Flat spot on 77 quadrajet when cold

[86c20]

10-12?? thought that it was around 8??? or is that just a good starting point? if it is 10-12 i need to up my timing lol

[INSIDIOUS '86]

That's where most sbc like it 8 will work in a lot of none stock apps
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[GM-power]

@insidious, my bad I jumped to the last post. A good tune will fix that issue.
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[86c20]

looks like iit is going up lol. thanks for the info.

[Dead Parrot]

Your electric choke should have a rich-lean adjustment. Nudge it a bit toward the rich side. Sounds like your choke is still a bit lean while cold. I would start there since it sounds like it is otherwise working fine.

On the timing, book will say 4-8 btc. But most stock 350s run better with 10-12btc. Some will take a bit more depending on how your vacuum and mechanical advance is set up. If you have emissions testing, advancing the timing can increase NOx so you might want to return to book before emissions testing.

[OxonCounty77]

Thanks dead parrot.
Sorry for the dealy in replying on here- we are 6hrs ahead so Im on my beauty sleep whilst you chaps have been tapping away.
You may be right with the choke cover.
There were no instructions with the kit. So I put the unit on whilst holding the strangler flap closed/throttle on the fast idle cam. There are no markings on the cover (which the old one had). So it may be 'set it up by trial and error.'
This actually sounds quite likely. (Will double check timing first as well)

Thanks again to all who have contributed to this thread-theres a wealth of info out there-it's great you folks are keen to share it.

[INSIDIOUS '86]

Originally Posted by Dead Parrot

Your electric choke should have a rich-lean adjustment. Nudge it a bit toward the rich side. Sounds like your choke is still a bit lean while cold. I would start there since it sounds like it is otherwise working fine.

On the timing, book will say 4-8 btc. But most stock 350s run better with 10-12btc. Some will take a bit more depending on how your vacuum and mechanical advance is set up. If you have emissions testing, advancing the timing can increase NOx so you might want to return to book before emissions testing.

This still will not change your mixture. They really should say long short. Turning one way or another will change the choke from staying on Nearly forever to warm up the engine or a short duration for warmer climate
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[OxonCounty77]

Got a chance to have a quick tinker with the old girl tonight,looking at the things you good folks have mentioned.

1/Realised (duh!) that the vac pipe from the carb to the valve that feeds the hot/cold flap in the nose of the air cleaner was missing. The take off port at the rear of the carb had been plugged off. A new length of hose, & the flap is held closed now drawing warm air off the exhaust manifold. Must help during the warmup period.

2/ Tried to check the ign timing following various suggestions that it should be 10 deg or similar. Have found & highlighted the mark on the damper pulley.There appears to be no mark to line it up with. I expected to see a toothed plate on the timing cover,but cant even see where one might have been/broken off etc.Nothing either looking up from underneath.The timing light seems to indicate timing is set towards the passenger side of the cover.(More or less where it is in the picture when the engine was stopped). There is a vertical ridge stamped into the cover pressing towards the driver's side,but that doesnt look right either. Any thoughts welcome.

(PS/ Santa just came to our local garden centre in Bicester Oxfordshire (England) The kiddies will get their presents super-quick this year...)