I have almost finished rebuilding my Luton Minor and rolled it out side today to try running the engine for the first time in 4 years. The engine is a VW fitted with a Zenith stromberg CD150 carb. When last run it had a pair of Lucas magnetos but these have been replaced with Leberg electronic ignition. other than this it is as it was when flying before.
I was unable to get it to run. handswinging it over a period of 2 hours I got it to run for anout 2-3 seconds about 4 times. It was firing some of the time but mostly nothing. Tried adding fuel to plug holes and other tricks but with no luck. The plugs appear dry and the exhaust does not smell strong of fuel. I am convinced my problem is lack of fuel. Any suggestions or advice?
Stuart Penfold
Starting a 1779 VW with a Zenith Stromberg Carb.
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Nigel Ramsay
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Stewart, I assume you have checked the normal things like; spark in the right place/time etc.? The Stromberg CD150 is similar in operation to the old SU Carbs (the diaphragm is the difference, SU having a piston).
The basic setting for mixture is about 1 1/2 turns out, from fully closed, i.e. the needle 'blocking' the jet and then 1 1/2 turns out to allow fuel past the needle (2 types of CD, one has adjustment from the bottom, so the jet moves up/down, mixture richer as the jet lowers. The other where you move the needle from the top, you would wind the needle up to richen, down to weaken the mix). If you aren't getting any fuel mixture then it's probably weak.
You should also make sure there are no pin holes in the diaphragm, even new ones have been known to have them!
Oil in the dashpot? I used 2 in 1 in SU's, no oil makes for flat spots during throttle increase.
That's all I remember!
Nigel
The basic setting for mixture is about 1 1/2 turns out, from fully closed, i.e. the needle 'blocking' the jet and then 1 1/2 turns out to allow fuel past the needle (2 types of CD, one has adjustment from the bottom, so the jet moves up/down, mixture richer as the jet lowers. The other where you move the needle from the top, you would wind the needle up to richen, down to weaken the mix). If you aren't getting any fuel mixture then it's probably weak.
You should also make sure there are no pin holes in the diaphragm, even new ones have been known to have them!
Oil in the dashpot? I used 2 in 1 in SU's, no oil makes for flat spots during throttle increase.
That's all I remember!
Nigel
Last edited by Nigel Ramsay on Sun May 29, 2011 9:25 pm, edited 1 time in total.
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cardiffrob
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Bit of crud above the inlet valve to the float chamber keeping the valve closed up? How about crud on the main jet needle holding it closed or sat at the bottom of the main jet?
Other thought is that the fuel might be 'off'. About 2 months and my MG won't start on old fuel unless I put fuel stabiliser in the tank (from Putoline)
Not enough resistance between coil pack and sparkplug tip (circa 5000 ohms)?
1835/CD150/Leburg and it starts on the first swing 99% of the time.
Other thought is that the fuel might be 'off'. About 2 months and my MG won't start on old fuel unless I put fuel stabiliser in the tank (from Putoline)
Not enough resistance between coil pack and sparkplug tip (circa 5000 ohms)?
1835/CD150/Leburg and it starts on the first swing 99% of the time.
Rob Thomas
034851
034851
Starting a 1779 VW with a Zenith Stromberg Carb
Thanks for the reply's. I plan to strip the carb completly and check through all the points discussed looking for leaks and crud etc. the fuel used was fresh. The leburg is set up exactly as per the instructions using carbon leads again as per instructions. I will measure the resistance just to be sure. I have this nagging doubt as to the choke circuit blocked or not working. I have fuel in the carb but appart from that nothing is definate.
I am a bit concerned as the previous owner told me it could be difficult to start but I put this down to the magneto's and thought the leburg would resolve this. Time will tell.
What I tried as a starting method was to open choke fully and close throttle. The choke has a cam that sets the throttle position for starying.
Rob, what is your technique for starting. do you prime with several blades prior to attempting start and if so what settings do you use. Does your carb have a choke that has a bar or cam that lifts the slide or as mine with a seperetae choke system on the side?
I still have to finish the final coats of paint on the wings so I am going to complete this first and then get back onto the engine. This will give me time to think about this. I am hoping to have the plane finished by the end of June.
Stuart Penfold
I am a bit concerned as the previous owner told me it could be difficult to start but I put this down to the magneto's and thought the leburg would resolve this. Time will tell.
What I tried as a starting method was to open choke fully and close throttle. The choke has a cam that sets the throttle position for starying.
Rob, what is your technique for starting. do you prime with several blades prior to attempting start and if so what settings do you use. Does your carb have a choke that has a bar or cam that lifts the slide or as mine with a seperetae choke system on the side?
I still have to finish the final coats of paint on the wings so I am going to complete this first and then get back onto the engine. This will give me time to think about this. I am hoping to have the plane finished by the end of June.
Stuart Penfold
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Nick Allen
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macconnacher
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Noel Howard
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Hello Stuart,
I have a 1985 VW engine on my VP-1. Mostly it starts on the third or fourth swing of the propeller - even on the first swing very occasionally! I have Lucas SR4 magnetos which are set to 27 deg BTDC. In your case, the electronic ignition system advances the spark automatically with the starting setting at about TDC. It is important that you have the timing correct. If you take all four top sparking plugs out and connect them to their plug leads with the body of the plug in contact with the bare metal of the engine you should see the plugs spark when you turn the engine over - best done in a dark hangar. As you have been able to get the engine to run for a few seconds, it seems likely that the timing is at least about right.
Regarding the carburettor, a squirt of petrol in the inlet manifold or into the cylinders should get the engine started if the ignition is OK. If your carb. is an early one with a fixed needle it is important that it is correctly centred in the jet. Otherwise it may be stuck in the closed position. You can check that by lifting the piston with the lifting pin on the side of the carburettor or with a finger or screwdriver through the inlet flange and allow the piston to drop. It should fall rapidly with a distinct click as it hits the bridge.
As someone has said, engines do become harder to start if the fuel has been standing for some time allowing the more volatile components to vaporise.
Best of luck.
Noel.
I have a 1985 VW engine on my VP-1. Mostly it starts on the third or fourth swing of the propeller - even on the first swing very occasionally! I have Lucas SR4 magnetos which are set to 27 deg BTDC. In your case, the electronic ignition system advances the spark automatically with the starting setting at about TDC. It is important that you have the timing correct. If you take all four top sparking plugs out and connect them to their plug leads with the body of the plug in contact with the bare metal of the engine you should see the plugs spark when you turn the engine over - best done in a dark hangar. As you have been able to get the engine to run for a few seconds, it seems likely that the timing is at least about right.
Regarding the carburettor, a squirt of petrol in the inlet manifold or into the cylinders should get the engine started if the ignition is OK. If your carb. is an early one with a fixed needle it is important that it is correctly centred in the jet. Otherwise it may be stuck in the closed position. You can check that by lifting the piston with the lifting pin on the side of the carburettor or with a finger or screwdriver through the inlet flange and allow the piston to drop. It should fall rapidly with a distinct click as it hits the bridge.
As someone has said, engines do become harder to start if the fuel has been standing for some time allowing the more volatile components to vaporise.
Best of luck.
Noel.
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Nigel Ramsay
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Bill Scott
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Starting a 1779 VW with a Zenith Stromberg Carb.
Good News, She Runs!
During the week I striped, cleaned and rebuilt the carb. I also checked the intake manifold was seating properly and not leaking. Nothing obvious wrong.
Tried to start it this morning. Set choke and throttle and gave it about 20 blades to prime then attempted to start. Not even a pop or fire. After about 10 minutes decided to give up.
Came back for a second attempt about half an hour later, again nothing. The carb has a small plunger that lifts the slide slightly. Decided to get my helper to hold this up whilst giving it a try. With the slide held up attempted to start and she fired on the first pull and started second pull.
I ran the engine for about 5 minutes. Oil pressure good, generator charging and she is sounding great. Attempted a second start after a couple of minutes and she went first pull.
I have had a look at one of the plugs and this is very black so obviously have a bit of adjusting to do. but at least I know apart from carb adjustment all is as should be.
I am particularly pleased with the sound as I have made new exhausts to replace the short open stubs that were fitted. These new pipes are longer as recommended by my inspector and are fitted with stingers from a Hardly Dangerous dealer to take away the bark of open exhaust and first impression is they seem to be working.
Stuart Penfold
During the week I striped, cleaned and rebuilt the carb. I also checked the intake manifold was seating properly and not leaking. Nothing obvious wrong.
Tried to start it this morning. Set choke and throttle and gave it about 20 blades to prime then attempted to start. Not even a pop or fire. After about 10 minutes decided to give up.
Came back for a second attempt about half an hour later, again nothing. The carb has a small plunger that lifts the slide slightly. Decided to get my helper to hold this up whilst giving it a try. With the slide held up attempted to start and she fired on the first pull and started second pull.
I ran the engine for about 5 minutes. Oil pressure good, generator charging and she is sounding great. Attempted a second start after a couple of minutes and she went first pull.
I have had a look at one of the plugs and this is very black so obviously have a bit of adjusting to do. but at least I know apart from carb adjustment all is as should be.
I am particularly pleased with the sound as I have made new exhausts to replace the short open stubs that were fitted. These new pipes are longer as recommended by my inspector and are fitted with stingers from a Hardly Dangerous dealer to take away the bark of open exhaust and first impression is they seem to be working.
Stuart Penfold
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Bill McCarthy
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Ian Melville
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Re: Starting a 1779 VW with a Zenith Stromberg Carb.
Thank you for that tip. Not only did I have a chuckle but a solution.G-AWMN wrote:Good News, She Runs!
I am particularly pleased with the sound as I have made new exhausts to replace the short open stubs that were fitted. These new pipes are longer as recommended by my inspector and are fitted with stingers from a Hardly Dangerous dealer to take away the bark of open exhaust and first impression is they seem to be working.
Stuart Penfold
Any specific Stinger? Google is a bit vauge. What did they weight?
Starting a 1779 VW with a Zenith
Ian,
I may have confused you with the term "Stinger" What I have fitted is a baffle designed to take the bark out of straight through pipes. I am at work at the moment so do not have the details to hand but I have posted a typical picture on Flicker (not sure if we can post picture here)
http://www.flickr.com/photos/54025441@N ... 803618782/
The exhaust is best described as "work in progress" and I will be doing some engine runs with and without these fitted checking RPM and nosie. I have been concerned that the baffles might affect performance. I suggest when I have proved this I will post details including weight etc. as it might be of interest to others.
If you click on the link above there is also some pictures of my Luton taken recently whilst parked on the drive. The pipes are visable in these. Since these were taken the wings have been fabric covered and doped to U/V coat level. Final top coat still to go.
Stuart
I may have confused you with the term "Stinger" What I have fitted is a baffle designed to take the bark out of straight through pipes. I am at work at the moment so do not have the details to hand but I have posted a typical picture on Flicker (not sure if we can post picture here)
http://www.flickr.com/photos/54025441@N ... 803618782/
The exhaust is best described as "work in progress" and I will be doing some engine runs with and without these fitted checking RPM and nosie. I have been concerned that the baffles might affect performance. I suggest when I have proved this I will post details including weight etc. as it might be of interest to others.
If you click on the link above there is also some pictures of my Luton taken recently whilst parked on the drive. The pipes are visable in these. Since these were taken the wings have been fabric covered and doped to U/V coat level. Final top coat still to go.
Stuart