Man do I need help, dual webbers Options

[dlindzey]

Short story is I am an idiot and did not ask enough questions about the rebuilt 1971 914 that I purchased. It has never run just right. Biggest issue is a slight bog down at 3000rpms.
Allegedly it was rebuilt with a kit and had the cam changed for the dual webbers. It has had a fuel pump put in by me via reputable shop.

I have taken it to a new shop and was told it had webber 44s and not the correct 40s. I asked if they could modiffy the 44s to work (says it be done on line) and they said no, it needs new 40s. They also said compression is only 100psi in each cylinder but equal through the 4. I bring this up to see if doing anything is even reasonable. So all of this undocumented-kit, cam and just told to me by prior owner. The rebuild shop is out of business.

so what would everyone do here, push for another shop to modify the 44s or go along with the 40s or just change the oil and live with it as a daily driver until the end?

[mmichalik]

What size is the engine?
44's are a bit much for any stock 914 motor but they could be made to work with the 2.0. Maybe.....
If it's a 1.7 or a 1.8, it's too much carburetor and you should change them out with 40's.
And then change the oil and drive it till the end!

[dlindzey]

started as 1.7 alleged kit to near 2.0

[Shivers]

It may have 34-36mm venturi's in those 44's. So you could swap out the venturi's for 28mm and re-jet. Get some velocity back. Link below.



28mm venturi

[GregAmy]

I'm running a 2056cc race car with about 9:1, bigger valves, 86C(?) cam, slight porting, and Dellorto DRLA 40s with 36mm venturis...and that is puh-lenty of choke through 6000 RPM (really, too much if it was a street car).

Time to learn carb sizing and tuning...I snag all my carb bits from CB Performance.

https://www.cbperformance.com

[Ace Le Count]

Have you checked for air leaks? My car was doing the same thing and it turns out when I put the carbs on, I for some reason left washers between the intake manifold and the gasket to the carb. air was coming in between that washer size gap that I, for some reason, decided to leave. As soon as I fixed the air leak, the car ran perfectly. Maybe that's your problem, maybe the car is just running too lean...?

[Superhawk996]

It may have 34-36mm venturi's in those 44's. So you could swap out the venturi's for 28mm and re-jet. Get some velocity back. Link below.

This is a reasonable way to go if cash is limited.

However, the IDF 44’s will never perform as well as IDF 40’s on a small engine because you inherently have 10% more circumference around the throttle blades that impairs off-idle transition. In addition, with the 44’s you have 21% more throttle bore area at WOT that will slow down air velocity more than would happen using IDF 40’s.

I respect the shop that is taking a principled stand and telling you that 44’s won’t work.

Of course they can work to some degree but they will never work as well as a set of 40s.

This business of over carburation is real. The American theory of bigger is better is so wrong when it comes to carburetors. Unfortunately I made the same mistakes when I way young and foolish. Some lessons are only learned though the school of hard knocks.

[burlybryan]

I second Superhawk. Even 40's overfueled my 1.8 (built to 2.0) and killed the rings in 10K miles. Could have been my PO's settings as when I got it I dialed everything back and changed jets. When I pulled it, compression was down to 70 across all 4 with scoring on the cylinders. Anyone want to buy a used engine (IMG:style_emoticons/default/wink.gif)

[cgnj]

@dlindzey
You need DRLA 40, DRLA 36, or IDF40. Italian or Spanish. I have never held a repop in my hands, so I have no first hand advice to offer. I freely admit I am a DRLA fanboy since the 80's. Better streetability, easier to change jets. If you have real Webers you may come close to break even.

[930cabman]

I would start with 40 IDF Webers (28 venturis) with the associated jetting AND research/read/ask/look for experienced help. Carbs are not that difficult, but you must have the basics in place. There is quite a bit available in print and online regarding Webers

An overcarburated engine is no fun

[aharder]

I'm running IDF 40's on my 1.8 along with a 123 Distributor. The 123 made a world of difference in the performance.

I get all my carb stuff from Pierce Manifolds, piercemanifolds.com

[GBX0073]

cheap trick to try if you have an air leak around the carbs or manifold with the engine running spray brake cleaner or starting fluid /wd40 etc and see if the rpm's change if they do you can zero in on the leak.
we all have our preferences for Carbs I am in the Dellorto DRLA camp !!!!

[cgnj]

This could be your answer. No affiliation. Just confirm the throttle shafts are not frozen and all the adjustment screws turn freely.

http://www.914world.com/bbs2/index.php?showtopic=379070