Start up idle

Reply Subscribe

Thread Tools

Search this Thread

Feb 21, 2019 | 09:55 PM

vincethome

Thread Starter

7th Gear

Joined: Jul 2017

Posts: 7

Likes: 0

From: Louisville, Ky.

Start up idle

I have a 77' L48. Just replaced the intake and carb. Edelbrock 2101 & a new Holley Street Warrior 4160 /600 cfm. It starts up with a bump of the key at 1500 fast idle then after about 10 to 15 seconds it gets a real rough idle for about 1 minute then it will smooth out and rpms increase to 1800. Man I hate that minute...

Feb 21, 2019 | 10:52 PM

TimAT

Le Mans Master

Joined: Oct 2006

Posts: 7,123

Likes: 433

From: Gladstone MO

C3 of Year Finalist (appearance mods) 2019

I would start by looking at the choke system. Your description sounds like the choke is coming on correctly, but the choke plate is not opening far enough to give it enough air to smoothly idle after start.

Feb 22, 2019 | 12:08 AM

Haggisbash

Melting Slicks

Joined: Oct 2012

Posts: 2,156

Likes: 273

From: Dunedin NZ.

Quote:

Originally Posted by vincethome

Hi, I assume you meant 800 rpm? What is the temp where you live? This will have an effect on the choke setting, if the weather is cool it seems to me that the choke is probably opening a little too quickly and the engine hasn't warmed enough to idle smoothly. If you keep the revs up above 1000 using your foot on the gas pedal when it starts to idle rough does the engine run smoothly?

Feb 22, 2019 | 05:18 PM

vincethome

Thread Starter

7th Gear

Joined: Jul 2017

Posts: 7

Likes: 0

From: Louisville, Ky.

Thanks, I believe you are right. I had to lean it up to get the choke plate to respond. Still have some fast idle speed to work on, it wants to start up at 2000!

Feb 22, 2019 | 05:52 PM

vincethome

Thread Starter

7th Gear

Joined: Jul 2017

Posts: 7

Likes: 0

From: Louisville, Ky.

Hello! No, it actually would start fine around 1400 then begin to sputter and as it started to smooth out the rpms would increase up to 1800! I'm in Louisville, Ky temps are 30's 40's. When I tried to accelerate it kept sputtering. Someone suggested it was not opening and I think they may be right. I had to lean up to get the choke plate to respond. It doesn't sputter but my idle speed is 2000! Got some adjusting to do.
Thanks!

Feb 22, 2019 | 06:21 PM

HeadsU.P.

Le Mans Master

Joined: Aug 2017

Posts: 8,336

Likes: 2,810

From: Cool Northern Michigan

Do you know for sure, the secondary throttle blades are even closing fully at idle? Its more common than you think on several carbs. If the throttle shaft sticks, even a frogs hair, your idle will be all over the place.