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1776 Build w/ single Solex carb - help needed
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StefansBus
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PostPosted: Thu Mar 22, 2018 1:30 am    Post subject: 1776 Build w/ single Solex carb - help needed Reply with quote

Dear Friends,

Following on from my question regarding using a stock exhaust on a 1776 or larger (the consensus was that this is not a good idea) I now have a question regarding the overall concept.

Here is what I know I want:

A simple, stock-ish looking 1776 (90.5 forged Mahle P&C) with good torque for my bay window bus. Not a screamer. I don't want dual carbs for this one. Instead I want to run a single Solex 34 PICT 3 carb possibly enlarged to 37 or 39 mm.

This exhaust: https://www.ahnendorp.com/VW-Kaefer-Typ-1-Motorent...anguage=de

Here is what I currently have:

An almost new aluminum HD (autolinea) case (4000 miles on it)
an otherwise stock 1600 single port engine with a 30 PICT 2 except that I have an external oil cooler and filter routed from an adaptor were the stock oil cooler used to be (not full flow), a Pertronix module in the stock SVSA dizzy.

What I think I need as a minimum:

90.5 P&C
200 mm flywheel and clutch (currently has 180mm)
A 34 or larger Solex PICT carb (rejected)
High flow intake manifold center piece. Aluminum intake end pieces SP or DP depending on route taken.

My main questions are:

Stay single port, keeping my good SP heads with 35/32 valves?

Or should I really go DP with the above set-up in mind? What will be the difference in performance for a mild single carb 1776 such as this?

Cam? Stock? If not, which one? Quality and longevity are important to me.

I'm pretty sure the valve sizes will be stock (35/32) for good port velocity at low and mid RPMs.

I will try to run a Bosch SVDA if possible. This may be difficult if the vacuum signal is changed too much by the bigger displacement and/or the possibly enlarged carb. Opinions?

In short: Do I stay single port, possibly with just a 34 PICT on an aftermarket three piece intake?

Or do I go DP (new heads stock valve sizes) and go up in carb size to 37 or 39 (a couple of companies do these conversions here in Germany)? Or a combination of the two (single port but larger carb)?

Heat exchanges will probably be stock which I think should be ok with stock exhaust valve size and the exhaust will be an equal lengths stainless steel with O2 sensor as per the link above.

Any suggestions and opinions will be much appreciated. Anything I have forgotten?

Have great day

Stefan


Last edited by StefansBus on Thu Mar 22, 2018 6:41 am; edited 1 time in total
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Paul.H
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PostPosted: Thu Mar 22, 2018 2:26 am    Post subject: Re: 1776 single Solex carb - help needed Reply with quote

The stock exhaust will be just fine
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StefansBus
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PostPosted: Thu Mar 22, 2018 3:24 am    Post subject: Re: 1776 single Solex carb - help needed Reply with quote

Thanks Paul,

I am sure a stock exhaust can work but I am also quite sure the heads would run hotter and I would lose out on power and torque.

The one I have linked to above one a comparison test in a German VW magazine. https://www.ahnendorp.com/info/Pressemitteilungen.html The results are quite stunning. They used an 1835 with dual Weber 40 IDF, a 308 degree Schleicher cam, 9:1 CR and heads with 39/35 valves. Not as mild as my project but not a wild screamer either.

With the stock Leistritz exhaust the engine produced 77hp at 4400 rpm and 132NM torque at 3100 rpm.

With the Ahnendorp exhaust it made 98hp at 5000 rpm and 163NM at 3000.

I am sure with a milder engine the difference will be less pronounced but I would very much expect it to still be significant.

However, I wouldn't want this to turn into just another exhaust discussion.

Any thoughts on the overall concept (SP vs. DP, 34 vs 37 or 39 Solex etc)?

Cheers

Stefan
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Paul.H
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PostPosted: Sat Mar 24, 2018 2:15 am    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

I just looked at the exhaust and at 999euro I'd be fitting something else Laughing
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Alstrup
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PostPosted: Sat Mar 24, 2018 5:40 am    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Yeah, and loose 7-10% torque and get a much noisier exhaust, right.
For the segment this is a very good exhaust.

T
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Zed999
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PostPosted: Sat Mar 24, 2018 7:44 am    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Which segment is that though? A segment that doesn't include a mild torque focussed small engine in a bus would be my guess?

I have the type-4 equivalent of a mild 1776 in my bus. Stock everything but the carbs works for me. Stock distributor, stock heat exchangers, stock muffler, stock cam, stock oil pump. My engine has always attracted advice (not asked for but appreciated nevertheless) on making it produce more power and torque, but that power would be at the expense of low end torque. For cars it's different but for a bus there's no replacement for displacement. The more hp you try and eek out of your 1776ccs beyond simple head and porting the less of a bus engine it will become.

If you fit a "better" cam then unless you also fit a better exhaust and twin carbs you will have wasted your cam money. There are plenty bus 1776's running with stock everything including the single carb with it's original jetting. The numbers from the rolling road won't impress anyone but the engine will retain it's characteristics, it's a pretty small increase in capacity.
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Paul.H
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PostPosted: Sun Mar 25, 2018 1:09 am    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Alstrup wrote:
Yeah, and loose 7-10% torque and get a much noisier exhaust, right.
For the segment this is a very good exhaust.

T


No
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JaredJ
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PostPosted: Fri Apr 20, 2018 5:26 am    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Why did you reject the Solex 34 pict 3 carb?
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calebmelvin
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PostPosted: Thu Aug 09, 2018 9:13 pm    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

JaredJ wrote:
Why did you reject the Solex 34 pict 3 carb?


I was wondering the same thing. What ever happened here?
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StefansBus
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PostPosted: Thu Aug 09, 2018 11:18 pm    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

auto-text happened.

re-jetted is what I had meant to write
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calebmelvin
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PostPosted: Sat Aug 11, 2018 12:17 pm    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

StefansBus wrote:
auto-text happened.

re-jetted is what I had meant to write


Laughing
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StefansBus
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PostPosted: Mon Feb 25, 2019 5:06 am    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Image may have been reduced in size. Click image to view fullscreen.


My new 1776 dual port, single 34 PICT-3, 28mm venturi, CB2239 cam, 1.25 rockers on intakes, CB center section, AA500 heads by Torben Alstrup, Ahnendorp exhaust.

79hp at 4500 RPM, 143NM at 2500 RPM. Nice flat curves. Still a bit rich.

Red curve is without the stock oil bath air cleaner. Much better air/fuel ratio.
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Brian_e
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PostPosted: Mon Feb 25, 2019 10:15 am    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Applause Well done!. What all did Torben do the the heads, and what was the compression?

Nice engine.

Brian
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Alstrup
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PostPosted: Mon Feb 25, 2019 11:04 am    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Yes. 8,9 I think they ended at. There is more in it once I get the last details with ignition sorted out and leaned it out a bit. - Actually a lot, plus a free flow filter in the stock canister. So there are still a few things to work with.

T
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StefansBus
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PostPosted: Mon Feb 25, 2019 11:39 am    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Yes, 8.9:1 CR is correct.

Torben built the heads "from scratch". He ported them, installed stock sized valves valves (3 angle valve job), HD springs, etc. He also match ported the intake manifold end pieces. I wasn't there and he may correct me but that's the bits I seem to remember.

He pretty much designed the whole engine for me and a local builder assembled the engine. If it's not perfect, it's not because of Torben. That's for sure. Because he is a perfectionist.

Also, the curves I posted is pretty much how it ran without any fine tuning. Just the set-up Torben recommended with the jetting on the rich side of his recommendations as I don't have an A/F sensor/display. So it wasn't a surprise that it runs rich but it's always better to approach optimum A/F ratio from the rich side. I'm not really concerned with getting the last few horses out of it but jetting it correctly will make it more fuel efficient so that's one good reason to do it.

Stefan
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Frank Bassman
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PostPosted: Mon Feb 25, 2019 12:25 pm    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Stefan, what kind of fuel economy are you expecting or observing with or from your motor, if you don't mind my asking?

-Frank
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StefansBus
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PostPosted: Mon Feb 25, 2019 12:46 pm    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Frank,

I don't have any numbers yet and I'm not sure what to expect. Right now it's running quite rich so fuel economy won't be good.

But it's also in a bay window bus so I'm not expecting miracles. My guess right now is 18-20 mpg when it's running a bit closer to optimum AFR. In a smaller and lighter vehicle like a beetle it should be quite a bit better.

Maybe Torben will be along to tell us what's a realistic number for this engine in a bus.

Stefan
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chrisflstf
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PostPosted: Mon Feb 25, 2019 7:09 pm    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Building a very same motor, only with CB2280 cam. same 1.25 rockers on the intake. Hoping for 80 plus HP. Would be interesting to see Alstrups ideas for ignition and exhaust optimization
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StefansBus
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PostPosted: Tue Feb 26, 2019 12:22 am    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

chrisflstf wrote:
Building a very same motor, only with CB2280 cam. same 1.25 rockers on the intake. Hoping for 80 plus HP. Would be interesting to see Alstrups ideas for ignition and exhaust optimization


There is nothing to improve on the exhaust side for me, I think. I also don't think Torben (Alstrup) said that. He will help me get some better ignition wires for a stronger spark and help me get the AFR just right. That's where the remaining few hp and ft/lbs are. Oh, and a better flowing air cleaner.

80hp may be achievable with the 2280 cam in a 1776 with a single 34 carb but probably not more. The 2280 is a little bit tamer than the 2239. It makes torque a bit earlier and makes a tiny bit less top end. I don't think it can quite handle the compression I run, which is why I have the 2239. You would be limited to around 8.5 to 8.7 with the 2280 using premium fuel. A tight eck will be important, too.

Think about it this way: 80 hp out of a 1776 means you only increase stock displacement by 12% but make 60% more power using a single 34 carb. That's pretty amazing, I think. Having said that, you will want that 28mm venturi in your carb. And an exhaust with equal length tubes and not too restrictive. Basically everything will have to be pretty much spot on and details matter. That's why Torben is so good.

I'm using a 123 tune ignition with vacuum advice and it works well.

Let us know how it all works out.

Stefan
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StefansBus
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PostPosted: Sat Jun 22, 2019 2:08 pm    Post subject: Re: 1776 Build w/ single Solex carb - help needed Reply with quote

Frank Bassman wrote:
Stefan, what kind of fuel economy are you expecting or observing with or from your motor, if you don't mind my asking?

-Frank


Back form a long trip from Germany to Croatia and back at crusing speeds of mostly around 65 and up to 75 mph and I averaged just under 20 mpg, so about what I expected.

Stefan
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