Dear All,
Just thought I’d give another update. I finished my locost 7 earlier this year and it passed its MOT! I’ve driven her a couple of times which was great but since then she has been back in the garage as the engine was not performing correctly and I’ve had to replace some parts on the twin 40’s. Also she doesn’t want to accelerate past 2500/3000 rpm under load which I think is a lack of fuel possibly due to a tired mechanical fuel pump? She will rev happily through the full range at standstill but when out on the road, she just ‘turtles’ at approx 2500/3000 rpm and won’t rev any higher. I’m now trying to work out why.
I fitted a high energy coil and distributor without a vacuum advance so it just works using the mechanical advance weights inside, and I’m pretty sure I’ve timed her up correctly otherwise she wouldn’t rev through the range at standstill.
Parts for the carbs are quite expensive so it has taken me a little while to get the bits I need, I’m still waiting for some to arrive in the post. I’ll probably order a new mechanical fuel pump too.
I also ended up having to lower the radiator to fit it under the nose cone which now means it sits below the bottom of the nosecone, which is fine although it could do with some kind of chin spoiler for the nosecone now, so to protect the rad from stones etc. I’ve not seen anything available out there so will end up fabricating my own I reckon.
My garage keeps flooding when it rains hard for a long period which is annoying, not sure where it’s coming in either? But that’s a minor issue!
Main thing is the car is back on the road.....sort of anyway! I’m looking forward to the better whether so I can drive her again and iron out those running issues.
Lastly, being furloughed earlier this year has allowed me to finish this project from a time available perspective, which I was grateful for. I do hope everyone has managed to stay safe and well over this difficult year battling the lab made covid virus and continues to do so in the new year. It looks like they have a vaccine now, at least that is something!

I will update again on the running issues once sorted.
All the best.
Andrew.

I think it highly unlikely that the fuel pump is to blame.

There is a 'reservoir' of fuel in the float chambers of the carbs, so even if your fuel pump isn't up to snuff, you'd find that when you floor the throttle, it will accelerate cleanly, but the the power will 'fade out' as the pump fails to keep pace replenishing the 'reservoir'.

It's almost certainly a jetting problem - if the car has been standing but ran well before it was laid up, probably due to a blocked or gummed up jet or progression drillings.

Webers don't like being left unused.

Another possibility is a fuel blockage somewhere allowing sufficient fuel to run but not at any power. Are there any filters in the system? sometimes crap in the tank will block the feed line.

What engine is it ?

As wrong Cam timing will produce a similar result, certainly on xflows and pintos
with one tooth out, the engine will run ok, and rev with no load, but on the road with a load, it will not, also a mis match of the firing order can also show the same

steve

Hi All, thanks for your replies.
I have totally stripped and cleaned the carbs and fitted new jets and reset the float heights etc so I think that bit is ok? Whether the mech pump can keep up with filling the carb reservoir was what I originally thought might be the issue. I do have an inline filter fitted before the mech pump but I doubt it gives much restriction if any at all. I can visually see the fuel in it as it is the glass type. I did fit a fuel pressure reducer after the mech pump which I realise I dont really need unless running an electric fuel pump, which I am going to remove before testing the car again. I might have to do a flow test to prove this though.
The engine is a kent crossflow 1600 built to a stage 3 fast road, I have indeed changed the cam and had to dial it in. I did ponder over the cam timing and firing order and think I have it correct but as I have little experience in running this type of engine I could have it wrong? I have uprated to a vernier timing chain wheel and duplex chain.
I must admit that when I rebuilt the engine I did struggle to understand the whole engine timing thing and it took a lot of research and head scratching to finally work it out. Maybe it's still not right?
I may need someone with good ford crossflow engine experience to look over it for me to make sure I do have it correct.

Andrew.

Were about s are you? if im local, i dont mind having a play with the cam timing, and other problems, as i do have quite a bit of history with xflows!
and rebuilt many, up to 1691 stage 3 and with twin 40 webers, (shyte) overated, and fuel guzzelers,

What type of distributor are you using, as if its a vacuum retard one, it will not work properly with a twin 40 setup,

Personly, i never used the vernier camshaft wheel, or if i did, as in a duplex chain, i set it up as per the standard settings, xflows, are so agricultural, that the difference is negligible

steve

Is the lack of power happening at the stated rpm in all gears?

Im pretty sure there is an insulating spacer that can be fitted between the engine and fuel pump.

From memory, for the higher capacity engines (not 1100/1300) it should be removed. Having it fitted reduces the throw of the pump arm so it delivers less fuel.

Check you do not have the spacer fitted. (also check that what I write is correct)

Replace fuel filter = just because you can see petrol flowing , I doubt it very much that you can tell if sufficient petrol is being supplied.

If the lack of power is occuring in all gears at the stated rpm, it is likely to be ignition system related.

Hi there, thanks for replies again. I'm in East Anglia just on the suffolk essex border. A far distance from Sussex unfortunately? I'd be more than happy for someone with knowledge on these engines take a look, many thanks for the offer.
As far as fuel pump spacer goes, I think I did install it when rebuilding, I'll check, it makes sense that the throw would change if removed in theory, Ive not heard that before nor have I read it in the Wallages engine manual? I'll have to do some research on that.
It is in all gears yes, could be the ignition system, and have wondered whether the distributor advance is working correctly, and yes it is the non vacuum type with the electronic points fitted.
I also checked to make sure I had 12v dc being supplied to the coil with engine running and it was indeed 12vdc. Some old wiring looms can have a resistor in the circuit to reduce power to the coil once the engine has been started, so I've read.

Theres many a thing it could be by the looks of things so I'll just have to persevere until I find it, I really hope its nothing serious, but rather stupid and simple! I can't deal with taking the engine out again.
I wondered about valve bounce but I changed the top rocker arm posts for the solid steel ones.
My initial gut feeling was an engine timing thing but lack of fuel is also a contender, especially if you are saying a stage 3 with 40's is a guzzler!?

Thanks for your thoughts,
Andrew

To me, it sounds like cam timing, especially as you have a vernier wheel in the engine, and its easy to check, even with the head on, but you really do need 360 protractor/wheel bolted to the crankshaft, or at very worst blue tacked!

Ive never heard about the black spacing bar issue, as ive always run an electric pump, but does make sense, and perfectly a valid suggestion, also the old pumps were not really very good, and filling four bowls up, will demand an awful lot of work from the pump, and at a low rev range, its not working very hard, so its not filling the bowls up ................

I would be removing the fuel filter, blow all the lines though, make sure the tank doesnt have anything in it, except fuel, new filter, and an electric pump in the system,

My old 1691 stage 3 , and my best engine by far, at full throttle did 10 mpg,

steve

[Edited on 29/12/20 by steve m]

Hi Steve, the issue is at higher rpm from approx 2500/3000, which would make your theory of the mechanical pump not being able to keep up with filling 4 float chambers a good possibility?
I did some research on the spacer and apparently it has to be there otherwise the actuating shaft from mech pump is pushed to far against the cam lobe and will wear putting metal filings into the engine. It could be that the actuator shaft is already worn and therefore not pumping to its full capacity.
I have read on another forum that if running twin 40’s then the mech pump cannot keep up with fuel delivery so maybe I will have to switch to an electric pump.
It has a bcf2 cam which I presume still has the same sized lobe for running a mech pump as the standard camshaft would of? And then you just fit a blanking plate if not using the mech pump?
10 mpg you say, flat out? That’s burning a hole in my pocket just thinking about it!
But I’ve got to get it to flat out first before I worry about that!
I did double double check the engine timing before I refitted the engine in the car and the fact it runs really well up to a point, surely I must have it all correct in regards to timing and firing order etc?
I’m still leaning towards fuel ( no pun intended!)
I might give Burton Power a call and see what they think about the issue as well.
Regards,
Andrew

Its well worth switching to an electric pump anyway, just to allow easy starting without having to crank the engine for some time to get fuel through when the car hasn't been used for a period.

re: valve bounce - that isn't going to happen until well over 6,000 rpm, certainly not at 2,500.

re: spacer - i went through all haynes manuals and other books but could not find reference to it so not sure where i got that information from.
maye contact burton power about this - they have responded to my queries in the past.

I would not call 2,500 high rpm, 5,500 upwards is.

My engine was 1660 cc, high lift cam (possibly bcf2), large valves in ported head, solid rockers, 1300 pistons, twin 40s and the mechanical
fuel pump had no issues at any rpm and load - and it was often revved to 6,000 ish.

re: fuel starvation - engine in my land rover 3.5 litre would run out of ommf when under heavy load, say 3rd or 4th gear going up hill with
accelerator pedal pressed - this was due to fuel filter being partially blocked (it had facet electric pump fitted). It is ex-mod and had at some stage been in the desert dueto the the amount of sand in the fuel tand when I drained it,

It is difficult to diagnose a problem remotely but I still don't see a description of your problem - are you saying engine is struggling to run in all gears as soon as you go over 2,500 or under heavy load, say 3rd gear up hill with pedal to the floor?

Has it ever run correclty or was something changed?

The dellorto 40 (and i think weber) have an accelerator pump that supplies extra fuel - is this set up correctly? But even so this would cause hesitancy and engine will catch up to reve quite happily to red line.

Do you have the correct jets fitted? I bought larger jets (engine originally was 1300) when fitting the 1660 and it would not run, so
I reverted and it ran fine.

What type of air filter do you have - can these be restricting air flow? (you could always remove them for a short test drive to see if there is any difference).

You checked the timing is correct and is seen to advance? Points and capacitor (is one fitted?) in good condtion and correct gap?

Look at the haynes manual - it describes how to test the fuel pump - there is a rubber diaphram that can get damaged so will reduce petrol flow and can also cause petrol to go into the sump to dilute the oil (very bad for the engine).

re: 10 mpg??? may be on a race track with contact acceleration/braking - my landrover gave those figure under heavy load and it has
engine 2x your capacity and 4x the wieght so I'd be surpise you are getting those figures.

If you decinde to fit an electric fuel pump, you may need a pressure regulator - cars want about 3.0 psi and the facet type pumps can exceed that.

I may well do that, but i've just thought, would the carb float chambers still be full of fuel from the last engine run or does it evaporate over time? If left for a few weeks/months they may dry out I guess and then your theory would make perfect sense, although it wouldn't hurt the engine to crank over a few more times which would give the oil a chance to pump round and pressurise before it started.
Have you ever run these stage 3 engines with twin 40's, with the mechanical pump or always switched to electric? It would be good to know 100% whether it will work on mech or not as then I think we may have just solved it if fuel related?

Once I've got these carb parts I'm waiting for I can rebuild them and fit them back onto the engine, then I'll remove the inline pressure regulator from fuel supply line and replace with a piece of fuel hose. I might double check the float heights on the carbs to make sure they are still good, I wonder if there are different float height settings for a stage 3 engine setup? I'll check.
Then I'll rebalance the carbs with the engine running. I'll do a flow test on fuel pump delivery with the coil lead off and cranking the engine on the starter motor.
Then I'll probably take for a test drive to see how she performs and go from there. What should the ignition advance be best set at for a bcf2 cam, some say 10, some say 11 some say 12 or 13' btdc. I've tried them all to be honest, none have cured the running issue.

Best,
Andrew

Testing the fuel supply by cranking over is a bit pointless, it might get to about 50 rpm and your problem is at 2500. Can you rig up a jury tank/can to the pump to eliminate the existing tank and supply line?
You have not yet answered whether this set up used to run ok.

what does it matter if there is fuel or not in the carbs? When engine is cranked over, they will fill up and be kept topped up by mechanical pump when ending is idling, it just takes a bit longer, 20-30 seconds that's all.

What are these carb parts you mention?

There is no need for a pressure regulator when using a mechanical pump. Is it the one with the glass bowl and filter (malpssi brand ? - filter king?) - if so, then you should see the bowl fill up with fuel.

I would need to look at the manual but I think the float height woiuld need to be miles out for starvation to occur, in fact I am not sure it is even possible - I'm guessing there are needle valves that the floats act on - are these free to move?

As mentioned above, you won't get meaningful result for fuel delivery when cranking engine over. Remove the plugs so engine is easier to turn over and do that test - if the fuel supply is more than adequate, then that is not the problem.

Has it ever run right?
Has this only started since you changed something (cam?)?

If it's a fuel delivery problem then lifting off and then re-applying throttle you would expect it to initially pick up before losing power again. Also you'd expect it to do it at other revs but be dependant on load. So lower revs, uphill, full throttle; but it'd also rev higher on low load (downhill, light throttle)... and as said above, a cranking fuel supply measurement won't tell you much.

quote:

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Originally posted by ahaggarty
Dear All,
Just thought I’d give another update. I finished my locost 7 earlier this year and it passed its MOT! I’ve driven her a couple of times which was great but since then she has been back in the garage as the engine was not performing correctly and I’ve had to replace some parts on the twin 40’s. Also she doesn’t want to accelerate past 2500/3000 rpm under load which I think is a lack of fuel possibly due to a tired mechanical fuel pump? She will rev happily through the full range at standstill but when out on the road, she just ‘turtles’ at approx 2500/3000 rpm and won’t rev any higher. I’m now trying to work out why.
I fitted a high energy coil and distributor without a vacuum advance so it just works using the mechanical advance weights inside, and I’m pretty sure I’ve timed her up correctly otherwise she wouldn’t rev through the range at standstill.
Parts for the carbs are quite expensive so it has taken me a little while to get the bits I need, I’m still waiting for some to arrive in the post. I’ll probably order a new mechanical fuel pump too.
I also ended up having to lower the radiator to fit it under the nose cone which now means it sits below the bottom of the nosecone, which is fine although it could do with some kind of chin spoiler for the nosecone now, so to protect the rad from stones etc. I’ve not seen anything available out there so will end up fabricating my own I reckon.
My garage keeps flooding when it rains hard for a long period which is annoying, not sure where it’s coming in either? But that’s a minor issue!
Main thing is the car is back on the road.....sort of anyway! I’m looking forward to the better whether so I can drive her again and iron out those running issues.
Lastly, being furloughed earlier this year has allowed me to finish this project from a time available perspective, which I was grateful for. I do hope everyone has managed to stay safe and well over this difficult year battling the lab made covid virus and continues to do so in the new year. It looks like they have a vaccine now, at least that is something!

I will update again on the running issues once sorted.
All the best.
Andrew.

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Hi All, and Happy New Year,
Yes the car has always had this issue before me starting the restoration and engine rebuild. The engine was in a standard state of tune before. Now it is a stage 3 fast road. The problem is that when driving on a flat road, not tried it uphill, I get what I can only describe as the engine 'turtling' as though its hit a flat spot and wont rev any higher and this seems to be in the higher gears and starts at around 3000rpm. I'd have to drive it again to give a more accurate description.

I found one carb was out of balance between barrels and when stripped down found the throttle shaft to be bent and the valves worn at the sides so too much air was getting past hence the unbalanced state, plus the leather washers in both carbs had dried out and perished so they will be replaced. I'm waiting on the shaft and valve at the moment. But I don't think this is the cause of the problem, just something I noticed which I wanted to put right in the process. Maybe I haven't got the correct jets in the carbs?

I realise that the fuel pump delivery would be much higher with the engine spinning faster but thought I should at least see a squirt of fuel from the fuel hose at a fast crank, with sparkplugs removed as mentioned?

So if your saying that you had issues with fuel delivery running 40's on a precrossflow then fitted an electric pump and all was fine then maybe that is all it is? Some people are saying mech pump is fine on a stage 3 some are saying its not? Interesting different view points on this.
Although, before I had started this resto the engine was running with a single downdraught, twin choke weber and still had the issue of lack of power under load at the same revs, I wonder if the fuel pump is actually shot altogether?

The rear core plug under the gearbox bellhousing had perished and was leaking fluid everywhere which is why I started this resto......7 years ago!!
Maybe it's electrical? It could be so many things, I've just got to work my way through them all

I had a cheap inline pressure regulator fitted inline before the carbs, which I know I dont need, but had put in because when I first started the engine after the rebuild it was running very rich and I suspected it was over delivering fuel, so fitted the regulator to eliminate that but it continued and then I found one of the carbs chokes to be stuck open, as they are not in use and have been blanked off. Once I'd sorted this it cured the rich running.
The carbs were in a worse state than I had previously thought when I bought them and so have been overhauling them since for various issues.

Thanks for all your thoughts and suggestions on this,
Andrew

I would suggest starting with the basics first, double check the valve timing, valve clearances , compressions ,dwell angle or points gap if still running points , correct coil and correct connections . Check timing at idle and also check you are getting the correct amount of timing advance at higher engine speed , Bosch distributor auto advance can and do seize which can cause your symptoms as will tight valves . I would recommend a good rolling road session to get the best of everything with someone familiar with Weber’s . Peter Baldwin at Regency Autos Cambridge has a very good reputation , several people on here have used his services . A RR session will probably save you money in the long run

Hi, that sounds a good idea, I had intended to get a rolling road tune done once the car was up and running, I'll contact Peter Baldwin and see if I can get the car booked in once I've put everything back together and checked all the settings etc.

Thanks,
Andrew

quote:

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Originally posted by ahaggarty
Hi, that sounds a good idea, I had intended to get a rolling road tune done once the car was up and running, I'll contact Peter Baldwin and see if I can get the car booked in once I've put everything back together and checked all the settings etc.

Thanks,
Andrew

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Hi,
I emailed the garage today, so just waiting for them/him to reply and I'll let you know.

I carried out a very basic fuel pump test today by just cranking the engine with the hose in a bucket. I tested it once with the fuel pressure regulator inline and one without. Both tests looked visually the same. The petrol was being pumped out of the end of the hose and when I applied a finger to partially block the end, it did squirt out so must be giving some kind of pressure at a low cranking speed. I think it's ok.
Whether it can keep up with demand at high revs is another question.

I also checked the basic engine timing which also seemed correct. I then checked the valve clearances and found them to be out, mostly they needed closing up as the gap was too big. Mine should be 0.014" inlet and 0.018" for the exhaust. I followed a guide in a Ford Capri GT Haynes manual which seemed straight forward.
Apparently these clearances can make a significant difference in engine performance if they are out, according to the Haynes manual.
Again, whether enough to cause the issue I have is to be seen.

I'm going to check what the recommended jet sizes etc are best for my carbs for a stage 3 tune as well.

Valve clearance will make a difference, though too tight/close is usually a bigger problem than too big.

Dear All,
Though I’d let you know how I’ve been getting on with the car recently.
After re adjusting the valve clearances and taking the car out for a run, it performed much better and I was able to get right up the Rev range to 6000 rpm.
I removed all the things on the fuel line such as filter and regulator so it is just a direct feed from the fuel tank. To confirm, the mechanical pump can supply enough fuel for a twin 40 set up and doesn’t need a pressure regulator.
I also found that my fuel tank had a leak from the sender seal which meant I had to drain the fuel and remove the tank to repair it. When I did this I was able to blow compressed air back through the whole length of the fuel line to tank to make sure it was clear. I also checked the tank vent as this can cause problems with fuel supply if not working correctly.
I made a new cork seal for the tank sender and used PRC on all surfaces when refitting. PRC is excellent stuff. No more leaks.
Whilst I had the tank out and the car jacked up at the rear I was able to change all the radius arm bushes for the poly type which has dramatically changed the handling, as the old ones were worn and hadn’t been fitted correctly. I also found that the whole rear axle had been welded out of line so I had to put this right with a bit of welding and drilling. It has transformed the ride to so much better!
After more test runs I noticed fuel leaking from the carbs after engine shutdown, coming from the pump jets. I am not using a manual choke and realising that the chokes just had a blanking plate fitted, but the cold start circuit had not been eliminated correctly inside the carbs, I bought the cold start elimination kits and carried out the mods. Tested and found them still dripping??
After some more head scratching I found that as my carbs sit at about 6 degrees from horizontal, I needed to reduce the height of the fuel in the chambers which I achieved by bending the tabs on the floats by a small amount. When the carbs are mounted like this the rear overflow hole in the chamber sits lower than the front which means the overall fuel height has to be lowered.
I have not encountered any fuel starvation since doing this. This has cured the dripping issue to almost nothing now.
I checked the engine with a gunsons colour tune and rebalanced the carbs etc and also modified the carb linkage as I wasn’t happy with it and all seems very good now.
The other thing I’ve done is change the tyres on the front wheels to a much lower profile than the back which has also improved handling and is lighter on the steering. It looks pretty cool too!
I am learning so much and enjoying the challenges, and also the results whilst out driving!! I’ll be keen to come to the next meet when one is going on!

All the best,
Andrew