I have a series 3 1972 E type that came with an XJ V12 HE engine, the original 5.3 ltr engine having been destroyed.
It came with what appears to be all the Strombergs and manifolds etc from the original engine. None of the fuel injection parts.
I have rebuilt it and in theory should run. BUT IT WON'T. I have checked and double checked the following :-
1. Valve timing is correct with both valves shut on cylinder A1
2. I set the static ignition timing at 12 deg BTDC and the little mark on the timing rotor lined up with mark on pick up module.
3. The carbs (Strombergs x 4 ) have had the nut at the base of them wound down 2.5 turns.
4. The engine is on a test rig, but all services (fuel etc) are connected.

NOW THE PROBLEMS:-
5. The engine will turn on the starter but only slowly. (new starter & ring new battery) Not sure how fast is normal.
6. Fuel doesn't appear to be getting in to the engine. (symptoms are dry plugs) Using Easy start does nothing.
7. Tried turning the engine over with 1 plug removed but connected and earthed close to plug hole. NO RESULT.
8. There is a slight suction on the air intake when turning it over. Can only be detected by using some tissue paper over the air intake. (No air filters fitted)
9. Strong blue spark at plug if connected to the HT lead.
10. Weak yellow spark at plugs when in normal mode.

11. This is an HE engine. Can they be used with Stromberg carbs? or am I hitting my head against a brick wall here?

Any help will be greatly appreciated.

Bob

 

HE engines are more set up to be EFI, well they were never available with carbs. The cams are wrong, as they need a more pointy lobe on the camshaft...

 

Daim has it, a HE will not run well on carbs, many have tried, but the lean burn needs better fuel control than carburetors.

It should start though.

What type of ignition does it have? get this sorted first.

 

Thanks Daim & Warren,
The ignition system is the old OPUS system. I have spoken to an "expert" on this ignition system and he reckons that because I can get a strong spark by earthing a spark plug connected to the HT lead that the OPUS appears to be working correctly. He suggested changing the rotor arm. I did, no difference.

As I don't know the true history of this engine, I don't know what cams are in their. It could be the original E-type or the XJ. Is there a way of telling? The car came with both E-type heads as spares but not fitted with any cams.

Bob

 

Erm, you should be able to find the head part numbers on the heads. I'm not sure where but I think they were at the front. Then you can dertmine at least if HE heads or PreHE. The cams have to be exposed (valve covers off) to check what numbers are on them.

 

I have made progress, sort of. I took the cam cover off and checked that both valves were shut when on TDC on cylinder 1A. I reset the static ignition at 10deg BTDC. No joy. So,
with the ignition off I sprayed Easy Start in to each carb intake with the throttle fully open so that it went right into the manifold body. I then tried starting and it did, but only for about 10 to 15 secs. approximately the amount of time it would take to use all the Easy Start. This rules out the ignition, and the timing and points to the carbs. There is suction at the intake but it's very weak. Can be detected by putting tissue paper over air inlet. I've checked for leaks and can't find any. Fuel is in the carb bowls, could it be fuel pressure. If so what is supposed to be?

Bob

 

$64 question Bob . . . low single figures for carbs . . . multiply by 10 for EFI. Even that is just the tip of the iceberg. I won't comment on "Strangle-bergs". Thank heavens our market saw them only on the 2.4L XK engine and owners soon realized they could gain a big increase in power by tossing them as quickly as possible in favour of big SUs.

However, as stated, your fuel pump should pressure match the carbs, especially if they came off original engine. Also, I agree your analysis of fuel starvation, regardless of fuel in carb bowls. Check needle/seat and float operation . . . and I don't like the sound of this "weak inlet suction" . . . check again with stethoscope at carb inlet and Easy Start injection as before for 10-15sec run. At first fire-up, carbs should be "hissing" at relatively sharp pitch . . . then at 1500rpm briefly, develop a deeper "roar".

Best wishes,

Ken

 

Thanks for your interest Ken,
I'm not too happy about the suction either. However I can't get it running long enough to use a stethoscope, or anything else for that matter. By spraying in to the inlet manifold direct eliminates the carbs. What I can't get my head round is that all 4 carbs are affected. If it was a case of just 1 or even 2 carbs causing very rough running then I could investigate further. Whatever is causing this affect ALL the carbs. Each manifold serves 3 cylinders. I've taken the non return valve apart and it looks ok.

I've run out of ideas !!!

Bob

 

you stated

" The carbs (Strombergs x 4 ) have had the nut at the base of them wound down 2.5 turns. "

run the nutz down another turn and try again... repeat as necessary....

it is good that you have fuel in the float bowels
if the fuel pressure was too high it will just keep the float needle valve open and the fuel will come out of the float bowel vents.. all over the FLOOR...


had twin SU's on the sprite and DCOE's on it later and on an MGB
similar tuning su and Stromberg
https://www.howacarworks.com/fuel-sy...rg-carburettor

 

I was wondering if the fuel pressure might be too low. I dismantled the non return valve on the return pipe, and it appears to be in working order. The fuel flows constantly when the pump is running.

I think one of the problems might be that the engine is not being turned over fast enough. I'm in the process of looking in to that by uprating the starter leads, so there is little power drop and have taken all the plugs out (well 10 of them, 2 are impossible to remove) pouring some engine oil down the bores and turning it over without plugs to make sure the bores etc are lubricated and compression is good., before attempting a re-start.

Will keep you guys informed if any success.

Bob

 

It's running ! Yipee !!

As I said in the last post it was a combination of slow starter. Cured with new leads direct to starter.
Lubricated bores. Poured a little oil into each bore and turned it over without plugs in
Not enough fuel getting in to carbs. Made a temporary cable connection to the choke quadrants, so that they could be operated by just me on the test rig.

It sounds rough, needs tuning badly and is deafening with only down pipes fitted. I will be able to check now for oil leaks etc prior to installing the engine in the car.

Thanks again for all you guys who helped me with this problem. A case of physician heal thyself !

Bob

 

Hey Bob, congratulations . . . she lives! . . . and you are so right about the value of your diagnostic method. The basics of Fuel, Spark, & Timing still hold true, even if the V12s add an added layer of complexity. Your efforts in adopting a structured approach to check each item in turn, before jumping to the next, are well rewarded.

Time to celebrate by breaking out some appropriate lubrication for the happy engineer . . . and posting some pics to dazzle us with your progress.

Well done, that man!

Ken

 

V12 on its test bed. Might sell it on after I've finished using it.<br/>Bob

 

the test bed of course... right?
a measured drawing of the test bed might be helpful to those of us that are not in GB...
Looks just Lovey! should be easy to plum an old muffler to the pipes for your ears sake...

 

Yes the test bed. Want the engine for when the bodywork comes back next week. (I hope).

Bob

 

1.5" square mild steel?

 

From afar, the weak yellow spark at the plugs has to go. Blue/white crackle will fix lots of issues. Getting there before fueling issues are challenged is a must. On any engine.


The same rules apply. Adequate compression. Then, fuel and spark in the right amount, at the right time.


Carl

 

No it's 65 x 5mm sq (2.5" x 3/16") Very sturdy and heavy.

 

Hi Jonathan,

When I get time I'll make up some drawings. I made this one as I went along. Welded the engine mountings while the engine was suspended on a crane over it. Did various mods as things dictated, eg battery mount, pump mount, petrol can mount, electrics etc.
One thing about it, it's sturdy enough to take the weight and power of an engine of this size. Have yet to find out how to operate the clutch and test the gearbox without adding all the hydraulics. Might be able to make some sort of lever that I can fit over/clamp on to the the operating arm.