G'day.
I've been going over the dualcarb 1800 motor with ever increasing detail to find what's up with it to make it so gutless that it can barely move under its own power.
Besides being totally gutless the main issues are:
* Low manifold vacuum. Only about 10-15"Hg.
* Sooty / extremely fast to soot up sparkplugs, especially on the left hand side of the motor.
* Unstable and randomly dying idle.
* Low compression on #3 cylinder (60PSI).
I have checked the vacuum pipes and brake booster line in every conceivable combination and have ruled out the vacuum drop being from a leak in the booster line, from the manifolds, or the balance tube.
I have also tried disabling the idle throat thing entirely by disconnecting the solenoid and plugging the tube downstream. The idle was around 500rpm, and fairly steady, but vacuum was still low and it was very difficult to rev the motor without it dying.
All valve clearances are correct.
Breaker gap is correct.
Spark is very strong.
Timing is correct.
Mechanical and vacuum advance is operational.
All four sparkplugs are firing.
Fuel delivery is not an issue. Tried with both electric and mechanical membrane pump.
A note on the electric membrane pump. On turning on ignition, pump would audibly fill the fuel line and then pretty much slow to a stop, with only a very occasional clunk. I don't consider that to be an issue as the pump may either have a little leakback or there could be a little seepage past the float valve as the carbies weren't really designed to maintain a perfect seal with nothing being drained from them with an electric pump trying to force fuel in. But it is important to note that it is pretty much stopping, so it's not dumping a mass of fuel into the manifolds.
I do however believe that fuel consumption is massively elevated. Hard to say for sure but it didn't take long to get through about 3L of fuel. The fuel is not draining into the sump.
Cylinder compressions are:
#1: 130PSI
#2: 110PSI
#3: 60PSI 🙁
#4: 100PSI
After considering the details I am wondering if the low compression on #3 is a red herring. Not a good thing obviously, but I don't think it's the issue. Please feel free to prove me wrong.
What I think is happening, and it has been mentioned by someone in the past, is that too much fuel is being dumped in. But given the float valves seem to be operational it gets a bit strange.
What I think is happening is it is sucking way too much fuel in through somewhere, or possibly even air and fuel due to a leak somewhere up the top of one or both of the carbies. If it were something like the throttle shaft it'd just be sucking more air, and leaning out, not sucking extra fuel.
If this sounds plausible please suggest what is happening! If it doesn't sound so plausible, I'd love to know what is more likely to be happening.
I only really have one test to do, and it's a real horror. Hopefully it won't come to that though.
So people, what are your thoughts?
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
no expert , just throwing some things out there.
exhaust blockage? seen this in modern cars with blocked cat.
vacuum gauge diagnostics might help give some ideas.
www.performanceprobe.com/doityourself/diagnostics/imvt.php?page=1
maybe a leakdown test would help find whether there is a breathing issue at all.
are you sure you adjusted the valve clearances properly?
try turning the mixture screws in bit by bit see if theres a rise in revs.
also take off your rocker covers and turn the engine over by hand, make sure every valve is moving in its turn.
pull your jets and check they are the stock size.
62/60 model bug eye baja bug, (Full Build in Progress)
1974 Chevrolet Luv
1970 MK2 Ford Cortina GT
1979 Yamaha RX125 Two Stroke tracker project.
2004 Harley Davidson Sportster XL Custom
Edmond, thanks for the link. I like what it says a little more than the manual that came with the vac/fuel pressure test gauge.
There is a small variation in vacuum which I have attributed to a badly seated valve on #3 anyway, but it's less than 1"Hg.
According to both static and strobe timing, the spark is correct, but if I hadn't repeatedly verified that myself, it'd be a prime suspect.
I went through and rechecked all the valves a couple of days ago. The clearances were all a little off, but that's all fixed. It had negligible effect.
If it weren't incredibly hard for me to comprehend, I'd think that retarded valve timing was a suspect. But how on earth would that even be possible...unless there was a broken tooth. Hmm. Highly unlikely but semi possible I guess.
Every valve is opening when it should be. Because I only have so much multitasking ability I checked a cylinder at a time, turning 1/4 turn and checking the state of the valves, for correctness. They all seem to be opening and closing when and as far as they should be.
Anthiron, Do you mean check the jets haven't eroded? Because everything used to be fine before the engine shagged itself. I could see the holes enlarging over time though.
What would a rise in revs when leaning out the mixture mean?
They are currently set to the factory default as stated in the Gregorys manual. Sorry, it's in the van so I can't reference it. Before I touched them the left would hve been cranked out maybe 5 turns and the right was hard closed. Why that is I don't know. I've never touched them.
As it is the motor revs and idles adequately, with an variation of maybe 900rpm +/-100rpm. The right hand accelerator pump delivery tube is fouled currently but will be addressed when i get the compressor. All that does is cause some minor chug on acceleration. Not enough to completely defeat it.
I'll tackle the mixture screws a bit later on today maybe. If not then in the next couple of days.
Thanks for the advice.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
A little update:
I just checked the adjustment on the idle mixture screws and central idle mix screw. AFter a lot of cranking and then realising that I forgot to reconnect the coil after the compression test, I started the van. It revved up to about 1900 RPM and refused to come down. I even wound the air bypass screw shut and only a slight difference.
I have an awful suspicion it had to do with the central idle mix screw. I was winding it in and near the bottom felt some resistance. It didn't feel like it had hit bottom though so I kept winding another two turns before it stopped with the uneven resistance. That seemed a little weird so I pulled the screw out and had a look. there was crud stuck around above the thread. There was also a little scuffing on the needle where it made contact. Didn't look out of shape though. I am a bit worried about the seat however. I am pretty convinced that it was a fouled thread though.
When I blipped the throttle it revved right up and didn't want to come down. Next time around I tried it and the motor died. I'm not sure why but I feel a little encouraged by this general result. Unfortunately I didn't have the vac gauge connected.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
I think you will find that the throttle shafts are worns very badly and you need to replace the lower plates on the carbies as its sucking air
call Vintage in Sydney they can supply recondition and bushed throttle plates 02-9789-1777
to test this get a bit of rubber hose one end in yr earhole and use the other end to detect the sucking noise around the throttle shafts
thats the reason i asked about the idle screws. basically just to see if they were adjusting properly, if it was delivering more fuel than it should then leaning the mixture out to a more ideal level would rise the revs and vice versa. i wasnt aware that the van was running well in your possession at one stage so disregard my comment about the jets.
if i was you i would strip down the carbies and check everything for wear and scrub them clean with some solvent and an old toothbrush, re assemble everything with a new gasget kit, if you need to re bush the throttle shafts then do it ( i dont know anything really about bus carbies so i dont know if this is possible)
62/60 model bug eye baja bug, (Full Build in Progress)
1974 Chevrolet Luv
1970 MK2 Ford Cortina GT
1979 Yamaha RX125 Two Stroke tracker project.
2004 Harley Davidson Sportster XL Custom
Thanks for the advice. I actually typed up a reply earlier but the internet was acting strangely Sort of like there was a firewall upstream or something. Go figure.
VW54, doing that test can't hurt. So I'll do it after I do a slight fuel line tweak. It was brought to my attention in general chat that putting a fuel filter in the engine bay is a bad idea. I mean I should know that but for some reason I still did it. I think it was so I could check for fuel flow and fouling. Can't say I remember anymore.
The throttle shafts / plates probably do need work. I won't deny that. But there is definitely something much larger at work here.
I'll give you a quick and rough timeline of events:
2003: Move to QLD using tired but functional van. Capable of towing a trailer.
2004?: Dropped a valve seat. Stopped the motor pretty much instantly to avoid damage.
2004?: Not too long after the dropped valve did a topend rebuild. Replaced one head and pistons. Replacement pistons were Porsche, as they were all I could get at the time. However I didn't realise I needed to use two head shims per cylinder. Whoops. Not too long after burnt a hole in the head shims and put a small crack in a head. That was the last time it ran properly.
There was some fiddling afterwards which I don't remember too well in attempting to ascertain the problem. I'm pretty sure the carbies were messed with and the fuel pump was swapped to an electric.
2005-6: After shifting it interstate in a container and sitting for about 15 months, I finally pull my finger out and decide to do the topend again. I replace the cracked head and the necessary shims and gaskets. I also put back in the three VW pistons that are still good along with a replacement which has been size and weight matched.
2008: After moving yet again (there were two moves in 05-06), I start again in earnest trying to find out what is wrong. I have tried in the interim, finding many issues and correcting them. Every time the van getting even weaker.
When we moved here two years ago it could still go 70-80 km/h while towing an empty car trailer. I know this because the car we brought it here with had a clutch assembly failure about 5km before reaching home, so I had to take the trailer back used to shift the van, using the van.
As I mentioned though, everything I have fixed it has just gotten weaker. I really can't understand it. Maybe the power loss is just progressive and a symptom of something unrelated. Because starts were few and far between.
I have cleaned out the carbies a couple of times, but haven't replaced the gaskets. I know that's a bit silly. But it had clogged jets, and a malfunctioning accelerator pump diaphragm which I fixed. It slipped a bit and instead of squirting a jet into the carby throat, it'd squirt out the top of the diaphragm assembly and spray all over the motor.
When I get a gasket kit I'll be happy.
A question i have about fiddling the mix. There are three mixture screws. How would I find the optimum of three. I read the Club Veedub Sydney tutorial on it, and followed best I could without balancing gear. At best I think it should be a little weak as opposed to completely gutless.
i know I stated it before but with the idle throat completely disabled, it idles at about 500rpm like it says it should in the tutorial. I have been tempted to see what happens if I try to move the van with the idle throat disabled. With it disabled vacuum is still low, but I'm not surprised considering the low idle speed.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
G'day.
I've really done it now. I did some more fiddling. Now even with the idle circuit disabled I can't get the revs below 900-1000.
With the idle circuit enabled, which is easy as I discovered the solenoid works perfectly, it wants to run at at least 1800rpm, unless I wind the mixture down to a fraction of a turn before closed, where it just dies, or if I cut off just about all the air using the speed screw.
So now it's revving like a maniac. With the idle circuit disabled it actually revs straight up instead of trying to die. In shifting the van a bit in the driveway and carport to test if it'd just die, I kind of accidentally laid down some rubber with both back wheels. Any idea how to get rid of rubber marks?
With the idle circuit disabled at about 1500RPM, there is about 15" Hg. in the manifold.
With the circuit enabled it's between 13 and 10" Hg.
Sorry if I hve missed replies. It has taken me over a day to write this out in bits and pieces when I have the time.
I got on to someone here that can get the carby gasket kits. $200 for the pair. Seems to be the going rate. When the shopkeeper looked it up when I was on the phone with him, he inadvertently let slip with a couple of expletives when he saw the price.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
Now even with the idle circuit disabled I can't get the revs below 900-1000.
because the throttle shafts are worn 4 the tenth time
ITS SUCKING AIR
vw54 wrote:
Now even with the idle circuit disabled I can't get the revs below 900-1000.
because the throttle shafts are worn 4 the tenth time
ITS SUCKING AIR
And I'm not denying it for a moment. But I'm absolutely convinced the issue is deeper than that. I can't account for a difference that large in a period of essentially zero use.
I was going to call vintage today for a quote but I ran out of time. Today could have gone better.
I was also planning on doing the WD-40 vacuum leak test with a slight addition. I put a tacho in the engine bay. I can usually hear the revs to about 100RPM, but it seems I need something more accurate while my head is buried in the bay. I'm going to do it initially with the central idle completely disabled to remove any ambiguity introduced from it. This way if air is being sucked from somewhere it will be forced to suck harder. The central idle has a tendency to smooth things out a bit.
Update:
I decided to blatantly ignore the settings for the mixture screws and air bypass screw, because after all it is dead easy to revert. Acting on it running painfully rich I leaned out the mix quite a lot. The exhaust no longer has the reek of half burnt fuel, and it no longer chugs and dies when I blip the accelerator.
There was a certain point where the revs stay the same but the sound of the exhaust becomes much more subdued and the random bangs coming from the exhaust stop. I figured it was just a sticking / badly seated exhaust valve. Looks like it was the half burnt excess kept igniting in the exhaust.
Still totally gutless on the test drive.
For the throttle shafts I got no reaction from WD-40 so I moved up to Start Ya Bastard. There was a reaction, which is no big surprise.
I decided to disconnect the central idle solenoid and go for another spin. After accidentally laying down more rubber the drive was a bit better. Probably due to the artificially elevated vacuum. Some more power and still torquey. Still not enough power to get it much above 50 km/h.
So early next week I'll talk to Vintage about the plates, but there is still something lurking which I haven't found, as the van went from drivable to not, with no intermediate.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
Here's a minor update. I had no time this week to anything of consequence. It took me nearly a week to get to doing the two minute run-in on the compressor!
So unfortunately I haven't made the call yet.
About all I have done is blast out the clogged accelerator pump jet with the compressor. I also tweaked the throttle bar adjuster again because I realised that something wasn't quite right and the reason it started revving higher was because one of the throttles wasn't closing completely. So I re-tweaked the central idle again. The strange thing is that with both carbs set to a turn leaner than normal and the central idle set really, really lean it still feels like its running too rich.
When I get time I'm going to check the float levels again but last time I checked (last week) they seemed okay.
Today was another hellish day. As I went to work, I was given a nice drowning of smoke from the vents in the Falcon. After all the following events and getting back home at the end of the day, it was time to shuffle the cars so the Falcon was in the carport for repairs instead of the van.
I had forgotten that yesterday I accidentally dislodged the vacuum gauge from the idle mixture tube, which resulted in the motor sounding better. When I went to move the van today with vacuum line still disconnected and happily sucking air it seemed to move better. A very strange result.
I'm tempted to emulate the result by further leaning out central idle and opening the air bypass a little more. Does that sound right?
I guess all this says is that I have no doubt that the carbies need a complete rebuild. Besides rebushing there is something going on that is just plain wrong.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
timing make sure it is not set 180% out took me a life time to find that little goodie outry using n0 3 as no 1 than just move the leads around as anti clock wise 1234 or clock wise 1432
👍👍😂🙅🥷😬🤓
Dude, sounds like you've got a right stuffed-around system there.
Did you end up going through EVERYWHERE looking for vacuum leaks? Pull off and plug the brake booster lines to eliminate that potential air leak.
The linkage balancing I find is for me a frequent source of crappy running. Making sure they open EXACTLY synchronously. It's really really sensitive.
I have a twin carbed 1800 too. I got some of these Solex carbies rebuilt and since then they just will not work. Absolute bog. So I put on my old set, bent flanges and all, and she drives just fine. Good luck with these bastards, these stupid dual-carby things, grrr!😬
Cheers, A.
Greedy53: I'm pretty sure that my leads aren't reverse ordered, but it can't hurt to check again.
aggri1:
Yep. Eliminated brake booster lines. Here's a helpful tip. If anybody wants to plug the lines, just grab some hose the right size. Sorry can't remember it, and shove a 3/8" extension bar in the hose. It's a snug fit and clamps down easily. Also because its big on one end there is no chance of it being sucked in.
I have also eliminated the manifold/head mating.
I also sort of eliminated the balance tube. It was a bit hard reading a violently pulsating vacuum gauge. Just when I wrote that I realised I could have had the brake booster line connected and disconnected the balance tube. Duh.
Still while I was at it I renewed the hose joins and clamps where necessary. It made a difference of about 1"Hg.
The linkage balancing seems different every bloody time I look at it, even though the adjuster hasn't budged at all. This most recent attempt seems pretty good though.
Can someone confirm / deny that the adjuster screws on the bottom throttle plates are initial mix for the carbies? I don't trust my Gregories one bit.
I'm tempted to buy / fabricate a couple of adapter plates and plop a couple of different carbies on and fabricate a throttle bar assembly for them.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
A sort-of update.
I had to shift the cars around in the driveway to free the Falcon from the carport. I replugged the open vacuum line on the balance tube on the van.
When it was the Vans turn to get shifted back into the carport I took a slight detour around the block because it seemed to be running a lot better. It could have been after my re-re-re-re-re X ? adjustment of the throttle bar or the blowing out of the brass accelerator pump jet on the right hand side carby. I've never seen such a bad clog. It took me about 10 minutes with an airgun and a piece of hose working each end until the clog opened. Is there something I can put in there to dissolve the muck, because I'm still not convinced that its as open as it could be.
Back to the story. So I took it for a night time lap through tiny suburban streets. So this meant I could only go 50km/h not that what I was doing was exactly right anyway. But it wasn't struggling this time or sputtering and chugging. It still feels a little weak but I'm sure I could have wound it out a lot more.
My goal is to get the motor running to registration quality. Longevity, power and economy aren't overly important right now. Just as long as it can start easily (done), not blow smoke (never has), pull itself along (getting there), not backfire (getting there), and not drip oil for the duration of the inspection.
It still needs some fashion of heating system added and the big dent / gouge in the left rear panel fixed for rego. Besides that it looks rough as guts but I see no actual problems. Maybe I should do a bit of work on its rough appearance to make it look on purpose. Ie rat look it.
The Falcon isn't going to last much longer with the type of driving it gets. Lots of start - stop. Engine running for a minute or two at a time because I don't know how long I'll be at each destination. If I were insane enough to use my van for work I have an old turbo timer I'd fit to keep the engine chugging for a few minutes. So if I make it back in time it can keep running. If I don't I won't run out of fuel.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
