STILL having start up issues

[tcodi]

I'm still having problems starting up my BB chev. If it's around 40 outside I have to pump the gas pedal 4 or 5 times to spray the intake before trying to start it. If I do that just the right amount of times depending on temperature it will start. Sometimes if I stop at a gas station when it's fully warmed it starts, sometimes not. I never know if I should give it a squirt or two, whether I should choke it, or just turn the key when it's warm.
If I guess wrong and it doesn't fire up then it is even harder to get it to fire on the next crank.
The cam is a 226 @ .050 hyd., I'm running 15 degrees static advance with vacuum that brings it up another 10.

I'm starting to get really frustrated, I don't know what I'm doing wrong or what I set up wrong. I've been working on this thing EVERY day for the past year and a half and now it's finally done and I can't even enjoy driving it because I'm constantly worrying about whether or not it's gonna start when I park it.
I might as well just flip a coin.

[tcodi]

the mixture thing is definitely a part of the problem. I'll have the idle set great and then it will be 15 degrees warmer one day and the thing will be all screwed up.

I also just bought a book on ignition systems, I suspect that may be a culprit too.

Hopefully by spring I'll have it figured out.

[thesals]

what carb are you running on the motor and how old is it?

[tcodi]

it's an edelbrock thunder series 650 cfm.
it's bran new, the motor isn't, but the cylinders looked fine.

it's a manual choke, is that what makes all the difference? I know I've used carbureted vehicles and boats that had electric chokes and they would start up first try every time, no pedal pumping or anything like that.
Could a slightly longer cam make that much difference?

[tcodi]

Could the fact that I'm using manifold vacuum and not ported vacuum be affecting this problem?

I feel like the plugs would have a better chance at lighting the mixture if it was a little later in the compression stroke so it would be more compressed at ignition.
I'm not really basing that on anything though.

[Aster]

I agree that the timing seems way off. Have you had a good carb shop look at it? Sometimes when you've been looking at it that long, you get blind to the problem. Sounds like getting a second opinion from someone who can look at it is going to be money well spent. I'd take it in before you lose confidence in it. Good luck.

[tcodi]

yeah, the baseline timing with no vacuum is 15. It seemed to idle much better the more timing I gave it.
Would the vacuum advance be kicking in while it is just cranking, or wouldn't that build enough vacuum to do it?

Also, do coils decay over time?

[thesals]

yeah thats too advanced... that'll cause startup issues.... if it seems to idle a little rough, try adjusting your vaccum advance, a lil.... and yes coils can decay over time, but ussually they dont... ussually its from being bumped around and from getting overvolted... the inside of a coil is thousands of spools of wire that cause a magnetic field.....

[tcodi]

as I read in my ignition system book I did some tests on coil and wire resistance. The book says coil primary side resistance should be less then 1 ohm, secondary side could be over 1000 ohms.
My primary side is about .8 or .9 ohms and the secondary side is over 4000 ohms. It is an msd blaster 2, I using an MSD 6AL box with it.

I measured the resistance of my coil to cap wire, which is about a foot long, and it measured 1300 ohms. I measured another arbitrary plug wire just to get a reference, (#2 cylinder wire), and it was about 400 ohms.

I haven't gotten very far in the book yet but I don't think my coil should have that much secondary resistance, and I also don't think the coil wire should have that much either.

[tcodi]

welp, just went to msd's site and apparently that coil is supposed to have those resistances.
that plug wire still seems sketchy.

[tcodi]

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