Carbs

[Big D]

The bases on my 356's zeniths being iron are shot due to the car not running since 1982. The rebuilt kits seem high and my solexs on my 912 run like crap. Is it worth it to get some more zenith bases and rebuild, replace with solexs for 20 more hp or go with new weber 40's. Thanks DG

[id10t]

The Webers are supposed to be "too much" unless you are running a SC or 912 engine, or you have to make lots of changes to venturis, etc. I'd rebuild what you got...

[Les Paul]

I had a stock 63 S that I put Webbers on. They worked perfect for years.

[id10t]

Like I said "supposed to be" . I've got a '65 C with 44 IDFs on it, and it drives fine. Of course, I've never driven another 356, so I have no real reference point.

[snowman]

Solexes are fine carbs. They can be reconditioned, with new bushings and will work as good as or better than the webbers. Zeniths work fine for the intended use, just make sure they are porperly reconditioned.

Anyone who sayes these carbs are constant problems DOES NOT KNOW WHAT THEY ARE TALKING ABOUT. The only advantage to a webber is for a race car where varied jetting is required, and then it is only advantageous in t he ease of modification, not the function. Solexes will support up to 180HP 912 engines, and work very well.

As for HP you do not get more HP out of a carb, you get it out of the heads, porting, the cam, the headers. If you change the heads, the valves, the porting, the headers, THEN the carbs may have to be increased in size, ie venturi size, to support the increased airflow capability. Increased airflow capability means HIGHER RPMS, which means, really good balancing, better rods, rod bolts, lower weight pistons, better valve springs and retainers, better crank.... IF you are not thinking of all this, stick to the stock carbs, properly rebuilt. Porsche did a very good job, if you stick with what they made.

[Big D]

So where do I get the iron lower unit of my zeniths. Have seen lots of solexs' out there, not alot of zeniths. Thanks DG

[id10t]

I'd start by calling Pelican Parts - they supply this forum for us to enjoy. If they can't get it for you, I'd post to 356talk, teh list serv that the 356 Registry sponsors. LOTS of vendors, etc. there.

[Grvlguy]

Some good information but not what you need to make a good decision for a normal driver. The Zeniths will never be a good carb without a great deal of machine work from someone who knows what they are doing to stop all the leaks. I agree with Snow the Solex's can be good carbs, but not for the everyday person. They are VERY expensive to have repaired. In fact, having the shafts rebuilt can cost more that a set of 40 Webers complete. Read Harry Pellow's articles and you will see that 40 Webers are the best choice for the everyday guy! good luck!!

Jerry

[brianradams]

Stick with the Zeniths, especially since your problem seems fairly simple to solve. Even if they required complete rebuild I'd put the money into the Zeniths rather than Weber or Solex. A complete set of Webers with manifolds/adapters and filters will cost around $700-$900.

I am running Webers on my '59 Super, but only because they came on the car. I don't have a set of Zeniths to rebuild. But I have rebuilt the Webers, am on my second set now due to a fire (more on that later) and have come to love them. They typically come with 28mm venturis, which are just fine for a stock 1600. If you go big bore, head porting, cam, etc. you can go up to 34mm I think in the 40s, but it might be better to get 44IDFs instead. As someone said, the carbs don't produce power, and if you get the venturis and jets set up right on Webers, they are no better ot worse than Zeniths, just a lot easier to swap jets in/out, you can do it in 5 minutes by just removing the air cleaners.

Another reason to stick with the Zeniths is they have flame arrestors for air cleaners, those metal cannisters. The K&Ns typically put on Webers are prone to ignition from any kind of backfire. I found out the hard way by letting my main fuel tank run dry, switching over to reserve at highway speed, waiting for the normal stuttering to stop as the float bowls refilled, only to find this time that the car continued to run crappy even after the reserve kicked in. I managed to get it home (2 miles) and when I stopped the car smoke was rising out of the engine cover vent. I popped the cover and found a K&N burned beyond recognition and still burning. Grabbed a fire extinguisher and saved the car, but molten carb metal had gotten down to the intake valves. I had to pull the head and clean it up before I could get any compression on that head, decided to just do a valve job on both sides since I had it apart. Zenith air cleaners are far less likely to ever have this problem.

Also, if you go with Webers, a VERY common problem is that the linkage to the throttle levers on the carbs is asymmetrical, i.e. the descending pushrod going to the left carb is shorter than the rod to the right (passenger side) carb. The right rod reaches farther rearward than the left due to the cylinder stagger (and resulting carb stagger.)

The two descending rods must be at the same angle relative to, say, the vertical face of the fan housing, and the ball studs on the carb's throttle levers must be the same horizontal distance from the fan housig.

Pointing the ball studs towards each other is a first step (left stud point rearward, right points forward) towards closing the gap, but on my 356 there still was a net 1.5-inch offset. The fix is to stick 3/4" threaded standoffs underneath the ball studs, essentially making them longer. This closes the 1.5" offset and puts the descending rods at the exact same angle/length.

The proof of all this is the Synchrometer readings. Try balancing the carbs just off idle @1500 rpm. Then open it up to, say, 3500 rpm and notice how the left side carb is drawing a lot more than the laggard right carb. When the left carb is against the stop, the right carb's lever will still be several mm off it's stop!

No Weber installation that does not equalize the linkage properly will ever deliver full performance. You won't believe what a difference it makes.

Brian Adams
Reno
'59 Super Coupe

[914Ghost]

I Have Dellorto DRLA on all my cars.
36's on my 1600 VW Single Cab, 40's on my 1.8L 914, and 40's on my 912.
The Dellorto's on my 914 run as smooth as the original Fool Injection, and they're great on the truck. 20-25 MPG in town and the plugs read perfect. They are maintenance free 100%.
I haven't touched them in 6 months.
I ran Zeniths on my 60' coupe 1600 Normal, then Switched to a good set of split shaft solex's- and had a NOTICABLE difference.
It revved free-er and smoother, and had a better idle "sound"- the Zenith's were muffled.
Weber's are fine, don't let any techno-speak talk you out of a good modern set of carbs that have proven their versatility for 35 + years.
The linkage problem mentioned is EASILY fixed with a long 8mm hex bolt on one side.
That said Dellorto's are better than all the above under most circumstances- they flow better than Zeniths (of course), Webers, and Solex's due to the longer 2ndary Venturi and availability of taller air correction jets.
AND they're tunable to your needs.
DRLA's have an air-bypass screw so you can tune air flow in each barrel to EXACTLY the same.
I think your Zeniths have 28mm (maybe 26?) Venturi's, thats what I have in my 36 Dell's. And I have a pile of jets to set them up and 3 different vent sizes.
Search for Solex's on Ebay, there was a set of Beautiful 40 P11's the other day for $249 Buy It Now, manifolds are cheap.
Or I can probably Sell you a set of 40 Webers OR Dellortos ready to bolt on for $375- (With Manifolds).
Someday the Zenith and Solex parts will be gone- period.
Might as well upgrade or start hording parts now.
-Bob O

[brianradams]

The linkage asymmetry is easy to fix, but you're about the only other soul I've met who has bothered. I suppose the Dels have the same problem. Maybe you could describe in more detail how you applied the 8mm bolt to fix it?

All the Webers I have had also had air bypass screws and are easy to balance to themselves.

I just got a used set of 40IDFs from the Italy E-bay source. These are from the late 80s, and have a different setup than any IDF I've seen, with idle jets vertical in the top, and different air bypass screws (O-ring jet style rather than tapered needle.) But now that you mention it, these happen to have much taller auxilliary venturis than the current crop of IDFs. I can't wait to get them set up.

Brian

[914Ghost]

Yeah, check it out, these things usually come with carb kits or are available from Cb Peformance-
Look at where the linkage is attached to the carb on the left.
And extra offset bolt is there next to it.
8mm hex size shaft with stud on one end and threaded on the other.
I guess using one of these means you have to use updated drop links. I drill the balls off the carbs and use the new stuff - for Solex's, it's looser yet has less play than the ball-sockets of old.
Very easy to adjust too.
Those linkage arms are from the Baby Dellorto / Weber 34mm kits.
I'm going to update all my throttle linkage up to the pedal with this stuff and see how it goes.
-Bob O
I think the reason most people dont compensate for the offset on the carbs is their linkage it attached at the Air-Filter- which has the same offset as the carb, 356/912's have the linkage straight across the top creating the problem.
Actually the 356/912 linkage design is great other than it's mounting = being attached to the engine / fan housing it transmits vibrations down the linkage to the carbs wearing out the carbs and linkage faster and causing more frequent adjustments.
The aftermarket VW kits eliminate this being attached to the air cleaner base where the linkage top and bottom encounter roughly the same vibration.
. ...Just something to think about.

[brianradams]

Thanks for the pics and more details. Interesting, they put the offset fix all on the left side, a very long standoff. This means that both sides are now equal but the net result is both sides are farther from the crossbar pivot, so a goven movement of the pedal up front results in a little less movement at the carbs, as opposed to, say, putting the long extension on the right side, moving that side closer to the crossbar. The sides are still equalized, but now both closer to crossbar, i.e. more vertical, so pedal movement is more directly translated into carb lever movement. Of course, it is probably impossible to put that long extension on the right side (facing forward), since it will interfere with the base of the carb before it reaches wide open, that's why I split the difference and put a shorter standoff on each side, in fact the short one lying nearby in the photo is about right. Thus I equalized the lengths, avoided interference, and got a little closer to vertical then the setup you show. Another issue is the large twisting moment (leverage) that single long standoff creates, as long as everything moves freely it won't be a problem.

Brian

[914Ghost]

I actually got the engine in and car running, the linkage was a pain.
The Offset was a problem as well as the linkage running into the air filter bases.
I have it set up fairly well, the left side only opens a split second before the right- can't find a solution without having a perfectly straight drop link from the carb to the arm on the right side- no amount of adjusting equalizes it exactly.
Dammit.
Maybe different air filter setup.
Bob O

[brianradams]

Yes, I think the rectangular filter shape is hurting you,
the typical oval K&N shape might give you enough
clearance. I'm struck by how short the levers are on
the carbs themselves, if they were longer it would
move the downlink rods more into the clear.

Brian