Petrol Pump

[alexander]

Thanks Keith for suggestions will try them once it gets a little cooler. I have a spare oil cap so will drill a small hole and try that if no improve to with second pump.
Dave

[David Morris]

Hi Alexander,

Yes, a faulty pintle valve can cause problems. Overhaul is a simple process. I suggest the easist way is to unscrew the union at the end of the pintle valve. Using a long extension, carefully unscrew the single bolt holding the oil filler tube to the front cover, BUT maintain pressure on the extension whilst you lift away the tube, complete with the pintle valve. If you don't maintain pressure on the socket extension, there is a real risk that the bolt will escape into the front cover and mean a lot of dismantling to reach it! Remove the pintle valve from the oil inlet pipe, now you have both in your hands.

You can now put the large hex nut of the pintle valve into the vice and simply unscrew the body with a pair of slip-joint pliers. There's not much inside but the spring might be broken or the seating or valve body might be pitted. Valve grinding paste will clean them up. In the good old tradition, reassembly is the reverse of disassembly, but remember to get that bolt held securely into the saddle on the end of the oil tube, before you push it into the front cover. Of course you could leave the oil tube in place, and unscrew the pintle valve, leaving the oil tube in place, but I recollect this means the dynamo has to come off?

My further thoughts on your engine might be that the carbs are unbalanced, due to the link rod being either too long or too short. You should adjust the link rod very carefully ( minding the fan! ). Only 1mm out will upset the carb balance. I use a synchronmeter on the top of the carb tubes, as it is a snug fit into the tops of the naked tubes. A reading of around 6 on tickover shows the carbs are set about right. Synchronmeters should be in every Javelin or Jubiter's tool box and are available from Amazon. My apologies if you already have one!

Hope this helps,

David

[Keith Clements]

Some net curtain and elastic band might be better as quite a lot of vacuum can be delivered by a faulty pintel.

[alexander]

Second recon pump fitted no difference .
Ran with oil cap removed no difference.
So in desperation with nothing to loose undid distributor clamp and with engine running turned distributor until highest rev’s then backed off a little. Took car for a run and there was an improvement but car did sound harsh .
I have been timing static at tdc with the points just opening.
On checking timing at 1000 rev’s I had 18deg showing on timing light at the tdc mark on fly wheel.
Not certain what this is telling me other than my problem may not be fuel starvation.
Thanks for help so far please keep suggestions coming
Dave

[Keith Clements]

If you have just had a dizzie from Distributor Doctor just set static timing at TDC. But make sure it is TDC with soft wire in spark plug hole. Sometimes people get confused with 12 deg mark on flywheel. Use multimeter across points to do this or with spark on spare spark plug on No1 lead. Simple and no gadgets in between. By all means check with strobe light but do not change until you have road tested. Do not change ignition timing from this set up until all the other avenues have been explored.

It seems you did not do the petrol delivery test that I suggested.

Did you check the throttle linkage opened both butterflies fully?

Can you post video to you tube?

When all this is done we should check valve timing. Was the engine ever running properly without 50 mph issue whilst you have had it? That is before you sent carbs off for recon.

[alexander]

Hi Keith
I think it was Barry who had re con carbs from the club and disc doctor distributor.
I had none of the above and performance has been better in the past but never managed above 60 mpg.
As I said it did seem like fuel problem so will check fuel from the pump as you suggest.
What seemed strange was performance was better after moving distributor to highest revs, but not perfect.

Question - if tappets were set at the wrong point of the cam would this give the symptoms of petrol starvation and have effect on carb operation.
Thanks again I’m learning all the time
Dave

[alexander]

Set timing by feeing number 1 piston reach tdc using plastic rod through plug hole , on fly wheel I have 1/2 showing so assume every thing is correct with how the engine was put back together by previous owner.
Petrol delivery.
Manual operation of pump, both carbs have same level of petrol after 4 lifts of lever.
Engine turning over both carbs have same level of petrol .
Difficult to judge if manual op and engine turning over produce same amount but both methods are providing petrol.

[Keith Clements]

ĺSorry for mix up.
Most distributors are worn or wrong specification fitted to Javelins. It is important to check the advance curve.
Worn dizzies show rapid advance after starting so if set up statically will be too advanced when running. If set up dynamically will be difficult to start.
Vacuum advance should be 10 deg.
I set advance at 2500 rpm with vacuum pipe off to 22 deg.

Carb jets should be checked for size. They also wear or get clogged with gum.
Colour of plugs will show state of mixture. Pull into lay by after run on full power to check. Should be light grey .

[Keith Clements]

Question - if tappets were set at the wrong point of the cam would this give the symptoms of petrol starvation and have effect on carb operation.
Thanks again

Valve timing will be affected by tappet setting. Usually this causes valves to not open or close at the correct time and would seriously affect power.
I have shown elsewhere how I check this both quickly and thoroughly. The inlet valve should start opening at 12 deg before TDC. Actually 13 thou of lift when cold with zero tappet gap.

[David Morris]

Hi Alexander,

Whilst I agree with Keith, you might find his description on setting the valve lift a mite confusing? He says that at the 12 degree before TDC postion the valve should start opening. I believe this should say that at the 12 degree position, the valve should by then have achieved the required 0.014" lift from the push rod.

I have attached my description of setting the valve lift on an engine we rebuilt last year below :-

"We were following the detailed instructions available in the Technical Notes in the Jowett technical Library. Vic had made up the bracket needed to hold my dial gauge positioned firmly up against the end of the push rod for No.1 Inlet valve, after taking up all the slack as instructed by the manual. I had printed out a circular timing chart that I had laminated to keep it stiff and we mounted this on the crankshaft nose, complete with a pointer. Having fitted the flywheel, we set it to the mark for TDC ½ and set the chart to 0 Degrees. Then, as instructed, we backed-off by 35 Degrees and then slowly went clockwise until the flywheel showed the 12 Degree BTDC mark. This agreed with the marking on the timing chart, which gave us some confidence. So, hopefully, the crankshaft was in the right position.

We then moved the camshaft clockwise, checking that the dial gauge was showing that the cam follower was on the heel of the cam and not showing any movement. We had set the indicator to 0. Then,we started to see movement on the pushrod, as indicated on the dial gauge. When this reached 0.014” lift, as instructed, we stopped moving the camshaft and, for safety, put a Tipex line on the camshaft boss. We then assembled the lower cam chain chainwheel, followed by the upper chainwheel onto the camshaft boss. It took a couple of repeats of this whole procedure to find the ‘sweet spot’ where the dowel pin could be inserted into one of the camshaft setting holes without anything moving. We found using the reverse end of a twist drill that was close to the size of the dowel helped to find the ‘best fit’ hole in the camshaft boss.

Having clamped-up the camshaft bolts, remembering the tab plate, we rotated the crankshaft two full turns until the 12 degree point arrived on the flywheel again and we checked the 0.014” lift on the push rod. It all seemed ok! We locked the tabs on the camshaft."

I think this means that at the 12 degree point on the flywheel, the No.1 inlet valve push rod should have achieved 0.014" lift. As Keith says, you need to set the gap initially on the rocker to valve head to zero, to read the lift correctly.

I hope this helps,

David

[alexander]

Update.
Using the information in”JowettPatient” I set tdc and placed the disc’s tdc in line with a mark I placed on timing chain cover then follow instructions .Results so far Exhaust 2,4 and 3 were .008 and exhaust number 1 was .006. All inlets were .003 except number 3 which was a tight .002.

Today I hope to check tappets again using Mike Allfrey’s method just to make sure I’ve done first method correctly.

Plus Also need to check lift .

[alexander]

Just checked using Mike’s method and re checked using the disc no difference.
Checked that spark was in correct firing order 1423 and to the mark on the disc- correct.
Checked on each spark that push rods were loose all ok except number 2 inlet rotates but is tight.
Thinking time before I do anything else . Number 2 inlet is set to .003 should I open it up slightly so push rod rotates when number two sparks?

[David Morris]

Hi Alexander,

Yes, I would open it up until you can rotate the push rod when at TDC on that cylinder.

With age, sometimes the valve stem ends and/or the end of the rockers get worn into a step. This can easily make setting the gap difficult.

Much safer to have a rotating push rod.

I can see that you have checked the ignition timing, but have you had a chance to check the camshaft valve timing?

Hope this helps,

David

[Keith Clements]

Also check that when rotating push rod it does not bind or not be concentric, which would indicate a bent rod.
Jowett cams can wear so much that little lift is delivered. So it is worth checking each one. Should be 0.224 in. (5.69 mm). Probably the easiest way is to measure the change on the valve spring top hat but lift should be multipled by 1.5.due to rocker lever.
Although safer to have a gap on inlet as per book of 3 thou, more power is obtained by setting so rod just rotates.

[Keith Clements]

David,

I have shown elsewhere how I check this both quickly and thoroughly. The inlet valve should start opening at 12 deg before TDC. Actually 13 thou of lift when cold with zero tappet gap.

I advised that because not everyone has a dial micrometer and the acceleration of the cam at 12 deg BTDC is quick. If you see the inlet valve gap closing at 12 deg the timing adjustment is not going to be far out. Sorry I got the lift wrong by 1 thou. Should be 14.
Also note when doing valve timing the lift is on the push rod, not the other side of the rocker. It can be difficult to check lift on what is not a flat surface. Perhaps a better method would be to check depression of valve cap with an appropriate adjustment made for the lever action of the rocker Somebody remind me what the factor is...Is it 1.5 times?

Valve timing is not an easy adjustment and requires multiple checks after adjustment. It requires dismantling quite a lot and needs care and patience.

Below is the cam profile used in Julian's racing Javelin. As you see the inlet valve opens earlier and there is more lift. Perhaps a tad off topic!
There is also a more sensible way of setting the valve timing by measuring at TDC

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