'73 V12 Flooding out

[enix187]

Introduction / first question thread. First off I'm american, broadcasting from beautiful North Carolina. Just purchased (around a month ago) a beautiful 1973 2+2. It'd been sitting for approximately 8 years, before we bought it we ran a compression check and the motor is all good. The issue has been with spark and fuel.

Spark has been sorted with a pertronix ignition that is putting out a bright blue spark. It's not timed in because a) i haven't had it running to where I can and b) i have no clue where the timing marker is?

Other info, air tubes removed and blocked off, manual transmission, and the carburetors have been gone through by an excellent mechanic with new gaskets and needle seats. and it's running a low pressure 2-3.5 psi solid state fuel pump.

The current issue is that the car will crank, but it will not idle without loading up and cutting out. I can pull the plugs that are on the crossover bungs (should that be installed, probably a stupid question but I don't know) and I can see fuel sitting in the very bottom of the intake. The car will hit a point where it doesn't feel like cranking at all.

When it does run it revs absolutely beautifully. Great throttle response and runs very smooth, it just can't idle. I need something to check. Suggestions welcome and I'll tell you if I've tried it and what it did. I would really like to drive this things, it sounds awesome.

[MarekH]

Dear [your name here],

The timing marker is at the bottom and front of the engine sump - helpfully obscured by the oval oil filter. The pulley ought to have a shallow groove with "A" marked and the 6 o'clock position will be cylinder 1A at TDC.

Having fuel in the trough at the bottom of the intake is not uncommon, especially if you are cranking but not running. It takes a lot of fuel to start it up. Once running and warmed up, most of this ought to eventually evaporate.

There is further useful data in the "knowledge base", elsewhere on this site.

kind regards
Marek

[enix187]

Sorry about that, names John Styron, been a while since I've used a forum, and thank you for pointing me towards the knowledge base. I'll most likely read through the entirety of it this weekend. Other than timing are there any big glaring things I should look for to see why it's stalling at idle?

[Alty Ian]

Hi John

I assume you have gone through the process of checking that there are no air leaks into the manifolds or carbs and set up the carbs using the idle adjustment screws on each side? Make sure the vacuum pipe onto the dizzy is connected and not leaking. Then check the timing.

good luck Ian

[christopher storey]

Make sure also that the servo /reservoir/associated vacuum piping is not leaking

[enix187]

what should the vacuum be on this motor at idle? I'll check it next chance I get. What I don't understand is why the motor becomes progressively harder to crank as I try. It still turns over fine it just doesn't seem to hit, still has spark and I'm assuming since the intake has fuel in it it still has fuel, it just doesn't combust. Could I be washing the cylinders?

[MarekH]

The fuel that is sitting in the bottom of the plenum isn't contributing anything to starting it up. It is simply the heavier fraction which didn't atomise enough at previous startup and thus get into the cylinders. It'll go nowhere and do nothing until the engine fully warmed up, at which point it'll progressively boil off and evaporate.

Since you feel that the spark is good, then I'd look at your timing and whether you are delivering enough fuel at idle rpm. If it idles better with choke, then that'll tell you about fuel and if it idles at high rpm only, then that generally tells you that you have vacuum leaks somewhere. A vacuum leak isn't typically going to stop it from starting, it'll simply set the minimum rpm high, e.g. 1400 to 2000 rpm, rather than 750ish.

For a hot restart, I used to find that cranking whilst holding the throttle wide open would clear it and make it fire.

You can check whether you are flooding it by looking at the plugs:- they be wet and black. If this is the case, then the next question is why am I not igniting the fuel?

If three adjacent plugs are different from the other nine, then it's probably related to that carburettor.

I note that you have only fitted new seats and not needles - these are precision items and the seat/needle height/match/taper is important.

There is further v12 background reading on the Roger Bywater AJ6 website. There is also a Haynes manual for the Stromberg carburettors. The carburettors also appeared on many other cars of this period (including s2 etypes).

kind regards
Marek

[christopher storey]

I would expect it to pull 18 to 20 inches at idle

[vee12eman]

Hi,

Marek, I too rebuilt the carbs without replacing the needles - to be honest, I forgot until you mentioned it. It is something I want to do, just wondered if you knew which needles would be the best for a standard car running a standard pattern stainless exhaust with the 4 branch fantail outlet? Ignition is ReOpus.

I guess the standard needles will be best for what is basically a standard set up, but although I am reasonably familiar with SU needle identification, I have no idea how Stromberg needles are identified and I don't know which ones were fitted as standard. Finally of course, where can I get a set of new needles? Burlen?

Regards,

Simon

[MarekH]

Dear Simon,

This is why you should buy the Stromberg book, which quotes:-

jaguar needle
v12 car type

73/74 auto B1CE
73/74 man B1CK
73/74 usa B1CQ
73/74 auto european B1CN
71/72 xj25 B1BH
71 B1BH

kind regards
Marek

[enix187]

Made me think of it, I guess it's not flooding as the plugs have been dry, a little black but not soaked like they would be to kill the motor like that. I'll try and get the timing done next time i crank on it which should be tomorrow or friday. I guess i need to go on a heavy duty vacuum hunt. I guess its good i bought new intake seals.

if not a vacuum leak what on the carbs do you adjust to richen/lean them out? i looked but didn't find anything obvious, do you adjust the actual needle like a motorcycle or what?

[Woolfi]

"Dear Simon,
This is why you should buy the Stromberg book, which quotes:"

With a special tool you can adjust the level of the needles in relation to the jets. I do it without a gas-analyzer. Turn the needles down is much as possible, that the motor does not start "puff" out of the exhaust. From this point turn back the tool roundabout 45 degree. Do this with all 4 carbs.
Done like this, the idle in my V12 is nearly perfect.

Regards Wolfgang Gatza

[enix187]

Thought you all would like an update on the ordeal. Upon your advice I started checking for vacuum leaks and I couldn't find anything obvious on a whim I pulled an intake and found fresh fuel in between the gaskets at the head, out of the four intakes only one didn't seem to be leaking. I smoothed and leveled all the gasket surfaces and installed replacement gaskets and buttoned it all back up. Much improvement but still wouldn't really crank well. I noticed that as I was trying to start the car the start would progressively turn slower so I hopped out and went to check the battery cables and promptly burnt my hand on the ground it was so hot. I put new cables on her and she turns over better than she has yet.

Onto how the issue as it appears now, i touch nothing, no throttle or choke on a cold motor and she will fire and run for a second before dieing. I can pull the vacuum cap I have where the gulp valve was on the cross over and there will be fuel sitting inside of the crossover tube. I'm feeling like I'm going too rich now as the more we crank on it the less it sounds like it wants to crank. I'm feeling like the needles have been fiddled with and I should lean it out. Along the line of engine timing I seem to have found a happy spot around 40 percent from full left (drivers side for my car).

Next step tomorrow I will be unhooking the vacuum retard, didn't realize it was a retard, as there's no emissions on it any way and trying to lean it out using the needles. Again I have great spark and fresh gas, the fuel is a 110 octane 93 octane mix that I like to run to clear out cars that've been sitting, don't know if thats a no no with these cars but I've kept the fuel filter checked for any un-due trash.

Sorry for the long read but any help is appreciated as you all have put on a better track already.

thanks, John

[MarekH]

Dear John,

1/ Don't kill your battery and don't kill your wiring whilst trying either.

2/ The fuel you are seeing would have come from the carburtettors in the proper way but wasn't ignited so sits in the bottom of the water jackets and on the inside of the inlet runners.

Your appear to have plenty of fuel and if I understand you, you are describing that it'll start and run fine but subsequently die once not cranking. In this case, check the electrical integrity in and around the ballast resistor, in particular ballast itsef. The car uses full 12v when cranking but runs through the ballast resistor once not cranking.

Vacuum leaks won't stop it from running - it'll just make it rev higher.

Similarly timing probably isn't the main issue either - it does run when cranking and from a timing point of view, ordinary running is simply the same but going faster - the timing is a simple mechanical system.

Edit:- this'd apply to the OPUS based system, but on rereading, you have a pertronix, so this may not apply.


kind regards
Marek

[PeterCrespin]

What Marek said, on all counts, except un-ignited fuel passes out of the exhaust and doesn't sit in the bottom of the carb plenums. That is unatomised or condensed wall-wetting fuel that never reached the cylinder in the first place. The water heating boils that off when the engine does run.

I'm not clear which surfaces or gaskets were fixed, but if the fuel referred to was that stuff in the plenum bases then of course it will show up every time the car is cranked but does not fully warm up.

I didn't understand the OP's reference to timing at '40 left' or whatever it was. the ballast and ignition switch feed are good places to look.

If the Pertronix is taking power only from the direct feed it will only spark while the engine cranks and cut out as soon as the key is released. I would either re-arrange the ignition switch wiring or splice both the feeds into one at the bonnet end so the pertronix has full time powercwith the ignition on or cranking.

Pete

[enix187]

on the timing question, I haven't been able to make the car run long enough to time it. I have the distributor at about forty percent of the possible adjustment when starting from the left.
The gasket surfaces on both ends of the intakes where cleaned and leveled, they were leaking where the runners meet the head. I simply used a flat bastard file to level them and checked them with a straight edge, new gaskets at the lower plenum and on the intake runners. I'll check the ignition power but i have had it running, if I reved it she'd stay running but she refused to idle and she reved very well.

[enix187]

Well peter you pretty much called it, turned out it was the coil, I was checkign for spark and it didn't show on my spark tester but was an orange spark with a spark plug as a tester. Checked the voltage at the coil and it was dropping to 9.5v while cranking, I'm not sure if the one I had was bad but it was a 3 ohm coil and we switched it with a 1.5 ohm I had forgot I had to see if the other was bad, she fired right up. I have to tune it in but I'm looking forward to my first drive of an e-type tomorrow!