1986 Chevy c10 stalls in gear until warm (even on hot mornings)

[Davidj]

I have a 1985 Chevy c10/Silverado with a 350cfm and a 600 holley vacuum secondary. Hei distributor at about 16° BTDC idle timing. Any less advance and it won’t idle worth anything. 19 psi on the vacuum gauge at idle (haven’t checked vacuum at idle in gear yet but plan on it.) anyways, this truck runs like a dream! I couldn’t be happier with it. Snappy taking off, doesn’t bog on decel. Idles about 900ish by ear (no tach) but when it’s cold, (even on a hot day) she Will start right up, idle hunt maybe 10-15 seconds and even out. BUT I still have to wait 3-5 minutes until my oil temp giraffe starts moving before I put it in gear or it dies 100% of the time. Once warmed up, I don’t need to use the electric choke at all to get it to start again. Hardly have to prime it. My question is, is this just a grumpy old 350 issue? Or should I expect on a 90° day to hop in, start it up, and take off in moments? This is my first classic vehicle so I’m unsure if it’s just my expectations that are the issue here.

 

[Davidj]

I have a 1985 Chevy c10/Silverado with a 350cfm and a 600 holley vacuum secondary. Hei distributor at about 16° BTDC idle timing. Any less advance and it won’t idle worth anything. 19 psi on the vacuum gauge at idle (haven’t checked vacuum at idle in gear yet but plan on it.) anyways, this truck runs like a dream! I couldn’t be happier with it. Snappy taking off, doesn’t bog on decel. Idles about 900ish by ear (no tach) but when it’s cold, (even on a hot day) she Will start right up, idle hunt maybe 10-15 seconds and even out. BUT I still have to wait 3-5 minutes until my oil temp giraffe starts moving before I put it in gear or it dies 100% of the time. Once warmed up, I don’t need to use the electric choke at all to get it to start again. Hardly have to prime it. My question is, is this just a grumpy old 350 issue? Or should I expect on a 90° day to hop in, start it up, and take off in moments? This is my first classic vehicle so I’m unsure if it’s just my expectations that are the issue here.

Oil temp giraffe was a typo but funny so I left it in. (Oil temp gauge)

 

[Ricko1966]

No what you are experiencing is not normal. It's 68 degrees right now,my choke is totally disabled I have zero doubt I could jump in right now pump the pedal twice it would start idle and drive away without hesitation. FAIL!!! I was working on the truck earlier today it did start right up but I could hear a huge vacuum leak. So let me fix that brb.

 

[Davidj]

Okay, let me know how it goes. Haha. Also forgot to mention I’m certain it’s not a vacuum leak. Replaced most lines and the others were perfect. I also saw you can adjust the vacuum advance? When I got this carb off the old man I bought it from he told me to hook the vacuum advance up to ported vacuum on the front metering block of the carb. Maybe this could be it? Should I try vacuum advance to full manifold vacuum or adjusting the vacuum advance itself? I sucked on the hose while it idled and I tell ya, my ex wife couldn’t have activated it. That’s for sure.

 

[Ricko1966]

If your vacuum advance isn't working that is a problem. And ignore what sticker says or what the book says for timing. You'll need to find out what your truck likes for total,then how fast we can bring it in and then how much vacuum advance we can add. Stock specs were written for stock trucks with factory everything.

 

[Davidj]

As far as timing goes I had it up to 22° initial and got pinging (I think… gravel shaking in a bottle sound) at WOT so I put it back down a few because it didn’t feel right. The vacuum advance does work. But with the hose I had to kinda use my tongue as a check valve and really add up the vacuum. I feel like my carb doesn’t pull nearly that much.

 

[Ricko1966]

Okay so you have a timing light? Vacuum advance disconnected and plugged point your timing light at the pulley see where your mark is Rev the engine a couple of times,verify the mark moves with engine rpm. Now hook the advance to manifold vaccum and see if the mark moves. That will tell us if the centrifugal advance is working and if the vacuum advance is working.

 

[Davidj]

Got ya. That’s what I was thinking of doing next. Just haven’t gotten to it. I thought of doing it to see if it would help at idle but it totally makes sense to do it to check the vacuum advances functionality to begin with. Thanks! I’ll make another reply with results after work tomorrow.

 

[Davidj]

Although I do recall seeing it advance while revving. Could this be just the mechanical advance though?

 

[Davidj]

I feel stupid that I don’t know how to edit old replies for more info but when I saw it advance before, it was while the vacuum advance was disconnected for initial timing. I now see the edit option.

 

[Ricko1966]

Well I feel stupid,I forgot I hadn't set my fuel pressure from 2 days ago when I changed the restrictor on my return line. Runs like a champ again.

 

[Ricko1966]

Yes you want to see it advance with engine rpm vac advance disconnected. That's tells us the centrifugal is working. Then hook and unhook the vacuum to a manifold source we want to see the mark move significantly.

 

[Davidj]

so I’m guessing it didn’t “start, idle and drive away without hesitation?”

 

[Ricko1966]

It does now,had to adjust fuel pressure. I had forgot I needed to do that. I feel much better now.

 

[Davidj]

Got it! I’ll post results asap! Glad you got yours sorted. Haha. Also there’s this odd canister on my exhaust that isn’t hooked up. Seems vacuum activated maybe a restrictor of some sort to create back pressure?