Struggling with PDSIT synchronization

[rustbus]

I'm going to set it at 5*BTDC....and the risk is that upon full advance (centri. and vacuum) that i may ping?

ugh - my poor brain. must be over thinking this.

[satchmo]

I'm going to set it at 5*BTDC....and the risk is that upon full advance (centri. and vacuum) that i may ping?

ugh - my poor brain. must be over thinking this.

No. You are going to set it at 5* ATDC at idle with hoses connected. See specs below (timing spec in bold). You will find/have found that timing affects idle speed and idle speed affects timing. Once you are at 5*ATDC and idling in the specified range, check where the timing goes when you hold the throttle at 3000 rpm. You should be in the 28-32* BTDC range. THEN proceed with carb synching and final adjustments. Don't worry about the max advance yet (that magic 28*), because this is a reiterative process where you will probably need to recheck the timing again, then maybe adjust the carbs a bit more, then the timing, etc, until you are making the finest of adjustments to get the idle timing and speed correct, with good advance characteristics (the carbs have to transition smoothly from the idle circuit to the speed circuit in concert with the advancing timing provided by the distributor) and end up close to 30 degrees BTDC while running at 3000 rpm.

Tim

Bus & Pickup 1972 * 1700

Distributor: VW 021-905-205E, Bosch 0231 173 005
Can Use:
Points: 01 011
Points Replacement Plate Assy: VW 311-905-227C, Bosch1237 110 161
Condensor: 02 054
Rotor: 04 033
Note: Originally equipped with Speed Limiting Rotor 04 016 (5400rpm)
Dust Cover: 039-905-241, Bosch 1230 500 139 > 1230 500 147
Cap: 03 010
Distributor Cap Clip: 034-905-265, Bosch 1231 251 033
Parts Kit (Shims, Washers & Hardware): 059-998-211, Bosch 1237 010 007
Coil: 00 015 (Blue Coil: 00 012)
Vacuum Can: 07 101
Ignition Wires: 09 171
Spark Plug: W8CC
Timing Set At:: 5deg ATDC @ 800-950rpm w/strobe, vacuum hose(s) connected
Advance/Retard Range: Vacuum: 8-12deg Adv, 11-15deg Ret; Centrifugal: 13-16deg @ 2000rpm, 23-26deg @ 3600 rpm

[rustbus]

ah geez...5 AFTER TDC - Sorry, I know i need to be accurate, and there i go making basic mistakes on the lingo.

Thanks for the clarity, I'm itching to get home and check it


3000rpm, 28-32 * BTDC, with hoses on. I fear it may exceed 32, but will find out

check!

[rustbus]

Ok, well, after setting to 5atdc, hoses on, this bad boy is running nice but hitting like 40btdc atmax (hoses on)advance...I do not, however, know exactly what rpm I am hitting since my tach only hits 2400....I may be way over 3000 rpm, for sure actually.

I went a few steps into the procedure anyhow , the high speed sync goes ok, idle sync is still a little off, mixture set ok! And now, finally, the left idle cutoff affects it! The right doesn't , but that's the bent one so I will replace that one tomorrow. Stopped at this step of course.

Anyhow, kinda looks like I'm hooped in the advance department, no?

Sorry for this lame update! It's late! But tomorrow the missus has things to do so it will be just me and the bus, no interruptions!
.

[Amskeptic]

hitting like 40btdc atmax (hoses on)advance...
.

Perfect!
Now, take the advance hose off and you best not see the timing mark go past the little square indentation on the scale (that happens to be the 23-26* window as allowed by the factory) no matter how you rev it with your lousy tach.
Achtung!
Colin

[rustbus]

hitting like 40btdc atmax (hoses on)advance...
.

Perfect!
Now, take the advance hose off and you best not see the timing mark go past the little square indentation on the scale (that happens to be the 23-26* window as allowed by the factory) no matter how you rev it with your lousy tach.
Achtung!
Colin

Colin! - my apologies, i took a hiatus from the bus - i was tuning every night after work and needed a break!

tonight I warmed it up, pulled the advance hose, and viola, it bounced around 26* at maximum addvance. "sigh of relief"

but not before i opened the carbs again -

i could smell gas, and i popped off the air horns. the left side is still leaking, after a brand new reproduction needle valve was installed. figures, i guess

this is what i saw: i was able to get my finger wet when i stuck it in there





fuel level at about 9mm, thats after splashing the top off. measured with the float installed obviously, right? I assume the vehicle needs to be perfectly level for this measurement? I will have to drive it somewhere perfectly level if thats the case. maybe on friday...hmmm..



so i have the new solex ones from a kind stranger on the samba. not that ball end type, but nice solex none the less. I do have one ball-type needle valve, will have to wait for another some day.

so i suppose since i have to remove the carb tops to check fuel depth, i wont proceed into the tuneup procedure again just yet, until after i have a chance to park it level and disassemble and check. I have to admit, i almost have removing the carbs down to a science, sadly! its actually pretty painless, only sucky thing is the need to be resync'd every time

[Amskeptic]

the left side is still leaking, after a brand new reproduction needle valve was installed. figures, i guess

fuel level at about 9mm,

IIRC, it should be 13mm, which is lower . . . which should prevent fuel from leaking into the throat. You would need a thicker washer under the needle valve.
Yaah?
Colin

[satchmo]

I may be missing something, but where is your accelerator pump jet/nozzle?

Tim

[rustbus]

the left side is still leaking, after a brand new reproduction needle valve was installed. figures, i guess

fuel level at about 9mm,

IIRC, it should be 13mm, which is lower . . . which should prevent fuel from leaking into the throat. You would need a thicker washer under the needle valve.
Yaah?
Colin

good call, I've installed thinner aluminum washers for now to drive it here to the shop today for level ground. that left side was 9mm with the shitty needle valve, so hopefully i get a true measurement with these solex valves in. I'll make sure i get the washer vs. fuel level figured out first! More washer=less fuel - check!

Can I use 2 washers if need be?

[rustbus]

I may be missing something, but where is your accelerator pump jet/nozzle?

Tim

whoa - you scared me, good thing i drove the bus to work today, so i ran out and looked - they are both there, must be hiding behind the choke plates (i cant see my own pictures here...)

[satchmo]

I may be missing something, but where is your accelerator pump jet/nozzle?

Tim

whoa - you scared me, good thing i drove the bus to work today, so i ran out and looked - they are both there, must be hiding behind the choke plates (i cant see my own pictures here...)

Gotcha - I see it in the last pic. Thanks for checking.

[rustbus]

OK! - checked float levels today on level ground. left carby @ 13.5mm and the right was a fat 14mm. another one down.

After work today i will redo the procedure. its close, i was shooting the temps on the intakes and exhausts earlier and they are only about 30 - 50*C different. before they were over 100* off each other

thanks guys, i'll report back with my luck tuning

[rustbus]

hey guys! - here's an update


since my last post i have been driving the bus around quite a bit. no problems with float levels, (i have also installed a 1/4" ball valve to the regulator as an added precaution/option). changed the oil again to be sure there's no fuel in there (shes kinda maybe seen too much fuel over the last couple years, and i perceive a knockish noise [or maybe im tripping myself out]).

mostly city driving, but out to the folks place yesterday loaded with 3 girls, to run a canoe down the river - good times! about a 40 min drive, 65mph - oil temp to about 200/210 tops, no funky smells, kinda gutless on the hills, ( I still have no frame of reference as to what "normal" power is on a bus, i have only ever driven my own engines, both of which have been 411 spec) very windy drive but the bus handled well on the new konis and swing plate bushings. the girls kinda thought i was all over the place though!

intake and exhaust temperatures are basically equal from side to side, ( say 70C intakes and 375C exhausts, as measured with lazer pointer thermometer). I have yet to get the tuneup procedure 100%...i know the high RPM is balanced, but the idle balance is still very poor - and it idles a little rough - i had it idling smoother last year. note my compression is about 10lbs lower on the left side - so that doesn't help! (valves double/triple checked, not too clattery, but i have not ever removed the rockers to inspect the valves stems for... concavity? is that a word?

last tank of fuel gave me about 16.5 MPG. better than the last set of carbs, but not stellar? seems to generally maintain the same level of power all day, but when hot in the city it can power out a tad on a hot restart initially (only once actually), and suffer a little low idle when hot. flat spot feels nominal if at all to me, but again no frame of reference

so, whaddya guys think? sounds normal?

[Amskeptic]

hey guys! - here's an update
idles a little rough -16.5 MPG. seems to maintain power
sounds normal?

Sounds like a C/C+ midterm exam.
Colin

[rustbus]

hey guys! - here's an update
idles a little rough -16.5 MPG. seems to maintain power
sounds normal?

Sounds like a C/C+ midterm exam.
Colin

well that's not a great grade!

I'll finish the 'semester' up soon - but a question on the low idle balance to keep me focused- in your procedure you mention adjusting the throttle stop screws 1/4ish of a turn in opposite directions to compensate for imbalance, and leave it at that - so if with my "snail type" syncronizer, I see, for example, a "2" on the left side and a "5" on the right side, and the 1/4" adjustment helps nominally, shall I just leave it at that and move on with the tuneup?

thank you

Kris