 11, which also smoothed out the idle. There was heaps of carbon in there, which as far as I can see was causing pre ignition of the air fuel mix because of glowing embers.(Me and my dads theory anyway) That was why it was popping so much and sending nice flames out of the carby. I put the jets back to the way I got them aswell so it would run a bit leaner because before the sparkplugs were black and wet with fuel. The car drives quite well now, with quite a lot of low end torque, but it does not like to rev. I get better acceleration in 3rd than 2nd or 1st. I am going to get the timing and carby professionally sorted out next week and get another dyno run. Then maybe I'll have a car to drive again.

 

[P100 Ute]

i had same prob with my Corty with my new motor and 34adm weber.. what i learnt

XF motor.. with X series Electronic dizzy NEEDS an Electronic Coil to run properly

so Electronic Dizzy = Electronic Coil
Points = Standard Coil

otherwise == problems

also i bought a 34 adm rebuilt kit and now runs beautiful.
also.. have u hooked up all the hoses and that.. vacume advance on the carby = important.. otherwise that messes up things.

too bad it was a street weapon and i killed it 2 days ago. lasted 3 months as a daily driver + GM killer

loads of Holden drivers wanted runs. and chop chop they got.
v6/v8 no worries

bent water pump and harmonic balancer and cracked the head coz i drove it home. now im stipping the car and pulling all the good bits off and buying a new one.. painting it.. tubbing it. custom motor. now that the XR6T is very possible if u use the Territory engine the sump is in the correct position. and just replace internals with Xr6T stuff.. or buy a brand new 2007 Ford Territory Turbo Block

even tho i just bought extractors for a 4.0L E Series in a Corty.
oh well depends on funds to wot my new car will have

 

[73GreenMachine]

The electronic coil might be one of the problems. I just have a bosch GT40 coil at the moment. would that be compatible?? I also have the GT40R coil if thats any better for the electronic, but i got told not to run it for some reason.
Currently, the dizzy has been supposedly recurved for no vacuum, but i need to check.
That and the carby tunings still off. You can beat the v8s??? Sweet

 

[addo]

According to Bosch Oz: MEC 717 suits your ignition. I have used an HEC 716 with good results. Guessing you have a GT40R presently. Also be sure to get 12V to the coil.

But overall, I somehow feel there may be more at stake than just the coil. Check all your lead resistances in case there is an issue.

 

[TCSTEVE]

Try checking all the leads like addo said and block off all the vacum lines. Do you know what compression ratio you ended up with by putting your worked 200 head on the 250 block?
The pistons and rods in that block are all stock 250 specs, the compression might be to high so the fuel mightn be good enough.
What else could stop the engine from reving, could it be stuffed lifters?

Good luck with it man, have to hook in a cruise once shes sorted out

 

[73GreenMachine]

I am running the GT40 coil atm, not the GT40R. Should I swap them??
I might give the leads a check... although they appear to be alright atm. How do I check them out?
As for the carby, I have all the ports blocked up on it with tube and ball bearings.
As far as I know, the 200 and 250 heads have the same chamber volume. If anything, the compression could be low..around the 8.6:1 mark but I'm not sure. The head has had 20-30 thou taken off it and the piston to deck clearance is 1.4mm or 56 thou(I think).

The timing is about 20 odd degrees of initial just to get it to idle nicely.
The jets are 135 main and 210 secondary with 160 and 180 air jets and stock idle jets.
The idle speed screw is very far in just to keep it alive.
I am going to get the car dyno tuned tomorrow at Dynalign or Boostin Oz not sure yet. It will prob be about $200-250, so theyd better do a good job. Hopefully they can sort out the problem.

Then cruise time!!

 

[addo]

That coil sounds as though it should work fine. Resistance is what you want to measure on the leads; test the longest one and all others should be less in resistance. A lead 3/4 the length of the longest, should have 3/4 of the resistance - simple?

Deck height seems massive. 5 thou would be plenty. How did that come about?

 

[73GreenMachine]

I ended up getting the car tuned on thursday at BoostinOz. I got a peak power of 97.2 kilowatts at the wheels in shootout mode on a roller dyno. An SR20 with stock cooler, big exhaust and 13psi boost made 112kw just before me. They set the ignition timing at 15 btdc static and 32 peak. They regapped the plugs at 40 thou. They removed the lid off my air cleaner setup too and got an extra 4 kilowatts! It was due to a mixture change. They didnt touch the carby tho which I was disappointed about(because it was the main reason I went in). The main fuel jets were supposedly ok, but the air jets and idle jets need doing.The whole thing felt like a bit of a ripoff for $150, but it did uncover one big problem. The guy who did the rebuild of the head of my motor never set up the valve heights or spring pressures. I had chronic valve bounce at about 4500-5000 rpm. This is the major reason why my two motors with this head have never ran smoothly or made much power. Its nice to finally have found it but it means I have had to pull the motor apart again. The head will hopefully be fixed up in the next week or two.

 

[addo]

How much torque did the Datto make? What about yours?

 

[TCSTEVE]

How much torque did the Datto make? What about yours?

ive got my money on the green machine!

 

[73GreenMachine]

From memory, the 180SX did actually out torque me. Those little hairdryers do make quite a difference to tractive effort (I think about 5500 to 3800 or so). A 2.0 turbo with 13 psi boost out torques a 4.2 litre straight six. Quite impressive hey?
One of my friends and I pulled the head off the motor and cleaned it up ready to have the valve heights sorted out. I am taking it into the shop tomorrow. The chambers are being ccd and matched in volume, the head is being decked and all of the valve heights and spring pressures matched. Then I'll get it all tuned up and maybe I can leave the bonnet shut for more than 5 mins lol.

 

[DYNOED250]

THe 2.0 would of had 4.11+ gears, so the torque on a dyno is a joke.. its a total waste of time... Diff gears make dynos tell good lies with torque doesnt change kw though.. THats a pretty good result, about as good as a stock EF 4.0, not bad the old log motor putting out the same HP as a ohc motor

 

[73GreenMachine]

Ah the diff gears make some difference do they? I might have won after all cos Ive got a 2.92 rear diff. Since fixing up the head may take some time, I have again considered the idea of making another intake manifold for it. From what I can see, it could be worth up to another 20 kilowatts or so above what I have now(comparing it to a 250 2v) and would be as good as a modded 250 2v(which I have seen produce 120kw at the wheels).

 

[Danielson]

Hi Greenmachine.. Just thought I should ask ? Have you a full 12V going to the ignition coil and bypassed the resisitior in the loom ?
Also have you checked all the diapragms in the carby and also is the 2 stage Idle circut bypassed and plugged ? I have had similar probs before with webers on XFs and both caused it to run similar to what you are describing..
Regards Daniel

 

[73GreenMachine]

Bypassed the resistor in the loom???? What resistor? And this two stage idle circuit you speak of? I seem to be missing some things here.
Today I started the process of designing the new intake manifold. I am practising on a spare head I have had laying around. The whole intake log is getting the chop. It is being cut at an angle of 90 degrees to the face of the exhaust ports. Then, six short tubes will be braised into the intake ports and a flange mounted to them. The tubes will have a large wall thickness to help reduce the size of the intake ports and increase the velocity of the airflow. At this point, I will design either an intake manifold out of mandrel bent steel or possibly fibreglass with high temperature resin. There is a bit of work in it I know, but the results should be worth it.

 

[Danielson]

You need to check that you have a full Battery voltage to the coil + when the motor is running.. On the older cars there is a ballist resistor in the loom to bring the coil voltage down. When the motor is not running and when cranking it should have full voltage but once running the voltage is passed through a resistor to give the voltage drop. When switching to the electronic dizzy you need a full battery voltage.. Mine would not run without it..

Towards the top of your carby (on the same side as the idle mixture screw) there is a screw in doodad that has about a 17mm nut and a single tube adaptor coming off it.. This is where the primary idle jets are. There are actually 2 one inside another. There is usually a tube that comes off here down to a temperature activated vacuum switch. basically just make sure they are all disconnected and plugged off..
Hope this helps
Regards Dan

 

[73GreenMachine]

This is the latest dyno graph.

 

[73GreenMachine]

Progress is slow with the Cortina right now, but I just thought I'd let you know whats happening with it and ask a couple of questions. I have decided to stay with the log intake for now as my original idea for adapting on the 2v manifold will not work as planned as the port spacings between the 2v and log head are different(not by much, but by enough to stop the plan from working.) I will save my custom intake manifold designing for the LPG conversion. This means that the issues with the log head need to be addressed to get the car going again. The intake manifold adaptor is being reworked to eliminate a number of flaws in its design and to increase the airflow. It will be more of a tapered cone design in cross section than a 'U' shape as it was previously. The intake log has also been opened up to its largest possible size to match the adaptor. I am also going to play with the carby design by milling off the top of the carby flat and seeing wether it performs any better.

Aside from that, does anyone know how to properly set up valvetrain geometry??? This appears to be the key problem at the moment as I was also experiencing the popping in the carby problem with this motor.

Also, how can I eliminate the resistor in the loom that Danielson mentioned??