Installed new carbs, now have flames shooting out the exhaust!

[Dean...]

Hey friends, it's been a couple days since I've posted an update. Not much to share, but before I go on I really want to thank the people who have read about my frustration, and I especially want to thank those who have offered some advice!

It's so cold here in Australia right now, so by the time I get home from work I just don't feel like freezing my butt off trying things. I might do some work on it tomorrow afternoon, but I said the same thing yesterday about today lol

I looks like its undeniable that the motor is running rich, and that's despite having main jets which should have been too small going by the size of the vents. The air filters are brand new and haven't been overly oiled. What I do remember is when I stripped down the Webers it really was the first time I've seen inside a Weber carb. There was plenty that reminded me of the pict 34 carb on my daughter's beetle, but the float is very different. I pulled the float shaft out and cleaned it all, but I'm almost sure that the little rod/plunger whatever it is that the float moves up and down to stop and start flow, was reinstalled 180 degrees. But upside down, but around. I didn't check the float height because it was fine before, so based on people's advice here and other stuff I've read, I think this could be the problem.

You see, I thought it was understandable for the plugs to soot up while tuning if the carbs were initially setup rich, but it appears from wrists been said here, that my assumption is incorrect.

I will be so pleased is all this is the case, because I also have a problem with my daughter's 1600 Beetle, it idles fine but when I drive it, it runs like crap, and backfires through the carb all the time. I'm also always having to replace the plugs, even after less than 30 minutes while I try to get it to run, because I keep thinking it's running lean, when it could be rich. So I now think her problem could also be the float.

I have to keep it simple.... It's just been difficult because when I recently had work done to it, he made so many changes.

I might actually make sure I do work on the car after work tomorrow, because I'm sick of freezing to death on the motorbike lol

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[Dean...]

I checked the floats this afternoon, and they are fine. I had turned the pin thing around when I was assembling the carb before, so that was corrected. I then put it all back together and the problem is still there.

If some or all of the cylinders had low compression, would that cause it to run rich and cause flames out the exhaust?

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[Dean...]

I was made redundant at work today. The positive is that I'll have more time now to get the car going lol

So I just finished doing a compression test. Results are from cylinder 1 to 4, are 105, 105, 100, 100. All those values went up after dropping a little engine oil into the cylinder and then retesting. Those results in same order were 123, 113, 124, 119.

Looks like I'm going to need some new parts, but are they why the engine is running so bad? The engine wasn't hot when I did the test, but it wasn't cold either. Before I did the test is moved the car from beside the house to into the garage, so I had to drive it there. First I had to roll the car down my driveway which is literally down, and it took me a while and many attempts to get it up the driveway into the garage!

I inspected the plugs and they are all looking the same as the previous set, which is sooty.

Is there anyways a blocked fuel filter could be causing an issue?

Another thing, I didn't use the tester attachment that screws in because it was too difficult. It come with another part so it could be pushed against the plug hole. But I did push hard!

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[Dean...]

Oh, and I forgot to open the carbs full, will that matter?

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[Piledriver]

Oh, and I forgot to open the carbs full, will that matter?

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Yes, i they were not open at all it invalidates the test other than for balance.
...But if you had them open even 20% that's effectively WOT on ITBs at least at cranking speed.

Do try to get the screw in adapter to fit.

Note that Webers and dells cannot deal with more than ~2.5 PSI fuel pressure, if lucky they might tolerate a little more
...but ~2 PSI works fine.

The float heights also must be right.

A very rich carb setup (for whatever reason) can "wash" the bores and cause poor ring seal.
Usually just fixing the rich condition will allow the rings to reseat, but some folks have had to rehone and replace rings.

[Dean...]

Thanks

And does the engine have to be running temp?

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[Piledriver]

Thanks

And does the engine have to be running temp?

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It would help to know exactly what we are dealing with here, what carbs/engine specs any other mods etc.

A weak ignition can cause sooty plugs and misfire under load.

It helps to have the comp test data both ways, but you need to sort the reason why its pouring fuel.(if it is)

I'd start by pinching off the fuel feed and see how it cleans itself up before running out of gas.
Ideally you need to check your fuel pressure from the pump, there are ways of reducing that.

[Dean...]

Ok thanks, I'll give that a go. So if I understand this right, if the fuel pressure is high, it could be causing the issue, but not if it's low... If this is true, what would cause the fuel pressure to be higher? Before the water went down the carbs, the engine ran sweet, so I would assume the fuel pressure was fine then. Can it really start pumping at a higher rate?

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[Piledriver]

Edited previous post we need more info, like how did water get down the carbs and how much?
Tell me the whole story, and all the details.

[Dean...]

The engine is a 1916 with twin Webers. Vents are currently 34mm with 145 mains and 55 idles.

When I first installed these Webers, the mains were 125 and idles were 52. I thought it was running lean lol. Based on the size of the vents etc, what I've read suggests I use the jets I'm currently using.

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[Piledriver]

Twin weber what? 40 or 44 IDF? ICTs are totally different.

I know you are on a phone but try to provide complete info.
Ignition too.

[Dean...]

Ok, it's possible some of this is in this thread somewhere, but I'll post it all here, because I really appreciate the help!

In January we had a lot of rain. The car had stand offs and heaps of water entered the carbs and into the cylinders. I was on stress leave from work from December last year until about 6 weeks ago, so I just couldn't be bothered. I started to get better and went to use the car and the engine turned over a little and then stopped. I knew immediately what the problem was so I stopped trying to turn it over. I turned the motor over backwards by hand a few times, then the other way by hand, and tried starting it again, and eventually it ran, and while doing so threw out heaps of water out the exhaust. No water was found in the oil.

After this event, the engine ran poorly. One of the main issues it had was it would after fire out the exhaust, to the point it was scaring people. So I had a Beetle mechanic work on it. The plan was this: he would rebuild a set of original Webers that I used to have on the car. They are IDF 40's with vents drilled out to 35. He would also replace the electric 009 with a CB Performance Magnaspark 2 setup, and change the plugs. He did all this, and at first it didn't run too bad, but it wasn't the car of old. When I had these carbs on the car before, when you revved it, it would go like a scolded cat, but not anymore. Then overtime I was noticing it was after firing out the exhaust all the time, as well as back firing out the carbs. I contacted the mechanic and he suggested I clean up the carbs that were on it when it rained, and try them. So this is what I did. They are 44's but had vents the size of the 40's, which I think are 28. Because I was after what I used to have with the old carbs when I first got it, I changed the vents in these 44's to 34mm. While swapping over the carbs I found the manifold nut on number 3 to be so loose I removed it with my fingers. Number 1 was only a little tighter. The gaskets were also hung up on the tinware. When I put it all together I made sure the gaskets sat nice and flat.

So I get the car running, but it won't rev very well over 2500. I start thinking it could be the main jets, because its still running the same size as when it had the 28mm vents, so I buy 145 to replace the 125. I also upped the idles one level.

Problem was still there, and when taking it for a drive I pull over and rev it a little while I'm at the rear of the car, and I see flames coming out the exhaust.

When I get home, I wonder if there is an ignition issue, so I removed the new system and put the old system back on. Guess what, the problem is still there.

When I first replaced the carbs I set the spark plug gaps to 040 because I thought that would work well with the Magnaspark, but I've since changed that by installing new plugs at 028.

Air filters are brand new and lightly oiled. Carbs are in sync.

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[Piledriver]

Can you check the timing, what coil are you using, and can you adjust your own valves?

Did your mechanic do _anything_ else to the engine while he had it other than swapping carbs and ignition?

After reading the full info it's probably something very basic.
Somewhat concerned you bent a rod(s) with hydrolock but that's probably not your immediate issue.

I have to crash now but I'll think about it and given the full info other may chime in as well.

[Dean...]

Thanks for your help, I really appreciate it.

A couple days after he did the work, I had him replace with pushrod tubes with ones that don't require the removal of the heads, so while he was at it he adjusted the valves.

I was worried about hydrolock which is why I proceeded so carefully.

The mechanic was always in a rush, so maybe he did the valves wrong. The plugs that he installed were not all the same. I even found that he has taken off one of the nuts from the alternator pedestal and probably used it elsewhere!

I am really hoping the issue is very basic. Tomorrow I'll go and buy a gauge to measure the fuel pressure, and before I warm the motor and retest the compression I'll check the valve gaps.

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[Piledriver]

Check that timing too. Certain of the timing mark?
coil polarity backwards? can idle ok and blow out under load.
firing order or bad plug wires, pull one at a time check for dead hole
Float height correct and equal?