Engine Racing/Cold Start

[DipStick82]

My 71 C10 with GW 350 seems to be racing while at idle, but once shifted into drive purs like a kitten, nice and quiet. Once the truck is warmed up it no longer races at idle. This doesn't seem normal to me... Any ideas as to what is going on?

[geezer#99]

What carb?
What choke?
What's your initial timing?

[DipStick82]

Geezer, its an Edlebrock 4 barrel carb. I just picked the truck up not too long ago so thats all i Know at the moment....

[Stocker]

You can sometimes kick the fast idle cam part of the way down with a quick on-n-off stab of the loud pedal.

If it's a Q-jet (dunno if others are similar) and if adjustment is needed, check this short video: https://www.youtube.com/watch?v=qmFCh8LhRrU

[DipStick82]

Could a faulty thermostat contribute to the racing?

[Stocker]

I don't see how. But if it uses a bimetal spring for the choke pulloff, that might do it if the spring is bad.

[Mmorgan32]

Edelbrock with an electric choke? If so the choke is kicking on. You can adjust it by loosening the screws and turning it

[hamjet]

If you're new to the carb/choke world thats the way they operate, unlike the new FI computor monitered stuff today. It possibly could be revving too high when cold which can be corrected but they are meant to rev higher when stone cold. it sounds like it's working as it should. how high is it racing?

[Saphiro]

It sounds like it's performing as it should on a cold start.
If you think it's warmed up, just blip the throttle and that should kick the choke off.

[Hayden Buck]

I have just started racing and every time I floor it it starts to surge. Any ideas why and how do fix this? It has a 4 barrel carb and it was just tuned and timed to drag race. It has a small block 355 motor with high performance headers
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[davepl]

Depends what you mean by "Racing". If you mean the engine idles up around 1000-1200 RPM until it warms up, that's normal. If it's higher than that, or staying that way once warmed up, that'd be abnormal.

[Hayden Buck]

Originally Posted by davepl

Depends what you mean by "Racing". If you mean the engine idles up around 1000-1200 RPM until it warms up, that's normal. If it's higher than that, or staying that way once warmed up, that'd be abnormal.

It does it only when its warmed up and around 1600 rpm.
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[Hayden Buck]

It also likes to lose power when I get started and I'm drag racing
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[AussieinNC]

Cold start fast idle cam sets cold start high idle level to keep cold engine lit.

You can adjust it down...look for a manual for the carb online, it will show you the screw to turn out...if its an electric choke, you must allow it to cool down before it can be set again...

Your surging issue could be a lot of things...sounds like fuel supply loss of pressure ...starting at the fuel tank...could be clogged strainer on the pickup, split pickup tube in tank, crushed fuel supply line, bad fuel pump, bad settings on carb float level...

Other possible causes, retarded cam action due to bad timing chain/gear, bad ignition timing, weak valve springs...your surge may be valve float...

Have fun my friend...

[Swar]

Put a manual choke on it.

[Hayden Buck]

[QUOTE=Swar;7974686]Put a manual choke on it.[/QUOTE

Ok I'll do that it has a electric choke Holley 750 ccm
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[Swar]

I don't know Holleys, but I'm sure you can convert it. Mine's a worked 350 with dual quads (Edelbrock 500 cfm each) I've never had a problem in the 10 years of driving it with the manual choke.

[Hayden Buck]

Ok
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