Hit and Miss

Ok,, got a puzzle. My 1600cc dual port has developed a pretty serious miss. It idles fine,,, and it pulls fine under heavier throttle (like when I stomp on it). But at normal cruise, and moderate accelerations, it now has developed a serious miss. Nothing seems odd or out of place as far as fuel or electrical connections are concerned,, but I have not pulled plugs or the cap as yet. I am thinking my old 34 Pict-3 is hurting,, maybe with a holed float. Any opinions or suggestions ?? Maybe it is telling me to open that new kit of dual 34 Brosals, that I have had on the shelf for way too long anyway !!!
Alan

Come on Alan - open that box and get them installed - you will wonder why you waited so long.

I'd adjust the valves and do a compression check first. At least then you know they are ok.

I'm a Weber guy, so my fix is "clean the idle jets". Be sure carbs are balanced, linkage all nice and snug, etc.

Wolfgang,, the valves are good, and although I have not done a compression test I am pretty confident there too, since it is pulling and idling fine.

Dale,, you are absolutely right,, I have been putting off the new carb's long enough. Just got to find a fuel pressure guage, so that I can set up the new regulator. Hopefully, I can find something local. Snow in tonight's forecast means I have a couple of days to play around. Never having done a carb swap before,,, any tips or tricks to watch for ?? It is the CB Performance kit. I am guesstimating a day to install ??

Alan

Prior to doing any carb replacement, always confirm the basics i.e. compression, valve adjustment, timing etc. Be sure to have good quality manifold gaskets.

Ok,,Ok,,, I will pick up a compression tester,, and treat it to a new set of plugs while I am at it. Looks like the tin's have to come off to install the new manifolds ??

Don't know if anyone caught the "bolt-on HP" article in Hot VW's ?? It was a little short on specifics,, but some interesting end results (especially the torque improvement). Alan

http://www.hotvws.com/issue_preview.html

Usually, you don't have to remove the upper cylinder tin to remove or install the manifolds. Do use a thin coat of silicone sealer or copper coat or better yet, three bond sealer between the gasket and their mating surfaces. Some people like axle grease however my preference is three bond sealer.

If you're daring, start the car and remove one spark plug wire at a time until you find the cylinder that's causing the problems. Once you've done that, swap it with it's sister cylinder in other words, if 1 is bad then swap the wires between 1 and 2. That will help determine if your problem is spark plug wires. It's a rare case when a spark plug goes bad but it's possible.

If you still have points/condenser then get rid of them and install a new set or better yet, install a point eliminator. While you're working on the distributor, check to make sure the vacuum advance/retard are working as well as the mechanical advance system. Look at the top of the distributor cap for evidence of carbon along arc lines. If there's a problem with the cap or rotor, these are sure fire tell tale signs.

The reason everyone is telling you to check the "system" first before you install the carb's is because they ""may"" not solve your problem and more than likely will exagerate your current conditions.

Spend a little time diagnosing the problem before you start throwing money into the endless hole created by your car.

Alan - of course everyone is right about checking everything out first before changing carbs,
but you already have them so install them once you know what is wrong - just trying to give you a little push. They will require some tuning and adjustments to get them right so make sure you get some help on that part if you are not sure.

Alan....Do both hot and cold......It is easier with a cold engine, and any radical difference between the two would indicate problems one test would not spot....Just a thought....

Ok, Gang,,
I finally managed to borrow a decent compression gage, as I could not bring myself to blow $70+ at the local auto shop for a new one. So I should get to the compression test this weekend. Different articles I have read differ on doing the test hot or cold ?? I would have thought to do it as reasonably close to normal operating temp's as possible. So what would you recommend ?? I could not find anything in the Knowledge library section.
thanks,
Alan

Well,,,, I finally got my compression test completed. It took this long because we are moving,, and my Speedster is still sitting in its old hanger. BUT,,, getting back to the test, which I would say it was a pretty good result. For cylinders #'s, 1,2,3,4 the readings were 130,143,135,135 respectively. But one thing I did notice, while performing the test was, that the gap's on a couple of the plugs seemed excessive. I am thinking this could produce the type of miss symptom that I described earlier. So I picked up a new set of plugs, and will pop them in tomorrow,, then test drive to see if the miss is cured.

Say,, what are you guys gapping plugs at these days. My plugs are Bosch Super Plus WR8ac+,, installed in a 1600 dual port. Local fuel is 85 octane with an ethanol percentage,, me thinks. I heard the plugs should be gapped narrower than normal,, because of the ethanol.

thanks,
Alan

Ok,, swapping out the plugs did not help. Sooooo,,, bring on the carb's. Hope to have them done by this weekend. But it sure was nice to have the car out for a test drive today, even with this mid-throttle miss. Stay tuned,, Alan

Hope you get it all sorted out, Alan. Just keep thinking how sweet it will be to hear the tune of your exhaust with your engine running smoothly at speed!!

Peace - Out!

Well,, finally got the new carb's in place, and am tidying up a dozen or so little details before trying to sync them up. But I could not wait to hear my engine run, after a couple of weeks of silence,, so I tickled the carbs a bit,,, turned the key,, and away it went !! A good sign,, BUT,, after I shut the engine off, an awful amount of fuel continued to drain down the carb throats (for about 20 seconds),,,, and of course when I tried to restart, it was totally flooded.

It seemed to me that fuel was even flowing out of the float bowl vents. Now I did check the fuel pressure, before I removed the old carb assembly, and it was about 3-1/4psi. The instructions call for 3-1/2psi, so I just left the stock mechanical pump alone. I plan to tee the fp-gage back in, to verify the pressure. And also, I have to go through the proper s/u and sync for these new Solex-34's. But I wondered if anyone has seen this condition before ?? I was bit concerned about all that fuel finding its way to the crankcase, and/or washing down the cylinder walls.
Thanks as always,, Alan
btw: it seemed to be running pretty good,, once it got running,, and that was music to my ears !!

That much over flow would indicate float or inlet valve issues, if the pressure is as stated.....
You might want to check the float level and action.....Just a thought...

Did not seem to leak as much today,, although I could hear the gas percolating in the manifolds, once I shut it down.

I have read that some have had to polish the needle cones out of the float valves, in order to get a good seal. btw,, the fuel pressure checked out at 3-1/2psi max.

Seems to be gushing less than yesterday though,, so maybe I will try a few more cycles to see if the improvement continues. If not, I will have to open up the bowels and take a look.

Alan

Well I had some pretty decent test drives with the new carb/s installed today. The flooding (from the float bowls) after shutdown, seems too have pretty much stopped. I am guessing that the float valve needles, for whatever reason, have started seating properly now. I will likely run some carb conditioner through with the next tank up, just for good measure. As for performance gain, I have to say that adding the dual 34mm Solex's alone, has not really resulted in any dramatic performance gains. They add a bit more grunt in the low/mid rev range (3000rpm),, and they sound great around 4000rpm. And, they are definitely smoother than my old Pict-3. What is needed now is my 1.4 ratio rockers, and a better exhaust/header. But I am going to have some fun driving my car again, for a couple of weeks.

But best of all,,,, that miss is, GONE !!
thanks for the input,, all,,,
Alan

Alan:

Not that much of a surprise that you're not noticing a really big difference.

These are remarkably balanced engines, meaning that whatever you do on one side of the engine (induction side, in your case) has to be balanced by doing something equally effective on the other (exhaust) side.

You should now see just as much improvement as you saw from new carbs by swapping in a new extractor exhaust system to get those spent gases out.

Folks on here should be able to help recommend which might work best.

Enjoy that smooth-running engine for a bit, and then tackle the exhaust system. You'll be glad you did.........


gn
The Speedstah Guy from Beaufort