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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: txchainsawgogi on February 20, 2011, 10:55:55 am

Title: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on February 20, 2011, 10:55:55 am
So I really need to adjust my idle after the rebuild. It runs and starts great but it sputters after it warms all the way up.

It doesn't die(fingers crossed), just sputters a bit and has a little shimmy to it.

Oh yeah, only at a stop or just coming from a stop.

My haynes says I need a hand held tach... autozone, o reillys and napa didn't have them. Autozone even said " we can't even order them anymore".

What do I do?
Title: Re: adjusting idle speed/ hand held tach?
Post by: VileZambonie on February 20, 2011, 12:16:53 pm
Don't worry about ur idle until you fix your sputtering.
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on February 20, 2011, 02:36:03 pm
well i figured their related as it only does it when im stopped, as in when it idles. it feels like it idles too low.
if i keep my foot just lightly on the gas it fixes it.

i've watched the carb while it does it, all the linkages are fine and the butterflies are operating properly. everything in the carb is how it should be...i went over the rebuild twice.

it only started doing it after i rebuilt the carb. im thinking the previous owner fiddled with the idle screws to try and compensate for the fact that it needed a rebuild.

Title: Re: adjusting idle speed/ hand held tach?
Post by: TexasRed on February 20, 2011, 03:21:22 pm
OK. They said no go on the tach? They don't have a small performance section at any o'reilly's? Wow. It doesn't have to be handheld. You can just hold the gauge while you're under the hood.
Title: Re: adjusting idle speed/ hand held tach?
Post by: topp on February 20, 2011, 05:11:25 pm
well i figured their related as it only does it when im stopped, as in when it idles. it feels like it idles too low.
if i keep my foot just lightly on the gas it fixes it.

i've watched the carb while it does it, all the linkages are fine and the butterflies are operating properly. everything in the carb is how it should be...i went over the rebuild twice.

it only started doing it after i rebuilt the carb. im thinking the previous owner fiddled with the idle screws to try and compensate for the fact that it needed a rebuild.



Perhaps you have a vacuum leak causing the sputtering, and the PO compensated for that by adjusting the carb.


I agree with Vile, fix the sputtering first, then worry about th idle as the sputtering will affect it if you try and set it first.
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on February 20, 2011, 05:16:53 pm
well im doubtful there is a vacuum leak, as the carb itself has new gaskets and is tightened properly. the hoses are all really snug as well but i can double check those.

Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on February 20, 2011, 08:26:24 pm
OK. They said no go on the tach? They don't have a small performance section at any o'reilly's? Wow. It doesn't have to be handheld. You can just hold the gauge while you're under the hood.


i was thinking about an aftermarket tach anyway... are they pretty easy to hookup?
Title: Re: adjusting idle speed/ hand held tach?
Post by: TexasRed on February 20, 2011, 10:27:00 pm
Just a power wire, ground wire, and tach wire.
Title: Re: adjusting idle speed/ hand held tach?
Post by: topp on February 21, 2011, 08:54:23 am
well im doubtful there is a vacuum leak, as the carb itself has new gaskets and is tightened properly. the hoses are all really snug as well but i can double check those.



Many other places for a vacuum leak than the carb.  Anywhere on the intake, for example....
Title: Re: adjusting idle speed/ hand held tach?
Post by: VileZambonie on February 21, 2011, 06:02:45 pm
OK. They said no go on the tach? They don't have a small performance section at any o'reilly's? Wow. It doesn't have to be handheld. You can just hold the gauge while you're under the hood.


i was thinking about an aftermarket tach anyway... are they pretty easy to hookup?

Why don't you buy an advance timing light with a tach?
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on February 21, 2011, 11:26:54 pm
I already have a timing light...I didn't think about it. I don't have a timing tab anyway thanks to the previous owner removing it? Haha.
Title: Re: adjusting idle speed/ hand held tach?
Post by: slammed79 on February 22, 2011, 01:53:22 pm
Is there are mark on the block and balancer?
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on February 22, 2011, 03:09:23 pm
Is there are mark on the block and balancer?

Nope, not that I can see.
Title: Re: adjusting idle speed/ hand held tach?
Post by: VileZambonie on February 22, 2011, 07:08:16 pm
Installing a timing tab would make sense if you are concerned about setting your idle speed to spec according to a tach don't cha think?

Another option is if you don't have a good meter, purchase a new meter with an RPM probe.
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on February 22, 2011, 07:56:06 pm
Installing a timing tab would make sense if you are concerned about setting your idle speed to spec according to a tach don't cha think?

Another option is if you don't have a good meter, purchase a new meter with an RPM probe.

FINE i'll suck it up and take off the power steering pump and try and put it a tab on there. how do i remove the pump? will i have to flush the pump or anything fluid wise?
Title: Re: adjusting idle speed/ hand held tach?
Post by: beastie_3 on February 22, 2011, 08:04:25 pm
no you can remove the pump with the hoses still attached. There should be three bolts holding it on.
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on February 22, 2011, 09:25:55 pm
 wouldnt my marks be messed up if i replace it with anything but stock? as in, how do i know where the original 0° mark is?

i dont get it.
Title: Re: adjusting idle speed/ hand held tach?
Post by: VileZambonie on February 22, 2011, 09:36:44 pm
This ship is veering way of course aye? Again I'd worry about fixing your sputtering issue first.
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on February 22, 2011, 10:12:13 pm
This ship is veering way of course aye? Again I'd worry about fixing your sputtering issue first.

it hasnt been doing it these past few days... it only did it on the way home from work once. then i changed the oil and the filter, and drove it did it again right after when i went to get groceries(all the same day). then out of no where on the way home from the store it ran fine. no low idle feeling, no shimmy when i take my foot off the gas.

so i dont really know how to diagnose it... i checked around the carb for vacuum leaks.

would maybe a sticking thermostat choke pull cause it to act weird? i noticed today when replacing the air cleaner that my forward most flap wasnt all the way closed, even after hours of rest. i had to push it closed and it seemed to have a lot of resistance to it. after i pushed it closed it operated smoothly again.
Title: Re: adjusting idle speed/ hand held tach?
Post by: Grim 82 on February 23, 2011, 08:45:06 am
Agreed with all of the above. I have a digital dial back timing light with a built in tach and it works great. Check all your hose connections to rule out a vacuum leak somewhere else besides the carb, and spray around your intake manifold with carb cleaner to see if the idle changes. Then remove the 3 fasteners that hold the p/s pump on, move it out of the way, and put one of those $5 gypsy chrome timing tabs on it.

I wouldn't worry too much about the choke closing all the way when it's cold, but make sure that it opens all the way when warm or you could get a sputter and hesitation.
Title: Re: adjusting idle speed/ hand held tach?
Post by: devanray on March 01, 2011, 08:38:51 pm
I'm thinking what Grim is thinking, rule out the vacuum.

I had a '70 duster that would sputter at stops because, of all things, the brake booster diaphragm had a puncture in it.  It was small but enough to cause a vacuum issue when stopping or with the foot on the brakes.

And a tach is so easy to install, did one today in about 15 minutes, most of the time was spent routing the tach wire and finding spots on my fuse box.
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on March 01, 2011, 08:52:45 pm
i have a tach now, it took like ten minutes. pretty good for 24$

my m/c needed to be replaced, and i did that also... the brake booster thing might be part of it, the metal vacuum line going to it has a kink.

HMMM....
Title: Re: adjusting idle speed/ hand held tach?
Post by: devanray on March 02, 2011, 10:26:14 pm
Yeah, I think the tach is in the top five for cheap upgrades on a rig.

So, work out the kinks yet?
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on March 02, 2011, 10:48:38 pm
the timing thing is still an issue....but i have it driveable... the best it's probably been in years. the actual kink is not worked out though haha i'd need a new vacuum line
Title: Re: adjusting idle speed/ hand held tach?
Post by: devanray on March 02, 2011, 11:10:48 pm
Well, better is just that, better. One step at a time, that's what my wallet always says. Just be sure your safe on the road.
I've got timing/fuel/air/idle issues, going to have someone else do for me, it will cost but then I will know its done right, just one more thing off the list. Pretty soon, well have safe, powerful and sweat looking rides.

Like your rig btw. It's no stepside but hey, not everyone can be as cool as me.  :D
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on March 03, 2011, 12:09:56 am
Haha well I'm actually converting it to a long wheel base stepside. I have never seen one in town so it'll standout for sure.

Finished product is gonna be a dropped flat black c10 lwb step, with a high gloss orange rust cab top and camper shell(70s style with bubble windows fingers crossed). Hood scoop, mild engine mods, dual exhaust and headers sitting on vintage 15" chrome cragars.
Title: Re: adjusting idle speed/ hand held tach?
Post by: devanray on March 03, 2011, 11:06:36 am
Wow, can't wait to see that when it is finished! Good on you for making it a stepside!

Keep us updated on your progress on your current issue and on the project itself.
Title: Re: adjusting idle speed/ hand held tach?
Post by: roger97338 on March 06, 2011, 07:51:15 am
Like your rig btw. It's no stepside but hey, not everyone can be as cool as me.  :D

Oh snap, son!
Title: Re: adjusting idle speed/ hand held tach?
Post by: Dr_Snooz on March 06, 2011, 11:59:29 am
What's the likelihood that adjusting the idle mixture would cure the sputtering?
Title: Re: adjusting idle speed/ hand held tach?
Post by: txchainsawgogi on March 06, 2011, 02:09:40 pm
its acting a lot better now actually. tightened down the carb and checked all the vacuum lines and adjusted the idle a bit. it idles nice now.