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txasylum
Samba Member
Joined: December 15, 2004
Posts: 389
Location: Boyers, PA
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 Posted: Sun Oct 27, 2019 8:32 am Post subject: New motor, won't start, backfire |
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Okay, this is not my first rebuild, but I also don't consider myself an expert, so I have a question.
I rebuild a 1600cc motor on F0 block. All good, marks on crank match up to cam.
Put motor back in car. Firing order is correct (checked it many times). I also pulled the valve covers off, adjusted them, turned crank to TDC and number 1 intake starts to open.
PROBLEM: Won't start. I get a backfire occasionally. Last one had a nice flame out exhaust. Is it possible it is 180 degrees out of order? I did not pull distributor gear on rebuild.
Help please. |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sun Oct 27, 2019 8:41 am Post subject: Re: New motor, won't start, backfire |
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| txasylum wrote: |
| Is it possible it is 180 degrees out of order? |
You just answered your own question:
| Quote: |
| turned crank to TDC and number 1 intake starts to open. |
#1 TDC occurs when #3 intake starts to open.
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txasylum
Samba Member
Joined: December 15, 2004
Posts: 389
Location: Boyers, PA
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| Posted: Sun Oct 27, 2019 8:48 am Post subject: Re: New motor, won't start, backfire |
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Just so I know, how can it get 180 out?
So if 180 out, firing order 3214?
I just swapped 1&3 and 2&4 plug wires, but nothing.
| busdaddy wrote: |
| txasylum wrote: |
| Is it possible it is 180 degrees out of order? |
You just answered your own question:
| Quote: |
| turned crank to TDC and number 1 intake starts to open. |
#1 TDC occurs when #3 intake starts to open. |
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AlmostHeavenWV_VW 
Samba Member
Joined: October 12, 2017
Posts: 1966
Location: WV
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| Posted: Sun Oct 27, 2019 8:56 am Post subject: Re: New motor, won't start, backfire |
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| txasylum wrote: |
Just so I know, how can it get 180 out?
So if 180 out, firing order 3214?
I just swapped 1&3 and 2&4 plug wires, but nothing.
| busdaddy wrote: |
| txasylum wrote: |
| Is it possible it is 180 degrees out of order? |
You just answered your own question:
| Quote: |
| turned crank to TDC and number 1 intake starts to open. |
#1 TDC occurs when #3 intake starts to open. |
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What busdaddy was telling you is this:
Your description of your procedure showed that you were attemting to "time" incorrectly. You weren't timing to TDC, you were timing 180* off.
You want to pop the valve covers and rotate until #3 intake starts to open; that is TDC for #1. Time from that position.
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txasylum
Samba Member
Joined: December 15, 2004
Posts: 389
Location: Boyers, PA
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| Posted: Sun Oct 27, 2019 9:04 am Post subject: Re: New motor, won't start, backfire |
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Okay, I will take a look, but for S&G (from reading posts) below is a picture of how the slot is oriented in the shaft when pulley is at TDC. From what I read this is correct. Going to check #3 intake now.
Okay, so I did what you said. when #3 intake starts to open, the rotor is pointing to #3. You said to time to that. Is that 180 out of time? How do I time to that? Do I turn the distributor to fire on #3? Sorry guys I'm a bit confused on this.
| AlmostHeavenWV_VW wrote: |
| txasylum wrote: |
Just so I know, how can it get 180 out?
So if 180 out, firing order 3214?
I just swapped 1&3 and 2&4 plug wires, but nothing.
| busdaddy wrote: |
| txasylum wrote: |
| Is it possible it is 180 degrees out of order? |
You just answered your own question:
| Quote: |
| turned crank to TDC and number 1 intake starts to open. |
#1 TDC occurs when #3 intake starts to open. |
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What busdaddy was telling you is this:
Your description of your procedure showed that you were attemting to "time" incorrectly. You weren't timing to TDC, you were timing 180* off.
You want to pop the valve covers and rotate until #3 intake starts to open; that is TDC for #1. Time from that position. |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sun Oct 27, 2019 9:18 am Post subject: Re: New motor, won't start, backfire |
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Don't sweat over the slot position right now, set the engine to #1 TDC (#3 valves both moving near TDC) and put the #1 plug wire in whatever hole the rotor points at, arrange the rest of the wires accordingly.
Once it's running like that you have to decide if you want to risk dropping the washers into the case while reorienting the drive.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
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txasylum
Samba Member
Joined: December 15, 2004
Posts: 389
Location: Boyers, PA
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| Posted: Sun Oct 27, 2019 9:22 am Post subject: Re: New motor, won't start, backfire |
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Okay, it is starting to fire. BTW it helps to have gas I the tank.
I am not going to mess with the distributor shaft. Not worth the risk of dropping washers or breaking the fuel rod shaft.
Thanks again, as usual.
Bob
| busdaddy wrote: |
Don't sweat over the slot position right now, set the engine to #1 TDC (#3 valves both moving near TDC) and put the #1 plug wire in whatever hole the rotor points at, arrange the rest of the wires accordingly.
Once it's running like that you have to decide if you want to risk dropping the washers into the case while reorienting the drive. |
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heimlich
VWNOS.com
Joined: November 20, 2016
Posts: 6621
Location: Houston, Texas
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| Posted: Sun Oct 27, 2019 9:43 am Post subject: Re: New motor, won't start, backfire |
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Is that TDC? The distributor gear looks a little off.
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txasylum
Samba Member
Joined: December 15, 2004
Posts: 389
Location: Boyers, PA
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| Posted: Sun Oct 27, 2019 10:01 am Post subject: Re: New motor, won't start, backfire |
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Yes, that was before I realized it is 180 off.
| heimlich wrote: |
Is that TDC? The distributor gear looks a little off. |
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txasylum
Samba Member
Joined: December 15, 2004
Posts: 389
Location: Boyers, PA
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| Posted: Sun Oct 27, 2019 10:03 am Post subject: Re: New motor, won't start, backfire |
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New question. How do I time it being 180 off? Do I use the same timing marks on the pulley? If so, it seems to run smoothly when TDC is at 10:00 position. If I go to TDC with it the car dies.
| txasylum wrote: |
Okay, it is starting to fire. BTW it helps to have gas I the tank.
I am not going to mess with the distributor shaft. Not worth the risk of dropping washers or breaking the fuel rod shaft.
Thanks again, as usual.
Bob
| busdaddy wrote: |
Don't sweat over the slot position right now, set the engine to #1 TDC (#3 valves both moving near TDC) and put the #1 plug wire in whatever hole the rotor points at, arrange the rest of the wires accordingly.
Once it's running like that you have to decide if you want to risk dropping the washers into the case while reorienting the drive. |
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heimlich
VWNOS.com
Joined: November 20, 2016
Posts: 6621
Location: Houston, Texas
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| Posted: Sun Oct 27, 2019 10:23 am Post subject: Re: New motor, won't start, backfire |
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| txasylum wrote: |
New question. How do I time it being 180 off? Do I use the same timing marks on the pulley? If so, it seems to run smoothly when TDC is at 10:00 position. If I go to TDC with it the car dies.
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It doesn't look too far off. The line in the gear should be perpendicular to the fuel pump hole. The smaller segment should be towards the pulley side.
If you are 180 degrees off you can just flip the drive on the bottom of the distributor.
_________________
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Classic Brands. Classic Quality.
Not all parts are made the same. NOS OE/OEM parts made mainly in West Germany, Early Germany, and Early Brazil are where VW produced the best quality parts and best fitting products.
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txasylum
Samba Member
Joined: December 15, 2004
Posts: 389
Location: Boyers, PA
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| Posted: Sun Oct 27, 2019 10:49 am Post subject: Re: New motor, won't start, backfire |
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I swapped out for a 30 Pict-1 carb. Seems to time better as it should, but now I need a SVDA list to match that carb.
| heimlich wrote: |
| txasylum wrote: |
New question. How do I time it being 180 off? Do I use the same timing marks on the pulley? If so, it seems to run smoothly when TDC is at 10:00 position. If I go to TDC with it the car dies.
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It doesn't look too far off. The line in the gear should be perpendicular to the fuel pump hole. The smaller segment should be towards the pulley side.
If you are 180 degrees off you can just flip the drive on the bottom of the distributor. |
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heimlich
VWNOS.com
Joined: November 20, 2016
Posts: 6621
Location: Houston, Texas
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| Posted: Sun Oct 27, 2019 11:16 am Post subject: Re: New motor, won't start, backfire |
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| txasylum wrote: |
I swapped out for a 30 Pict-1 carb. Seems to time better as it should, but now I need a SVDA list to match that carb.
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You have a dual port engine so you should switch back to the 34 PICT 3 that you have unless there is a problem with it. Then you could gain the full advantage of an SVDA. What's wrong with the 34-PICT 3 that you have?
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Not all parts are made the same. NOS OE/OEM parts made mainly in West Germany, Early Germany, and Early Brazil are where VW produced the best quality parts and best fitting products.
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tasb
The Distributor Distributor
Joined: April 27, 2002
Posts: 6371
Location: Pentwater, Michigan
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| Posted: Sun Oct 27, 2019 12:33 pm Post subject: Re: New motor, won't start, backfire |
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With the 30 PICT carburetor you want to run a SVA distributor not an SVDA. You'd be looking for:
113 905 205 K
113 905 205 M
113 905 205 T
There's nothing wrong with running a 30 PICT on a dual port engine, it's done all the time. There's even an adapter plate to make it work.
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txasylum
Samba Member
Joined: December 15, 2004
Posts: 389
Location: Boyers, PA
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| Posted: Sun Oct 27, 2019 12:58 pm Post subject: Re: New motor, won't start, backfire |
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My 34 PICT 3 small air screw broke, so the body is pretty much trash. If I go back to a pict 3 I will need a matching distributor. Or stick with the pict 1, and get a distributor.
Not sure if there is a real advantage of one over the other.
| heimlich wrote: |
| txasylum wrote: |
I swapped out for a 30 Pict-1 carb. Seems to time better as it should, but now I need a SVDA list to match that carb.
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You have a dual port engine so you should switch back to the 34 PICT 3 that you have unless there is a problem with it. Then you could gain the full advantage of an SVDA. What's wrong with the 34-PICT 3 that you have? |
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txasylum
Samba Member
Joined: December 15, 2004
Posts: 389
Location: Boyers, PA
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| Posted: Sun Oct 27, 2019 1:00 pm Post subject: Re: New motor, won't start, backfire |
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Okay, thanks for the list models. The car has a new motor, but it runs like crap and I rack it up to the distributor. I put the 30 PICT 1 on it with 009s today. Big hesitation. Then I put it on with an old SVA, but the vacuum is not working. I do have the adaptor, so all I need now is the correct dist. From what you say there is no big difference between a 34P3 and a 30P1, just need correct dist.
I will look for these three for the Pict 1. Is any one better or easier to find than others? Are there any interchangeable distributor for these? I see Bosch dist mentioned too. Or is it easy to find a canister and repair/replace it on the existing dist?
| tasb wrote: |
With the 30 PICT carburetor you want to run a SVA distributor not an SVDA. You'd be looking for:
113 905 205 K
113 905 205 M
113 905 205 T
There's nothing wrong with running a 30 PICT on a dual port engine, it's done all the time. There's even an adapter plate to make it work. |
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ashman40
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Joined: February 16, 2007
Posts: 15987
Location: North Florida, USA
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| Posted: Sun Oct 27, 2019 2:40 pm Post subject: Re: New motor, won't start, backfire |
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This below is more a comment for future readers of this thread...
| txasylum wrote: |
| ... turned crank to TDC and number 1 intake starts to open. |
The above is the first indication something is wrong. Think about it from a 4-stroke engine POV... the spark for #1 cylinder is needed when the #1 cylinder is at TDC at the end of the compression stroke. At this point in the 4-stroke cycle BOTH #1 cylinder valves will be closed so compression can be built. So if #1 intake or exhaust are moving at TDC it says that cylinder is at the end of the exhaust stroke, not the end of the compression. You need to rotate the crank 360deg where the TDC mark on the crank will again line up with the case split but this time #1 valve will be closed.
Remember, within the 720 crank degrees needed for the 4-strokes there are two points when the crank will indicate #1 TDC. The end of the compression and the end of the exhaust. A common mistake is that TDC on the crank pulley ONLY indicates the TDC at the end of the compression stroke. This is the case only 50% of the time.
It is up to the engine builder to ensure the distributor delivers a spark to the correct plug wire at the correct time. Without assuming anything, you need to rotate the crank until the #1 piston is at TDC (TDC mark at the top of the crank pulley lined up with the case split) AND the valves for #1 are BOTH closed. If either #1 valve is in motion near TDC it means #1 cylinder is at the end of the exhaust stroke, not compression. Rotate the crank 360deg and check again. When crank is at TDC and #1 valves are closed you are at the end of the #1 compression stroke.
Next, with the distributor properly installed and mated with the drive gear in the case, make sure the #1 plug wire is installed over the tip of the rotor. This ensures a spark is delivered to #1 when it is at the end of the compression stroke. If you find that the #1 plug wire is not installed where you believe it should be it means the drive gear under the distributor was installed incorrectly. The drive gear has 12-teeth so being installed 1-tooth off means a 30deg movement of the #1 plug wire around the cap. 6-teeth off and the #1 plug wire will be "180deg out". I think this is what had happened in your case. From your pic, I'd guess you are still 1-tooth off (30deg).
| txasylum wrote: |
| New question. How do I time it being 180 off? Do I use the same timing marks on the pulley? If so, it seems to run smoothly when TDC is at 10:00 position. If I go to TDC with it the car dies. |
Even if your distributor is 180deg out... the firing order is based on the cam lobes and is ALWAYS 1-4-3-2 in a CW rotation (1-2-3-4 in CCW direction). This means once you determine WHERE #1 plug wire needs to be installed on the distributor cap, the remaining wires are installed CW 1-4-3-2 from #1. This is because the cam controls which cylinder will be at TDC of the compression stroke next. Unless you replaced your cam with a custom cam that didn't follow the stock firing order the firing order is always the same, regardless of where the #1 plug wire is on the cap.
If you plan on switching to a distributor with a vacuum canister (SVA or SVDA) then making sure the drive gear in the case is properly installed becomes more important. The vacuum canister will interfere with the intake in some positions. So trying to rotate the distributor body to get the correct timing may be impossible without moving plug wires around the cap along with distributor rotation.
On the carb topic. The only difference between the capacity of the 30Pict and 34Pict are max flow rate. The 30Pict has a smaller diameter throttle opening which limits its max airflow ability. This means while a 34Pict can get your 1600cc engine up to around 80mph, the smaller 30Pict may only get you to 70mph before reaching max flow. Unless this is a requirement there is no real downside of running a smaller carb on your DP engine.
On the up side, a smaller carb usually means better response to throttle changes. Also, the 30Pict is easier to tune with just a throttle screw for rpm control and a volume screw to manage idle mixture.
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tasb
The Distributor Distributor
Joined: April 27, 2002
Posts: 6371
Location: Pentwater, Michigan
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| Posted: Sun Oct 27, 2019 4:17 pm Post subject: Re: New motor, won't start, backfire |
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The list I gave you is the interchange, any of those distributors will work with the 30 PICT 1. The differences between them are mostly advances in tune up part design. The 113 K(1966-67) and T(1969-70) are more common since they were used for two years while the 113 M was only used in 1968. The 113 M and T vacuum canister delivers @ 32 degrees of advance while the 113 K canister delivers just @ 25.
You read way too much into my remark on carburetors fortunately Ashman40 has done an excellent job of explaining the differences.
The part numbers I am referencing are the VW# for the German Bosch part. Both can be found on the distributor body. It is possible to R&R the vacuum canister but it should be best left to someone with experience. Not that the work is hard its a spring and a couple of screws but I often find the wrong canister on cores. At this vintage the canisters don't have any part numbers on them.
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tasb
The Distributor Distributor
Joined: April 27, 2002
Posts: 6371
Location: Pentwater, Michigan
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| Posted: Sun Oct 27, 2019 4:27 pm Post subject: Re: New motor, won't start, backfire |
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Another upside to the 30 PICT carburetors is that the quality and simplicity of the matching distributor is much better than with the 34 PICT 3. The SVA only distributors are almost bullet proof as long as your vacuum only canister is good and the distributor is regularly maintained.
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1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018
1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc
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