57 replies to this topic

[klivins]

Let the dizzy drive position alone for now, you can put it the conventional position in a second moment, now just think about making the engine work fine.
What you have to do now, is to put cylinder #1 (nearest the rad of course!) at TDC - fireing stroke and see where the dizzy rotor is pointing. Thats where you put HT leads for cylinder #1, then place the other leads 3-4-2 counterclockwise as usual. No matter if cylinder #1 Lead is pointing downwards.
Take the spark plugs out, 3rd gear on, remove the rocker cover and start to pull the car slowly, until you can see both valves at cylinder #1 are closed.
Put a screwdriver in the plug hole, you should see it at TDC. Now if you're at the firing stroke, the valve #8 should be rocking (to be honest i just look at valves #1 and #2, if after pulling the car a bit more the next valve to open is the exhaust, then push it back to TDC and that is TDC firing) and you should be able to see the timing mark in the crank pulley pointing very close to the 0° in the timing marks.

thats exactly what I have just done. First cylinder at firing stroke, marks on the pulley clearly seen! What puzzles me is the engine runs fine(ish) but I cant see any marks in strobe light!

Edited by klivins, 03 November 2011 - 12:58 PM.

[jaydee]

Strange one, should be connected to engine lumpyness.
Double check you have a good connection between #1 lead and the timing gun.
Also, with a white marker or something similar colour the dot on the pulley so you can see it more clearly with the strobe.
When the engine is running lumpy you'll see the timing dot go up and down on the timing marks scale, very out, when this happens i set the idle speed at 1500rpm, then time the dizzy at 10° with vac disconnected.

[klivins]

Dont think it is that. When I had the marks alligned in the light it was obvious. Now seems they are gone totally opposite the pulley! Could I damage the strobe? I briefly put it pos to neg...

Am I right in thinking before mixture adjustment the ignition should be in best of nick? Then I think I will gather all new components first and will give it a go when have them. Have wrote to Aldon and Accuspark (online their prices differ by large margin!) for advisable dizzy for my set up.

This might be dumb question, but what is bridge in the carburettor?

Thanks

[jaydee]

I'm in a rush..You have PM!

[warrenc]

Is your fuel tank breather blocked or fuel pump not working? The engine seems to run fine at first, then start mis-firing and slowly die like its starved of fuel....

[klivins]

warrenc, this was our first thought in the spring (see 1st post). It isnt that, now I have installed a facet electrical pump.

[klivins]

right. Figured out the distributor was 1) with slight play, and 2) wrong to my specs altogether. Aldon dizzy would have been 250 quid... Thats megajolt kit now ordered! So more soldering of wires when this arrives, and after Ive delt with ignition I will continue to sort mixture out.
The Mini is getting dearer and dearer...

[jaydee]

With the megajolt you can get the perfect timing for your engine, and gain some power too, its well worth the money

[klivins]

right. the electronic ignition installed! Without even Megajolt installed just in so called 'limp home mode' engine sprang into life much better as before. My wife was glad there was no laptop at home, otherwise I would have spent all night in the garage fiddling with the megajolt!

[klivins]

thanks for all advices. Seems ignition was the problem, with megajolt and simple aldon yellow dizzy map engine does not have the misfiring.
Now im saddened by my broken ankle and have to wait until it is fixed when Im allowed back to the garage.
Meanwhile I have at least month to search the web for most appropriate megajolt map for my engine...

any advice as of how to determine what map to use is highly appeciated

cheers

[klivins]

Hi all, Im back after the winter and broken knee healing.
Last post was a bit too optimistic. She didnt detonate at start, but now still detonates even with correct Megajolt ignition.
I just do not understand why it is only after a good while on keeping say 3000 rpms the engine starts to detonate, not imediately? Megajolt has helpful thing - digital MAP gauge, showing when detonation occurs the vacuum jumps up and down by biiiig margin, from zero to half the scale. What would that mean?
What would be the ill effects if I had wrongly calculated CR (I think it is 10.8:1) and had it even higher? Im using 98 octane fuel. I checked it with a gauge, it showed 10.5 to 11 for different cylinders, but I did mistake testing it cold, is there a way to calculate if for warm engine?
Or is it just engine leaning out? Now my Gunsons tester shows 2.5 % of CO, when the engine starts to detonate, showing it is rather rich, is it not?
Off to file some more metal of my needle and try again...

[klivins]

well, after some more filing of the needle, and at 4000 rpms getting 3.5% of CO engine still misfires. Guess Im taking the head off to recalculate the CR, and check valve guide clearences.

[klivins]

well, seams in the beginning of my engine build I had been massively wrong in determining the CR. I have lost sheet of calculations what I did as long as 2 years ago, but seems I didn't take in account dish in the pistons.
Sadly my results of this morning (got up at 6 AM to be ready for breakfast!) dont give too high CR. I got 9.09 to 9.14, having different figures for ring load volume (0.78 from Vizards bible, 0.75 from Cooperman) and head gasket volume (4.2 and 4 respectively).
My estimates were - 8 cc for standard piston 21962 dish, appr 4 cc on top of piston (1 mm below the block), and 22.5 cc for volume in the head, measured by syringe.
Now what?
The CR is somewhat low-ish. Think I will have someone to look at my head to check valve guide tolerances. At same time I could skim it a bit to get 10:1 Then it is down to fuelling really...

[klivins]

although I am comunicating to myself, haha, just measured the needle what I have filed. It is still couple of thousandhts of mm leaner than the needle suggested by Vizards bible (BP), according to this useful tool http://www.mintylamb.co.uk/suneedle/

in case someone finds it useful, here is exel sheet where you just put in your measured numbers and it calculates the CR http://dl.dropbox.co...sion ratio.xlsx

[jaydee]

Hi mate, been away for a while, i''m quite busy these days and have little time for the forum.
But still had time to build a new engine spec in the meanwhile
Anyway:

I just do not understand why it is only after a good while on keeping say 3000 rpms the engine starts to detonate, not imediately? Megajolt has helpful thing - digital MAP gauge, showing when detonation occurs the vacuum jumps up and down by biiiig margin, from zero to half the scale. What would that mean?

Something wrong in the carb or an air leak somewhere.
Even if CR is 9,1 it should be massively missfiring. While you're skimming the head, inspect the valves for damage, and re-lap them.