Hello everyone i recently purchased a 1984 Chevy c-10 pickup and i have a few questions. This truck is running a 4.1 L GMC 250 I-6 linked up to a 3 speed Saginaw and I am thinking about swapping it out to a high output 305 Linked to the 3 speed. I know this has been done many times before but i am new to mechanics. What is it going to take to do this, Is this 305 better or will i regret this decision down the road. any input will be appreciated Thanks.
a few things...you are talking about a bolt in swap. but there are a lot of changes..the motor mount to frame brackets are different.. if you swap.. do put your brackets up on ebay.. there have been several people looking for them.. frame to mount.. mount... and mount to engine bracketsa few things. and these are my personal feelings..a straight six.. 3 on the tree... is COOL.. hint.. you can also .. swap to a 4 speed transmission.. even something like the A833 overdrive 4 speed.. that has the lever flipped on the forward shift shaft... and a morse cable to move reverse (the third lever ) in and out.. so you could have 4 on the tree with the 4th being overdrive.. i don't know if you will have to change the drive shaft length.. but it should almost bolt in.. and yes.. thats a chrysler transmission.. but they made GM versions.. in the overdrive variant as i recall..you could also... switch to a floor shift 5 speed... .. like an NV4500.. there are several articles on that...all this with the straight six..one thing.. there are several versions of the emission systems on the straight six.. can you identify the emission label under the hood.. the bottom 2 lines usually say... federal emissions standards.. or california emission standards.. and.. are you planning on keeping this truck for the lONG run.. its hard and expensive to create a smog legal swap in those years.. without buying and this is the easy way.. a complete wrecked truck to grab all the parts off to fix yours up..six cylinders.. if properly adjusted.. and in good running condition can beat the fuel economy of a 305.. and there are issues with keeping the 250 six..let me go over a few.. since its made it this long...#1... DO NOT REMOVE THE THERMOSTAT... rule #2.. refer to rule #1.. these have to have the OEM temp thermostat.. 50% to 70% coolant to water blend..no rust in the cooling system... no leaking hoses or pump.. or heater core...and a cap that actually holds pressure.. some have the center disk that dangles.. others have one that is spring loaded.. go for the spring loaded version..why run a thermostat.. the cylinder head on these is so long.. that in order for it to last.. you need to keep it at a stable temp.. without a lot of range in temp..so the thermostat does.. this by keeping the engine coolant circulating in the block and cylinder head.. when thermostats are removed.. the engine takes forever to warm up.. the heater does not work as well if at all.. when you are driving down the highway.. the heat starts building in the engine and the coolant circulating thru the radiator so fast that it cannot cool.. so it gets hot eventually.. when you take your foot on the gas... the engine slows down and the ram air thru the radiator can cool that water some.. now that cooler water is circulated into the engine shrinking the head.. this expanding and contracting is not bad on a V8.. but on a straight six.. its fatal.. this will cause fatigue cracks.. and the loss of mechanical fluid pressure of the water pump pushing coolant against a closed thermostat and only some of it flows thru the bypass.. each pound of pressure increases the boiling point of the coolant 3F.. the hot spots in the head.. can get over the 260F during high speed operation or high load operation.. the trick would be.. to start gathering parts.. starting at the frame brackets and moving upward.. you might in a short while run into a far better motor than the 305.. perhaps a complete TBI 350.. or a 96 or 97 Vortec 5.7... you will need to find an 87 fuel tank.. or perhaps just the sender to allow you to install an intank pump.. or a combo motor.. a vortec with a carb intake.. or a vortec with a vortech bolt pattern TBI intake.. or even something like a 6.0 or 6.2L LS Motor.. even if you drop a carb on it.. with the ignition controller.. you are going to be happy..plan ahead.. start collecting parts.. wait till you have them all.. and have decided to do it..unless your straight six is broken.. there are lots of issues with carb wear.. there are also issues with the hei... and some of these straight sixes might have had feed back carbs.. and since i took a quick look.. wow.. your truck has a factory 2bbl carb.. the varajet.. thats way cool... more depending on which system you have.. feed back.. or non feedback...keep the straight six.. is my thought right now... but again..as i said at the front.. you are the car owner.. and this is only my opinion..
Well it is a straight 6, 3 on the floor forward is reverse. I will be working out of a 87 Gmc for the motor mounts and such. the carb on the motor is shot and i cant seem to get my hands on a carb for it, so that is why i was planning on doing the swap im still very hesitant. I would really like to keep this truck original but its so hard to find the parts and pieces to allow that. i have every original piece to this truck down to the hub caps and beauty rings. I am going to do some code collecting on the truck this weekend on most of my parts, like i said im new to mechanics ill do my best to all the information right.
autozone sells reman carbs...you did not mention if its a feed back carb or not...do you have an oxygen sensor in the exhaust manifold..??? or NOT.. whats warn out on the carb.. as those are completely rebuildable.. there is also an adjustment inside. that some people screw up.. and.. if the feed back electronics are not working properly.. it will run horrible..i have a lot of experience in feedback carbs and fuel injection...i can help you with it...and if its a floor shift.. you can go to like the NV4500 really easily.. get 5 speeds instead of 3... snap some images from under the hood.. include the emissions label.. and there is a white plastic chart with a bunch of 3 digit letters on it.. place a piece of tape across the VIN number on that and then take a picture of it.. so i can read the 3 digit numbers...upload the images to photobucket dot com.. its free.. and paste the links here..there is also a web site called gmpartswiki. you will have some fun there.. there are here is the motor mount pages... you will have to view this in a new window.. straight six..
Ok from what i see on that gmpartswiki i actually have a 292.. i guess. I'm going to advance auto and getting a rebuild kit for the carb its like $16 or something like that, I talked to my brother hes convinced its a feed back, its over at his house I'm headed out there this weekend to grab the carburetor. I will keep shooting back here while i rebuild the carb for advice but that is the only thing wrong other than the break lines , we had it running by feeding gas in the top of the motor it sounds excellent I cant in my right mind swap the entire motor over a carb that's just ignorant. I am looking into the NV4500 that is a great idea.
these are not simple carbs.. please read the instructions several times..and you will need torx...if it is a feed back system... jump the A and B terminal under the dash and grab the codes..please.. also photograph the carb area.. and put tags on every hose before you take it apart.. so you know where it all goes back.. you will need to stop over to an autozone.. there is a tool display out in the middle of the floor.. and it will have a green handled torx folding set.. that has small enough sizes to get the carb apart...there is a big main jet inside the carb.. please.> DO NOT ADJUST OR MOVE THE SCREW THATS DOWN iNSIDE THE MAIN JET.. this is a variable adjustment engine.. and if that screw gets messed with.. it't not going to be good.. autozone has instructions.. on that carb also.. http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c1528004c521you will want to read this..GENERAL INFORMATIONThe CCC System monitors up to nineteen engine/vehicle operating conditions which it uses to control up to nine engine and emission control systems. This system controls engine operation and lowers the exhaust emissions while maintaining good fuel economy and driveability. The Electronic Control Module (ECM) is the brain of the CCC system. The ECM controls as many as 12 engine related systems constantly adjusting them for maximum efficiency. In addition to maintaining the ideal air/fuel ratio and adjusting ignition timing, the CCC System also controls the Air Management System, the transmission torque converter clutch (certain automatic transmission models only), idle speed, Evaporative Emissions System, the EGR valve operation and the early fuel evaporative (EFE) system.The CCC system is primarily an emission control system, designed to maintain a 14.7:1 air/fuel ratio under all operating conditions. When this ideal air/fuel ratio is maintained the catalytic converter can control oxides of nitrogen (NOx), hydrocarbon (HC) and carbon monoxide (CO) emissions.There are two operation modes for CCC System: closed loop and open loop fuel control. Closed loop fuel control means the oxygen sensor is controlling the carburetor or throttle body delivered air/fuel mixture ratio. Under open loop fuel control operating conditions (wide open throttle, engine and/or oxygen sensor cold), the oxygen sensor has no effect on the air/fuel mixture.On some engines, the oxygen sensor will cool off while the engine is idling, putting the system into open loop operation. To restore closed loop operation, run the engine at part throttle and accelerate from idle to part throttle a few times.The carburetor mixes air and gasoline into a combustible mixture before delivering it to the engine. However, carburetors have reached a point where they can no longer control the air-fuel mixture sufficiently close to the ideal 14.7:1 ratio for most operating conditions. Therefore, an electric solenoid has been incorporated into the carburetor to control the air-fuel ratio. The solenoid is connected to the ECM. The ECM provides a controlling or adjustment signal to the solenoid. The solenoid controls the metering rod(s) and a idle air bleed valve to maintain the ideal air-fuel ratio throughout the operating range of the engine. Since conditions that would effect the air fuel ratio vary widely, the ECM monitors conditions through several sensors. This provides for proper adjustment of the solenoid, for all driving conditions.One of the most important sensors that the ECM relies on for controlling mixture is located in the exhaust stream and is known as the oxygen sensor or simply an O 2 sensor. The sensor functions when the engine's exhaust temperature rises above 600ºF (316ºC). There is a direct relationship between the mixture delivered by the carburetor and the amount of oxygen left in the exhaust gases. The O 2 sensor detects the level of oxygen in the exhaust and signals the ECM by varying the voltage signal to the ECM. From this signal, the ECM is able to calculate whether the mixture is too rich or too lean and will adjust the mixture control solenoid accordingly. This process goes on continually and is referred to as Closed Loop operation. Closed loop operation tries to maintain the optimum 14.7:1 air/fuel mixture to the engine.In the morning when the engine is cold, if the system keep the air/fuel mixture at the 14.7:1 ratio, the engine wouldn't run very well. When the engine is cold, it has to have a richer mixture. An automatic choke is used to give the engine a richer mixture until it is up to normal operating temperature. In addition to the choke, a temperature sensor located in the water jacket of the engine is used by the ECM to monitor engine temperature. When the temperature sensor signal indicates that the engine is cold, the ECM will ignore the oxygen sensor signal. During the period that the O 2 sensor signals are ignored the ECM is running in a mode known as open loop. During this open loop period, the ECM adjusts the mixture control solenoid to deliver a richer mixture based on a preset program retained in the ECM's memory. The ECM also uses information from other sensors during cold start operation. After the engine has warmed up to normal operating temperature, based on the temperature sensor's signal, the ECM will switch to closed loop operation.While the oxygen and coolant temperature sensor influence the ECM the most in control of the fuel mixture, there are three other factors which influence the ECM. One of these is the load that is placed upon the engine. When an engine is working hard, such as pulling a heavy load up a long grade, it requires a richer air/fuel mixture. This is different from a vehicle that is operating in a cruise condition on a level highway at a constant rate of speed. Manifold vacuum is used to determine engine load. A vacuum sensor is used to detect changes in the manifold vacuum which are signaled to the ECM. As load changes occur, the vacuum signal varies. The ECM takes this varying signal into account when determining what mixture the carburetor should be delivering to the engine.Another factor in determining what air/fuel mixture should be is the amount of throttle opening. The more throttle opening at any given time, the richer the mixture required by the engine. On most applications, a Throttle Position Sensor (TPS) is used to signal the ECM as to the position of the throttle, whether it is at idle, part throttle or wide open throttle.The final factor in the fuel mixture equation is the speed the engine is running. Certainly, when an engine is operating at 600 rpm, it doesn't need as much fuel as it does when it is operating at 4000 rpm. Therefore, a tachometer signal from the distributor is fed to the ECM for calculation in the fuel mixture equation.The ECM is a reliable solid state computer, protected in a metal box and located in the cab. It is used to monitor and control all the functions of the CCC System. As explained previously the ECM can perform several functions at the same time but it also has the ability to detect certain faults within the CCC system. Generally when it detects a fault in the system the ECM will do three things; one is it will warn the driver by turning on the "CHECK ENGINE" or "SERVICE ENGINE SOON" light on the instrument panel, second it will try to compensate for the fault in many cases and third it will record what system or circuit is faulty in it's memory. When the engine is started, the CHECK ENGINE light will remain on for a few seconds, then turn off. This is normal operation but if the CHECK ENGINE light remains on, the self-diagnostic system has detected a problem. The ECM records the fault in it's memory in the form of a diagnostic trouble code. The diagnostic trouble codes recorded in the ECM's memory can later be accessed to aid in diagnosis of the Computer Command System fault. It should be understood though, that as powerful as the ECM is as a computer it does have limitations and cannot detect all the possible failures that could be encountered.SCAN TOOLSAlthough stored codes may be read with only the use of a small jumper wire, the use of a hand-held scan tool such as GM's TECH 1 or equivalent is recommended. There are many manufacturers of these tools; a purchaser must be certain that the tool is proper for the intended use.The scan tool allows any stored codes to be read from the ECM memory. The tool also allows the operator to view the data being sent to the ECM while the engine is running. A scan tool makes collecting information easier; the data must be correctly interpreted by an operator familiar with the system.An example of the usefulness of the scan tool may be seen in the case of a temperature sensor which has changed its electrical characteristics. The ECM is reacting to an apparently warmer engine (causing a driveability problem), but the sensor voltage has not changed enough to set a fault code. Connecting the scan tool, the voltage signal being sent to the ECM may be viewed; comparison to either a chart of normal values or a known good vehicle reveals the problem quickly.TROUBLESHOOTINGDiagnosis of a driveability and/or emission problem requires attention to detail and following the diagnostic procedures in the correct order. Resist the temptation to perform any repairs before performing the preliminary diagnostic steps. In many cases this will shorten diagnostic time and often cure the problem without further testing.Visual/Physical Underhood InspectionThis is possibly the most critical step of diagnosis. A detailed examination of connectors, wiring and vacuum hoses can often lead to a repair without further diagnosis. Performance of this step relies on the skill of the technician performing it; a careful inspector will check the undersides of hoses as well as the integrity of hard-to-reach hoses blocked by the air cleaner or other component. Wiring should be checked carefully for any sign of strain, burning, crimping, or terminal pull-out from a connector. Checking connectors at components or in harnesses is required; usually, pushing them together will reveal a loose fit.Diagnostic Circuit CheckThis step is used to check that the on-board diagnostic system is working correctly. A system which is faulty or shorted may not yield correct codes when placed in the Diagnostic Mode. Performing this test confirms that the diagnostic system is not failed and is able to communicate through the dash warning lamp.Reading Trouble CodesOnce the integrity of the system is confirmed, enter the Diagnostic Mode and read any stored codes. To enter the diagnostic mode: Turn the ignition switch OFF . Locate the Assembly Line Diagnostic Link (ALDL), usually under the instrument panel. It may be within a plastic cover or housing labeled DIAGNOSTIC CONNECTOR. This link is used to communicate with the ECM. The code(s) stored in memory may be read either through the flashing of the dashboard warning lamp or through the use of a hand-held scan tool. If using the scan tool, connect it correctly to the ALDL. If reading codes via the dash warning lamp, use a small jumper wire to connect Terminal B of the ALDL to Terminal A . As the ALDL connector is viewed from the front, Terminal A is on the extreme right of the upper row; Terminal B is second from the right on the upper row. After the terminals are connected, turn the ignition switch to the ON position but do not start the engine. The dash warning lamp should begin to flash Code 12. The code will display as one flash, a pause and two flashes. Code 12 is not a fault code. It is used as a system acknowledgment or handshake code; its presence indicates that the ECM can communicate as requested. Code 12 is used to begin every diagnostic sequence. Some vehicles also use Code 12 after all diagnostic codes have been sent. After Code 12 has been transmitted 3 times, the fault codes, if any, will each be transmitted 3 times. The codes are stored and transmitted in numeric order from lowest to highest. The order of codes in the memory does not indicate the order of occurrence. Switch the ignition OFF when finished with code retrieval or scan tool readings. Due to increased battery draw, do not allow the vehicle to remain in the Diagnostic Mode for more than 30 minutes. If longer periods are necessary, connect a battery charger.Clearing Trouble CodesStored fault codes may be erased from memory at any time by removing power from the ECM for at least 30 seconds. It may be necessary to clear stored codes during diagnosis to check for any recurrence during a test drive, but the stored codes must be written down when retrieved. The codes may still be required for subsequent troubleshooting. Whenever a repair is complete, the stored codes must be erased and the vehicle test driven to confirm correct operation and repair.The ignition switch must be OFF any time power is disconnected or restored to the ECM. Severe damage may result if this precaution is not observed.Depending on the electric distribution of the particular vehicle, power to the ECM may be disconnected by removing the ECM fuse in the fusebox, or disconnecting the positive battery terminal. Disconnecting the battery cables to clear codes is not recommended as this will also clear other memory data in the vehicle such as radio presets or clock.Field Service ModeIf ALDL terminal B is grounded to terminal A with the engine running, the system enters the Field Service Mode. In this mode, the dash warning lamp will indicate whether the system is operating in open loop or closed loop.If working in open loop, the dash warning lamp will flash rapidly 2 1 /2 times per second. In closed loop, the flash rate slows to once per second. Additionally, if the system is running lean in closed loop, the lamp will be off most of the cycle. A rich condition in closed loop will cause the lamp to remain lit for most of the 1 second cycle.When operating in the Field Service Mode, additional codes cannot be stored by the ECM. The closed loop timer is bypassed in this mode.The following is a list of possible diagnostic trouble codes that could be stored in the Electronic Control Module's (ECM) memory. It should be noted that a diagnostic trouble code does not identify that a particular component has failed, but a problem in the circuit of that component has occurred. Therefore, if a code is found to be set in the ECM's memory, the related circuit must be checked completely. Be sure to perform the visual inspection before proceeding with additional testing and pay particular attention to wiring terminal connections at connectors for loose or corroded connections.CODE 12 -No engine speed sensor reference pulses are being received by the ECM. This code is not stored in memory and will flash only while the fault is present. This code is normal when the ignition is on and the engine is not running. Code 13 -The ECM has detected a problem in the oxygen sensor circuit. The engine must run at part throttle for at least four minutes before this code will set. Code 14 -The ECM has detected a short in the coolant temperature sensor circuit. The engine must be running for at least two minutes before this code will set. Code 15 -The ECM has detected a open in the coolant temperature sensor circuit. The engine must be running for at least two minutes before this code will set. Code 21 -The ECM has detected that the throttle position sensor circuit voltage is high. This is and indication that the throttle position sensor is out of adjustment or an open in the circuit wiring has occurred. The engine must run for a least 30 seconds at idle before this code will set in the ECM's memory. Code 22 -The ECM has detected that the throttle position sensor circuit voltage is low. This is an indication that the throttle position sensor circuit is shorted to ground. The engine must run for at least 2 minutes at 1250 rpm before this code will set in the ECM's memory. Code 23 -The ECM has detected a short or open in the mixture control solenoid circuit on carbureted engines or the Manifold Air Temperature (MAT) signal is high indicating a open circuit on fuel injected vehicles. Code 24 -No vehicle speed sensor signals are being received by the ECM. This is an indication that the circuit has an open or is shorted to ground. For this code to set, the vehicle must operate at any speed for 10 seconds. Code 25 -The ECM has detected that the Manifold Air Temperature (MAT) signal is low indicating a short to ground on fuel injected vehicles. Code 32 -The barometric pressure circuit signal voltage is low. Code 33 -The ECM has detected low vacuum in the Manifold Absolute Pressure (MAP) sensor circuit. Code 34 -The ECM has detected a problem in the vacuum sensor or the manifold absolute pressure sensor circuit. The engine must run for at least 2 minutes at curb idle before this code will set in the ECM's memory. Code 35 -The ECM has detected a problem with the idle speed control circuit. Code 41 - No distributor reference pulses to the ECM at specified engine vacuum. Code 42 -Electronic spark timing bypass circuit is grounded or open. Code 43 -Electronic spark control retard signal for too long a time period; causes a retard in the electronic spark timing. Code 44 -The ECM has detected a lean exhaust condition. The engine must run for two minutes in closed loop operation before this code will set. Code 45 -The ECM has detected a rich exhaust condition. The engine must run for two minutes in closed loop operation before this code will set. Code 51 -Faulty or improperly installed PROM or calibration chip in the ECM. The ignition must be on for approximately 10 seconds before this code will set. Code 53 - Exhaust Gas Recirculation (EGR) valve vacuum sensor circuit. The ECM has seen an improper EGR valve vacuum. Code 54 -The ECM has detected a short in the mixture control solenoid and or a faulty ECM. Code 55 -The ECM has detected a problem with itself. Replacement of the ECM is required.
on your emission vacuum label.. look at the upper left corner of this one.. see the XCA..what number is in the upper left corner..it will be a XC?