How to de-pollution a X-flow ? Just got one for the boat :)

[Anonymous]

Thanks addo, i'll wire it up as soon as i can, fix those fuel leaks, and (somehow) get the timing sorted. And then who knows? Maybe the boat will be back on the water soon

L6, thanks a lot for the tips, you've been immensely helpful. One question i have about the timing is, you say its pretty easy to set it, which is fine, but *what* shall i set it to? The same as in a car - 6' BTDC ?
The reason i ask is that the timing markers are on the water pump, which obviously is going to be removed soon. So i need to set the timing before i take the water pump off and bolt on all the marine bits.

Or - should i just play with the timing on the river till it feels good, and then draw a whiteout mark on the flywheel and on the engine somewhere as a reference.

 

[Vaughano]

40° represents up to 20% difference in temps - that's significant all right.

<useless-fact>

It may be significant, but it isn't 20% difference.
That would be true if 0°C was actually zero temperature, but absolute zero is -273°C (0°Kelvin).

</useless-fact>

Sorry to be pedantic... I couldn't help myself!

 

[L6]

Sorry to be pedantic... I couldn't help myself!

Now young fellow, a word of advice from old fart, never try to out-pedant an archpedant.

The temperatures quoted were in degrees Fahrenheit, and absolute zero corresponds to -459.67 degrees using that scale. The parallel scale using absolute zero as 0 degrees is the Rankine scale.
Degrees R = Degrees F + 459.67

The figure of -273.15 relates to absolute zero in degrees Celsius, this has the parallel Kelvin scale with 0 degrees at absolute zero.
Degrees K = Degrees C +273.15

 

[addo]

I say 20%

200°

160°

200-160=40

(40/200)=20%

QED

 

[Anonymous]

Damn you and your percentages!!! blah blah blah...
So i'm to take it that nobody knows what i should set the timing to. Great!

 

[Vaughano]

Now young fellow, a word of advice from old fart, never try to out-pedant an archpedant.

Hahaha, lesson learned!

Chubs, sorry to hijack your thread. How's it all going?

 

[Anonymous]

Hows it going? Well, nothings changed - i can only work on it on the weekends. I just need to accumulate some information (such as what TIMING??? ) so come saturday i can get it all going.

So far, my todolist is:
* Teflon tape the fuel pump fittings (no more leaks!)
* Wire the dizzy/coil up - red to +, green to - on coil
* Set the timing
* Put an oil sender in
* Put some OIL back in it
* Make an oil cooler for the sump
* Start it!

Remaining questions are:
* What to do with the fuel pump return line? The old motor didn't have one. Can i just block it off?
* What to set the timing to. If nobody knows, i'll set it to 7' BTDC

 

[addo]

"L6" did discuss how to do the timing.

 

[Anonymous]

The simplest way to set the timing is to mark the harmonic balancer or flywheel with the correct timing for the engine speeds corresponding to the particular operating applications described above, then run the engine up to that speed and check with timing light.

I know, i must sound like a noob, but *what* is the correct timing? Or am i missing something.

 

[2nd.gunman]

According to the XF factory manual, base ignition timing is:

auto 10 degress +/- 2
manual 6 degrees +/- 2

Hope that helps.

 

[Vaughano]

I know, i must sound like a noob, but *what* is the correct timing?

Maybe 35 degrees BTD at 3000rpm? : Just a guess, I've never timed an engine at those revs. But disconnect the vacuum advance when measuring and by the sounds of it you might want to leave it off.

If I understand it correctly, at wide open throttle the vacuum advance would have little effect, so if that's the way a boat is normally driven (I wouldn't know, I've never driven one) it probably wouldn't contribute much to the timing anyway under those conditions. So if you check the timing at revs with no load you'd want to make sure that vacuum advance is playing no part (so advance is purely a function of rpm via centrifugal advance).

To set timing at N degrees I'd probably mark a line N degrees clockwise of the timing mark on the pulley and then line it up to zero on the markings plate at the engine speed that you decide is critical (rpm that gives most power).

L6 makes sense when he says to time the engine at the revs for max power under WOT, because that optimizes your timing at the critical rev-range regardless of the advance curve for your dizzy (which is exactly what he said, in different words).

But as to what advance and at what revs, maybe others could improve on my guess. And what effect would this have on initial timing for starting? Would vacuum advance be of benefit at all?

 

[Anonymous]

By the way, i wakeboard at 2000rpm. 3000rpm is frigging fast in my boat - more like skiing speed.

So aim for 2000 if that helps calculations?

 

[L6]

Sorry not to have replied earlier, started to type it up, was called away from the computer, then only got around to logging in again today.

First to reflect on why the timing issue has even been raised.
If a distributor has a mechanical advance curve which is absolutely spot-on over the full rev range, then setting the ignition timing accurately at idle will mean it must correct everywhere.

However the advance curve is dependent on the springs, the pins, the actuating cam, fly weights and the range stops, consequently manufacturing variations in these components, wear over time, tweaking by mechanics, or incorrect replacement parts means the curve is rarely accurate and the ignition timing can only be correct at one point in the full rev range.

If ignition timing can only be correct at one point it makes sense that it is optimised at maximum load, rather than at idle.

The torque demand of a propeller is approximately proportional to the square of the shaft speed, so halving the engine speed reduces the engine torque to a quarter. This means the most sensible place to set timing is at the maximum revs the loaded engine will pull at WOT. There is far too much risk of personal injury attempting to set timing when moving under these conditions, so just run the engine up to the same revs in neutral without the vac advance attached –which in most boats is not used anyway.

A factory repair manual for your engine will list the centrifugal advance in degrees for different engine revs. If you do not have a manual, someone here will surely be able to provide this info. Remember, the actual ignition timing is the static timing plus the centrifugal advance, so before even pulling out the timing light you should do the sums and write up a table with RPM in one column and the corresponding engine timing in another, rather than trying to do mental gymnastics on the fly.

Timing marks up to the most centrifugal advance the engine runs will be required. There are not too many engines running more than 25 degrees total, so markings to 30 degrees is usually adequate. From previous posts I am surmising you have a snout drive with the flywheel facing towards the front of the boat so will lose the normal timing marks.

Some non-boatie readers might be wondering what this means. The harmonic balancer, water pump, and timing cover are removed. A drive coupler is fitted to the snout of the crankshaft where the harmonic balancer would normally reside. The chain case is covered by an alloy casting which houses a dog clutch and the propeller drive flange. A V belt pulley bolted to the flywheel drives the alternator and water pump. There is an alloy casting (similar to a very short bell housing) which covers the ring gear and the outer 50mm or so of the flywheel as a safety measure and also provides the engine mount pads.

The reason for this arrangement which at first sight appears unduly complicated is to bring the propeller shaft coupling closer to the bottom of the boat allowing a flatter shaft angle.

For future reference you should make permanent timing marks at the flywheel end of the motor. There is more than one way to tackle this, the following is my preferred method.

1. Fit the flywheel cover while the timing cover and harmonic balancer is still in place. Turn the crankshaft until TDC is indicated. At this point it is worth checking the engine really is at TDC. If you do not propose to remove the head, TDC can still be established quite accurately with a piece of wire in the plug hole and some perseverance. Spend as long as it takes to get this right because any errors here will be transferred to your new timing marks.

2. Identify a suitable place on the lip of the flywheel cover to make the timing marks. This should be away from the V belts and anything else that could bite when the engine is running. For markings from TDC to 30 degrees BTDC the distance required around the lip of the cover will be about 100mm.

3. Calculate the spacing between the markings. Measure the distance from the centre of the flywheel to the lip of the cover where the markings will be made. Call the distance R. Using a calculator multiply R x 0.0873, this is the distance along the edge of the cover corresponding to 5 degrees of crank rotation.

4. Mark the cover. For 30 degree advance range you will need seven marks on the lip of the cover each spaced apart by the calculated distance. It is far too difficult to measure this directly on the curved housing, so cut a piece of thick paper about 25mm wide by 150mm long then mark this out while it is laying flat. Stick the paper to the lip of the flywheel cover then transfer the marks using a punch. Make the marks more visible using a hacksaw blade or triangular file. You now have marks corresponding to TDC, 5BTDC, 10BTDC, ……30BTDC

5. Label the marks. Remember when viewed from the flywheel end of the engine, the crank turns in a counter clockwise direction, so the most counter clockwise mark is TDC. Typists whiteout correcting fluid which comes in a small bottle with brush in cap is easy to apply and surprisingly durable.

6. Mark the flywheel. If you are happy the engine is at TDC, mark the flywheel next to the TDC marker on the cover. This has to be a durable mark and the easiest way is use a 3mm drill to make a cone shaped divot which can be filled with white paint or whiteout.

This whole exercise should not take longer than an hour and will pay off numerous times over the service life of the engine.

One more item to deal with. You will need a new carby wedge if as I suspect the base of the new carb has a different bolt pattern. Quite likely the old air cleaner will not fit the new carb, and if this is the case buy one with the fine wire mesh which acts as a flame arrestor in the event of a backfire.

 

[Roath]

L6
I just want to say , thankyou sooo much.

As the owner of a Hamilton Jet with a Ford 250 ( non cross flow) I have been struggling to get my replacement motor tuned correctly. ( old one got full of salt water after blowing a hole in the exhaust manifold)

The timing seems to be the big problem for me also, and last weekend after tweaking the dizzy while on the water. Put the jet in neutral, fiddle with timing- Then go for a blast, then back to idle , try moving timing and go again etc. I managed to get back 5 mpg top end and lots more acceleration.

I also seem to have cured my large oil usage (was never any smoke or oil in the bilge) and I hope the petrol consumption has come down!

I am still down 5mph from previous motor so I will try to get a engine manual and remove the vacuum advance as you advise. (my top revs are 3300).

Thankyou so much for your wisdom and your time in this forum. Your posts are exactly the information I have been looking for for a few months.

 

[Anonymous]

Brilliant post, L6, you've got some awesome advice.

You asked why the timing is an issue? Its because the previous owner removed the distributor while painting the engine, and replaced it a LONG way out - he didn't even tighten the hold-down clamp.

Anyway, i just static timed the engine by removing the rocker covers, and watching the valves open and close so i could figure when TDC was at the ignition stroke, then i moved the distributor into place and aimed it at the #1 post.

Tried starting it, and couldn't even get it to cough. There was definitely petrol in the carby, i just can't figure it out. It doesn't seem to be sparking. I even swapped the dissy and coil from the old (precrossflow) motor - i know this distributor works - and it still won't fire.

Any ideas? I'm just going to get a lube mobile guy to come around and take a look at it if i can't figure it out soon.

As an aside - is it a bad idea to be using the precrossflow dissy? It fitted pretty much fine.

 

[Roath]

Hey Chubs

Hope you get there with that motor mate. I wish I had enough engine bay for a 2v head.. but I don't so I have to stay with the old precross flow. ( Not enough width)

L6 isn't experianced with Ford 6's ( he said earlier) so hopefully someone else can answer about the dizzies.

On the same topic, I went to the library today to get the timing curves for my motor and I notice that the dizzy for the precross flow has vacuum advance AND centrfugal advance.

L6 , I can disconnect the vacuume , but do I need to disable the centrafugal advance as well? I imagine I do. A mechanic mate suggested I would need to lock the vacuum advance in the dizzy to stop it moving as well. Any thoughts?

Sorry to steal your thread Chubs, but I've been struggling like youself asking hesps of people questions and L6 is the first that can answer everything and explain why.
God I love the internet.. how the hell did we do this stuff before... hmm I can't remember.

 

[addo]

Chubs - have you got the oil pump drive shaft in there?

 

[L6]

You asked why the timing is an issue?

Sorry there, I meant the reason I had raised the issue was …..

As an aside - is it a bad idea to be using the precrossflow dissy? It fitted pretty much fine.

I am a 250 novice but seem to remember reading the early dissy uses a thinner drive shaft to the oil pump. If that is the case it might just turn in the pump and leave the motor without oil pressure.

On the same topic, I went to the library today to get the timing curves for my motor and I notice that the dizzy for the precross flow has vacuum advance AND centrifugal advance.

Most conventional distributors have vacuum and centrifugal, they serve two quite different functions.

For best performance, peak combustion pressure should occur about 14 degrees after top dead centre. The time that elapses from ignition until peak compression pressure is developed is roughly the same regardless of engine speed. This means the faster the engine is running, the earlier the ignition has to be started if it is to reach peak value by 14 degrees ATDC. Centrifugal advance solves this requirement.

WOT particularly at revs close to maximum torque provides best cylinder filling and consequently highest combustion pressures which can result in detonation (pinging), so it is desirable to reduce the amount of advance under these conditions. If you have driven a vehicle with a vacuum gauge fitted you will have noticed those are exactly the conditions the manifold vacuum plummets. This means the manifold vacuum can be used to "fine tune" the amount of advance so the engine has large a amount of advance under partial throttle for good fuel economy and less advance where there is a potential for detonation.

Look at a vehicle using typical figures -not necessarily for a 250

Cruising down the highway at 2000 rpm
Initial timing 6degrees
Centrifugal timing 14degrees (7degrees @ 1000 rpm)*
Vacuum 10degrees (5degrees @ 15")*
Total 30degrees

WOT at same speed.
Initial timing 6degrees
Centrifugal timing 14degrees (7degrees @ 1000 rpm)*
Vacuum 0degrees (0degrees @ 4")*
Total 20degrees

WOT at 5000 RPM
Initial timing 6degrees
Centrifugal timing 20degrees (10degrees @ 2500)*
Vacuum 0degrees (0degrees @ 5")*
Total 26degrees

*Note Timing curves are generally given in distributor RPM and distributor degrees. If the highest RPM shown in the curve is about half the maximum engine revs and maximum advance is about 10degrees, the figures are likely to be distributor readings and both the RPM and advance must be doubled to convert to crankshaft figures.

I can disconnect the vacuume , but do I need to disable the centrafugal advance as well? I imagine I do.

If an engine is hammered at WOT and economy is not an issue for example in a competition vehicle, or run for long periods under high load where detonation could go unnoticed for example in a boat, the vacuum advance is often blocked off. Leave the centrifugal advance in place or you will strike problems with mid range RPM being over advanced.

A mechanic mate suggested I would need to lock the vacuum advance in the dizzy to stop it moving as well. Any thoughts

The canister spring will hold the vacuum against the stop so locking is not necessary.

 

[Anonymous]

Cheers all,
we got the engine working!!
The main problem was the ignition wiring - i had the negative of the coil connected to the negative of the battery when i shouldn't have. I actually figured this out, believe it or not, from reading the workshop manual for my old celica.
We also had to use 2 sets of jumper leads to get enough juice to start it.
And finally we had to clean and gap the plugs.

Anyway, since nobody here could tell me how to wire it up properly, here's how to get it working:

Thanks for all the help

 

[xdee]

Red goes to the + on the coil, and this terminal also gets 12V supplied to it. Use a good gauge of wire. Green goes to negative on the coil. Only other wire off the negative coil terminal goes to the tacho.

Sounds exactly like your picture looks, except Addo didn't mention a funnel