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> What went wrong?, it was running great and then not at all
930cabman
post Mar 20 2023, 04:30 PM
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Back in the day it was difficult to find (and keep) a real mechanic. These days it's near impossible to beg, borrow or steal a real mechanic. Being a backyard mechanic for 50+ years(at best) I have had a few victories and a many failures. It's a mindset to understand and diagnose any machine. Personally I like to use Sir Issac Newton's model "put the issue in your brain and wait until it surrenders". Works well for me, best of luck
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Dustin914
post Mar 20 2023, 04:54 PM
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QUOTE(Superhawk996 @ Mar 15 2023, 11:22 PM) *

What is the static timing set at? Should be about 5-7 degrees BTDC. Have you confirmed this?

we are at TDC...how do we set it to 5-7 degrees BTDC?

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ChrisFoley
post Mar 20 2023, 06:35 PM
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with a timing light while the engine is running.
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Superhawk996
post Mar 20 2023, 07:24 PM
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QUOTE(ChrisFoley @ Mar 20 2023, 07:35 PM) *

with a timing light while the engine is running.

Not really a solution when the engine won’t start and they have no idea where the timing is set at. (IMG:style_emoticons/default/confused24.gif)

Static timing is set without the engine running - Google is your friend as is the link that was posted previously.

Post #21 from Gatornapper is one way to do it by observing the spark.

I prefer to use a multimeter across the points to know exactly when the points open. The engine is set at 7 degrees BTDC by referencing the timing mark on the fan without the engine running. The distributor is rotated until the points just open as observed on the multimeter. Lock down the distributor firmly enough that it doesn’t rotate inadvertently when cranking.

This will set the timing such that you know where the spark is going to occur when the engine is cranking. Once started, then you can use the timing light to fine tune and to observe the mechanical advance from a 009 distributor.
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Type 47
post Mar 20 2023, 08:23 PM
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QUOTE(ChrisFoley @ Mar 20 2023, 04:35 PM) *

with a timing light while the engine is running.

We did get it running, kind of. So we used a timing light. But i'm not sure how to use it. I was able to hold rpm at 3,500 while it was scoped and the mark was there.

not sure how to related that to a static timing of 7.5 degrees.

engine is still popping and backfiring like it was originally.

it was running so good, getting a little discouraged.

BTW, did the test on the lift plate and all is good!
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Superhawk996
post Mar 20 2023, 08:29 PM
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QUOTE(Type 47 @ Mar 20 2023, 09:23 PM) *

QUOTE(ChrisFoley @ Mar 20 2023, 04:35 PM) *

with a timing light while the engine is running.

We did get it running, kind of. So we used a timing light. But i'm not sure how to use it. I was able to hold rpm at 3,500 while it was scoped and the mark was there.

not sure how to related that to a static timing of 7.5 degrees.

engine is still popping and backfiring like it was originally.

it was running so good, getting a little discouraged.

BTW, did the test on the lift plate and all is good!


If you have it running and can use the light - disregard the static timing. That was only pertinent when you couldn’t get it started.
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Superhawk996
post Mar 20 2023, 08:35 PM
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Now that the carbs have been removed - you’re going to have to work your way back through balancing airflow in each barrel, setting idle mixture, setting idle speed and then synchronizing the two carbs.

Have you done that?

Also what are the Venturi sizes and jets that you’re working with?
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Type 47
post Mar 20 2023, 09:18 PM
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QUOTE(Superhawk996 @ Mar 20 2023, 06:35 PM) *

Now that the carbs have been removed - you’re going to have to work your way back through balancing airflow in each barrel, setting idle mixture, setting idle speed and then synchronizing the two carbs.

Have you done that?

Also what are the Venturi sizes and jets that you’re working with?


Why would we have to do that? Kid took them off...I made him put them back on. Nothing changed except making sure they were good and tight.

Airflow is a final adjustment we were almost there when things went south.

you make it seems so simple. I get the synch'n the carbs, but i'm kind of lost at idle mixture/speed.
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Type 47
post Mar 20 2023, 09:40 PM
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Could a valve be stuck and causing chaos? then not sticking and runs fine?
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Superhawk996
post Mar 20 2023, 09:55 PM
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QUOTE(Type 47 @ Mar 20 2023, 10:40 PM) *

Could a valve be stuck and causing chaos? then not sticking and runs fine?

Not likely at all
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Dave_Darling
post Mar 20 2023, 09:58 PM
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Distributor. Check that distributor. Do not f**k with the carbs, do not pass go, do not collect $200. Make sure that the distributor is in the right place. Rotate the engine until both valves on #1 are slack, then check where the distributor rotor is pointing. If it's not pointing at the distributor cap terminal that is connected to the #1 cylinder, it's wrong and the car will have one heck of a time starting.

Verify this first. Then make sure that the plug wires follow the firing order as you go around the distributor: 1-4-3-2. If you get the wires wrong, the car either won't start or will run like s**t.

Static timing is basically done by turning the engine by hand until it is at TDC for #1, and turning the distributor so the points are just opening (or could be just closing; I forget which triggers the spark!). Forget 7 degrees or whatever, setting it to TDC will make it close enough for the car to start.

Verify the spark, make sure your distributor is in the right place, then set the static timing so you're somewhere close. The car should be able to run at that point, unless the fuel or the compression is messed up somehow.

--DD
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Superhawk996
post Mar 20 2023, 10:02 PM
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Sorry - not trying to over simplify

However tuning is an iterative process. Airflow affects idle mix, mix affects idle speed, idle speed affects timing (due to centrifugal, mechanical advance on 009), and synch between the two carbs goes right back to affecting airflow.

All the above are interrelated to Venturi and jetting.

It’s anything but simple. But it needs to be worked through in a methodical way with each incremental adjustment becoming smaller.

Since you never got to a stable idle below 1200 rpm per your original post I can only conclude that something was not adjusted properly.

Your most recent post of having popping and backfiring could at a bare minimum be tied to it getting lean as you transition off idle.
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Superhawk996
post Mar 20 2023, 10:04 PM
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QUOTE(Dave_Darling @ Mar 20 2023, 10:58 PM) *

Distributor. Check that distributor. Do not f**k with the carbs, do not pass go, do not collect $200. Make sure that the distributor is in the right place. Rotate the engine until both valves on #1 are slack, then check where the distributor rotor is pointing. If it's not pointing at the distributor cap terminal that is connected to the #1 cylinder, it's wrong and the car will have one heck of a time starting.

Verify this first. Then make sure that the plug wires follow the firing order as you go around the distributor: 1-4-3-2. If you get the wires wrong, the car either won't start or will run like s**t.

Static timing is basically done by turning the engine by hand until it is at TDC for #1, and turning the distributor so the points are just opening (or could be just closing; I forget which triggers the spark!). Forget 7 degrees or whatever, setting it to TDC will make it close enough for the car to start.

Verify the spark, make sure your distributor is in the right place, then set the static timing so you're somewhere close. The car should be able to run at that point, unless the fuel or the compression is messed up somehow.

--DD


(IMG:style_emoticons/default/agree.gif) I sort of assumed you have done this when you said you have it running And had verified timing.

Note: the moment when the points OPEN is when the spark is triggered.
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brant
post Mar 21 2023, 07:48 AM
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Taking the carbs off will effect the linkage

Having unbalanced carb linkage can causing significant popping and back fire

It’s a systemic that requires each step to be correct
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Type 47
post Mar 21 2023, 09:15 AM
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QUOTE(Dave_Darling @ Mar 20 2023, 07:58 PM) *

Distributor. Check that distributor. Do not f**k with the carbs, do not pass go, do not collect $200. Make sure that the distributor is in the right place. Rotate the engine until both valves on #1 are slack, then check where the distributor rotor is pointing. If it's not pointing at the distributor cap terminal that is connected to the #1 cylinder, it's wrong and the car will have one heck of a time starting.

Verify this first. Then make sure that the plug wires follow the firing order as you go around the distributor: 1-4-3-2. If you get the wires wrong, the car either won't start or will run like s**t.

Static timing is basically done by turning the engine by hand until it is at TDC for #1, and turning the distributor so the points are just opening (or could be just closing; I forget which triggers the spark!). Forget 7 degrees or whatever, setting it to TDC will make it close enough for the car to start.

Verify the spark, make sure your distributor is in the right place, then set the static timing so you're somewhere close. The car should be able to run at that point, unless the fuel or the compression is messed up somehow.

--DD

checked the valves, there slack, rotor pointing @#1. checked the wires and replugged them to make sure good contact.

car runs but pops, sputters, and backfires.
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Type 47
post Mar 21 2023, 09:16 AM
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QUOTE(brant @ Mar 21 2023, 05:48 AM) *

Taking the carbs off will effect the linkage

Having unbalanced carb linkage can causing significant popping and back fire

It’s a systemic that requires each step to be correct


we did tighten up the linkage. It may be time to get a better one though.
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Type 47
post Mar 21 2023, 09:26 AM
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QUOTE(Superhawk996 @ Mar 20 2023, 08:02 PM) *

Sorry - not trying to over simplify

However tuning is an iterative process. Airflow affects idle mix, mix affects idle speed, idle speed affects timing (due to centrifugal, mechanical advance on 009), and synch between the two carbs goes right back to affecting airflow.

All the above are interrelated to Venturi and jetting.

It’s anything but simple. But it needs to be worked through in a methodical way with each incremental adjustment becoming smaller.

Since you never got to a stable idle below 1200 rpm per your original post I can only conclude that something was not adjusted properly.

Your most recent post of having popping and backfiring could at a bare minimum be tied to it getting lean as you transition off idle.


We did have it idling OK before I replaced the plug wires. I should have mentioned that. I was idling OK but still a slight bit of vibration/shake. When I replaced the wires it ran smoother but idle had move up from about 900 to 1200.
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nditiz1
post Mar 21 2023, 09:29 AM
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If the car pops stutters backfires at IDLE here are the things to check:

Idle circuit is dirty - are the carbs clean? Have they been cleaned?
Mixture screws are set too lean - richen them up to see if the popping goes away.
Get the Syncrometer on the throats and see if all 4 are in sync. You don't need linkage at this step.

Timing could be off, but I believe you ran it up to 3500 and set the timing to 27/ the mark on the pulley. If you did, then the timing is correct, no need to touch the timing anymore.

Getting a smooth idle of around 1000-1100 is the key right now. You can worry about smoothness up to 3500 in a later step.

EDIT - Adjust idle speed with the carb idle speed adjusters which will in turn adjust the vac pull so double check they are back in sync. When you want to make the car smooth throughout the RPM band you will need to use the syncrometer to check the vac pull at a few different intervals up to ~3000 rpm. Hold the rpm steady at 1500, check both sides, 2000 check both sides, 2500 check both sides. Each interval should have the same pull which means the linkage is in sync.

EDIT2 - some engines like to idle at a higher RPM then 950. 1200 is a little on the high side I would shoot for between 1000-1100. The best budget linkage is the CSP center pull. You can see it on Zach's latest 2.3 PMB engine.
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brant
post Mar 21 2023, 09:58 AM
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QUOTE(Type 47 @ Mar 21 2023, 09:16 AM) *

QUOTE(brant @ Mar 21 2023, 05:48 AM) *

Taking the carbs off will effect the linkage

Having unbalanced carb linkage can causing significant popping and back fire

It’s a systemic that requires each step to be correct


we did tighten up the linkage. It may be time to get a better one though.



even a worn out linkage can be balanced... it just won't hold it well over time
balancing the linkage ensures both banks open the butterflies at exactly the same time
and does not create a lean condition (popping) on one bank...

after a good baseline balance is found
then fine tuning can be done with the carb balance screws
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technicalninja
post Mar 21 2023, 10:12 AM
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QUOTE(Type 47 @ Mar 20 2023, 09:23 PM) *

QUOTE(ChrisFoley @ Mar 20 2023, 04:35 PM) *

with a timing light while the engine is running.

We did get it running, kind of. So we used a timing light. But i'm not sure how to use it. I was able to hold rpm at 3,500 while it was scoped and the mark was there.


I'm not sure if the 914s have a full advance timing mark but most cars don't.

If a standard style mark (usually idle with vac lines removed from dist) is being used and he saw that mark at 3,500 rpm he may still be way off on his timing.
3,500 will usually have almost all of the mechanical advance in and some of the vac adv/retard in.

I am not a 914 timing guru yet but I'd expect that the "timing" would be way the hell out at 3500 rpm if I could see the timing marks in the indicator. I'd expect 25 degrees + of advance at that speed.

Ignition function and timing FIRST. Then setting up fuel, balance airflow, set throttle linkage second.

The linkage has to be adjusted, just being "tight" is not being adjusted.
Replacing linkage before understanding how the linkage is to be adjusted will only further the OPs frustration with this process IMO.

On my 914 we didn't even get feeler gauges out to check points. A dwell meter was used from the start. I had to find my dwell meter as I hadn't used it in 20 years.
It took longer to find that critter than it took to set the points...

Just checked my "tune up" specs tag on my 75 L-jet 1.8. It says timing is to be 7.5 degrees advance at 850 +/- 50 rpm with vacuum hoses to distributor removed...
So the Germans are using a "normal" timing procedure and if he's seeing the marks at 3500rpm he is 25+ degrees RETARDED!
It is completely IMPOSSIBLE to adjust carburators at these timing settings.

The distributor should be twisted toward advance 20+ degrees.

Get it running with a slightly lose distributor clamp and try to twist it either way.
One direction it will get worse and the other it will clean up.

I can set what I call "base" timing with a timing light hooked up to the coil wire and the fuel system disabled. I'd want to see the timing mark in the window without the car running. The coil wire will flash 4 times for 2 revolutions and two of those flashes will be on the marks. two will not but your brain will overlook them and all you will see will be the marks themselves.

Your timing is still WAY out. That has to be addressed first before the carbs are messed with.

If my son had completely removed a pair of ITB carbs before we diagnosed what was wrong with the car I'd kill him.

If he left the intakes wide open, I'd bring him back to life and kill him again...

I don't use rags for closing off open intakes. Had too many sucked into engines when they were turned over by accident, I use the aluminum tape (has the paper covering the sticky side). This stuff doesn't break, and it peels back off nicely when you need to remove it. Nothing gets into intakes.
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