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Hard starting...timing issue?

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Bryan Boyle:
Lately I've been noticing that the TC buggy has been a bit recalcitrant to start...even with a spritz of ether...it eventually catches and then runs (ok, stromberg carbs, starting device engaged, no foot on the accelerator, dashpots topped off, etc.) and when it does warm up...after a run, seems to like to idle at 1200 or so...smooth idle, but a bit high.  Dizzy is a pertronix, high-volt coil, new wires, plugs have maybe 1500 miles on them...up to now has been a couple seconds cranking but it's fired off ok.  Now, not so fast.

First: is it getting gas, right?  Fuel filter has fuel in it, pumping the priming lever eliminates the little bubble I saw from it sitting.

So, figured I'd investigate further...pulled the plugs (NGKs)...checked the gaps, they're where I left them (I mark the plugs with the gaps), removed the cap, some roughness on the edge of the arm contact surface cleaned up with crocus cloth, cap is clean, no carbon, all the wires are firmly seated in both the coil and the cap.

Got her started after churning a bit...stumbled to life and let it idle with carb starter mechanism engaged till it settled down and warmed up by driving around the block so I could turn the starter circuit off.  Hooked up timing light (I know too much advance can make it hard to start), and (it's an adjustable timing light, so I can dial the strobe to zero her out and read the advance off the dial) find, at 1000-1200 rpm...I'm at 15 degrees advance.  I'm thinking that is a bit much for idle (and may, once the engine starts, account for some of my higher idle speed.)

So, wondering (Federal engine...) what folk who have an electronic dizzy, mechanical advance, have found is a reasonable idle advance figure.  I can't believe that 15 degrees is right; that never lets the compression (my 1-4 compressions are all in the 155-165 lb range) get close to TDC...and may account for a bit of hard starting.

Yes, I know carbs need a refresh (hence my questions earlier)...but they've been reasonably working until now...can't believe that they went tango uniform between an easy starting day and 2 days later...Tanks are filled with avgas/pump gas, so I don't believe there's a varnish issue or clogged jets, or I'd never get the car to smoothly settle down (as much as 1200 idle after a run is settled...lol). 

Thoughts? 

BDA:
The timing spec for a Stromberg TC is 5 degrees BTDC static. I think I would start there.

Bryan Boyle:

--- Quote from: BDA on Wednesday,March 20, 2024, 04:47:05 PM ---The timing spec for a Stromberg TC is 5 degrees BTDC static. I think I would start there.

--- End quote ---

Should have looked that up...;)   Thanks!  I guess I can always loosen up the clamp and swing the dizzy a bit...and see if that makes a difference...but that's a good starting point...it only cranks over at 100 RPM to begin with...Have to look at the curves in Wilkins to see where it should be at idle, I guess #2.

Kendo:
When my Stromberg TCS was hard to start, I traced it to a corroded ground strap. But I imagine you have that sorted pretty well.

jbcollier:
A 4-port Europa TC is set to 12° at idle and has 14° of mechanical advance which gives a total advance of 26°.

A 2-port Europa TC is set to 5° at idle but it has a vacuum retard unit so the timings are probably similar.

I always start with valve clearances.  Stromberg carbs (and SUs) are very sensitive to tight valves.

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