syncronizing carburators using vacuum gauges

piggdekk · 08-06-2010, 11:33 AM

I'm about to rebuild my zenith carburetors and I'm trying to find out how to syncronize them afterwords. I know there exists a syncrometer, but I was wondering if I could connect 6 vacuum gauges and check the vacuum on the 6 carburetors all at the same time, this should ensure a much more accurate syncronization.
To connect them I believe the best solution would be making some holes on the intake manifolds, but I was wondering, couldn't I connect the vacuum gauges to the auxiliary enrichment hole?

I was thinking connecting the vacuum gauge where the rubber tube 14 goes.
As any one tried this?
thanks
luca

red 2.7 · 08-06-2010, 02:34 PM

It would only work if the 6 units were perfectly calibrated to each other.With 1 unit moving around it's always the same reference. Although 2 are handy if you want to adjust linkage. To sync 2 is not to hard but 6???

HarryD · 08-06-2010, 04:30 PM

You sure can. In fact, it IS the porsche way!

Porsche Manometer tool...any experience?

rw7810 · rw7810's Garage

Luca send me a PM with your email address and I will send you a good Zenith tuning procedure.

piggdekk · 08-06-2010, 11:09 PM

Quote:

Originally Posted by HarryD

You sure can. In fact, it IS the porsche way!

Porsche Manometer tool...any experience?

Thanks Harry,
looking at the tool it doesn't look like they are using the auxiliary enrichment plug, but I don't see why it shouldn't work.
Using multiple gauges it is a very well proven procedure for motorbikes, and I don't think there should be too much difference in the calibration as long as they are good quality.
Thanks a lot
luca

RoninLB · 08-07-2010, 01:04 AM

Quote:

Originally Posted by Soukus

- monometer or the synchrometer, you are still getting a relative flow rate (cylinder to cylinder comparision).
- Accuracy in this case is your ability to make a good comparision, and it has less to do with the precision of the device you are using.

Quote:

Originally Posted by wholberg

- I used the tool....
- ....it worked great for me.....

Quote:

Originally Posted by maze

- write up from S......ds on line catalogue..
- If each cylinder doesn't have exactly the same air intake volume, the horsepower produced by each cylinder will vary, causing the loss of power and shortened engine life.

all above from Harry's site

My take is you measure EGT for fine tuning. Air flow sync doesn't have to be deadly accurate for HP sync. Putting two racks of carbs in air sync at lower and higher rpms ain't easy. Ah educated ballpark is good enough imho
Even if I readjust air with a syncrometer and it's not exactly as before EGT is not bothered in any way that could be found in my experience. It's your idle screws that greatly affect EGT. I read in a weber manual that all idles should be set same. For the most part that's true if you have good heads & rings. If you have the right toy you can tweak 1/4 to 1/2 a turn on some cylinders. But that's if you know which cylinder has a noticable differential than others.

[img]http://forums.pelicanparts.com/uploads18/JPIConsoleEGT+CHTreading
1281171252.jpg[/img]

Some say good carb tuning under sane conditions has a differential between the least powerful cylinder and the most of 100-125F EGT. That decent FI has a differential of around 75F. And that very good FI has 50-60F Diff

RoninLB · 08-07-2010, 01:07 AM

oops

1QuickS · 08-07-2010, 07:28 AM

Hi Luka,

I put ports into my intake manifolds to use mercury sticks for sync-ing Webers. I have a 4-column "Motion Pro" mercury stick that allows for setting three barrels and checking balance with second bank of carbs.

Paul Abbott
Performance Oriented

piggdekk · 08-07-2010, 07:52 AM

Still no one has tried to use the auxiliary enrichment port to measure the vacuum. My reason for using it is that I can test the carburators now, before pulling them out. After I've removed them I'd put ports on the manifolds, unless the enrichment port looks good enough.
My concern with using the enrichment port is that it is in the same passage of the air bypass, but that shouldn't make a difference.
luca

James Brown · James Brown's Garage

I used my aux vacuum ports for a MAP sensor. They all led to a manifold. Tried each one with a Vacuum gage but didn't see any difference nor could I change the readings like a sync. tool can.

piggdekk · 08-09-2010, 08:03 AM

ok, so that's not the way to go. I'll put some ports on the manifold at the first carb rebuild
thanks