Sbc idle rpm

Register or Log In To remove these advertisements. Web chevytrucks. Rather than staring WWW III asking more timing advance questions, let me just ask you this: When your V8 cubic inch small block chevy is warmed up properly and purring like a kitten, what is your tachometer reading?

What RPM is it happy at? Since the manual splits the idle adjustments into Automatic and Manual, please let us now which one you got an auto or a stick, thank you very much. Did somebody say timing advance? My 79 with the vortec idled about rpm in drive with the R. The 78 with the old I had around rpm. The current will probably be or so.

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Playtoy and first vehicle. Find More Posts by Tom. Red Ryder stock auto in park about in drive. Green Jeans built barely idles at in park and in drive with a stall. May I ask a somewhat related question? What would a high speed idle be with the choke engaged at cold start?

Originally Posted by t5noel. Any lower in rpm and it's pretty "iffy. Find More Posts by SkinnyG. In work. Ran and idled great that way. Originally Posted by rich weyand.

Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 20 years! A 12si is an easier conversion than a cs Never realized they where that much better at idle than a 10si. Originally Posted by Axle. I see where new cars have as much as amp alternators to handle the computers and all the power doo-dads that are now standard equipment.

I did it a few years ago on a 55 Chevy. Using a DC clamp-on multimeter, the max I saw was around 35 amps!

sbc idle rpm

Of course the car had a basic radio, no electric radiator fans, no power windows or seats, and no computers. Engine was running and battery voltage was around When the engine idles, there will usually be a misfire that you can feel just from holding onto the steering wheel.

Furthermore, the RPM of your engine will be higher than normal when the vehicle is idling. This is definitely not a normal situation. If you are experiencing a rough idle or your RPM is running high when idling, then there are a variety of reasons for why this could be happening.

It is not always easy to diagnose the cause because there are so many factors involved here. Remember that spark plugs are what send a current of electricity into the internal combustion chamber to ignite the mixture of fuel and air.

This will cause the fuel and air mixture to burn inconsistently, which will result in rough idling engine. If your ignition coils or spark plug wires have gone bad, you will experience similar symptoms to having bad spark plugs. Ignition coils, coil packs, and spark plug wires transmit a very high voltage to the spark plug which enables electricity to jump the gap. If the insulation on these components has worn away, they may be unable to produce a consistent high voltage output.

Any time the spark is unable to jump the spark plug gap, that cylinder has a misfire and no power is produced on that particular combustion stroke. There are a lot of hoses that help deliver both fuel and air to the internal combustion chamber. One very common cause of idling rough is a problem with a vacuum hose in the vehicle. The hose could be damaged, loose, or worn out, creating a leak. Then, the result of that would be a car that is idling rough or having a higher than normal RPM.

Carburetors were previously used in vehicles before fuel injectors were invented. Perhaps you have a vehicle which still has a carburetor in it. If so, the carburetor itself could be having issues resulting in rough idling of the engine. A telltale sign of this would be if your exhaust was blowing out black smoke.

sbc idle rpm

Fuel injectors are the modernized way in which vehicles deliver fuel into the internal combustion chamber. The only thing is that these fuel injectors can get dirty or clogged after a while. This will result in your car idling poorly.

You could also see your gas mileage take a nosedive as well. Related: Best Fuel Injector Cleaners. The engine needs air from the outside to mix with the fuel in the internal combustion chamber. An important component under the hood of every car is an air filter which prevents debris from getting sucked into the chamber.

This will cause the engine to idle rough. The idle air control valve IAC or IACV adjusts the amount of air that is allowed past the throttle body while the throttle plate is closed.

sbc idle rpm

This regulates the engine idle speed and allows idle to remain constant even if you switch on the air conditioning or turn on your headlights, both of which put more load on the engine.See all 4 photos. Does your stock or mildly modified Pontiac engine idle higher than it should because each time you try to dial it down, it runs rough? If so, this article is for you. We'll tell you why it's happening and how to fix it. No Pontiac mill was ever designed to leave the factory with an excessive idle speed.

Rather to the contrary, it was meant to idle very slowly. The hallmark of a refined and well-tuned engine is a low idle speed. The information supplied will be just as effective with a stock Pontiac as a modified one. It's easy to state that the engine should idle slowly, but a value needs to be attached. The component that has the most impact on the potential idle speed is the camshaft profile. The carburetor is the second determining factor.

If your Pontiac is stock or nearly so, then the factory specification for idle speed should be your first target. Once that is achieved, it's good practice to try and get the engine to idle about five to ten percent slower than that.

For example, if the idle specification is rpm, then the goal may be between rpm and rpm. The caveat is that the engine needs to be as smooth at the lower speed and run as well. You may ask, "Why should we try to have our engine idle slower than the specification listed by Pontiac? Thus, the specification is slightly on the high side to guarantee a smooth idle regardless of the abuse the owner has given the Pontiac or the lack of maintenance.

A modified Pontiac with any style of performance camshaft will traditionally have an increased amount of overlap. This describes keeping both intake and exhaust valves open simultaneously for a longer period of time, measured in rotational degrees. When overlap is increased, there is a reversion of exhaust gas back into the cylinder bore, which dilutes the incoming charge.

sbc idle rpm

The propagation of the flame in the bore is not as smooth due to the reversion the inert exhaust gas disturbs the burn rate. Thus, a Pontiac engine with a modified cam profile may require more fuel at idle but still should be able to run at a slow speed.Remember Me? What's New? Last Jump to page: Results 1 to 10 of Thread: Ideal idle RPM?

Thread Tools Show Printable Version. Ideal idle RPM? When not in gear, it idles aroundhowever when in gear it hovers around at best. Run it rich? Or is there an ideal number in RPM? Last edited by jaketoolson; at PM. Very good question. I can tell you that if not in gear idle is and in gear it drops all the way to you need to make some adjustments.

Do you have specs on Cam? Do you have a vaccum gauge that you can put on to help with tuning? Do you have power brakes? How do they work at idle? If I had to guess I'd say you have idle turned up a bit to high but also ignition is a bit retarded. If your sure everything is in order and I mean tuned with no vaccum leaks etc then try this. Advance the timing a bit. Back idle down at the Carb to about rpms. You want to see about rpm drop from out of gear to in gear with foot on brake. For manual, rpm at full operating temp.

Yes, I have an auto trans and power brakes. Sometimes it diesels at shut off. Check your timing. Cant help it,Gain extra benefits by becoming a Supporting Member Click here find out how! Send Private Topic View Profile. Execution time: 0. All times are GMT Pacific. Current time is PM Top. Attach Photos to Posts. Contact Us. My Cookies. Frequently Asked Questions. Forum Rules. Username Post: What rpm should my idle be? Now it's carbureted and I have it set low like But the local guys insist that is the best idle for a carbureted engine.

Is there a reason that I should raise my idle? How do you decide the best idle rpm? About 15 years ago I used to idle a sbc with a qjet in a 76 El Camino around rpm maybe rpm, don't remember and it idled smoothly without stalling and easily passed smog tests.

Sometimes people couldn't tell if it was running or not. I was younger and thought it would help with gas mileage, I wouldn't do that now. If you have a big cam or the engine is rough or the oil pressure is too low, you may want more rpm at idle.

9 Causes of a Rough Idle (or RPM Running Too High While Idling)

But if the engine is smooth, oil pressure is fine, and there is no stalling then there is no good reason to idle at a higher rpm other than personal preference.Login to Your Account. Remember Me? Idle too high. Results 1 to 7 of 7. Thread: SBC settings. Thread Tools Show Printable Version.

Join Date May Posts 7. SBC settings. Just reinstalled my Chevy small block and the current settings produce a to RPM idle. As stated for an automatic and the IAC Postion was about When I put it in park it is idling at Also the engine will continue a short time after the key is turned off. Join Date Nov Location Ont. Canada Posts 1, You set idle speed with it in Park.

The instructions do say "in gear" for Auto trans, but it does sound like a misprint. The engine will race in neutral, with a IAC of in gear.

Should be in neutral, and then the IAC will be at say 40 in gear at target idle speed. Is the Atomic setup to control the ignition timing? If so, what are the current Advanced Setup Settings?The areas marked on the map by the agent indicated all the interesting places to see on our tour, all of which were within very easy reach of the main road.

How To Fix Idle Problems - Idle Time

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