Calling engine experts

[kevlarian]

I give up. Let me start with all the BRAND NEW parts I've purchased in the last 30 days:

- Bosch Blue Coil (good one... not the crappy one)
- Bosch (German) Plug Wires
- Bosch Spark Plugs
- Distributor (High Quality) 009
- Points / Condenser

My engine:

- 1914cc
- Kadron Dual Carbs

Now, what I've tested...

- I did a compression test on all four Cylinders, all of them were between 120-125 psi.

- I did a valve adjustment

- Carbs are balanced

*** PROBLEM ***
When I pull plug wires 1 or 3 the engine runs exactly the same at both idle and under acceleration. I can pull BOTH 1 & 3 it still runs... with little to no difference.

Pulling 2 or 4, the engine can barely run...

It would appear that I am running (basically) on 2 cyls, but I can't figure out why. I have compression on all four cylinders... I'm getting a spark to all four...

No oil leaks, at least no more than normal

So... what next!? What do I test. Is it my Heads?... what possibly could it be.

[Brian]

This happened to me a while back, taking off 1 and 3 made 0 difference. I ended up just doing the basics: valves, static timing and dwell. I have dual FRDs and they were ""tuned"" how are the Jets on the kads?did you do the $1.98 tune up or dump ATF down the carb throats?

You have compression, so all you have left to rule out is fuel and spark.

High quality 009?
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[Juanito84]

I'm no expert, but from what I do understand there is a big difference in how #3 and #1 run compared to #2 and #4 UNLESS you have some sort of intake that treats each cylinder separate (like IDF's or Mexican EFI.)

Whenever you have dual carbs, such as in your case, the engine starts intake on #4 or #2, which starts with no air nor fuel flowing and must get the air and fuel starting to flow through the carb on that side, then that cylinder closes and it goes to #3 or #1, which starts out with air already flowing through the carb and so therefore gets more air and usually a richer AFR.

So because of this #1 and #3 cylinders usually put out more power.

But ya. If it's very noticeable it's probably bad spark on one or both of those cylinders. Or possibly too lean?
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[Brian]

Oh not to scare you or anything, but 1 and 3 share the same cam lobe. So just something to think about.
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'69 Bug
'68 Baja Truck
'71 Bug
'68 Camper

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[Juanito84]

[modok]

When you asked the same thing last week you just complained it idled on 2/4, which is normal for kadrons.

This time, you have also added the word "acceleration", which would seem to mean, you drove it with a spark plug disconnected, and noticed no difference. Is this true?

[kevlarian]

[kevlarian]

[modok]

When did the problem start?
How slow is it?

[kevlarian]

[modok]

Could be you have a flat lobe.

Check valve lift.

So, summary of problem:
A-it's getting slower
B-it's hard to start
C-both?

[wcfvw69]

Have you checked for a vacuum leak on that side carb? I had dual 44's on an engine. Same symptoms you're experiencing. I found that side carb was bolted tightly to the head. Once I snuged it down, the vacuum leak was gone and it purred.

It's a quick check to insure you have no vacuum leaks.
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[Juanito84]

[vwinnovator]

try pinching off the balance tube from manifold to manifold and see what happens.

[kevlarian]

I recently checked the manifolds, and the carbs to make sure there were no air leaks. We're solid there.

Remember 1 & 2 share a carb, and 3 & 4 share a carb. My problem is with 1 & 3... so that really isn't a carb issue. Someone indicated that 1 & 3 don't work right with Kads, but I have never heard that from anyone.

What else can I test? Would a full leak down be the next test?

[Dale M.]

Look up "recursion" (I think the term is) its where one cylinder (per side of single throat carb on dual port head/manifold) will rob all the fuel function and starve the other cylinder... Pretty common problem with single throat carbs on dual port heads and usually 2&4 will prevail over 1&3 for some reason... Balance tube is supposed to help... But...

Get dual throat carbs (Weber IDF or EMPI HPMX) and it will do away with the problem, but then its a whole new tuning game for you...

Dale
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[PumaVW79]

[mark tucker]

did you try swaping 1&3 wires? , or replacing the plugs? check cam?

[[email protected]]

Kads idle on 2 cylinders. VW firing order is 1-4-3-2, or 4-3-2-1. 4 before 3, and 2 before 1. By the time the valve opens for 3 and 1, there's nothing left. Dual 2bbls do not have this problem. So all the idling is driven by 4 and 2. 3 and 1 do nothing until the throttle is opened.

Pull a plug wire on 4 or 2, and it's now idling on ONE cylinder. Pull a wire on 3 or 1, and there's no difference.

This is pretty much the case with all dual 1bbls. It's one of the reasons I don't like dual 1bbls, unless you have no choice (like a single port).

If the VW firing order was alternating each side, instead of 2-1 on one side, then 4-3 on the other, it wouldn't have this characteristic. But it does, and it's shocking that more guys don't know about it. It's not rocket science.

I suspect your hard starting is fouled plugs from jetting which is too rich, and/or plugs which are too cold.
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[HRVW]

Trying to think out loud here.

Kads with a balance tube.....solid like new or cut and held together by a hose slamp.....have seen that with a problem

Have seen where a person had a vac leak there affecting both Carbs.(toss up)

Intake man for a SP or a DP head. (one hole or split man)

I read a vac leak. Try to hold the RPM high while spraying/dripping gas in the Carb throat. If it picks up then there was a vac issue. If it dogs you know nothing wrong there.

Opposing cyls is the key here.

What is there in common to effect opposing cyls?