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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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 Posted: Wed Jun 12, 2019 6:28 am Post subject: No power at low rpm under load |
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So I finally got my bug driving on the road but it has an issue. When I take off, it is slow to build up rpm but once it reaches a certain rpm, it will accelerate like I think it should. When I shift into a higher gear and get back in it, it does the same thing to a lesser degree. It will crank and idle fine and I can actually go down the road at 55/60 and get up to speed...eventually. It free revs pretty decent but is still a little rough. Timing is 10 at idle, 31 or 32 at full advance. I dont know when it advances because I have no tach. I have synchronized the carbs and they are set at stock idle mixture screw setting(2 turns out). Is it time for me to start messing with jetting? Let me know if you need/want any other information about the car.
Engine specs:
1600 DP
dual empi 34 epc's
aftermarket 009 distributor
Engle 110 cam
Header and dual quiet packs
Im getting minimal response on my build thread so thats why im posting here. |
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hobbybob517
Samba Member
Joined: June 02, 2011
Posts: 1194
Location: Netherlands
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| Posted: Wed Jun 12, 2019 6:43 am Post subject: Re: No power at low rpm under load |
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Post your jetting,
might be lean (or very rich) till the mains kick in
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THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
| SBD wrote: |
3 million rpm? Well there's your problem! No wonder it blew up! |
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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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| Posted: Wed Jun 12, 2019 7:15 am Post subject: Re: No power at low rpm under load |
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They are the stock jets that came in the carbs. I am at 650 ft elevation. From my internet searches, these settings come up for stock empi 34 epc's:
1.75 needle/seat
.130 main
.55 idle
.160 air correction jet |
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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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| Posted: Wed Jun 12, 2019 7:50 am Post subject: Re: No power at low rpm under load |
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The jetting could most definitely be off. I messed with the idle air mix yesterday and with it at 2-1/2 turns out, it loaded up and puffed black smoke so i put it back to 2. Tried it at 1-1/2 and it didnt seem as happy but it wasnt much different than 2.
I will turn my idle speed screw in to 1-1/2 out and tune for the idle mix when I get home today as I dont think I did it initially. I cant remember if it wouldnt run at that idle speed setting or if i just didnt follow instructions. I just figured I could tweak it after I got the car on the road but maybe not. Maybe you can see the source of my confusion in the first paragraph. Either way, the "slow-to-rev-under-load" spot stayed pretty much the same throughout my experiments.
Figured that may be useful info. |
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KTPhil 
Samba Member
Joined: April 06, 2006
Posts: 33986
Location: Conejo Valley, CA
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| Posted: Wed Jun 12, 2019 8:40 am Post subject: Re: No power at low rpm under load |
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| The aftermarket 009 isn't doing you any favors here, either. |
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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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| Posted: Wed Jun 12, 2019 8:54 am Post subject: Re: No power at low rpm under load |
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| KTPhil wrote: |
| The aftermarket 009 isn't doing you any favors here, either. |
I purchased about 8 years ago when I was still in college/working and had never even been in a vw of any kind so I will plead initial ignorance on that purchase as I thought it would be an upgrade at the time lol.
I am going to put my vac advance distributor in tonight to see if that clears up the issue. Its free to try and I prefer vacuum advance for street cars anyways. What could be messing up in the distributor to be making this happen though? Something internally doesnt allow it to advance early enough?
Id like to add that it runs worse at the lower throttle positions, sometimes sounding like its misfiring |
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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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| Posted: Wed Jun 12, 2019 1:54 pm Post subject: Re: No power at low rpm under load |
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| HELP! lol I will be working on this thing within the hour so if ya got any more suggestions, id love to hear them. Ill try to keep updated with findings via my phone. Would a video of it running help? Ill try to get one of me pulling away which is where the problem lies. |
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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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| Posted: Wed Jun 12, 2019 7:11 pm Post subject: Re: No power at low rpm under load |
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These are my exhaust temps at each exhaust port. Gonna post a video of how it's running. It ran out of gas a few run minutes afterwards so I can't say that it wasn't running out of fuel or not, on said video.
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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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| Posted: Thu Jun 13, 2019 7:32 am Post subject: Re: No power at low rpm under load |
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?Anyone? Do I need more info or is everyone else just as clueless as me?
Is the cam too big?
Could emulsion tubes be part of the issue?
Fuckingstumped  :2gunfire:  |
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hobbybob517
Samba Member
Joined: June 02, 2011
Posts: 1194
Location: Netherlands
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| Posted: Thu Jun 13, 2019 7:35 am Post subject: Re: No power at low rpm under load |
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Cam should be OK for dual carbs,
Do you have a way of checking the advance of that dist? (timing light)
_________________
THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
| SBD wrote: |
3 million rpm? Well there's your problem! No wonder it blew up! |
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hobbybob517
Samba Member
Joined: June 02, 2011
Posts: 1194
Location: Netherlands
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| Posted: Thu Jun 13, 2019 7:36 am Post subject: Re: No power at low rpm under load |
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How much psi is that fuel pump putting out?
Did you set the float height on the carbs?
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THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
| SBD wrote: |
3 million rpm? Well there's your problem! No wonder it blew up! |
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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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| Posted: Thu Jun 13, 2019 9:06 am Post subject: Re: No power at low rpm under load |
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| hobbybob517 wrote: |
How much psi is that fuel pump putting out?
Did you set the float height on the carbs? |
Timing is around 10 at idle and 31 at max advance. Checked with a timing light.
Set the floats last night to 4mm and 12mm since they have the plastic floats.
I dont know the actual pressure but the temporary mr gasket FPR is set at 3.5. Not gonna use a unit because I dont know if it is even accurate. When I go lower than that, it seems that it starts to run the bowls dry.
I am planning on pulling all the jets out and blowing all the orifices out tonight, as well as adding a balance tube between the manifolds. I didnt take the jets out to clean them before i put them in. I just blew through the jets with air because I was anxious to get them on the car(dumb i know). |
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hobbybob517
Samba Member
Joined: June 02, 2011
Posts: 1194
Location: Netherlands
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| Posted: Thu Jun 13, 2019 9:27 am Post subject: Re: No power at low rpm under load |
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Fuel pressure should be 2 - 2.5 psi
Floats should be 6.5 - 7 mm
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THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
| SBD wrote: |
3 million rpm? Well there's your problem! No wonder it blew up! |
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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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| Posted: Thu Jun 13, 2019 9:38 am Post subject: Re: No power at low rpm under load |
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| hobbybob517 wrote: |
Fuel pressure should be 2 - 2.5 psi
Floats should be 6.5 - 7 mm |
For float settings I used the link below. There is a misprint but I read between the lines....Or numbers lol.
https://www.piercemanifolds.com/v/vspfiles/templates/34/pdfs/Float_Level_3.pdf
I was planning on putting a gauge on it to rule this out as well. However I know when I turn the pressure down, it runs worse, and with the pressure up, it runs worse. |
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hobbybob517
Samba Member
Joined: June 02, 2011
Posts: 1194
Location: Netherlands
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| Posted: Thu Jun 13, 2019 9:42 am Post subject: Re: No power at low rpm under load |
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| Quote: |
I was planning on putting a gauge on it to rule this out as well. However I know when I turn the pressure down, it runs worse, and with the pressure up, it runs worse. |
If you st your floats, you will need less fuel pressure [/quote]
_________________
THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
| SBD wrote: |
3 million rpm? Well there's your problem! No wonder it blew up! |
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dubsteez79
Samba Member
Joined: November 22, 2017
Posts: 194
Location: star nc
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| Posted: Thu Jun 13, 2019 10:01 am Post subject: Re: No power at low rpm under load |
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| hobbybob517 wrote: |
| Quote: |
I was planning on putting a gauge on it to rule this out as well. However I know when I turn the pressure down, it runs worse, and with the pressure up, it runs worse. |
If you st your floats, you will need less fuel pressure |
[/quote]
They are set higher than you suggested, therefore there is more fuel in the bowl before it cuts off. So technically I would need less fuel pressure as they are, compared to setting them at 6.5mm. Plus I have no idea how accurate the marks on the FPR are. Need to put a gauge inline to check that.
My issue seems more like its leaning out when it has no power as opposed to being too rich. There is no black smoke from the exhaust ever, and im not fouling the plugs. |
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hobbybob517
Samba Member
Joined: June 02, 2011
Posts: 1194
Location: Netherlands
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| Posted: Thu Jun 13, 2019 10:17 am Post subject: Re: No power at low rpm under load |
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You could try some bigger idle jets,
Have you ever seen color tune? I've used it on older motorbikes before,
They are usually jetted lean for emmissions
It let's you see the burn in the cylinder at idle.
Not as good as a wideband, but it is a lot cheaper.
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THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
| SBD wrote: |
3 million rpm? Well there's your problem! No wonder it blew up! |
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mcmscott
Samba Member
Joined: March 12, 2010
Posts: 4856
Location: sanger ca
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| Posted: Thu Jun 13, 2019 10:32 am Post subject: Re: No power at low rpm under load |
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Those carbs do not play well with that cam. This is also why your exhaust temps are all over the place. It is "2 stroking" 1 cyl on each side fighting with the other cyl. As the rpm comes up under load the air speed increases and the other 2 cyl start working. This is why it is lazy at lower rpm.
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[email protected]
Samba Member
Joined: August 15, 2002
Posts: 4394
Location: Brew City
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| Posted: Thu Jun 13, 2019 10:51 am Post subject: Re: No power at low rpm under load |
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| mcmscott wrote: |
| Those carbs do not play well with that cam. This is also why your exhaust temps are all over the place. It is "2 stroking" 1 cyl on each side fighting with the other cyl. As the rpm comes up under load the air speed increases and the other 2 cyl start working. This is why it is lazy at lower rpm. |
I 100% agree with this. That 110 is going to make tuning those carbs a complete pain in the ass. You would need weber dual 40IDF's with that cam choice.
It also depends on your heads as well. If you just have some stock valved, rebuilt heads on there, that isn't helping. You could run a stock cam, W90 or W100 and be just fine.
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