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Ken
Samba Member
Joined: November 14, 2005
Posts: 129
Location: Spokane, WA.
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 Posted: Fri May 10, 2019 6:56 pm Post subject: Edited title.....Spitting, sputtering, popping & low to no power |
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*** I edited the title, since I have learned the effects of the 1 & 3 cylinders with their non to limited firing at idle.
New rebuild, 1600, the "builder" put in a NEW crank, pistons, cylinders, heads, rocker arms/shafts, pretty much everything was put in new, case was align bored, etc. During the "build" the shop cracked the case doing a full flow conversion, and did not fix it correctly, not happy about that and will be going to small claims court after I have someone weld it up and bills me for the repair, so needless to say there is no repor for me going back to the builder for them to get this running right.
Anyways, it's in a dunebuggy, it has a Weber "copy", a tall intake, and all the normal,things were done, checked and rechecked...
Compression test, 76psi in 3 cyls., 73psi in 1,
I suspect the low psi to being rebuilt and rings not fully seated (o miles on this motor, just 20 minutes of 2000rpm run in time by the shop).
TDC set for #1 cyl and rechecked
Firing order 1 4 3 2, checked and rechecked
Carb adjustments per specs, 1/2 turn from touching on idle speed screw
1 turn from seated on mixture screws
Air bypass closed
Pertronix ignition with matching coil
All 4 plugs have spark I have rechecked this more than a couple of times, and I have switched plugs around, along with wires.
Set and rechecked timing, static and with a light
When the motor is running I can pull the wires off #1 & #3 plugs and no change in idle, pulling #2 & #4 kill the motor.
The valves have been checked and rechecked
Checked for vacuum leaks by spraying starting fluid all around rubber intake seals, and intake at head.
Even if it were debri or something wrong with the copy carb, cylinders 2 & 4 are receiving fuel and firing.
Fuel pump is pumping fuel fine, although I don't have a pressure gauge for checking that.
Has equal length header with a stinger on it
I'm stumped,
backfires and spits (which I realize is usually lack of fuel) but the 2 & 4 are firing fine, seems like it's not getting fuel to cylinders 1 & 3 but fuel is obviously getting to the stock factory manifold inlets???
I have fuel, air, and spark, but somehow that mixture is not getting into cylinders 1 & 3.
I have physically pulled off the intake manifolds and watched the intake valves move off and back onto the seats and made sure there were no obstructions and resealed them with new gaskets. The valves are moving as I first suspected a flat cam, and pulled the valve covers to actually see the rocker arms moving.
If there's already a thread covering this, lead me to it and I'll delete this one, but I've spent lots of time searching every combo I could think of but didn't come up with this particular scenario!?!?
Last edited by Ken on Sat May 11, 2019 8:54 pm; edited 3 times in total |
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modok
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Joined: October 30, 2009
Posts: 27754
Location: Colorado Springs
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Ken
Samba Member
Joined: November 14, 2005
Posts: 129
Location: Spokane, WA.
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| Posted: Fri May 10, 2019 8:58 pm Post subject: Re: Cylinders 1 and 3 not firing. |
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| Well shit, guess I didn’t look hard enough!!! It’s running just like that, although i have a single 2 bbl. I’ll peruse thru those other posts too, thanks fo the heads up. Kinda sounds like that “recursion” that Dale M. mentioned?!?! As well as what [email protected] mentioned, but again a different carb situation. And after reading the first post, I'm kinda inclined to say it's not getting enough fuel because of the "lean popping", upon acceleration instead of cylinders 1&3 being non functional at idle |
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Kauai/5
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Joined: August 16, 2016
Posts: 76
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| Posted: Fri May 10, 2019 10:16 pm Post subject: Re: Cylinders 1 and 3 not firing. |
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First off, are 1&3 not firing at all or only when idling? If you give it some gas do they start firing?
If not firing at all, are you sure you set your valves correctly by rotating the crankshaft properly while moving from cylinder to cylinder?
When doing the compression test, are you holding the throttle wide open?
Did you properly gap your plugs? And are you sure you are getting strong spark? A plug will spark easily when outside a cylinder not asked to work under compression. Ground the plug out and turn off the lights and make sure you have a good strong concentrated and not scattered spark.
Lastly, a timing light works as a great troubleshooting tool. Put it on the 1 & 3 wires and make sure you are getting a steady spark when cranking over and running and that there is no interruption or hiccup in the pattern.. Also, pull 1 & 3 plugs and look/smell for gas. |
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modok
Samba Member
Joined: October 30, 2009
Posts: 27754
Location: Colorado Springs
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| Posted: Fri May 10, 2019 10:27 pm Post subject: Re: Cylinders 1 and 3 not firing. |
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No problem. Only way I can even find it with the search is... I put my own keywords in the threads!
The idle behavior tends to be better or worse depending on the cam.
Engle 110 seems to be the worst idle, but hit the gas it comes alive.
Some folks will tell you the single IDf is no good, use something else.... but they can work very well when all is right.
I'd say....single IDF on a VW,,,is like adopting a kid with Asperger syndrome. It IS a good idea, but, some adjustment required.
Doesn't just automatically work out of the box.
God that's terrible analogy, but, First thing that came to mind |
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busdaddy
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Joined: February 12, 2004
Posts: 53210
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Fri May 10, 2019 10:37 pm Post subject: Re: Cylinders 1 and 3 not firing. |
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| modok wrote: |
No problem. Only way I can even find it with the search is... I put my own keywords in the threads!
The idle behavior tends to be better or worse depending on the cam.
Engle 110 seems to be the worst idle, but hit the gas it comes alive.
Some folks will tell you the single IDf is no good, use something else.... but they can work very well when all is right.
I'd say....single IDF on a VW,,,is like adopting a kid with Asperger syndrome. It IS a good idea, but, some adjustment required.
Doesn't just automatically work out of the box.
God that's terrible analogy, but, First thing that came to mind |
Having raised a son with Aspergers and dealt with a few single IDF's and 110's I'd say you are right on the money. It'll never behave the way everyone expects, but it'll get it done in it's own strange way if you invest the time and learn to deal with it's oddities. 
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modok
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Joined: October 30, 2009
Posts: 27754
Location: Colorado Springs
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| Posted: Fri May 10, 2019 11:42 pm Post subject: Re: Cylinders 1 and 3 not firing. |
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Thanks for not being offended.
Thank goodness he doesn't have a progressive.
by the same ;ogic, the progressive would be..... "developmentally disabled" |
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Vanillagurilla
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Joined: November 21, 2017
Posts: 1061
Location: California
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| Posted: Sat May 11, 2019 12:37 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| Could be the idle jet or fuel mixture screw on that side of the carb. Did you clean the carb before you installed it? Does the running issue change after it warms up? I have a 110 and dual 40s and when cold it will cough and idle around 500rpm but when warm it runs great and idles at 1000 rpm, I can only imagine a single being a bit worse lol. |
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Slow 1200
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Joined: July 02, 2004
Posts: 2132
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| Posted: Sat May 11, 2019 2:11 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| with new heads and those compression numbers i wonder if they just bolted some heads with big chambers without flycutting to get decent cr in a 1600 |
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FreeBug
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Joined: March 12, 2012
Posts: 4277
Location: deepest, darkest Switzerland
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| Posted: Sat May 11, 2019 3:11 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| What's the cam? The lopiness and non-firing of those cylinders is largely because of the cam. I say this because engines with stock cams do not have this problem with twin carbs. |
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FreeBug
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Posts: 4277
Location: deepest, darkest Switzerland
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| Posted: Sat May 11, 2019 3:13 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| modok wrote: |
Thanks for not being offended.
Thank goodness he doesn't have a progressive.
by the same ;ogic, the progressive would be..... "developmentally disabled" |
The proggy is physically challenged, too. |
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oprn
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Joined: November 13, 2016
Posts: 15235
Location: Western Canada
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| Posted: Sat May 11, 2019 3:42 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| A picture of the carb and intake would clear up a lot of misunderstanding here. |
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Alstrup
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Joined: July 12, 2007
Posts: 7954
Location: Videbaek Denmark
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| Posted: Sat May 11, 2019 3:57 am Post subject: Re: Cylinders 1 and 3 not firing. |
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Did´nt the original "builder" give you a specs card telling what´s inside?
It does sound very much like the scenario Modok lines up. If he is correct that IS a challenge with limited carburetion. |
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Ken
Samba Member
Joined: November 14, 2005
Posts: 129
Location: Spokane, WA.
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| Posted: Sat May 11, 2019 4:36 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| oprn wrote: |
| A picture of the carb and intake would clear up a lot of misunderstanding here. |
Here is the carb/intake style. |
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Ken
Samba Member
Joined: November 14, 2005
Posts: 129
Location: Spokane, WA.
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| Posted: Sat May 11, 2019 4:52 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| Alstrup wrote: |
Did´nt the original "builder" give you a specs card telling what´s inside?
It does sound very much like the scenario Modok lines up. If he is correct that IS a challenge with limited carburetion. |
No he gave me nothing, this was supposed to be a relatively cost effective overhaul, and with my limited knowledge of VW engines, and him at the time a “friend”, I left it in his hands. I wasn’t planning on spending the money on a whole lot of brand new parts (crank, heads, flywheel) I was expecting remachining, turning, surfacing, etc., and rebuilding, but months later, a damaged case and a pending smal claims court date, we’re no longer in communication so I’m unable to get any specifications from him. This is actually my daughters DuneBuggy we built together after she went thru Cancer treatments, (if any interest the build up is in the DuneBuggy forums) so dealing with this issue back then wasn’t a priority as much as her health was, not posting that for sympathy as she’s in remission and doing pretty good, just figured someone may be interested in seeing the younger generation involved in our hobby as well? |
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Ken
Samba Member
Joined: November 14, 2005
Posts: 129
Location: Spokane, WA.
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| Posted: Sat May 11, 2019 4:59 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| Slow 1200 wrote: |
| with new heads and those compression numbers i wonder if they just bolted some heads with big chambers without flycutting to get decent cr in a 1600 |
I highly doubt there was any flycutting!! They are new EMPI heads bolted onto new 1600 jugs and pistons. I was surprised that I spent a fair amount of money with him and he kept it a 1600, not a larger displacement. |
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Ken
Samba Member
Joined: November 14, 2005
Posts: 129
Location: Spokane, WA.
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| Posted: Sat May 11, 2019 5:00 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| FreeBug wrote: |
| What's the cam? The lopiness and non-firing of those cylinders is largely because of the cam. I say this because engines with stock cams do not have this problem with twin carbs. |
Engle 110 |
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Ken
Samba Member
Joined: November 14, 2005
Posts: 129
Location: Spokane, WA.
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| Posted: Sat May 11, 2019 5:08 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| Vanillagurilla wrote: |
| Could be the idle jet or fuel mixture screw on that side of the carb. Did you clean the carb before you installed it? Does the running issue change after it warms up? I have a 110 and dual 40s and when cold it will cough and idle around 500rpm but when warm it runs great and idles at 1000 rpm, I can only imagine a single being a bit worse lol. |
My next step will be to clean the carb, again. I was stumped and frustrated, couldn’t figure it out, so relented and started asking for help here. Spits and sputters all throughout the throttle range, doesn’t get any better after warming up. |
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mcmscott
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Joined: March 12, 2010
Posts: 4946
Location: sanger ca
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| Posted: Sat May 11, 2019 8:24 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| Ken wrote: |
| FreeBug wrote: |
| What's the cam? The lopiness and non-firing of those cylinders is largely because of the cam. I say this because engines with stock cams do not have this problem with twin carbs. |
Engle 110 |
And there you go, that cam does not play well with a single carb, also bleeds off cylinder pressure so the static compression needs to be set higher, this explains the low compression numbers. Simply put, a very bad combination.
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Ken
Samba Member
Joined: November 14, 2005
Posts: 129
Location: Spokane, WA.
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| Posted: Sat May 11, 2019 11:14 am Post subject: Re: Cylinders 1 and 3 not firing. |
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| mcmscott wrote: |
| Simply put, a very bad combination. |
That figures, i run a Flathead in my Model A, and a Y-Block in our Roadster and i can tune them fairly well by ear. I trust a “simple” flat four to someone and I get screwed. |
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