Finn5033

Thanks to the help from a lot of you on this site I got the 350 changed out in my cutlass and it is now on the road cruising and running great. The one thing I am having trouble with is cold starting. I have to crank it over for about 5 seconds and pump the pedal to get it to start. Once it starts it runs great, and when warm it fires right up. What could be the cause of this? Also I am confused about what the timing should be set at. It is a 77 engine with a 72 intake and carb. It is a factory HEI distributor I do not know what year it is. I was told the timing should be around 20 and that is what I set it at while idling and everything hooked up. I have seen that possibly I should have the vacuum line to the distributor off and plugged while setting timing? Any help would be great, thank you.

brown7373

A 72 350 4bbl has an initial timing of 12 degrees BTDC. What kind of choke do you have and is it set up and adjusted properly, and is it a 72 Q-jet? I own 3 Q-jet cars with stock chokes and they are all working properly. You push the gas to the floor once, release it and turn the key. All fire within about 1 second and are on fast idle. I let them run on fast idle for 5, maybe 10 seconds then bump the gas which lowers the carb to the 2nd step of the choke cam and a idle speed approximately between the fast idel and the regular idle when warmed up. I can put any of the cars in gear and drive away immediately wioth no issues.

20 degrees initial sound a bit much to me. Too much initial can sometimes make it harder to start. Is your vacuum advance connected and working properly? It is difficult to know for sure until you know exactly what components you have and how they are set up.

Finn5033

I do not know what kind of choke I have. But I also did not know about the 1 pump to start and tapping to slow idle after idling for a few seconds. I will try that and see if it works. However everywhere I look I am being told that if you have HEI you should set your timing at 20. Where did you find your info saying to set to 12?

MDchanic

You're kidding right?
Five seconds?
My '98 BMW doesn't start in five seconds, hot or cold, between the one-second RFID pause for the key chip to be identified and the need to crank over two or three times to confirm function of the cam and crank position sensors before the computer fires the plugs.

20°BTDC for non-modified HEI is about right, but you've got to tune for your exact application.

Timing at idle is always set with the vacuum advance disconnected and the source plugged. If your vacuum source is ported, this will not actually matter, but if it is straight manifold vacuum, it will make a significant difference.

- Eric

edit: Just saw Brown's post, before mine, and your response.

You're not setting the choke before you crank it over?
Sounds like that could be your problem right there.
I've got to start looking at these problems with a broader view...

As for timing, the HEI distributor has less mechanical advance built in, so it needs to be set more advanced at idle in order to give you the right advance at speed.

Finn5033

10-4