Wow! Great progress here. Need to have a proper read as I haven’t been able to spend much time on the forum for a couple of months. As for the glowing headers, definitely retarded timing or lean. Not picking holes in your method of finding TDC ,but it is not as accurate as you would like to think it is . . As the piston is stationary for awhile whilst the conrod changes direction,all you are measuring with the DTI is where this starts to happen, not true TDC.
A much more accurate method would be to put a protractor on the bottom pulley. Weld a piece of roundbar or a bolt onto an old spark plug that you have taken the porcelain insulator out of,so that the bolt goes into the cylinder. Turn the engine over until it touches the bolt. Take a note of the protractor reading. Then turn the engine backwards until it touches. Take note of the protractor reading. True TDC is the mid point of these two readings.
BE CAREFUL WITH THIS METHOD. Most timing chain tensioners will take up the slack when you turn an engine over backwards. You snap the timing chain very quickly if you start the engine having done this, if you don’t reset the timing chain tensioner Once the tensioner has adjusted itself out,mechanically there is a system built into its design that stops it retracting. So, it’s easier done when the head is not on,or the timing chain and pushrods are not fitted…
Good to hear from you johnnybravo , and thanks for the advice. All your laser cutting hasn't gone to waste
Doing the TDC with the DTI - I could definitely feel the slack/dead-spot at TDC you mentioned, I didn't go so far as to use protractors, but averaged it out. I reckon I've got it within a degree - two at most.
I'll do your method when the engine is out and on a stand, as I want to make up a metal pointer for TDC work in future.
I can check the timing marks with a strobe later in the week, and plug them into the ECU. I've not played with the map for ignition yet - I'm trying to only change one thing at a time.
But I have ordered a wideband lambda sensor - so we'll know if it is running lean soon enough.
I'm going to have to change tack soon, as I want to paint the dashboard, so that can be refitted for the final time. There will be quite a bit of work with that.
Thinking about it, you can get it knob on with your DTI. Do the same as you did before. Put a protractor on the crank with a bent piece of wire as a pointer. Turn the engine over just under two full turns until the DTI shows say 0.5mm before where you think TDC is. Look what the protractor reads. Then carry on turning past TDC until the DTI shows 0,5mm past, look at the protractor again. Add the two readings and divide by 2. That’s where true TDC is. Turn crank forward two turns to that reading. Job done. No need to turn engine backwards 😊
Took another look at this tonight. The static timing was previously 3degrees out I reckon. It is NoDiz specific, but I had the missing tooth set at 71 degrees BTDC previously. Tonight being much more careful, I measured and set it to 68 degrees BTDC.
I've not run it for long, but the coolant and exhaust manifold is still getting very hot.
I'm not sure that 3 degrees of static timing will make that much difference.
It is still idling very fast. But I managed to get this screengrab off of the laptop.
I'm thing 17 degrees of advance isn't enough. But I've never done any engine mapping before.
The lambda sensor is out for delivery tomorrow - looking forward to seeing what that says.
Check your valve timing. Does that system run wasted spark? To get that exhaust that hot ,that quickly,it definitely seems you are burning fuel in the exhaust. As a matter of interest,what wall thickness are your headers?😊
This is what I use on the old Peugeot engines. The 204/304/, 404, 504, 305 etc all had adjustable timing plates with two notches. One was tdc and the other was your timing mark. Simply screw it into the spark plug hole and away you go.
Check your valve timing. Does that system run wasted spark? To get that exhaust that hot ,that quickly,it definitely seems you are burning fuel in the exhaust. As a matter of interest,what wall thickness are your headers?😊
I am running wasted spark.
You just knew I wouldn't know the wall thickness of the headers They are made by Double-S but my Google foo is weak today. I've chopped them apart previously, and they aren't much more substantial than regular exhaust pipe.
The valve timing one is interesting. It looks as if I can't do that without pulling the front timing cover - which is a pain. So I'll leave that until I pull the engine.
I was getting some fairly shonky compression test figures - typically less than 100psi. I'm thinking poor exhaust valve seal would give a similar result, of fuel being burned in the exhaust ??
Maybe a leakdown tester is my next tool to invest in, before pulling the head ?
Are you running a leary cam with a lot of duration/ valve overlap? That would also possibly contribute,however timing and mixture are more likely. Discounting timing,fuel is next.
Gut feeling though,is you are running way too lean.
Engine internals are 100% stock - it was rebuilt by the PO with an unleaded head etc. Hasn't really done many miles since. Not ideal for sure - but it is my starting point.
There is a cam designed for supercharged MGBs which might be a good fit for my engine, and it is on the wish/investigate list. But I'd rather get it running better with what I've got, rather than throwing expensive hardware at it.
The carb is a HS6 - I didn't until this evening know what was fitted - turns out it a BCP Difficult to say for sure, but I reckon it has an ickle bend in it too - which can't be helping.
Running the same carb on a MGB with a supercharger - a BCG needle.is recommended. That is for a 1800cc engine, and I'm at 1622cc So I hunted around and a BCF looks like a good fit between what I have and the MGB needle.
The supercharged MGB instructions also recommend a red damper spring for the carb. I'll order one of those up too whilst I'm on the phone tomorrow.
Quite a fun part of the build, this stage. I've not really delved into engines and tuning this deep before.
So I decided I needed an air/fuel ratio gauge, to see if my engine is running rich/lean. For unleaded fuel the ratio is 14.7:1
I went for a fancy AEM gauge. Way too fancy to look period in a 1967 dashboard. The plan was to hide it in the glovebox, to keep it hidden/visible. Fire up the 3D printer....
My printer isn't big enough to do a whole glovebox, so I did two ends, and bridged it with a folded piece of ali. The original glove box liner was painted cardboard that was warped and repaired - fit only for the bin.
The get a finish that was a good compromise between finish, and effort - I used some etch, and then an aerosol of stonechip, with an old paintbrush to adjust the texture. It'll get sprayed in dove grey to match the car, when I spray the rest of the dash.
Mounting the gauge is only 1/2 the story, a lambda probe also needs to go in the exhaust. I removed this section which joins the manifold to the silencer. The sensor needs to be mounted at least 10 degrees off of horizontal. I set the bung up on the bench at 20 degrees to give a bit of slack in the fitting.
Welded up and re-installed. The wiring is routed along the gearbox cross-member, and through the floor, and into the cab.
I ran out of time to give it a proper test, but fired up the engine briefly. The gauge was reading 14.something, which is pretty close for zero tuning.
Thats a nice and sneaky place to mount the wideband gauge
Although I'm pleased that exhaust clamp won't be seen in my place of work pointing down, ready to scalp someone
Id be inclined to aim for a slightly rich mixture on an old engine design. The 14.7:1 AFR is mainly for catalyst equipped vehicles to get the honey comb up to temp and not burn out or get washed out with unburnt fuel
Although I'm pleased that exhaust clamp won't be seen in my place of work pointing down, ready to scalp someone
Clamps will get rotated to maintain ground clearance, but for now, as a garage queen will be fine. I hear you about running a little rich - makes sense.
But I've found a problem with the ignition timing - which is very good.
NoDiz has a setup mode, where you set the offset of the missing tooth on the crank pulley. In this mode it will fire No1 at TDC, so you can do a form static timing, with a strobe.
I was dropping out of the mode when doing the static timing, so the timing gun wasn't firing at TDC, but had the advance from the map added. So my static timing is at least 10 degrees out.
I've had a quick play, but don't have it dialed in just right yet, but manifold temperatures are right down - which is great
My carb spring and needles have arrived too, and I'm hoping these will get the idle speed down, as forcing the SU piston down manually, does bring the idle speed down.
Although I'm pleased that exhaust clamp won't be seen in my place of work pointing down, ready to scalp someone
Clamps will get rotated to maintain ground clearance, but for now, as a garage queen will be fine. I hear you about running a little rich - makes sense.
But I've found a problem with the ignition timing - which is very good.
NoDiz has a setup mode, where you set the offset of the missing tooth on the crank pulley. In this mode it will fire No1 at TDC, so you can do a form static timing, with a strobe.
I was dropping out of the mode when doing the static timing, so the timing gun wasn't firing at TDC, but had the advance from the map added. So my static timing is at least 10 degrees out.
I've had a quick play, but don't have it dialed in just right yet, but manifold temperatures are right down - which is great
My carb spring and needles have arrived too, and I'm hoping these will get the idle speed down, as forcing the SU piston down manually, does bring the idle speed down.
I am not convinced but hope I am wrong. The difference between the BCP and the BCG needle at idle speeds is insignificant. The main difference is mid range and mostly at high rpm. I also doubt the spring will alter the idle speed. Pushing the piston down on any SU carb will drop the idle speed as it is the air entering the engine that lifts it in the first place. At then end of the day if the throttle is closed the idle speed should be low or the engine should stall?
