adjust idle speed without tach - The 1947 - Present Chevrolet & GMC Truck Message Board Network

theredmeadow · 11-17-2013, 04:54 PM

Is it possible to adjust the idle speed on a 70 c10 350 stock without a tachometer? I recently got the project truck 3 weeks ago and since have raised it back to stock height, adjust panels, cleaned up the interior, connected the heater hoses, adjusted a loose lifter. Yesterday I changed the oil and oil filter, also changed out the spark plugs. I found the old spark plugs in bad shape and one fell apart as I took it out. SO since yesterday the truck has been running really smooth, the knock even went away. Except it seems to be idling fast, the oil pressure gauge at idle sits just a bit above 1/2 and the second I release the brake pedal it wants to get up and go.

Any way is there some way I can or should I slow the idle down? Can it be done without a tach?

Skid99 · 11-17-2013, 04:56 PM

adjust it to where it will a little more than barely stay running.

BMERDOC · 11-17-2013, 04:59 PM

Slowing the idle down is fine. It is almost necessary. Youll have a stronger vac signal at idle and it won't fight the brakes. You'll probably find that you'll need to lean out the idle mixture after slowing it down too. Just slow it down so its not fighting the brakes but not enough so that it won't die.

theredmeadow · 11-17-2013, 05:27 PM

ok so I've got it to where when I release the brake it pulls forward slowly instead. Still too fast? When I slow it down more than that sounds like the engine starts making a knock noise and sounds rough.

BMERDOC · 11-17-2013, 06:03 PM

It's probably fine at that speed. You don't need it so fast that it fights the brakes or so slow that it causes other problems. It's not a complete science. Personal choice for idle speeds vary between people by several hundred r.p.m. If that idle speed works for your truck then rock it. The next step would to be to check timing and idle mixture bit you'd need equipment for that. Some sort of tach, a vacuum gauge and a timing light should be considered basic tools but it sounds like you are fine where you are. If you wanna tweak the tune some more you'll have to invest in at least a vac gauge.

Longhorn 70 · 11-17-2013, 06:06 PM

I agree with above. Make sure that if you are stopped and blip the throttle a little bit then hit the breaks it doesn't kill the engine. If it does, it's too low.

theredmeadow · 11-17-2013, 10:36 PM

I'm not going to start another thread but I'm assuming the hose that connects to the PCV isn't correct and isn't there a piece that sits on top of the PCV? Also, what kind of problem can this create?

**davischevy** · 11-17-2013, 10:41 PM

Just get an L shaped PVC valve and run emissions (fuel) hose to the carb.

BMERDOC · 11-17-2013, 11:02 PM

Looks like someone used a "Poor Man's dress up kit" and just wrapped the hose in some corrugated wire loom. Take the hose clamps off peel it back and see whats underneath. Even if you have to replace the "whole system" it shouldn't cost more than $10.00. Valves that are stuck open or closed can cause oil consumption, low end driveabilty problems, sludging and other problems.

theredmeadow · 11-17-2013, 11:09 PM

I don't see any PCV valves that are L shaped so I'm guessing that I just get a new hose that fits properly and some new clamps.

BMERDOC · 11-17-2013, 11:23 PM

By the way it looks, if a PCV valve is in there its a straight one. The new one will have a 90 degree end on it. Pull the end out of the valve cover, snap a pic down the barrel of the end of that hose and I'll tell you what it has in it.

Longhorn 70 · 11-18-2013, 10:20 AM

MOST times the PCV valve is in the passenger's side valve cover toward the rear isn't it???

theredmeadow · 11-18-2013, 12:29 PM

Quote:

Originally Posted by Longhorn 70

MOST times the PCV valve is in the passenger's side valve cover toward the rear isn't it???

I have no idea. I'm far from being a mechanic. I got this truck 3 weeks ago and this is the shape its in. Do I need to swap the VC sides or can I leave it the way it is? Will it create any issues?

BMERDOC · 11-18-2013, 12:59 PM

You can leave it that way. As long as it has filter air for ventilation and a properly work vent valve hooked to vacuum it doesn't matter how its hooked up. I would rather see the fresh air supply attach at the bottom of the air cleaner so that the engine recieves filtered air a push in unit on the V/C will do just fine.

bbcmudtruck · 11-18-2013, 03:12 PM

It can be hooked up to either side of the motor. So seeing one on the passenger side is completely normal. Its just the way the p/o put the motor together. I like to run my pcb exactly like the one pictured. Its the cleanest/most direct way to run it in my opinion. As far as your idle goes, just adjust it so that your not lunging forward when you let off the brakes. It may want to creep forward, but as long as it doesn't want to take off and drive, you'll be fine. A very good and cheap investment would be a vacuum gauge. You can tune your carb and your timing with just a vacuum gauge. Easy to use and you will use it more than you'd think! There has to be at least a dozen things you can do with a vacuum gauge to help you with your motor.

DT1 · 11-18-2013, 05:56 PM

Quote:

Originally Posted by bbcmudtruck

It can be hooked up to either side of the motor. So seeing one on the passenger side is completely normal. Its just the way the p/o put the motor together. I like to run my pcb exactly like the one pictured. Its the cleanest/most direct way to run it in my opinion. As far as your idle goes, just adjust it so that your not lunging forward when you let off the brakes. It may want to creep forward, but as long as it doesn't want to take off and drive, you'll be fine. A very good and cheap investment would be a vacuum gauge. You can tune your carb and your timing with just a vacuum gauge. Easy to use and you will use it more than you'd think! There has to be at least a dozen things you can do with a vacuum gauge to help you with your motor.

I agree. That is how my PCV is installed. A vacuum gauge is inexpensive and in my opinion, a "Must" for fine tuning. With the exception of a mild RV cam and a few Carburetor mods, my engine is stock. I'm sort of fanatic when it comes to tuning. I'm happy when I can pull up to a light and can't feel the engine running. I've even gone as far as placing a glass of water on the air cleaner and adjusting the idle screws until the ripples almost disappear.

theredmeadow · 11-18-2013, 06:03 PM

Quote:

Originally Posted by DT1

I agree. That is how my PCV is installed. A vacuum gauge is inexpensive and in my opinion, a "Must" for fine tuning. With the exception of a mild RV cam and a few Carburetor mods, my engine is stock. I'm sort of fanatic when it comes to tuning. I'm happy when I can pull up to a light and can't feel the engine running. I've even gone as far as placing a glass of water on the air cleaner and adjusting the idle screws until the ripples almost disappear.

that's exactly how I am! Thats what I'm going for, to pull up and at idle I hardly feel the engine running. I've adjusted the idle lower but at some lights I'll feel it, almost like it's knocking and then other times I can hardly feel it. any tips?

**davischevy** · 11-18-2013, 06:31 PM

Quote:

Originally Posted by theredmeadow

I'm not going to start another thread but I'm assuming the hose that connects to the PCV isn't correct and isn't there a piece that sits on top of the PCV? Also, what kind of problem can this create?

I really can't tell much about that apparatus that is supposed to be the PCV valve, but is there any chance you have a vacuum leak there? That could affect your idle.

theredmeadow · 11-18-2013, 06:40 PM

Quote:

Originally Posted by davischevy

I really can't tell much about that apparatus that is supposed to be the PCV valve, but is there any chance you have a vacuum leak there? That could affect your idle.

Yes very well could be a leak. Thats not the only ghetto rig I've found in the truck. I've looked up the PCV replacement and there's none that have an L shape. I'm assuming that I just replace the hose with the correct size and clamps?

DT1 · 11-18-2013, 06:46 PM

Quote:

Originally Posted by theredmeadow

that's exactly how I am! Thats what I'm going for, to pull up and at idle I hardly feel the engine running. I've adjusted the idle lower but at some lights I'll feel it, almost like it's knocking and then other times I can hardly feel it. any tips?

Yes, I have a few and will be glad to share them with you. Right now, it's time for me to hit the road but I'll wright something up for you tonight (If someone here doesn't beat me to it). Also, I think I'm seeing a Carter Carburetor?

theredmeadow · 11-18-2013, 06:48 PM

Quote:

Originally Posted by DT1

Yes, I have a few and will be glad to share them with you. Right now, it's time for me to hit the road but I'll wright something up for you tonight (If someone here doesn't beat me to it). Also, I think I'm seeing a Carter Carburetor?

ok I appreciate it. I'm not sure, I haven't had a chance to find out the brand of Carb.

DT1 · 11-18-2013, 06:48 PM

Quote:

Originally Posted by theredmeadow

Yes very well could be a leak. Thats not the only ghetto rig I've found in the truck. I've looked up the PCV replacement and there's none that have an L shape. I'm assuming that I just replace the hose with the correct size and clamps?

I found a 90 deg one O'rielly Auto Parts

bbcmudtruck · 11-18-2013, 07:04 PM

I had to replace my brand new pcv with the L shape that I got from oriellys. It was a mr gasket push in style. It was leaking around the seal when it had any sort of side presure on on it. I returned it and just got an exact replacement and it fit snug. A vacuum leak will create tuning nightmares. I go as far as trimming all excess vacuum hoses. That not only cleans up the engine bay, but also helps keep the excess hose up and off of heated objects that could burn a hole or out of the fans or belts! Make sure that all of your carb nipples are in good shape and not dry rotted or cracked also.

11-17-2013, 04:54 PM	#1
theredmeadow Registered User Join Date: Oct 2013 Location: Albuquerque NM Posts: 129	adjust idle speed without tach Is it possible to adjust the idle speed on a 70 c10 350 stock without a tachometer? I recently got the project truck 3 weeks ago and since have raised it back to stock height, adjust panels, cleaned up the interior, connected the heater hoses, adjusted a loose lifter. Yesterday I changed the oil and oil filter, also changed out the spark plugs. I found the old spark plugs in bad shape and one fell apart as I took it out. SO since yesterday the truck has been running really smooth, the knock even went away. Except it seems to be idling fast, the oil pressure gauge at idle sits just a bit above 1/2 and the second I release the brake pedal it wants to get up and go. Any way is there some way I can or should I slow the idle down? Can it be done without a tach?

11-17-2013, 04:56 PM	#2
Skid99 Registered User Join Date: Oct 2012 Location: Bolivar, MO Posts: 38	Re: adjust idle speed without tach adjust it to where it will a little more than barely stay running. __________________ 2004 GTO H/C/I/E 6mt 430hp 2001 2500HD 6.0 Gasser Leveled on 33's 73' C10 SWB 5.3 L59/4L60E 4/6 Dropped 70' K/20 "Family Heirloom" 292/SM465/NP205 - Project

11-17-2013, 04:59 PM	#3
BMERDOC Registered User Join Date: Jun 2011 Location: Richmond,Va Posts: 2,934	Re: adjust idle speed without tach Slowing the idle down is fine. It is almost necessary. Youll have a stronger vac signal at idle and it won't fight the brakes. You'll probably find that you'll need to lean out the idle mixture after slowing it down too. Just slow it down so its not fighting the brakes but not enough so that it won't die. __________________ Nick Carter 1967 C10 Short bed Fleetside Project Cheap Thrills! 2WD C10 Modern/Performance Alignments Easiest Alignment Ever!

11-17-2013, 05:27 PM	#4
theredmeadow Registered User Join Date: Oct 2013 Location: Albuquerque NM Posts: 129	Re: adjust idle speed without tach ok so I've got it to where when I release the brake it pulls forward slowly instead. Still too fast? When I slow it down more than that sounds like the engine starts making a knock noise and sounds rough.

11-17-2013, 06:03 PM	#5
BMERDOC Registered User Join Date: Jun 2011 Location: Richmond,Va Posts: 2,934	Re: adjust idle speed without tach It's probably fine at that speed. You don't need it so fast that it fights the brakes or so slow that it causes other problems. It's not a complete science. Personal choice for idle speeds vary between people by several hundred r.p.m. If that idle speed works for your truck then rock it. The next step would to be to check timing and idle mixture bit you'd need equipment for that. Some sort of tach, a vacuum gauge and a timing light should be considered basic tools but it sounds like you are fine where you are. If you wanna tweak the tune some more you'll have to invest in at least a vac gauge. __________________ Nick Carter 1967 C10 Short bed Fleetside Project Cheap Thrills! 2WD C10 Modern/Performance Alignments Easiest Alignment Ever!

11-17-2013, 06:06 PM	#6
Longhorn 70 Registered User Join Date: Dec 2012 Location: Chandler AZ Posts: 1,149	Re: adjust idle speed without tach I agree with above. Make sure that if you are stopped and blip the throttle a little bit then hit the breaks it doesn't kill the engine. If it does, it's too low. __________________ 1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9

11-17-2013, 10:36 PM	#7
theredmeadow Registered User Join Date: Oct 2013 Location: Albuquerque NM Posts: 129	Re: adjust idle speed without tach I'm not going to start another thread but I'm assuming the hose that connects to the PCV isn't correct and isn't there a piece that sits on top of the PCV? Also, what kind of problem can this create?

11-17-2013, 10:41 PM	#8
davischevy Senior Member Join Date: Sep 2008 Location: Harrison, Arkansas Posts: 9,807	Re: adjust idle speed without tach Just get an L shaped PVC valve and run emissions (fuel) hose to the carb.

11-17-2013, 11:02 PM	#9
BMERDOC Registered User Join Date: Jun 2011 Location: Richmond,Va Posts: 2,934	Re: adjust idle speed without tach Looks like someone used a "Poor Man's dress up kit" and just wrapped the hose in some corrugated wire loom. Take the hose clamps off peel it back and see whats underneath. Even if you have to replace the "whole system" it shouldn't cost more than $10.00. Valves that are stuck open or closed can cause oil consumption, low end driveabilty problems, sludging and other problems. __________________ Nick Carter 1967 C10 Short bed Fleetside Project Cheap Thrills! 2WD C10 Modern/Performance Alignments Easiest Alignment Ever!

11-17-2013, 11:09 PM	#10
theredmeadow Registered User Join Date: Oct 2013 Location: Albuquerque NM Posts: 129	Re: adjust idle speed without tach I don't see any PCV valves that are L shaped so I'm guessing that I just get a new hose that fits properly and some new clamps.

11-17-2013, 11:23 PM	#11
BMERDOC Registered User Join Date: Jun 2011 Location: Richmond,Va Posts: 2,934	Re: adjust idle speed without tach By the way it looks, if a PCV valve is in there its a straight one. The new one will have a 90 degree end on it. Pull the end out of the valve cover, snap a pic down the barrel of the end of that hose and I'll tell you what it has in it. __________________ Nick Carter 1967 C10 Short bed Fleetside Project Cheap Thrills! 2WD C10 Modern/Performance Alignments Easiest Alignment Ever!

11-18-2013, 10:20 AM	#12
Longhorn 70 Registered User Join Date: Dec 2012 Location: Chandler AZ Posts: 1,149	Re: adjust idle speed without tach MOST times the PCV valve is in the passenger's side valve cover toward the rear isn't it??? __________________ 1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9

11-18-2013, 12:59 PM	#14
BMERDOC Registered User Join Date: Jun 2011 Location: Richmond,Va Posts: 2,934	Re: adjust idle speed without tach You can leave it that way. As long as it has filter air for ventilation and a properly work vent valve hooked to vacuum it doesn't matter how its hooked up. I would rather see the fresh air supply attach at the bottom of the air cleaner so that the engine recieves filtered air a push in unit on the V/C will do just fine. __________________ Nick Carter 1967 C10 Short bed Fleetside Project Cheap Thrills! 2WD C10 Modern/Performance Alignments Easiest Alignment Ever!

11-18-2013, 03:12 PM	#15
bbcmudtruck Registered User Join Date: Nov 2012 Location: ravenwood, mo Posts: 709	Re: adjust idle speed without tach It can be hooked up to either side of the motor. So seeing one on the passenger side is completely normal. Its just the way the p/o put the motor together. I like to run my pcb exactly like the one pictured. Its the cleanest/most direct way to run it in my opinion. As far as your idle goes, just adjust it so that your not lunging forward when you let off the brakes. It may want to creep forward, but as long as it doesn't want to take off and drive, you'll be fine. A very good and cheap investment would be a vacuum gauge. You can tune your carb and your timing with just a vacuum gauge. Easy to use and you will use it more than you'd think! There has to be at least a dozen things you can do with a vacuum gauge to help you with your motor.

11-18-2013, 07:04 PM	#23
bbcmudtruck Registered User Join Date: Nov 2012 Location: ravenwood, mo Posts: 709	Re: adjust idle speed without tach I had to replace my brand new pcv with the L shape that I got from oriellys. It was a mr gasket push in style. It was leaking around the seal when it had any sort of side presure on on it. I returned it and just got an exact replacement and it fit snug. A vacuum leak will create tuning nightmares. I go as far as trimming all excess vacuum hoses. That not only cleans up the engine bay, but also helps keep the excess hose up and off of heated objects that could burn a hole or out of the fans or belts! Make sure that all of your carb nipples are in good shape and not dry rotted or cracked also.



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