Rethinking carbs

In short words, No, you don't need anything larger.  You're limited by cylinder displacement and flow.

This will probably create a firestorm amongst the carb gurus on here, but if it were mine, regardless of the "big valve" heads, I would stick with the 34's.

Why?  Because we're talking flow rate of air/gas volume through the cylinders and with a stock 1,600 the flow rate the cylinders are capable of pulling is pretty much matched to the 34's.

If you run something larger for carbs, you STILL get the same flow rate, you just have to match the jets and correctors to that flow rate.  That means you'll be leaving potential flow from the carbs on the table because the engine simply can't provide it.  

If you were to go to, say, 40's or larger, pretty much nothing new would happen (no more power).  If you were to use those same carbs on a larger displacement engine that better matched the carb's flow capabilities, then more power would be realized.

All that said, if you were to stumble upon a pair of rebuilt Dellorto 40's for a good price, I would get them just for their reliability.

Boothy- Is there a reason you decided on larger valve heads for your 1600?

Thanks Gordon! Will do. That makes sense.

The only reason I went with the big valve heads is I had a stock set on there where I replaced valves and guides only to find the intake wouldn't torque up. With everything else I already did for it I figured screw it and let some moths out of my wallet. Why? Bad choice?

There are larger valve heads and then really larger valve heads - a stock bump up wouldn't hurt but going ultra large would.  I went to 041 heads years ago for the beefier USA castings with 3/4" reach plugs and 39mm Intake (vs 35mm)/32mm stainless steel Exhaust valves.  Wish I had waited a decade and gone with the new smaller spark plugs.

Hey Wolfgang, Yeah these are the newer ones with the not radically large vavles and smaller plugs so I'm hoping all goes well.

The stock dual port head is good match for a 1600, even when you extend the rpm range and up the power a little. You may notice that gas mileage (and low end/midrange torque) is not quite all it could be with the bigger valves and ports. Then again, you may be having so much fun tearing around that you don't... I occasionally read about guys on the Samba with the same combo and they always say it runs great.

The engine will be a fun little bomb and push around your car quite nicely. With either 40mm Webers or Dellorto's they might make a little more power at the very top of the rpm range, but that's it. What you will find that (once you manage to familiarize yourself with them if you aren't already) the engine will run just that little bit smoother than with the 1 barrels. Hope this helps. Al

Thanks Al. It does. Best!

Gordon is right-- a 1600 with "big valve" (but stock intake ports) isn't going to flow enough to need a set of 40s. They'd just be overkill on this engine

... but a set of 36 DRLAs might be just about perfect.

I was just over on theSamba, and the place is LITTERED with 36s for sale. More than I've ever seen. Enough that I'm tempted to buy a set... you know, just to have. Maybe I could use one for a paperweight or doorstop. They're cheap, too-- $350 buys a decent set. A guy could leave a trail of them through the forest to find your way back home. Maybe I'll buy a set, put them on my desk, and put pens and mechanical pencils down the throats. Maybe I'll use them for bookends.

You, however, could use them on an actual engine. Individual runner carbs are quite a bit nicer than even the nicest "plenum"-based single barrel carbs. Better idle, better throttle response, better everything really. The misconception is that they are harder to set up. I'm not buying. How many guys with Webers or Dellorotos have come on this site asking why their car is only idling on 2 cylinders?

None, that's how many.

Every third guy with Kadrons is going to ask that if he's paying attention. Every other guy is going to struggle with even the faintest fuel pressure overwhelming the needle and seat on his Kads. ICTs are better, but ICTs are nowhere near as nice as an individual runner carb set.

Thank you Stan -and everyone. As always, stellar advice. I'll post a pic once everything is in. You all have given me advice on everything from the tranny back. Tranny, engine, firewall, carbs, you name it.  How great is the SOC? Aces in my book.