'NNN' and the overheat saga

[mickthefitter]

Well I can't say as I've gained anything from this afternoons activities. Just been out and its as splutterly as ever. I had to curtail things because the light was going and I think I'd started to annoy the nearest neighbours a bit with that screechy starter the autos have, keep stopping to connect different things up, move the Sparktune plug to a different cylinder, and re start it. So I didn't re-check the timing after supposedly 'balancing' the carburettors but I can tell the timing is still a mile out. I'm wondering if it smells of petrol so much because its not burning fuel properly. It smells of neat fuel at the tail pipe a bit.

So next chance I get, I'll time it with the vacuum pipe on. Which to me is crazy because I always thought you timed cars at idle with the pipe off, and its like setting the mixture - I always thought you had to do it with the air filter on because the air filter would alter the fuel-air balance after if you set the mixture up with it off. But as far as I see the manual tells you to set the mixture with the filter off because of lifting the piston with that little pin to see if it alters the revs, and setting up the linkage for the two carbs, which you cannot do with the filter body on.

As for that Carbalancer - what a piece of tat. Yes, I suppose it helped, if it is to be believed, and my hearing certainly isn't good enough to notice a different 'hiss' from two carbs inches apart with an engine clanking in the background. But the crodcodile clip with a ball joint that is supposed to act as a mount is a joke - with the thick vacuum pipe in the kit the float scale wouldn't stay straight, especially with some engine heat, and when I finally gave up trying to hold it straight AND use two hands to hold the venturi adapter and adjust the carb throttle screw, I taped the scale to the bulkhead where the washer bottle should be, but then had to repeatedly keep tapping it because the little float would stop in different positions every time, on the same carb, just by pulling the venturi adapter off and putting it straight back again. It was a bit because the float was just a loose fit in the scale and twisted a bit, and then more engine bay heat wafting around made it even worse. At least I've proved the radiator is good and keeps the car within temperature on a warm day stuck on my drive!

As far as tuning the mixture is concerned, I didn't follow a start-from-scratch strategy, I tried using the Colortune plug, ended up winding the mixture nuts each way until the engine stumbled, set them in the middle, then started playing a bit with those lifting pins to see if I could fine tune it better, since my impression was that both before I touched anything, and after I thought I'd found the halfway point, the engine stumbled a bit if I lifted the pin. But I was never happy with that method of tuning when I had Minis with one carb. I think you need a piano tuner's ear to detect the change in engine revs, especially to get that 'sweet spot' where the revs are meant to rise a little and then drop again. Today, as when I tried this with the Minis, I expected a significant increase in revs going by the description in the manual, but in my experience you get the merest change at all, barely detectable, unless you go too far and then the revs stay up, but even then they don't rise by much. And all the time, if ther Colortune plug is in, the flame still looks blue! I've been mucking about with basic cars since the start of the 80s but in terms of tuning, I'd be happier with one carb, and as for the timing on my Marina, I don't know what's happening with it.

[david painter]

Lets go back to basics here! Remove Rocker cover and Spark plugs Adjust tappets to 0.013 inc using the rule of nine ie with valve 1 down adjust no8 2 down adjust no7 no1 valve being valve nearest the radiator and no8 valve being nearest to the bulkhead. Next turn engine over till no1 TDC is reached (both valves on no1 cylinder closes and both valves on no4 cylinder rocking )no1 is on radiator end, the timing mark for TDC should now line up or there abouts. IF not your camshaft is incorrectly timed! Remove distributor cap,rotor arm will now be pointing at no 1 Cylinder ( can you move rotor arm against its springs in direction of travel? yes mechanical advanced is free no mechanical advance is seized ) now work out your firing order on the cap starting where rotor arm is the firing order of the engine is 1 3 4 2 in a anticlockwise direction. Ensure contact points gap is 0.015 inc. Now connect you bulb to negative side of ignition coil and earth switch on the ignition turn engine back in the opposite direction it normally turns about 25 degrees,not mega important this is exact nowturn crank slowly in direction of rotation until bulb lights,now check your timing mark this should be about 6deg BTDC ( this may not be book figure exactly but will run happily at that setting) repeat this with adjusting distributor as required until setting is achieved. Now lock distributor in place do not move it again. Now carry out compression test with throttle held wide open you are looking for about 175psi for a healthy engine with + or - 5psi between cylinders. Refit spark plugs gapped 0.025 inc refit plug leads in order 1 3 4 2 remove vacuum pipe from distributor and plug it now start the engine let it warm up and set idle to 800/900RPM connect timing light to NO1 plug lead and check your dynamic timing at this speed you should now have 8/10deg BTDC ( do not alter it but if substantially different let me know what figure you have) . Now with the help of an assistant hold RPM steady at 3000RPM and re check your Dynamic timing at that speed you should now have something in the region of 25-30 deg BTDC ( the exact figure depends on distributor number) If those figure you achieve are nearly what I have stated you may now set the ignition timing to 5deg BTDC at 800 RPM without vacuum. Reconnect vacuum pipe to distributor and disconnect from manifold now suck on pipe with engine running does timing advance Yes everything is ok and working No vacuum advance / pipe is faulty investigate as required. Now set you carbs up as I described earlier. Road test car and see how it runs if good happy days if not Report back on here but DO NOT ALTERANYTHING!! Let me know now if car just feels flat of has what feels like a misfire. One other thing to check is your Exhaust Blocked I would use a pressure gauge to determine that in my workshop but get an assistant to rev car up while you are by tail pipe whats the flow of gas like compared to a similar sized car Good luck hope that lot sorts it for you.
Dave

[mickthefitter]

Half of this or more than half of this I've already done Dave, based on advice given in earlier posts or just from my own prior knowledge and desire to eliminate things.

Tappets yes
No.1 cyl at TDC matching timing mark yes
Rotor arm pointing to cyl 1 yes
Not sure about moving rotor arm against springs - I thought the baseplate was on springs, rotor arm shaft on a solid drive from engine?
Points correctly gapped yes
Firing order correct yes
Statically timed to 7 BTDC prior to refitting the radiator yes, using a digital multi meter to determine points open as I don't have a bulb on wire.
Plugs gapped yes
Haven't done a compression test yet
Don't have easy access to an assistant when I get time to do adjustments.
When I put the vacuum pipe back today, after dynamically timing the car at 10 BTDC, adjusted the engine revs down again from their sudden rise to (1500rpm?) back down to 1000rpm and shone my timing light on the pulley, the notch on the pulley was more something like 35-40-45-50 degrees BTDC, in the middle-of-nowhere related to the pointers, rather than the 10 degree BTDC I'd put it with the vac pipe off. At 1000rpm. Nowhere near the 3000rpm you're telling me to try it at.
The car isn't misfiring - saying that though its an auto. Misfires don't feel the same as with a solid drive. But the impression is of serious lack of power and huge reluctance to pick up speed.

Can you settle an argument please? With me and a mate. Say, 20 degrees BTDC. Is this ADVANCED or RETARDED? In comparison to book value of 10 degrees BTDC. I say its advanced. My mate says retarded.

[david painter]

The springs on the rotor arm, are for the Mechanical Advance and work against two centrifugal weights known as Bob weights. When the base plate is removed, the amount of advance they can give is stamped on them. The fact you engine RPM picks up when reconnecting vac pipe suggests vacuum advance is working. The Base Plate movement is for the Vacuum advance, ( not a important as the Mechanical one) its a timing trim for cruse conditions when inlet manifold depression is high think on it as a 3D map. 20 deg BTDC is Advanced BTDC stands for Before Top Dead Centre, so any number higher than 10 is advanced and below it retarded. I Know you say you have done tappets but have you checked valve timing as described ? If you haven't got an assistant handy top open throttle wind up idle crews equally until a 3000RPM idle is achieved then you can recheck you Dynamic Advance. I need the timing figure at 3000RPM without the vacuum connected so I can asses whether your mechanical advance is working correctly.
Dave

[mickthefitter]

I think it was Chris (if not somebody else earlier in this thread) who told me about turning the engine over until both valves for no.1 cylinder were 'relaxed' then using a probe in cyl.1 to determine TDC to see if the timing mark on the crank pulley is in the right place. Or do you mean have I set the tappet gaps by rule of nine? Yes! I have a Haynes manual and Autobooks manual. I've been setting plugs, points, timing and tappets on BMC/BL and Vauxhall products (not tappets on Fords with OHC) since 1980 until I ran out of easily self-servicable cars when they came fitted with electronic ignition, ECUs and hydraulic tappets in the 1990s/2000s, then I started doing it again with classic cars since 2003. I always feel a bit unambitious because I don't restore cars or bring cars back from the brink like some people are able to, but basic work under the bonnet, changing brakes linings, simple wiring jobs I'm no stranger to. Its easy. This Morris Marina is being an obstinate pig for some reason and this is probably why it ended up at auction. Somebody had given up - probably feeling out of their depth.

Surely JUST connecting up the vacuum pipe at around 1000rpm should not ADVANCE the ignition timing by (I estimate) 20 degrees past where I set it dynamically with the vacuum pipe disconnected? Literature says the vacuum advance STARTS to work at about 1000rpm. My car is dreadful to drive and the general concensus is that what I describe is caused by timing. The work I've done so far has been done accurately. I've not yet established if the mechanical advance is correctly working but at the moment (sat at my laptop at breakfast time and following a pub discussion of my problems last night) the timing seems to leap in the advanced direction when I connect the vacuum pipe, and then the car becomes very poor to drive - as if the timing is out. Obviously I've got to investigate further but my impression is either than there is too much vacuum (I'm not even sure if that is possible) or something on the distributor is very wrong. I've never removed one and never dismantled one, but my distributor must have been removed in the past for some reason, because one of the flange mounting bolts is missing from the block - in the familiar half-arsed style I get used to on the old cars I buy - someone else in the past thought one bolt holding the dizzy was good enough so job done. So whether someone has tampered with or buggered up the internals, I'm yet to discover.

[MarinaCoupe]

I'm wondering if the distributor complete or just the vacuum advance is not the correct unit for the car. If you can confirm the model and year of the car and the numbers on the side of the dizzie and on the vacuum advance unit, I can check them off against the parts catalogue.


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[mickthefitter]

Doubtful I'll be working on the car today but I'll certainly look under the bonnet later. I have satisfied myself it is a 45D but yet again, the masses of handwritten notes (with bad handwriting) that the Haynes manual with the car was peppered with, which at first indicated a conscientious owner, had something about the distributor where he'd written "25D or 45D? Ask auto electrician" when the supplement section clearly says a Mk2 1.8 Marina has a 45D. Likewise he's got the auto transmission down as the wrong version for this car. I've thrown the notes away. Now I've only got his underlining of certain sections in the manual to worry me!

[david painter]

The reason I say we need to go back to basics is so many things in this thread have been altered! If the car came into my workshop, what I am asking you to do is exactly, what I would do in the order I would do it. I ask about the valve timing because sounds to me someone before you has been working on it clearly not knowing what they are doing. It is very important the valves on no4 are rocking at no1 TDC because if cam timing is incorrect. Nothing else will work right. Far easier to use this method rather than removing the timing cover to check it. A good engine will produce a steady 20in hg of vacuum at idle. Where is the vacuum take off on your carbs is it the manifold side of throttle butterfly ( high vacuum at idle) or is it air filter side if throttle butterfly ( low vacuum at idle).
Dave

[david painter]

25D has a rounded type cap wire held to points with a nut 45D square type cap points wire held on with spring clip.
Dave

[mickthefitter]

Hi Dave. Thanks for your input, I do understand doing a diagnosis over typed text isn't the easiest, and also the need to work through things in a certain order. I'd been longing to check the tappet clearances since I got the car, and once problematic timing became apparent, trying to establish whether 'TDC' was 'true TDC' using the method described to me earlier in this post, was also a priority. I've worked on this car three days this week. The main priority had been to put the rebuilt radiator back, but because I wanted to go through some other stuff, on Monday that never happened because instead I did valve clearances, gapped the plugs (and checked they were the right ones), double checked my points gap set some weeks ago (when I removed them to check the condition of the contacts - they were good) then timed it statically.

I also replaced my fuel pump spacer block with one for Minis with a narrow slot (because of the aftermarket pump) and greased the front suspension. I also 'crimped' the non-locking choke inner cable in the car, which then seemed to result in the choke operating in a different way because it looks to me like the linkage was under tension at the carbs when the choke was pushed in. I've now ordered a brand new cable anyway.

Rad went in on Wednesday which was then the first fire up after checking tappets, TDC, static timing etc. It took a lot of cranking and didn't drive well.

Then I re - timed it dynamically yesterday, and because of the seemingly over active vacuum advance, plus the fact I'd already bought a Carbalancer, and vacuum advance at idle was possibly down to carb imbalance, I decided to bite the bullet and try my hand at that.

Over the past 30 years I've successfully used my Colortune spark plug on both old and new SU carburettors, and a manual choke Weber I fitted to a Ford Pinto engine to replace the Ford VV autochoke carb it came with. I've never balanced twin SUs before. That Gunson Carbalancer is a nightmare. I showed it my mate Dennis down the pub last night (he being an ex motorbike racer, 350 Yamaha owner, 1926 Velocette KN owner, one time Mini Cooper owner twice over, and a long time ago a Marina Coupe owner!) and he reckoned the rubber that the venturi adaptor is made of is too hard to form a good seal at the intake. All I know is the float in the scale was unreliable and the clip-on mount that's supposed to hold the scale vertical while you work is useless.

So going back to you saying "so many things have been altered", back here at home, there has been a progressive logic. But days pass when no work is done then there's a flurry of activity (helped by the fact that last week I was off work)

Initially after purchase I needed to get to know the car, and I haven't driven it that much. I didn't think it was performing properly. After Quorn, I knew it wasn't for sure, and that it was in danger of boiling up.
So I checked the timing dynamically as I have done for 30 years.(Set to a 7 BTDC recommendation from the forum to allow for unleaded fuel). It didn't perform well.
I then set it to 10 BTDC dynamically as per technical literature. Still no better.
I took the water pump off and jet washed the block because of the overheating problem. It still overheated (or went 80% towards red anyway).
I had the rad rebuilt which appears to be a success.
And now we're up to speed where I've put the rad back, checked TDC, set tappets, gapped plugs, gapped points, static timed it (7 BTDC) , ran it, drove it, dynamically timed it (back to 10 BTDC again), put the vac pipe back, seen the white mark on the pulley leap over towards the battery, checked the carb balance and mixture, driven it, still crap.

[mickthefitter]

Dave, what specifically do you mean by 'valves on no.4 rocking?' Do you mean one on the way down and the other on the way up? The way I've already checked, on previous advice (but no mention of no.4) both rockers on cyl. 1 relaxed, no.1 piston at top, pulley timing mark at TDC, rotor arm pointing to fire cyl.1. Mick.

[david painter]

If you move the crank pulley in both clockwise and anti clockwise directions with no1 on TDC of the firing stroke gap in both no1 valves either side of TDC no4 cylinders valves will open and close slightly this is what we call rocking its a way of checking the camshaft timing without striping the engine not the same as checking/setting valve clearances using rule of nine. below is link to video explaining valve timing.
https://www.youtube.com/watch?v=cAlw9RpTZ4I 2.25 in the valves are rocking also pay close attention at 2.55 in when describing valve overlap.
Dave

[mickthefitter]

Chris,

My car is an April 1976 registered Mk2 1.8 automatic HL. As best as I can make out, the numbers on the distributor are 41410H 45D4. Equally 'as best as I can make out', the numbers on the narrow top part of the vacuum can are 11 12 on a top row, and 28147 below.

Cheers, Mick.

[mickthefitter]

Dave,

I believe I've done everything you asked barring running the engine up to 3000rpm. It is unlikely I'll be running the car again until next weekend at the earliest, so we'll have to pick up where we leave off. Pretty much all of what I'm about to go over here, I did on Monday, except looking at the rockers for cyl no.4. So most of this I've now examined twice.

First, a couple of shots of where my vacuum pipe to the dizzy is tapped into.



Another closer shot. The thick pipe near the thin dizzy take-off is the vac hose to the (apparently) TR6 replacement brake servo.



Now the work part. Here we have piston number one in the plug hole at the top of its stroke.



And next, white notch on my pulley aligned at the same time with the pointer for TDC, uppermost in the picture. The middle pointer in white is highlighted because that's 10 degrees BTDC and that's the one I keep aiming for, or near to depending on whatever book or latest advice I'm following.



Next, the rotor arm pointing towards cyl no.1



...while at the same time, the rockers on cyl no.1 are relaxed (sorry about the blurred images)



...and the rockers on cyl no.4 are one coming up, one going down. Unfortunately you are going to have to take my word for this in a still image, because it was going to be too hard to hold a phone camera taking video, hold an LED inspection lamp, and turn the engine back and forth using the fan and vee belt. No way was I going to bash the fins on my new radiator with a socket and ratchet on the crank pulley, which is why I did most of this investigation work on Monday before the radiator went back in.



I can also confirm that I can turn the rotor arm anti-clockwise slightly against a spring, and the dizzy baseplate clockwise slightly against a spring.

I'm jumping the gun somewhat but I had the horrible thought, I wonder if the engine has got valve seat recession?

Cheers,
Mick.

[david painter]

OK First things first your distributor is a 45D/4, I don't have any specific data here for that distributor but will have it on data file at work. Will let you know next week when im back at work. You are using the correct mark for TDC, where crank pulley is set in picture is TDC and tipex mark is 10deg BTDC. So picture you describe showing rockers show camshaft timing is correct. The numbers on the vacuum can are the start and finish of vac advance top row is 12deg at11 inc hg and finish is 47deg at 28inc hg. Your Vacuum advance pipe is on manifold so will give you full vacuum advance at idle because you should have around 20inc hg in the manifold at idle!! wow that's ridiculous considering they were trying to reduce Hydrocarbon Emissions by this time. Never the less its doing what it should. Its good that you can move rotor arm against spring means mechanical advance is not seized. When you adjusted the tappets were any tight? have you reset them to 0.013 inc? if you have valve seat recession you will have had very tight tappets. Once you have done your compression test, and refit your spark plugs and run engine warm disconnect vacuum pipe from inlet manifold and connect your vacuum gauge. Now let engine idle what is your vacuum gauge reading and is the needle steady?
Dave