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Thanks for having me. Not a mechanic. Have some experience with general basics though. I may be in the wrong place though. Car isn't exactly a classic to some for sure. Anyway, the car is in fair shape. Odometer has rolled over once and reads about 25000 now. I sorta tried to go through it today and get it ready for work. I noticed one seemingly short vacuum line near the firewall that came off a tee and went to a box with maybe four other small vacuum lines. A rat had eaten through it. I replaced that one. The rest seemed flexible, not brittle, and in place, except for one. It came off a tee or module or something small near the carb. heading back towards the firewall from the right/ driver side of the carb. It's a long piece of hose. I could bring it pretty much all the way around the engine. I didn't see where it could go. I'm terrible at reading vacuum diagrams i guess. Might help if i knew what all the little
devices were. The hose is slightly larger than the 5/32" ones that abound near the back. So i was wondering what that might be. Past that it is idling high and i know the carburetor isn't adjustable. That isn't too big of an issue at the moment, but i would like to get it addressed. I'm trying to get it running properly and have the "maintenance" light go off. There is an elbow that comes off the side of the cat that was rusted away on one end so i put a piece of heater hose on the remaining pipe going back to the small exhaust clamp. I didn't clamp it down. It is definitely not air tight. Probably a bad idea. Not sure quite how hot that gets. Past that there was a decent sized hole in the exhaust pipe at a bend past the converter. I patched it for the time being. I think it may also be leaking at the donut gasket at the manifold. Exhaust shop wont mess with it. Hit it with some penetrating oil and waited before trying to snug the spring tensioned bolts. None of them moved. I didn't go crazy with it. Any tricks to accessing that donut? Wanted to replace the o2 sensor but didn't. Thought maybe that might make the maintenance light go off. Didn't get to it yet though. Seemed kinda fragile and fused in place. Changed the sparkplugs. None had any oil or really crazy wear pattern. Some had rust though. They all came out pretty easy. Seemed like the valve covers have been leaking for some time. Could barely make out the bolts due to crud buildup. Can i just tighten those down gently or do i need to go ahead and change the gaskets? Was gonna change the distributor cap and wires but couldn't figure out how to get the cap off. Didn't even think to buy a coil. Saw two small screws that seemed to hold the top of the cap on that were barely accessible. I loosened them with a nut driver but the cap didn't loosen any. I saw on the new cap that there were three screws and not two, but on the original one i couldn't see an accessible third screw. I figured i was missing something simple and just put the air cleaner back for now. Would like to change the wires cap and rotor though. I gotta be overlooking something simple. I was gonna try to change the shocks tomorrow...maybe more my pay grade. I saw someone mention service manuals. Is there a digitally accessible version for the second generation custom cruiser? Isn't that called a b platform or something? The car is growing on me. It's dark right now but i can try to take pics tomorrow.
Thanks again. Glad to be here.
Last edited by carpenternotmechanic; December 30th, 2020 at 09:01 PM.
Find a new exhaust shop. If the air injection line to your catalytic converter is rusted through then it eventually needs to be deleted or replaced. If you used heater hose to patch it then once the car gets hot the heater hose will incinerate. Remove it before you cause a fire.
After removing the heater hose from the catalytic converter you should find out what codes are stored.
You can either take your car to an auto parts store to have the codes read, or you can do it at home. Use a paperlcip to short the A and B terminals of your Assembly Line Data Link to flash the codes. Do this with the key in the run position.
The Check Engine light will flash 1,2 1,2 1,2 and then it will flash any codes that are stored. It ends with 1,2 1,2 1,2 and then repeats.
BTW, show us a pic and let us know where you're at.
Find a new exhaust shop. If the air injection line to your catalytic converter is rusted through then it eventually needs to be deleted or replaced. If you used heater hose to patch it then once the car gets hot the heater hose will incinerate. Remove it before you cause a fire.
After removing the heater hose from the catalytic converter you should find out what codes are stored.
You can either take your car to an auto parts store to have the codes read, or you can do it at home. Use a paperlcip to short the A and B terminals of your Assembly Line Data Link to flash the codes. Do this with the key in the run position.
The Check Engine light will flash 1,2 1,2 1,2 and then it will flash any codes that are stored. It ends with 1,2 1,2 1,2 and then repeats.
BTW, show us a pic and let us know where you're at.
thanks for the advice. I brought it the parts store yesterday. They plugged into it but it wouldn't power up there scanner. I will jump it today and see if i get any flashes. Thanks for the diagram.
Also, would the computer still store codes if i disconnect the battery? It usually rides around for a few minutes and then thw maintenance light comes on. Thanks again.
Last edited by carpenternotmechanic; December 31st, 2020 at 05:22 AM.
I was wondering about this air compressor system. Could it be used as a power adder; similarly to a blower? If it blows more air as the engine turns faster then could you not use it to add air pressure to the fuel mix? Im sure you would have to upgrade the fueling but.....was just curious.
Could it be used as a power adder; similarly to a blower?
I doubt it. The smog pump doesn't put out much volume or pressure. If you disconnect the main line from the smog pump with the engine running it doesn't blow very forcefully. The engine probably looses more power turning the smog pump than would be added if you changed it to forced induction. Plus, it would be engineering wizardry to get forced induction on an OBD 1 system.
Welcome. Your car has an Olds 307 motor with the computer controlled Quadrajet, called the CCC system. The entire engine, from heads to cam to carb to ignition, is optimized for low end torque and gas mileage. There are no easy ways to increase power, short of jacking up the air cleaner and replacing the 307 with a 455. The best you will do is to ensure that the engine is in good shape and properly tuned. Virtually no one knows how to properly tune and adjust these CCC cars, heck, almost no one knew how to do it when they were new. Your very first step should be to buy a factory service manual for your car and read the section on repairing and adjusting the CCC system. If you or any mechanic tries to do anything that doesn't follow that factory process exactly, I guarantee the car will run worse. Note that if ANY vacuum lines are cracked or mis-connected, the car won't run right, so be sure everything is connected as the factory shows.
As for the on-board air compressor, that's a tiny, low volume, high pressure pump for the factory air shocks. Look at the diameter of the line coming out of it vs the size of the snorkel on the air cleaner, and think about how much air it flows.
I doubt it. The smog pump doesn't put out much volume or pressure. If you disconnect the main line from the smog pump with the engine running it doesn't blow very forcefully. The engine probably looses more power turning the smog pump than would be added if you changed it to forced induction. Plus, it would be engineering wizardry to get forced induction on an OBD 1 system.
Mine put out pretty decent pressure at idle and it runs off a pully system right? Could t you bypass the obd1 system all together?
Welcome. Your car has an Olds 307 motor with the computer controlled Quadrajet, called the CCC system. The entire engine, from heads to cam to carb to ignition, is optimized for low end torque and gas mileage. There are no easy ways to increase power, short of jacking up the air cleaner and replacing the 307 with a 455. The best you will do is to ensure that the engine is in good shape and properly tuned. Virtually no one knows how to properly tune and adjust these CCC cars, heck, almost no one knew how to do it when they were new. Your very first step should be to buy a factory service manual for your car and read the section on repairing and adjusting the CCC system. If you or any mechanic tries to do anything that doesn't follow that factory process exactly, I guarantee the car will run worse. Note that if ANY vacuum lines are cracked or mis-connected, the car won't run right, so be sure everything is connected as the factory shows.
As for the on-board air compressor, that's a tiny, low volume, high pressure pump for the factory air shocks. Look at the diameter of the line coming out of it vs the size of the snorkel on the air cleaner, and think about how much air it flows.
It has air shocks? I thought the pump was for emissions purposes. I got gas replacement shocks. Wonder if they are gonna work?
So no one has copied the service manual to digital yet?
Thanks for the advice
It has air shocks? I thought the pump was for emissions purposes. I got gas replacement shocks. Wonder if they are gonna work?
So no one has copied the service manual to digital yet?
Thanks for the advice
Sorry, I missed the part that you were talking about the smog pump. These cars were also optional with air shocks that had a small electric compressor mounted under the hood. Your car may or may not have that.
Spend the money, buy a paper original. There were no digital originals, so any electronic version is a scan of an original paper copy. Scan quality frequently sucks, especially on the small details like wiring diagrams. In any case, there is exactly zero market for an electronic version of the manual for this car. No one would possibly waste the time scanning it.
I found a digital copy of the service manual for my 96 98 but as Joe said the scans usually suck.
To delete the computer you would need to do more than remove the smog pump and catalytic converter. The CCC Quadrajet won't operate properly without the computer, plus the spark curve and valve timing is set for emissions. You would need an aftermarket carburetor and distributor.
I found a digital copy of the service manual for my 96 98 but as Joe said the scans usually suck.
To delete the computer you would need to do more than remove the smog pump and catalytic converter. The CCC Quadrajet won't operate properly without the computer, plus the spark curve and valve timing is set for emissions. You would need an aftermarket carburetor and distributor.
an aftermarket dissy and carb arent out of the question. I know the engine is geared towards torque and cant rev too high, but on the street torque is your friend. A nominal increase in fresh air to thw intake might work pretty good. No doubt any significant increase in compression would cause serious longevity issues foe the stock motor. Are the top ends of these things pretty stout or no? Bout to see id i can jump the reader and get any codes. Thanks for all the input everyone. I really so appreciate it. Ill take some pics of the distributor later. About to have to leave to get it registered. Gonna see if i can get an antique plate.
Sorry for all the spelling and other grammatical errors. I can't see too well or spell very well.
The heads on your motor now are restrictive smog era heads. You could get better small block heads but the best power adder would be to remove the smog 307 and install a 455 (or even a 350/403).
The heads on your motor now are restrictive smog era heads. You could get better small block heads but the best power adder would be to remove the smog 307 and install a 455 (or even a 350/403).
if i ever want to really add power then I'll probably put my 552ci fbb in it. Its set up for turbos but is ridiculously powerful without them atm. And restrictive valves don't really hurt too much when forced induction is involved.
Sorry, I missed the part that you were talking about the smog pump. These cars were also optional with air shocks that had a small electric compressor mounted under the hood. Your car may or may not have that.
Spend the money, buy a paper original. There were no digital originals, so any electronic version is a scan of an original paper copy. Scan quality frequently sucks, especially on the small details like wiring diagrams. In any case, there is exactly zero market for an electronic version of the manual for this car. No one would possibly waste the time scanning it.
so back to this smog pump thing. You couldn't route it pump straight to the air cleaner? Is there a way to adjust the amount of fuel through the carb? Change secondaries or something?
so back to this smog pump thing. You couldn't route it pump straight to the air cleaner? Is there a way to adjust the amount of fuel through the carb? Change secondaries or something?
The CCC Quadrajet isn't very adjustable. If you have your heart set on modifying the 307 in your Olds then you should put an older Quadrajet or aftermarket carburetor on it.
Before you make grand plans of increasing the output of your 307, you really need to educate yourself about what you're up against. These 1985-90 VIN Y roller cam motors have tiny ports, tiny valves, a crappy intake, and the worst exhaust manifolds Oldsmobile ever bolted into a car. The cam is lazy, the advance curve is awful, and the settings assume the emissions equipment (like EGR) is functional. Simply disable the EGR valve and you usually get pinging at part throttle for your efforts. Changing the carb and distributor with no other changes is like putting whipped cream on dog s**t. You can spend a bunch of time and money, and I'm sure your "butt dyno" will register a huge improvement. The drag strip clocks will not.
The CCC Quadrajet isn't very adjustable. If you have your heart set on modifying the 307 in your Olds then you should put an older Quadrajet or aftermarket carburetor on it.
really im more interested in getting it back properly functioning for dependability reasons at the moment. Modifying the AIR system or what have you eas just an aside being thrown around.
Before you make grand plans of increasing the output of your 307, you really need to educate yourself about what you're up against. These 1985-90 VIN Y roller cam motors have tiny ports, tiny valves, a crappy intake, and the worst exhaust manifolds Oldsmobile ever bolted into a car. The cam is lazy, the advance curve is awful, and the settings assume the emissions equipment (like EGR) is functional. Simply disable the EGR valve and you usually get pinging at part throttle for your efforts. Changing the carb and distributor with no other changes is like putting whipped cream on dog s**t. You can spend a bunch of time and money, and I'm sure your "butt dyno" will register a huge improvement. The drag strip clocks will not.
i would never bring a 307 olds to a strip, though i read up on some guys that got really good numbers out of a fully built on. I have a fully forged bbf waiting for twins if i ever decide to make this thing a toy. For now i need it reliable quickly so i can get back to work.
Ok. Back to the vacuum leak and distributor cap and rotor. The vacuum line in question is the upper one in the pic...
The hose is about 3' long...
The distributor looks original as does most everything else. I know it has four half turn hold downs, but was thinking you could also remove the cap on the cap in order to access the wire boots better.
Gonna try jumper wire now.
Showing codes;
15, 21, and 44. With the jumper wire in place it drops the idle speed a little and then it picks back up when the jumper is removed...
How can i find a reference to what those mean, here on the forum. I apologize for my ignorance. Thanks.
Last edited by carpenternotmechanic; December 31st, 2020 at 01:01 PM.
IMO the manual is more detailed then you will get from any other source... They were developed for the GM technicians and most likely used on a daily basis... Includes wiring diagrams, trouble shooting, charts, engine information section covering cooling, fuel, electrical, emissions, etc...
Last edited by CRUZN 66; January 4th, 2021 at 07:35 PM.
Code 15 is coolant temp sensor
Code 21 is throttle position sensor
Code 44 is lean O2 sensor reading.
Coolant sensor code could be caused by low coolant (an air pocket in the system) or a bad sensor
TPS code is likely a bad TPS. This is not uncommon.
Lean exhaust could be caused by about a hundred different things.
Get the manual, which has troubleshooting flow charts for each of these.
Okay so o2 sensors says too lean, throttle position sensor says high idle and coolant temp is too low...
If i wasn't getting enough fuel would i get a code for low pressure or bad fuel pump or something? I guess it could be a fuel filter issue, but also i have an exhaust leak near the o2 sensor at the side of the catalytic converter. Wouldn't introducing fresh air through an exhaust leak cause a lean reading on the o2 sensor? Lastly the throttle position sensor. Where is that please, and would that have to do with vacuum leak? Thanks.
Code 15 is coolant temp sensor
Code 21 is throttle position sensor
Code 44 is lean O2 sensor reading.
Coolant sensor code could be caused by low coolant (an air pocket in the system) or a bad sensor
TPS code is likely a bad TPS. This is not uncommon.
Lean exhaust could be caused by about a hundred different things.
Get the manual, which has troubleshooting flow charts for each of these.
thanks for the info. I don't really have time to wait on a manual to come in the mail. Need to be back working no later than Monday. Gonna see if i can locate the TPS and do something about the exhaust leak at the cat.
Okay so o2 sensors says too lean, throttle position sensor says high idle and coolant temp is too low...
No, TPS says VOLTAGE is too high, not idle. The TPS is a potentiometer that outputs a voltage to the computer that changes in response to throttle position. The computer is designed to screen for bad data by looking for voltage readings that are out of bounds based on other measurements. For example, if the computer senses RPM at about idle speeds, but the TPS voltage corresponds to wide open throttle, the computer says "this is bad data" and sets a flag. Now you need to follow the troubleshooting process in the CSM to figure out whether the problem is actually the TPS itself (highly likely in this case) or something else like a shorted or broken wire. Same thing for the coolant temp sensor, The error message indicates that the VOLTAGE is low, not the temperature, necessarily.
If i wasn't getting enough fuel would i get a code for low pressure or bad fuel pump or something? I guess it could be a fuel filter issue, but also i have an exhaust leak near the o2 sensor at the side of the catalytic converter. Wouldn't introducing fresh air through an exhaust leak cause a lean reading on the o2 sensor? Lastly the throttle position sensor. Where is that please, and would that have to do with vacuum leak? Thanks.
Again, code 44 does NOT mean you aren't getting fuel to the carb. It means that the O2 sensor is reading too lean. As I said above, there are about a hundred possible causes for this, but a bad fuel pump is probably 99th on that list. Follow the flow chart to avoid wasting time and money replacing parts that aren't bad. I'll give you an example of an obscure failure mode that can cause a code 44. The smog pump blows air into the exhaust ports when the engine is cold (in open loop mode), but once the O2 sensor warms up, the computer is supposed to switch the smog pump output to the tube in the catalytic converter to help cool it. On one of my cars, this switching valve had gone bad, and the smog pump was blowing fresh air into the ports all the time. The O2 sensor saw this as running too lean and set a code 44. This caused the computer to command the carb to run full rich to compensate, which was not what the engine really wanted. The result was fouled plugs, crappy mileage, and a contaminated cat. It took me a month of weekends to figure that one out.
Now, for this issue:
That upper port on the VRV is a vent to atmosphere. There is NOT supposed to be a hose connected to it, so someone who didn't know what they were doing stuck that on there. From the factory there was a small piece of foam on over that port that served as a filter. That foam crumbled to dust decades ago. This is NOT a vacuum leak.
This may help, but it should already be stuck to the radiator top plate on your car anyway.
And finally, to this comment:
i would never bring a 307 olds to a strip,
Sorry but you completely missed the point. My comment wasn't about racing. My point was that you can spend a lot of time and money trying to modify this 307, and after you invested all that time and money, your seat of the pants (your "butt dyno") is going to tell you that you made an improvement. Your butt would be wrong, and a real back-to-back comparison test with timing clocks would prove that there was no difference from all that work.
No, TPS says VOLTAGE is too high, not idle. The TPS is a potentiometer that outputs a voltage to the computer that changes in response to throttle position. The computer is designed to screen for bad data by looking for voltage readings that are out of bounds based on other measurements. For example, if the computer senses RPM at about idle speeds, but the TPS voltage corresponds to wide open throttle, the computer says "this is bad data" and sets a flag. Now you need to follow the troubleshooting process in the CSM to figure out whether the problem is actually the TPS itself (highly likely in this case) or something else like a shorted or broken wire. Same thing for the coolant temp sensor, The error message indicates that the VOLTAGE is low, not the temperature, necessarily.
Again, code 44 does NOT mean you aren't getting fuel to the carb. It means that the O2 sensor is reading too lean. As I said above, there are about a hundred possible causes for this, but a bad fuel pump is probably 99th on that list. Follow the flow chart to avoid wasting time and money replacing parts that aren't bad. I'll give you an example of an obscure failure mode that can cause a code 44. The smog pump blows air into the exhaust ports when the engine is cold (in open loop mode), but once the O2 sensor warms up, the computer is supposed to switch the smog pump output to the tube in the catalytic converter to help cool it. On one of my cars, this switching valve had gone bad, and the smog pump was blowing fresh air into the ports all the time. The O2 sensor saw this as running too lean and set a code 44. This caused the computer to command the carb to run full rich to compensate, which was not what the engine really wanted. The result was fouled plugs, crappy mileage, and a contaminated cat. It took me a month of weekends to figure that one out.
Now, for this issue:
That upper port on the VRV is a vent to atmosphere. There is NOT supposed to be a hose connected to it, so someone who didn't know what they were doing stuck that on there. From the factory there was a small piece of foam on over that port that served as a filter. That foam crumbled to dust decades ago. This is NOT a vacuum leak.
This may help, but it should already be stuck to the radiator top plate on your car anyway.
And finally, to this comment:
Sorry but you completely missed the point. My comment wasn't about racing. My point was that you can spend a lot of time and money trying to modify this 307, and after you invested all that time and money, your seat of the pants (your "butt dyno") is going to tell you that you made an improvement. Your butt would be wrong, and a real back-to-back comparison test with timing clocks would prove that there was no difference from all that work.
So chances are the tps sensor itself is faulty, and i need a manual to follow the best troubleshooting procedure basically? It that sensor difficult to access?
It's just kinda cool to me how it has an air injection system basically. You could also basically fault out an electronically controlled valve in order to add air to the mix at all times, then compensate for missing fuel. I mean; isn't the cr on these like 8.5? A little air isn't gonna hurt... Im just talking. The stuff interests me is all. It would be a cool project. Add a little pep to that poor little engine. Your point was bang for buck i thought. Ole ford 460 can be stroked 90 additional cubes with no modifications to the block itself. All forged and set up for torque and additional air....8.5 cr... Aluminum heads worked over. Can't speak to it's longevity as of yet, but that seems to have been decent bang for buck. Got lots of room in this Olds... Me having time, place, and money to both have another working vehicle, and do the swap with lots of help....pretty unlikely atm. Just have to see how it goes. Im glad none of the codes seemed super bad. Wipers just stopped in the rain. Are these cars prone to electrical issues?
Sadly, the 1980s cars saw GM make some bad cost cutting decisions, especially in the wiring. I've had more than my share of electrical problems with my 1980s cars, which is the complete opposite of the older Oldsmobiles that I own. The wipers have definitely been prone to problems, frequently from corrosion at the connector terminals. I've also found that the replacement wiper motors are complete crap. I finally broke down and paid for an NOS wiper motor that I found on ebay. That solved my problems.
It's just kinda cool to me how it has an air injection system basically. You could also basically fault out an electronically controlled valve in order to add air to the mix at all times, then compensate for missing fuel. I mean; isn't the cr on these like 8.5? A little air isn't gonna hurt... Im just talking.
Time for a little common sense. If you plan to use the A.I.R. pump as a supercharger, that means that to create boost, you have to seal off all other air inlets to the carb - otherwise the boost just flows out the air cleaner snorkel. That means that 100% of the air going into the motor has to flow through the A.I.R. pump. Now look at the diameter of the outlet on that pump and ask yourself it you think can flow 600 - 700 CFM or so through it.
Time for a little common sense. If you plan to use the A.I.R. pump as a supercharger, that means that to create boost, you have to seal off all other air inlets to the carb - otherwise the boost just flows out the air cleaner snorkel. That means that 100% of the air going into the motor has to flow through the A.I.R. pump. Now look at the diameter of the outlet on that pump and ask yourself it you think can flow 600 - 700 CFM or so through it.
We'll wait...
Doesn't the air already go directly into the heads? Does it only pulse with the opening of thw exhaust valve? There is probably a way to make it pulse on thw intake side instead or stay pumping thw whole time. I wouldn't expect it to replace the air naturally coming in to the carburetor. I agree that plumbing to thw cleaner wouldn't work very well, but you keep bringing up the diameter of thw snorkel. But that's atmosphere plus vacuum. Not really comparable to thw volume that compressor puts out, or maybe it is. And really you could use the check valve like thw one for thw heat riser to still pull in air too if the pump didn't put out enough. Having it go straight to the heads is better though. Its just brain storming. Part of that is omitting stupid ideas; so thanks for showing this carpenter a thing or two.
Last edited by carpenternotmechanic; December 31st, 2020 at 10:26 PM.
that's cute and all, but not really the same. Our air pump is already plumbed and would produce more air as rpms climbed due to the pully drive. All kinds of people hacking up these parts for no gain. At least they would be being used amd all the plumbing is done sorta. Unfortunately that leaves little nees for a leaf blower. Hell, hou could increase the output of the pump by changing pully size. And if you really wantes to go all ghetto fabulous then you could tap into thw air line with methanol injection to insure low temperatures. Im still just talking out of my butt. But im very curious as to why this wouldn't worm in some fashion or iteration or another.
Doesn't the air already go directly into the heads? Does it only pulse with the opening of thw exhaust valve? There is probably a way to make it pulse on thw intake side instead or stay pumping thw whole time. I wouldn't expect it to replace the air naturally coming in to the carburetor. I agree that plumbing to thw cleaner wouldn't work very well, but you keep bringing up the diameter of thw snorkel. But that's atmosphere plus vacuum. Not really comparable to thw volume that compressor puts out, or maybe it is. And really you could use the check valve like thw one for thw heat riser to still pull in air too if the pump didn't put out enough. Having it go straight to the heads is better though. Its just brain storming. Part of that is omitting stupid ideas; so thanks for showing this carpenter a thing or two.
No, that is not how it works. Nor is that how the engine works in general - you don't "pulse" air into the combustion chamber from the exhaust side (and yes, I understand about reversion and Helmholtz resonators and tuning the intake and exhaust lengths to improve volumetric efficiency - this isn't that). And no, it is not "the atmosphere plus vacuum". A normally aspirated engine only has air pressure to work with, period. At sea level it's 14.7 psi. The "vacuum" is actually just a lower ambient air pressure - the two are not additive. This is normally aspirated why engines at altitude make less HP - there is less air pressure to feed air into the engine. This is also why many reciprocating aircraft engines are turbocharged.
Sorry to say this but a 85 GM car is probably one of the worst cars to pick to have as a collector car or a daily driver. They were a stop gap cobble job that was put together to try and pass emissions before electronic fuel injection was figured out. They are not supported well and as Joe says most didn't know how to work on then when 2-3 years old and almost no one does now. The early 70's and older were basic carburetors and point ignition. The early 80's started the throttle body fuel injection. I think it was 1996 when all manufacturers went to a standard system on diagnosis. Anyway- not a good car to learn and become a expert on as you probably never will have another- unless you just like the challenge.. I am NOT trying to slam your car as I really like the Mid 80's Olds. But It is what it is.. Good luck, Let us know how it goes.
No, that is not how it works. Nor is that how the engine works in general - you don't "pulse" air into the combustion chamber from the exhaust side. And no, it is not "the atmosphere plus vacuum". A normally aspirated engine only has air pressure to work with, period. At sea level it's 14.7 psi. The "vacuum" is actually just a lower ambient air pressure - the two are not additive. This is normally aspirated why engines at altitude make less HP - there is less air pressure to feed air into the engine. This is also why many reciprocating aircraft engines are turbocharged.
all i meant was that it was na. Atmosphere + whatever suction the air pump/ engine creates when the piston is forced downward due to an explosion. And looming at the tubes that are right next to the spark plugs it just seemed like it might be putting fresh air into the heads.
all i meant was that it was na. Atmosphere + whatever suction the air pump/ engine creates when the piston is forced downward due to an explosion. And looming at the tubes that are right next to the spark plugs it just seemed like it might be putting fresh air into the heads.
Sorry, incorrect on both counts. It isn't "atmosphere plus vacuum". It's atmosphere, period. In reality, there is no "engine vacuum", there's just lower air pressure inside the intake manifold than there is outside the engine. That pressure comes solely from the weight of the column of air above the carb inlet, period. This is Physics 101. And the A.I.R. tubes do not penetrate the combustion chambers, they are in the exhaust ports, downstream of the exhaust valves. The exhaust valve would have to be open for any flow from the A.I.R. nozzles into the combustion chamber, and any time the exhaust valves are open, the pressure in the port is significantly higher than anything coming from the smog pump, which is why those A.I.R. manifolds have a check valve between the high temp metal part and the rubber hose that connects to the smog pump. And more to the point, you might want to educate yourself about cylinder pressures. Direct injection gasoline engines have just become common in the last few years, and in order to successfully inject fuel directly into the combustion chamber, the DFI systems run at something like 3,000 psi. Your smog pump is about three orders of magnitude lower pressure. Do the math.
Sorry, incorrect on both counts. It isn't "atmosphere plus vacuum". It's atmosphere, period. In reality, there is no "engine vacuum", there's just lower air pressure inside the intake manifold than there is outside the engine. That pressure comes solely from the weight of the column of air above the carb inlet, period. This is Physics 101. And the A.I.R. tubes do not penetrate the combustion chambers, they are in the exhaust ports, downstream of the exhaust valves. The exhaust valve would have to be open for any flow from the A.I.R. nozzles into the combustion chamber, and any time the exhaust valves are open, the pressure in the port is significantly higher than anything coming from the smog pump, which is why those A.I.R. manifolds have a check valve between the high temp metal part and the rubber hose that connects to the smog pump. And more to the point, you might want to educate yourself about cylinder pressures. Direct injection gasoline engines have just become common in the last few years, and in order to successfully inject fuel directly into the combustion chamber, the DFI systems run at something like 3,000 psi. Your smog pump is about three orders of magnitude lower pressure. Do the math.
"That pressure comes solely from the weight of the column of air above the carb inlet, period. This is Physics 101."
So the explosion doesn't deplete the oxygen and the piston being forced down doesn't create a vacuum!? Its the weight of the air which is the same as atmosphere that causes air to be sucked in thw engine? Im not a physics major but that doesnt sound correct.
And there is no way to modify the system so it would blow air into the combustion chamber while the intake valve is opened? Now im starting to understand....maybe.....a little... Thanks for your kind words of encouragement and guidance towards this ignoraimie. For real though, thanks. Hope your year gets better.
So the explosion doesn't deplete the oxygen and the piston being forced down doesn't create a vacuum!? Its the weight of the air which is the same as atmosphere that causes air to be sucked in thw engine? Im not a physics major but that doesnt sound correct.
Originally Posted by Briggs and Stratton
During the intake stroke, the intake valve between the carburetor and combustion chamber opens. This allows atmospheric pressure to force the air-fuel mixture into the cylinder bore as the piston moves downward.
December 30th, 2020, 08:51 PM
