Hot starts...

[Impalaguru]

HI Everyone,
I've got an older 9000 series carter on my stock 340hp engine and its seems to be soaking up heat pretty quickly when I shut the car off. All there is between the aluminum carb and the iron intake is a gasket. Its a little more difficult than I would like to get it restarted, sometimes it will die if I don't feather the throttle for a couple of seconds. I'm going to be pulling the AFB off in a week or so for a rebuild, should I think about putting some kind of insulator in there? Like one off a 300hp 327? Any help would be great!
Ross

[bowtieollie]

Did you check the heat riser and verify that it is not STUCK shut?

Hot restarts on an 09 are really rare.....

Are you getting black smoke out the exhaust during the restart?
If so, then the float level may need a tweak.

[Impalaguru]

BowtieOllie-
YEP, its the heat riser valve! It isn't totally stuck but it wasn't opening. This valve is only a few months old, is there any sort of lube or anything I can do to get it working smoothly again? Thanks for your help!
Ross

[bowtieollie]

Visit your local friendly Chevy dealer.

GM has a specific lubricant for Heat Risers.

You can't use "just any" oil, as it will carbonize and cause binding.

Glad you found it! Ahhhhhhh, another happy 409!:cheers

[SS425HP]

Mine was bound up by the exhaust pipe sticking through the welded cone, that the donut rested on. Had the damned thing jammed shut. Didn't know what it was for 4 months. Made the motor run hot. Actually, I spent about $500.00 trying to fix the heat problem, before finding the riser stuck shut. Was doing an oil change, and like we always used to do, reached up to check it. Was stuck. I had recored the radiator, changed the water pump, changed 3 thermostats, tried no thermostat.
The key was, it ran hotter the faster I ran. Slow down, and it cooled down. Oh, also bought 2 fan clutches. Drove me nuts. After I found it, the car runs nice and cool, and MUCH FASTER at high RPMs. Sure loosened up the thing. Was very much quicker. Felt like a complete idiot. I had told several people, that when I found the problem, it would be something stupid, and it was. I had told numerous people about this problem, and we all missed it for 4 months. :cuss

Fred

[Rockfish39]

Heat riser valves one and only one purpose in life is to increase exhaust pressure on the right side to warm up the intake (via cross over ports) as fast as possible. Theoretically the thermal coil spring on the side of it releases tension on the valve when hot... Exhaust pressure then pushes the valve open

That works fine for people who have to start and go on a cold day, all in 30 secs.

Cars Inc. makes a really nice spacer that takes the place of that valve. Want to do it even cheaper??? Remove the spring and rotate the valve open with channel locks. (problem solved)

The trade off is that your warm up time goes up to about 2 minutes, but who cares on a car that you dont drive to work every day???


Rock

:cool:

[Mr Goodwrench]

I agree with rockfish get rid of it, most chevy truck engines (366/427) use just a spacer block in place of the heat riser, looks just like it but not drilled for the shaft no weight or flapper, just open.

[Impalaguru]

Well, I would have gotten rid of it except I am driving this car EVERY day! Check my signature. I've been driving it everyday since Jan 18th. I was running this car in sub-zero temps and without that heatriser I would have never gotten to class on time. If this was only a spring/summer car (like it should be) I would ditch the heat riser. Thanks for your input.
Ross