single 45 DCOE on a Lynx mani, about to throw in the towel!

[Harv]

18 hours ago, inquisitive said:

FWIW, the engine won't idle under 1 1/4 turns out. I also double checked that the idle lever screw is set to 1/2 a turn past initial contact. 

 

Thats interesting. I still think that's waaay to big. I think you will see big changes with your new jets. 

 

John

[inquisitive]

So I took the pump jets, main stacks, and idle jets out upon receiving an array of jets from Pierce Manifolds (awesome people BTW!). 

 

I was shocked to learn I had 75 idle jets in there!! I feel bad for the guy who tried to tune this for me, although at least the darn thing ran...

 

Here's what I pulled out: 

 

32mm venturi's 

75 idles

45 pump jets

F15 emulsion tubes

170 air correction jets

140 mains

 

Here's what I installed based on many hours of reading different combinations for single DCOE's on a Lynx mani:

 

36mm venturi's

55F8 idles

50 pump jets

F16 emulsion tubes 

180 air correction jets

145 mains

 

Now the car is almost undrivable. I got it up to temp (initially by holding it at 2k for 5 min and then bucking my way around my neighborhood!) and set the idle. The idle is very nice and steady with around 2 turns off of fully seated. When driving though, it's a complete mess. 

 

It only runs at about 1/10th throttle and completely bogs at anything beyond that. And even at 1/10th, it bucks really bad...Looks like it's time to hit the shop.  

 

FWIW I'm running a high(ish) compression motor as follows:

 

9.6:1 compression

overbored to 2100cc's

port n polished E12 head

288 cam 

MSD ignition on a mechanical advance VW "Pro Billet" distributor 

Edited June 20, 2017 by inquisitive

[zinz]

Darn it... when the engine was bucking, did it "pop" or backfire out the carburetor?

 

Where is the fuel level set? (very important on a DCOE)

 

What fuel pump are you using? If it's electric, do you know what pressure it is rated ?  Webers only want about 2, 2.5lbs psi... many electric pumps are 7-8psi and will push fuel past the needle valve seat. You can easily install a fuel pressure regulator between the pump and carb, if necessary.
 

Pull a couple of plugs and check their color/condition.  Are they wet with fuel?

 

Ed

[Harv]

Throw those 32's back in and tell us what happens. 

 

John

['76mintgrün'02]

Please tell us more about the VW distributor.

Based on the ones I have, the body is shorter on the old air cooled VW units; so this must be from a newer VW?

Have you plotted the curve?

Timing first, then fuel... so they say.

Although it is actually a bit of back and forth, to fine tune things... I believe.

(if this is a distraction, ignore me.  I will understand)

[Stevenc22]

Agreed. That's why i asked about the distributor setup on page 1. When you have bad timing, you can bad aid it with more or less fuel, doesn't mean the car will run right though.

[inquisitive]

5 hours ago, Harv said:

Throw those 32's back in and tell us what happens. 

 

John

 

Well, Top End claims my engine should run 36mm, as do most people who are running similar setups here. Hmmm.

 

7 hours ago, zinz said:

Darn it... when the engine was bucking, did it "pop" or backfire out the carburetor?

 

Where is the fuel level set? (very important on a DCOE)

 

What fuel pump are you using? If it's electric, do you know what pressure it is rated ?  Webers only want about 2, 2.5lbs psi... many electric pumps are 7-8psi and will push fuel past the needle valve seat. You can easily install a fuel pressure regulator between the pump and carb, if necessary.
 

Pull a couple of plugs and check their color/condition.  Are they wet with fuel?

 

Ed

 

No popping or backfire out of carb. 

 

Not sure what you mean by fuel level. Is this the float level? I haven't messed with that, but guessing it is whatever TEP set it at. 

 

It has a brand new aftermarket mechanical fuel pump. It's a German brand, but can't remember. Will check this evening. 

 

Def need to check the plugs. 

 

3 hours ago, '76mintgrun'02 said:

Please tell us more about the VW distributor.

Based on the ones I have, the body is shorter on the old air cooled VW units; so this must be from a newer VW?

Have you plotted the curve?

Timing first, then fuel... so they say.

Although it is actually a bit of back and forth, to fine tune things... I believe.

(if this is a distraction, ignore me.  I will understand)

 

I just reached out to the PO, since I am not sure exactly what distributor this is. I have paperwork for it stating it's a VW Pro Billet distributor from White Performance. Looks identical to this one. I do have a stock M10 "points" distributor in a box though. Maybe I can give that one a shot? 

 

EDIT: The PO just informed me this is the distributor in my car: 

 

Also noted "It has adjustable mechanical advance via different springs, it was set with the lightest springs for fastest advance curve."

Edited June 20, 2017 by inquisitive

['76mintgrün'02]

Identical, except for the drive gear and length of the housing/shaft.  

 

I know of a car that has a modified MSD distributor from a Ford application.  The owner machined the shaft a bit to fit; but have not heard of VW units being used.  

 

The 123 distributors have a tall-necked gear attached at the bottom, to make up for a shorter housing.  I have wondered if they used the VW length housing and 'lengthened it' using that gear.  Maybe you will see something similar, when you pull it out.

 

In any case, I'd look into what you currently have, in terms of timing.  If you do not have a timing light with variable advance, I would suggest the Innova 5568.  It will allow you to set the all in advance and even plot the advance curve, with it on the engine.  They can be bought for $100 online, including shipping.  Money well spent, imho.

 

Which stock distributor do you have?  (if you'd care to share).

Tom

[Harv]

 That bog that you're experiencing is either one of two things. It's either the carb going lean, or the carb going way rich. The smaller the Venturi, the more fuel is sucked through the main jet sooner. The larger the Venturi, the later the sucking will happen. 

 

John

[Stevenc22]

^ nice explanation of the venturi

[Harv]

Please try the 32's again. You should not need to touch anything else on the carb. This is an easy way to confirm they are not the way to go. That 288 cam is pretty mello and the 32's might be the way to go. Only one way to find out. Asking around will get you some info, trying it yourself will not only confirm what you (and us) think but will teach you in the process. I've been around these carbs for years but I'm still learning every time I change something. I've learned more by experimenting with the webbers on my 1600cc Porsche 912 than I could have ever gotten from asking advise. And trust me, I asked. 

 

Try those 32's and see what happens. Maybe nothing?

 

john

[chargin]

I looked at this at one time thinking it would be cool, a lot of people told me to go 38/38 downdraft instead.

 

It looks like a lot of towels were thrown in over this system 

[inquisitive]

16 hours ago, Harv said:

Please try the 32's again. You should not need to touch anything else on the carb. This is an easy way to confirm they are not the way to go. That 288 cam is pretty mello and the 32's might be the way to go. Only one way to find out. Asking around will get you some info, trying it yourself will not only confirm what you (and us) think but will teach you in the process. I've been around these carbs for years but I'm still learning every time I change something. I've learned more by experimenting with the webbers on my 1600cc Porsche 912 than I could have ever gotten from asking advise. And trust me, I asked. 

 

Try those 32's and see what happens. Maybe nothing?

 

john

 

Put the 32's back in and it made almost no difference. I was able to get a tiny bit more throttle in before it completely bogs. 

 

I upped the idle jets to 60's and it helped a bit more. I then changed the mains to 150's (from 145) and it made no discernable difference. 

 

So still running like absolute garbage. Bogs completely and shuts off if I keep it at WOT for more than 3 seconds. I have yet to check the float level. Maybe that's a likely culprit? 

 

FWIW, it idles beautifully.

Edited June 22, 2017 by inquisitive

[Stevenc22]

Well at this point you need to either get that AF gauge or dump the setup for a simple 32/36..

 

Where are you located by the way?

[Harv]

11 hours ago, inquisitive said:

 

Put the 32's back in and it made almost no difference. I was able to get a tiny bit more throttle in before it completely bogs. 

FWIW, it idles beautifully.

 

Ahh! The thick plottens! I think you are too rich on those mains. Do you have smaller (or bigger) mains hanging around?

 

The fact that there was an improvement is big!

 

john