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B20 timing woes

vwbusman66

Stößelstange über alles
Joined
Oct 12, 2016
Location
SE MI
So here's the story: recently rebuilt B20 with about 2k miles on it. Isky 171 cam with steel timing set, F head skimmed to 9.5:1 SCR.

I went to start it after install with no luck. Swapped pertronix to points after no spark, advanced timing and viola. Re-gapped points to .017", adjusted timing to 10 degrees BTDC. Engine coughs barely but wont start. Re-advance timing to 30-something degrees and it'll run. Distributor is a B20E dizzy with no wires (twin SU's).

What am I missing?
 
Are you sure the crank pulley is indexed properly? The tang on the stamped steel pulleys can shear off if the crank bolt isn't tight or get bent if not aligned properly during installation.
 
Are you sure the crank pulley is indexed properly? The tang on the stamped steel pulleys can shear off if the crank bolt isn't tight or get bent if not aligned properly during installation.

I'll double check tomorrow. Does the E/F distributor require any special timing procedure other than 10 degrees at idle?
 
Are you sure the distributor isn’t 180 off? Because for some reason I always set mine up that way and then I never fix it. I just flip the plug wires around and forget about it.

Just asking because the car absolutely will run (badly) with it 180 off.
 
With it at TDC - look in the oil cap (assuming it's the common front oil cap, not the early mid oil cap) and see if either of the #1 rocker arms are open. If so, the dist should be pointing to #4. If they're both closed, the dist should be pointing to #1.

Getting that timing gear in at the 'correct' position is a real PITA. Especially when you have to get it to seat into the oil pump over the last bit of downward travel, as the gear turns on the angled teeth.

I think half the time I end up with it technically 'off' some, and I just move wires around (if I missed it by a bunch) or twist the dist around (missed it a little) to accommodate, rather than fighting it.
 
I am kinda battling the same, but I think I got it stable.

Mine came down to mixture I believe.

I'm no B20B guru, but here's what I did to get mine going when I encountered this. First I loosened the dist bolt to where it could be turned with force but would not vibrate out of the timing I set it to.

Advance dist to where the engine will start & run, retard timing with engine running until engine gets a little rough.
Adjust carb mixture to 'bring it back to life'
Repeat until you're at 10 BTDC

You might be running too lean. A lean mixture will not propagate the flame kernel properly and may be requiring the absurd advance at idle you are seeing.
 
John, I had been using the "oil cap hole" method to verify TDC as well. Pretty convenient.

- Checked the pulley and it was identical in keying and marks to the one off of the B18. No problem there.
- Double checked points gap. Put it at .016" for my own sanity. It refused to start.
- Re-verified firing order 3 more times while futzing with timing settings to get it to show life. After switching to what I knew was 180* out, it acted like it was 180* out (popping out of the carb).
- Pulled the distributor to gap the points on the bench and inspect for any other issues. Lobes all looked good. Double checked the gap and installed a new condenser.
- Pulled the distributor clamp/housing/thing and went ahead and set the drive gear to the specified 35* CW from horizontal. I knew it was 180* out due to the rotor never pointing to the notch at #1 TDC.

- Put the rotor and cap on, moved the wires around to match the correct rotor position, turned the key, and it fired right up. I hooked my timing light back up and was able to back the timing off to 10* BDTC at idle with no vacuum. It now starts right up and I was able to tune the carbs. For some reason, when you rev it, it takes a few seconds to completely return to idle. I have no idea what that is, maybe just a product of way too much cam on the SU's?


TLDR; The distributor drive gear was installed about 200* out meaning something wasn't kosher. I don't actually know what the problem ended up being, but it runs well and the timing is where it should be and it behaves itself.
 
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