Mallory Dual Point owners

Hi Jim,

It is all a process of elimination, so that is good that the distributor is in top nick. A timing light will be an excellent tool, as will a dwell tachometer which you can use for both checking the dwell angle and as an independent source for engine rpm.

The Mallory dist will advance the timing much more quickly compared to the factory setting on the OEM Lucas unit, in the region of all in by 2700 rpm compared to over 4000 rpm. So given that your engine does not ping when under acceleration that would so far rule out a lean fuel mixture. When an engine is going to ping it will always do so before reaching peak torque, either because the mixture is too lean or there is too much ignition timing or both.

Old fuel is a definite negative and prone to cause problems, especially as fuel starts to deteriorate after only 6 months from the date of manufacture, so the sooner you drain and remove the better... :wink:

Ron.
 
Ah yes there is a dwell setting on my multimeter, thanks for reminding me Ron.
I'll investigate that tomorrow :)
 
Got the colourtune today but didn't have time to try it.
I did replace the plugs (autolite) with new ngk, and she started the very second i turned the key- so that's some progress today.
Still exhibiting the same rev bounce at around 2000 rpm, but i can sometimes coax it out of it by blipping the throttle.
After which i'm able to rev it fully (smooth) :?
The old plugs which i cleaned only a few days ago revealed:
1,2,7,and 8 were all terribly sooty, and the remainder were fine.

I'm going to bite the bullet and drain the fuel tank tomorrow. What's the best way to deal with the inevitable crud at the bottom?
Do you think it's worth trying to pump some fuel through the reserve piping with the electric fuel pump into a large container?
Am i correct in thinking the reserve pipe has a filter at the tank?

Chris I will have to wait another week or so to order the magnecors, just cant afford them currently :(
But i should be able to get an ignition amp around the same time :)

Jim
 
Now we're cooking on gas!

So steps to take while waiting for the Magnecors and ignition amp to turn up:

1) drain tank and refill with fresh fuel.

2) set up the distributor points using your dwell meter.

3) set static timing - I'd suggest going for TDC in deference to the fast build up of advance on the Mallory. We can play with it later after the carbs are somewhere near.

4) inspect and set up throttle linkage.

For draining the tank, I'd suggest pumping the vast majority of it out into buckets etc via the main line. If the fuel comes out nice and clean to start with, I might try switching to reserve and seeing if the flow is equally as strong and again clean. If so I might skip the next bit. So only if there is ecidence of dirt, remove the tank level switch and fuel pickups from the tank and inspect the filter around the reserve and the general level of crud remaining.

For setting static timing, just use a bulb with a couple of bits of wire - that way you'll be able to see when the points open and close. We'll go back and set this up properly once everything else is sorted.

On the throttle linkage, the first check is to see that all the rubber bearings are in place - particularely the one on the firewall where the throttle shaft takes off to jump to the engine. The point of this is to make sure you can achieve full throttle at the carbs - lots and lots of Rover V8's can't! Next, take the carb elbows off (just pull) so that you can see in to the throttle butterflies.Then adjust the linkage between the carbs so that you get full throttle on both carbs simultaneously. Then check that both butterflies also close fully together (you'l have to wind the idle screws out of the way for this). If they don't fully close at the same time, then you may need a compromise setting - but remember full throttle is the most important - closed throttle is taken carre of to some extent by the idle screws. The point of this is to ensure that operating the throttle picks up both carbs simultaneously - you then have a full V8 instead of a strong four cylinder being chased by a weak four cylinder.

Oh and what do your air filter elements look like?

That'll do for now!

Chris
 
chrisyork said:
but remember full throttle is the most important - closed throttle is taken carre of to some extent by the idle screws. The point of this is to ensure that operating the throttle picks up both carbs simultaneously - you then have a full V8 instead of a strong four cylinder being chased by a weak four cylinder.
Click to expand...

You've said that before, and then I said the same thing as I'll say now, and that's that you're giving very poor advice. Unless you're talking about setting up a full race engine where part throttle openings are of little or no consequence, the way you suggest setting things up is exactly how to get one carb dragging the other one along at all intermediate throttle openings. They need to be balanced at idle with the carbs seperated, then the link rod set so that both carbs come off the stops at the same time, and then full throttle will take care of itself. You can also check the balance at various rpm from idle upwards, to check that they are still synchronised. I don't know how you came by this method, but you need to do a lot more research before you start passing it on as advice for others to follow.

Also you advise using the dwell meter on the twin point distributor, I hope that you know how to do that.
 
I absolutely don't agree with you on the link adjustment, Harvey. There shouldn't be any conflict between the open and closed matching, but even if there is, it should be very minor. If you set the linkage for full throttle operation then by the time you get to about 1/4 throttle any minor error at closed will have been evened out. At idle and just above, then the idle screw adjustment will take care of smooth running.

If you set the link adjustment to be exactly equal at closed throttle, then the error will get worse as you open the throttles. That's silly, as you will ruin the fuel consumption without having improved smooth running.

If you use the method you suggest (if I understand you correctly), then the carbs will not be balanced either at shut throttle or at fully open. The only situation where your method works is where you can't be bothered to sort out the fall times of the pistons in the dashpots (which we'll get to with Corazon's car in a bit!) Your method is, I think, only suitable for a professional garage maintenance situation, where you are wanting to do a reasonably quick job on a set up that isn't too far out anyway. ie the sort of thing you'd do to a reasonably new car, back in the day. Nowadays I would assume that you needed to start from scratch with all the important characteristics of the carbs requiring to be set up from scratch. ie much more thorough.

We'll see on the dwell meter when Corazon gets to it!

Chris
 
I just can't be bothered to even try to understand what you're getting at, to me it just sounds like you're talking about things that you haven't got any real world experience of. Carry on as you are, I won't mention it again, it's just not worth the effort.
 
chrisyork said:
If you use the method you suggest (if I understand you correctly), then the carbs will not be balanced either at shut throttle or at fully open.
Click to expand...

Sorry Chris, I don't agree with you on the carb balancing either - Harvey's advice is sound as far as I can tell... I use the setting at idle method on my camper (two x twin-choke Dellortos), and I'm more than happy with it.

Setting it up as Harvey suggests would surely mean the carbs were balanced at idle (shut throttle)?

I'm no expert on those nasty SU carbs though ;)
 
I've been reading up on setting up the mallory correctly, so will be giving that a go tomorrow with the dwell meter.
I think draining the fuel tank may just make all the difference.
The carb balance was checked before the car was laid up by a local land rover specialist.
He reckoned they were spot on then, so i wont touch them until everything else is officially ruled out

I will post all my findings tomorrow :D
Jim
 
Sounds good Jim (Corazon).

Jim (tofufi), the carbs would indeed be balanced at idle - but not necessarily at shut throttles on the carbs. They will also be balanced at full throttle - but only if the carbs are perfect. So Harvey's method is quick and gives a fine result if everything is spot on. I use my method because it flushes out problems with the carbs along the way. Plus Harvey's method is biased towards getting a very smooth running engine at low throttle openings whereas my method is biased towards getting full power and economy spot on. We had a discussion off line so as not to inflict disagreement on you all!

Chris
 
Drained the tank as much as possible with the pump.
Bearing in mind i've put 10 litres of fresh fuel in within the last couple of weeks, i got near that amount back from the main fuel line.
It was all very brown, darker than apple juice :shock:
Once the main feed was exhausted, i tried switching to the reserve but only a couple of weak spurts would come out.
So it now appears i should remove the tank and thoroughly clean and de-rust it.

The reserve piping must be blocked? there's no leaks from the tap area. I know there's meant to be fair few more litres of fuel once the reserve is pulled, and i have used the reserve regularly in the past.
A little confused i tried tapping the fuel tank in different places to hear any variation. It sounds completely hollow and empty :?

Anyone done a vinegar/salt or bicarb solution to de-rust, or used the electrolysis method. POR-15?
I'm assuming i'll have to clean through the reserve lines now too.

Jim
 
From other peoples experience that is the right sort of colour for simply old fuel, so don't panic just yet about the reserve line. If you have access to old ladies stockings :oops: (or perhaps a coffee filter?) try filtering a bit of what you got out. That'll give a clue whether there is loads of gunge in the tank. Then use it top up the tank a tad again and have another try with the reserve line.

Chris
 
Do you think it is possible for the reserve tap to become stuck providing only flow from the lower fuel tank feed?
Even though the reserve handle isn't pulled?
(No visible leak)
Jim
 
Take a leaf out of Mad Pom's book and dump half a gallon of molasses into it, fill it with water and give it a good shake and wait a week or so.
 
I did look into that organic method, looks great for some things.
Sugar in the gas tank though? :LOL:
 
Hi Jim

Your'e not at that point yet! First try adding some of that dead fuel back into the tank so you can try the reserve line on the electric pump again. It could just be truly empty! I'm a great believer that a defect is very unlikely to have occured at precisely the time you were looking for it, so if the reserve system has been known to work recently, why should it have chosen predisely now to block up?

If you do gail to get anything through the reserve line, then, yes, time to drop the level switch and supply points assemble out of the tank. Accessible from under the car, that should be pretty easy. That gives enough space to insert a digit into the bottom of the tank. Then you will have a clear idea as to whether the tank is full of muck and debris or not.

My betting is that so far all you are certain of is some stale fuel.

Chris
 
I know Chris, I haven't been able to work on the car for a couple of days but my mind won't stop working :wink:
Tomorrow hopefully i'll have some definitive results
Jim
 
Today I strained some of the fuel and added it back in to the tank.
With the reserve handle pulled, it all pumped back out again in a healthy manner. Phew.
First thing i'll do tomorrow then is to try some brand new fuel undiluted by any old stuff.
Then it's onto dwell tweaking if no better, and some investigation with the colourtune
Jim
 
Just test driven the car with a gallon of fresh fuel, after fully draining the tank of any old stuff.
Absolutely fine now :D
No hesitation or strange behaviour when revved, even up to the top of the range.
Gear changes were in turn very smooth and predictable.
It is running slightly lean, but i'm going to play with the colourtune this afternoon :D
very happy with the mallory now i've had a chance to drive the car properly 8)

So in my case, 2 gallons of fresh fuel diluted by the tiniest amount of old fuel became pretty much useless fuel for my engine :shock:
Jim
 
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