Tuning issues.. Jake can you advise?, advance curve or jetting (that is the question) Options

[brant]

I finally got my latest project running but not well enough
I need to do a little tuning...

its a 1.7 motor with a cam (don't know the specs of the cam) from the previous owner
I can get leak down/compression, but don't have them at this moment.
I also don't know the compression, but it is mild... probably stock

the P.O. claims it was rebuilt and I believe it
I took all of the tin/push rod tubes off, and it looks to have been rebuilt with out worn/shot stock cam lobes and with lifters showing no significant wear
doesn't seem to burn-smoke or leak any oil at this point.

Its running 40mm dual webers, currently testing at 3300 foot altitude
(motor came from a running car at about 5500 ft)

I rebuilt the carbs and the jetting is:
-28mm (chokes) main venturis
-2ndary venturis 4.5
-main jets 115
-air jets 200
-emulsions F11
-acc. pump ball jet 50
-acc. pump towers 50
-idles 50
I've never carbed a 1.7 before

The motor came with a 009 distributor and points
I ditched it and put in a L-jet 914 (1.8) distributor with points, blue coil, and no retard/advance lines hooked up
the cap/rotor/plugs/wires are all good-new

car idles smooth, pulls fine from standing, and then stumbles mildly from 2000 - 3000
the car clears out and runs great at 3000 or 3100rpm
timing is currently set at 29degree's, but this is my norm for altitude.

dad and I are in disagreement about the cause
he thinks its too rich for the tiny motor

I think its a distributor curve issue

Jake, do you know?
I have a Djet distributor available easily... or could put the 009 back on... or think maybe I should buy an 050 somewhere to see if the curve is actually the problem

We discussed buying 110 mains also to play with it...

thanks in advance for any advice from the guru's out there
brant

[dlestep]

...may I be so bold to add something here.
This is what I do to settle any carb-distributor issues. I start at the ignition. Ensure that everything is what it should be as far as gap, if using points; condenser, coil and wiring.
Engine and transmission to good ground.
Clean all grounds and check wiring terminations.
Eliminate all wiring problems. Electricity flows on the outside diameter of the wire, make sure that all of those issues are taken care of in the iginition circuit, from key thru fuse block to ground via plug wires and plugs themselves. "Cleanliness is next to Godliness".
I set my points static, with a light, key-on engine-off. Light will come on just as the lobe opens the points, lock it down. If using points, remember that a conical build up on one, causes a concave portion on the other. If trying to measure point gap with that condition, it will always be too much. Replace points if it exhibits that condition.
After ensuring ignition is spot on, move to carbs. (based on Webers and Dells).
First check float bowls for cleanliness, including the jet at the bottom. A piece of debris from oxidation, dirt, piece of gasket and even water condensation can create havoc. Remove and check all orifices, then thoroughly clean and reinstall them.
...sidebar: In my day, we removed the floats and placed a plate near the top of the bowl, and using three fuel pumps, one scavaging (both), two supply, kept the system from fuel starvation on hard corners, heavy braking and vibration.

Richie Ginther set his carbs up with unequal length velocity stacks and thick resilient gasket bases between the carb body and the intake manifolds. He also used springs with the mounting screws to dampen the inherent vibrations of the horizontal four reducing the fuel sloshing in the bowls.

Adjust float, check it at least three times. Ensure float itself functions as expected.
Check fuel pressure, replace filters (all of them). Check the sock in the tank as well, if you find your filters filthy. If you are using the metal kind. Cut it open lengthwise and inspect the contamination.
Utilize the stock height velocity stacks for these adjustments. The taller versions look good, but give incorrect readings affecting lower rpm settings.
Use a flow meter to see whats up at idle and part throttle (3200 rpm). Note who's doing what. Disconnect throttle linkage, (both sides). Adjust idle stop, usually 1 and a 1/2 turns out from soft stop, (all in). Smooth (balance side to side) with air flow ajustments using meter, then readjust idle stops to a smooth 900 rpm.
Snaping and poping occurs for three reasons under load; Lean mixture, ignition and valves. For example: throttle shaft wear allows airflow under load, leaning out mixture; bent values, usually from water ingestion; or valves that are incorrectly adjusted too tight; or ignition too advanced, or distributor shaft wear, causing uneven firing.
IF ALL THINGS ARE GOOD TO GO, loosen all adjustment points of the throttle linkage. Reconnect them and remove all preload. At the central point, move off idle position and rev it repeadedly, allowing it to fall back to idle. Watch closely the mechanical movement. It will always be unequal. The throttle linkage is a tolerance nightmare. The throttle linkage is the connection between your foot and the butterflies in the carburator. All four must move in concert. I would even replace the manifold to carb body gaskets. At which point is your chance to check the butterfly mounting position in relation to the flats on the throttle shafts to ensure that they are "concentric" to the bores. The screws are often worn and damaged from others using the incorrect tools during rebuilds.
If you have the cast or formed metal base for the filters, they collect dirt and debris. Clean them. Water also collects there with the filters installed. Look at the base of the emulsion tubes when installed into the carb body. That's where the water collects as well. I live in Florida and water is an issue.

I cut my own bases and lowered the interface with the base of the filters below the original surface by about an eighth of an inch and added slots to allow water to drain (to keep the water from forming around the base of the emulsion tubes). I modified a fine nylon mesh material from Outerwears to ensure that the drain holes don't allow debris to enter.

Back to throttle linkage adjustments....replace the bushings in the shaft to ensure only one plane of movement. There should not be a side to side deflection during its' rotation. Also add a second locking piece on the cable at the cross bar. One is not enough. It sees constant stress.
As all things mechanical, when everything was new, it was as good as it gets. Over time, the system deteriorates in many different places for many different reasons. Collectively it all stacks up against you. Inspection and maintenance here is a must for crisp throttle response and carb flow, balancing ensures correct breathing. Once everything is adjusted properly, one can hear and feel the difference.
Compression differential problems are straight forward and easy to remedy by comparison. Cam problems are a different breed and require a complete teardown, at which time, all engine wear issues can be addressed. Jake would be the guy to discuss cam issues and remedies.
My only addition would be to check, double check and triple check, as I do, the valve adjustments. We have solid lifters for a reason. I personally don't like hydraulic lifters on the horizontally opposed engine. It's like wearing socks in the shower. It's not right.
...this is my 4 cents worth....