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Posted by: trekkor Aug 20 2004, 10:38 PM

I'll be rebuilding the carbs on my SIX next week.

I wonder if I should do internal baffling while they're open.
What are the benefits to this mod? Perry, Gint, JP, Brad, Lawrence, Sean, Root?

Any other advice ( besides keeping the four ) would be appreciated.

KT

Posted by: McMark Aug 20 2004, 10:51 PM

Yes, you should, it's easy and fairly quick. You also get to do some "custom metal work".

I have the cutting burr you need to get into the tight places.

Posted by: trekkor Aug 20 2004, 10:54 PM

Soooo....tell all.

KT

Posted by: J P Stein Aug 20 2004, 10:56 PM

I've never had the need for the baffle mod (this is a rerun). I would do it if I ever get starvation problems, not likely at AX....maybe I ain't pullin' enuff G's. I'll work on that.

Good things to do:

Anti-precolation mod.
The thick insulators under the manifolds.
PMO can fix you up....may as well get the rebuild kits there while your at it.
Tall secondary venturi....Helps the mid range torque, I'm told. Mine have em'. Dunno if they do any good, but they look cool
You'll want a Syncrometer & float gauge.

Learn the Weber dance

Pay somebody that has their shit together to show you how, if necessary.

Posted by: ! Aug 20 2004, 10:56 PM

THROTTLE SHAFTS...HOW ARE THEY?

Posted by: Eric_Shea Aug 20 2004, 10:59 PM

with JP

Posted by: McMark Aug 21 2004, 12:27 AM

I'm worried about the throttle shafts as well. I'll show you the baffle when you've got it apart and you can decide. It's a picture. thing. I think there was a thread about it awhile ago. I'll search for it.

http://www.914world.com/bbs2/index.php?act=ST&f=2&t=10525&hl=weber,and,epoxy

Posted by: ArtechnikA Aug 21 2004, 06:42 AM

you've got a SIX now, you need to go buy more books...

JP's pretty much got the list; i never saw the need for the baffles either, and he's lots faster than i ever thought of being. maybe that's the key - finish the course before the float bowls run dry!

anyway - in '911 Performance Handbook' they show removing an 'anti-sediment' boss at the bottom of the float bowl that also helps with pickup issues. the percolation mod is important nowadays.

i definitely agree on the 906 preatomisers.

i ran a set of slightly larger venturiis, jets, and emulsions on my car - some day i'm gonna hafta open it up and see what 'the kit' consists of really ...

Posted by: Gint Aug 21 2004, 08:50 AM

with all of the above. 'Specially JP. Mine WILL be going to Erometrix for a full rebuild and throttle shaft rebush. My shafts (housings anyway) are shot. I have the carb insulator blocks, will do the perc mod, but that's about all for mods.

Check the shafts!!!

I have at least one Weber dance procedure around here. Seems like I had one from Carl Cilker and one from someone else (I can't remember who off the top of my head). I'll see if I can dig 'em up later tonight. Gotta go to work for most of the day.


JP, How tall are the "tall" secondary venturis anyway?

Posted by: J P Stein Aug 21 2004, 03:31 PM

Bout this tall


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Posted by: J P Stein Aug 21 2004, 03:49 PM

I've never been able to tell fer sure that the shafts are too far gone....but I've only run 2 sets of 3 barrel Webers.
From what I can gather, they're not too far gone till they leak so much air that you can no longer tune the hole (usually 1 and/or 4). All them springs in front cause the wear.

I'm not positive, but think that the later IDAs have a teflon(nylon?) bushing at the front ends of each carb (1&4).
This can be replaced fairly easily. IDTs ....no bushing..at least not on the set I had....you're screwed, Gint. Having this repaired is NOT CHEEP so I wouldn't do it "just because you're there".

Posted by: Eric_Shea Aug 21 2004, 04:21 PM

ToB... thing of beauty

Even the engine compartment is 1/2 primer

Posted by: Gint Aug 21 2004, 07:38 PM

That's exactly what I've got. Couldn't get that pig to hold a consistent idle to save my can. It made it a real PITA to get it smogged. It would keep dropping from 1100 (high specifically for the test) to 600. Then it would load up and fail. I won't screw with 'em anymore. They're going to Eurometrix.

Posted by: trekkor Aug 21 2004, 08:56 PM

The carbs are off the motor and in my shed now.
I'll break 'em down in the next day or two.

Rebuild kit will be here on Mon or Tues.

JP, you say no to the baffling.
Has anyone ran into problems that baffling fixed?
I'll do it if I need to- only if I need to.

Remember, I a/x one time per month.

KT

Posted by: J P Stein Aug 21 2004, 10:53 PM

I don't say "no".
I said I haven't needed it.
I got nuthin' against it.....other than the chance of boogering up your carbs. I think someone had a problem with that.

I'd do it if I found it necessary.

Posted by: trekkor Aug 21 2004, 11:08 PM

JP, I guess what I'm asking is, "Do I need it? ".

KT

Posted by: ArtechnikA Aug 22 2004, 06:37 AM

rebuilding: do one side at a time. there are places where it can be really handy to have one done right to compare to ...

baffles: there are two approaches on race prep. one says do everything you know about when it's convenient because it will never be easier and then you'll -know- you're ready, and you won't lose an event due to something left undone - especially, if it's something you knew about and decided not to do.

the other approach says there is never enough time nor money to do everything that needs doing, so first concentrate on the places where little investments have big payoffs -- the "low-hanging fruit." then address the things that need addressing when they rise up the priority chart.

'best' is probably somewhere between. i never needed a baffle fix for fuel starvation - but i never AX'd my /6 on slicks, and the street tires available to us then were nothing like today's. JP's said he's never seen a starvation issue, and he's running both slicks -and- a big engine. but maybe the courses available to him don't have the kind of long, high-g sweepers some of the CA courses have.

you won't know if you -need- it until you start dropping a bank on a long, tight sweeper. if that costs you a class win, you'll be pissed. are you running within a tenth of the class leaders now ?

my guess is you won't -need- it until you've got the rest of the car sorted and have learned to drive to maximise its potential - by which time, you'll probably be ready to take the tops off again - maybe to adjust the float levels (do you have the sight gauge ?)

Posted by: J P Stein Aug 22 2004, 07:52 AM

Rich has said it better than I could....which ain't all that hard

One of the keys is setting the floats at the proper levels.
I've never had the guts to set em' with the engine running, but have come up with a way (prior to installation of the carbs) that works for me....one of them typical backyard mechanics deals.

I also agree with one of Rich's prior posts on getting Anderson's book (maybe even Wayne's) and would add a book on Webers to that.
Weber Carburetors by Pat Braden seems to be a pretty good one. One can study the basics there.

Also, look at the bird board's engine rebuild FORUM. There are some real live 9eleben engine gurus that post there. Lotso good stuff can be found by doing a search, but (IMO) it's not a replacement for good books. Type in Webers and you'll be inundated.

Posted by: trekkor Aug 22 2004, 09:11 AM

Rich, JP, I can see that these Weber dance lesson are gonna pay off!

I still need to learn the tunes and keep the beat first.

I'll be in the studio.

KT

Posted by: trekkor Aug 23 2004, 07:31 PM

O.K.- tonight's the night.

I'm going out in the shed to break 'em down.

Number one reason to stay home from work on Monday?: you'll miss the Weber rebuild kit deliverd by " Priority mail" .

Oh well, my wife'll get for me tommorow.

KT

Posted by: trekkor Aug 23 2004, 09:08 PM

ready...


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Posted by: trekkor Aug 23 2004, 09:15 PM

clean and scattered...

one down


KT


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Posted by: Brad Roberts Aug 23 2004, 09:49 PM

What size are the venturi's ?? That will tell us real quick if it makes 5000hp. They have a number stamped on them unless somebody opened them up by hand.

Oh.. dont do the baffle trick. It is a road racing thing... it works for AutoX but unless you plan on tracking the car... not worth the hassle.


B

Posted by: trekkor Aug 23 2004, 11:18 PM

30's on the venturi's.

I'd be happy with just 1000hp

Trekkor

Posted by: Brad Roberts Aug 23 2004, 11:36 PM

30mm ?? Stock 9146 2.0 was something like 28mm and it made 110hp or so.

Interesting.


B

Posted by: trekkor Aug 23 2004, 11:48 PM

Brad, 180 on the emulsion tube top jet and 55 idles

What've I got here?

Have you seen my start-up video, or no?

Everytime I see it, I smile.

Trekkor

Posted by: trekkor Aug 28 2004, 10:21 PM

Carbs are back on the SIX.

Started instantly. High Idle. Tuned it down. Good.

Problem is this: I think the float level adjustment is wrong on one bank.

Fuel is leaking out around the base.
I turned the fuel PSI down to 2.5 but it still dribbles.

I guess I'll pop the top and bend the tab up a scoaschie.

The rebuild kit came with new fuel inlet needle valves.
The length of them may be a hair shorter or the washers thicker not allowing the fuel to shut off when the bowl is full.

I have to set the a/f after the flood is over.

KT

Posted by: ! Aug 28 2004, 10:37 PM

WARNING...thread hijack......

Took Frank out for a ride and noticed that when warm I had a high idle...when I turn it down the car dies when cooler.....is this a job for ....da-ta-daaaa....HAND THROTTLEMAN?

Posted by: trekkor Aug 28 2004, 11:08 PM

*THREAD RECOVERY*

I'll start by removing the washer under the inlet needle valve...

I was careful not to tweak the tabs during tear down and cleaning.

One side is fine, so it must be close.

PSI should be 3-4, right?

KT

Posted by: Gint Aug 28 2004, 11:16 PM

3.5 I think. And IIRC, you are suppposed to shim the needle valves rather than bend the floats.

Posted by: trekkor Aug 28 2004, 11:38 PM

Thanks, Mike.

How's the tub?

KT

Posted by: Gint Aug 28 2004, 11:41 PM

Sittin around at the moment.

Posted by: McMark Aug 29 2004, 01:47 AM

WTF Trekkor.

You're too good for me now, is that it?

No, it's cool. I didn' wanna see your dumbass engine run again anyway.

Posted by: trekkor Aug 29 2004, 09:42 AM

Mark, easy...you're the best.

Engine is at my house now.

KT

Posted by: McMark Aug 29 2004, 01:19 PM

Oops, I forgot my last emoticon on that message...

No worries. I didn't think I heard a six fire off yesterday.

Posted by: trekkor Sep 2 2004, 10:22 PM

Fuel leak is gone now due to the fact that *someone* didn't tighten the fuel inlet covers...Wait, that was me.

Ran it again today...Music...Song...I was happy.
KT

Posted by: Gint Sep 3 2004, 08:23 AM

Trekkor,

Try this.

http://914world.com/downloads/Weber%20Tuneup.zip

Posted by: Root_Werks Sep 3 2004, 09:39 AM

Good job on the carbs!

Your venruries affect your torque, so I would probably stick with 30's for the streat or AX, it will give a little more torque than say 32's.

Stock 914-6's came with 27.5's I believe?

Posted by: trekkor Sep 22 2004, 06:47 PM

Thanks, Brad and Rich.
Now I have the sync and float level tools.

Getting closer to the goal.

KT

Posted by: Carl Sep 22 2004, 11:56 PM

Just to give proper credit, the article that Mike posted came from Mid-Engine Views (as it says on the first page), the newsletter of the Porsche 914 Owners Association. It was not published by Panorama.

C

Posted by: trekkor Sep 27 2004, 07:32 PM

The article was very easy to understand.
Thanks again, Mike.

Part of flat out said there is no "black art" to the process.
I knew that. Glad, too...Don't like voodoo.

I set the float height and got a very good idle.
Next I'll adjust the valves, set the timing and finish the sync.

The motor fires up nice and runs well.
It is even quieter since removing half of the supertrapp discs.

KT

Posted by: Gint Sep 27 2004, 07:52 PM

I corrected the link title after reading Carl's post. I forgot where it came from and just posted it real quick to get you going. The real credit goes to Carl for providing it to me in the first place.