Switching 72 carb setup to 73/74 style.

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grandfatherjim
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Switching 72 carb setup to 73/74 style.

Post by grandfatherjim » Fri May 09, 2014 5:00 am

I am gathering parts to convert my '72 from the original oil bath air filter to the paper type. So far I have the different central idling tube, the air filter housing and its standoffs, and the taller manifolds. I also possess a crusty set of carbs mounted on said taller manifolds (they would need to be refurbished) and a guy I know is offering me a "newly rebuilt and never used set" - I need to find out what that means of course. We're talking PDSITs here.
I see ports on the taller manifolds that must be for the EGR system that appeared in later years, which initially, I assumed I should just block off.
However: I have an acquaintance who has been telling me for several years about how he made some pipe a much larger diameter, with great improvement to performance. I had been thinking he meant the vacuum pipe for the brake booster but now realize it must be this EGR pipe.
Since I am at this juncture and need to do something with those ports, what is recommended?
I need to talk in general terms now, as my new engine is a bit of a Frankenstein - 1800, with Q heads, and with the carbs lifted from the previous stock 1700 and dropped right on with no adjustments having been made. (It performs better than the previous engine ever did but gas mileage is poor.)

Thanks,
Jim

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Amskeptic
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Re: Switching 72 carb setup to 73/74 style.

Post by Amskeptic » Fri May 09, 2014 6:57 am

grandfatherjim wrote: I have an acquaintance who has been telling me for several years about how he made some pipe a much larger diameter, with great improvement to performance. I had been thinking he meant the vacuum pipe for the brake booster but now realize it must be this EGR pipe.
It is called a "balance pipe" and evens out the pulsing that occurs through dual carbs. Do NOT get all big about it, max 10mm diameter. Just find a factory EGR pipe (illustrated with green in the below) and pinmch off the EGR inlet, this pipe will have the two intake manifold flanges with pre-drilled holes all ready to go, just slap on some 10mm nuts to install.

Image
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 206,865 miles
Naranja - 77 Westy . . . 132,040 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 94,225 miles

zeta
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Re: Switching 72 carb setup to 73/74 style.

Post by zeta » Tue May 04, 2021 9:53 pm

Well not sure if this post will get any viewing but thought of trying...why would you want to change from ‘72 to ‘73/74 setup?

I ask because my bus (‘74) came with a Weber single progressive and I received a ‘72 setup with air cleaner and linkage. I am about to invest (time/$) to get it ready but wondered if I should gather the original Solex setup (‘74) it was originally designed with.

Thus what is the advantage of a ’74 setup over the ‘72, if I don’t need the EGR?

Thanks
Z

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grandfatherjim
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Re: Switching 72 carb setup to 73/74 style.

Post by grandfatherjim » Wed May 05, 2021 6:21 am

The primary reason for me, was to switch from the oil bath air filter to the paper air filter. But when VW made that switch in 1973, they also switched to longer intake manifolds, and so the top of the carbs was higher up, meaning if you just tried to put the housing for the paper filter on the 72 carbs, it would sit too high for them. I have also been told that there were several iterations of the carbs themselves (5?) from 72 through 74 as VW made various improvements, such that later carbs are "better". For me it came down to what I could get my hands on to rebuild, or have rebuilt. I see I started this thread seven years ago but haven't quite got to this yet...been busy building a house. That's done and now I'm on to the garage which has a tall bay so that I will finally, for the first time, be able to bring my hightop indoors to work on it. Luxury! I won't have to lie on my back on gravel to drop my engine!

zeta
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Re: Switching 72 carb setup to 73/74 style.

Post by zeta » Wed May 05, 2021 6:22 pm

I have never used these filters (oil nor paper) due to the weber progressive. what were your experiences with the oil type ('72) that made you want to switch? I do have all components for the '72 setup, so then changing them were not a performance improvement decision?

Seven years! I have been dormant since 2011 and just now woke up as well. Congrats on the awakening and on the luxury garage! Thank you for responding. It sure helps me.
Z

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