Justinp551 Posted March 18, 2012 Share Posted March 18, 2012 I have done some searching and have a few good ideas but wanted to get some more direct suggestions. I have a 75 280 and just swapped in a 76 engine I rebuilt. Both engines have been running great. The 75 distributor stayed with the car but the intake manifold and afm stayed with the engines. The only item I changed on the 76 engine was swapping a 17lb flywheel with a 11lb flywheel. The Engine will not crank over with the key. It acts like the batter is almost dead. If I use a screwdriver to connect the pos and starter relay tab it will crank over ok. I do need to charge up the battery but it still does the same with a jumper vehicle running. After about 10 min of attempts to start it will finally catch and barely idle. The more it idled the better it got. Prob purging the air out of the lines. It still has a really rough idle and will pop and back fire a bit at low rpms playing with the throttle. The idle is really rough actually real lopey like it has a big cam. It doesn't appear to be running rich from a bad sensor though. I know the lighter flywheel doesn't have that much intertia but would it cause it to idle that rough? I have checked timing and did a quick check for air leaks(will do a more thorough one shortly). I have done a quick check of connectors and they all appear to be fine. It runs fine at higher rpm and drives around fine but just has the idle issue. Also it seams the idle screw has no where near the sensitivity it did before the swap. I cannot get anything over 750 rpm with the idle screw and turning it down will get it to about 400rpm. I briefly played with the temp sensors to make sure I got the right ones on but will double check. I actually swapped the connectors and to no gain. After letting it sit over night it still doesn't want to start up again. Barely catches on one cylinder then will run for a few second then die. Looks like the cold start/high idle circuit is not putting any effort in to help either. So here is what I have done Put a great running 76fi engine in a great running 75fi car Took 17lb flywheel off 76 engine and installed 11lb/ centerforce clutch. Took 75 3 wire dist that was in car and was installed on the new 76 engine. Removed and reinstalled intake/headers for easier removale/install of engine(yes used a new gasket too) Painted engine bay What its doing Barely starting and then dieing, takes a bunch of attempts then seems to finally start Really rough idle, like a real big race cam(sounds cool though) Idle control screw has very limited influence Slight hesitation and little pops/backfiring just off idle. What I have investigated I have checked to make sure I have reattatched all connectors I have checked and retime it. Only seems happy above 13ish degrees. Did a quick prelim check for air leaks. Still need to do the carb cleaner spray test What I still need to do Do a better check for air leaks Check all the grounds after painting engine compartment. Double check cam timing(never was touched but doesn't hurt to check) So I appreciate any suggestions from those who have scratched their heads and spoke lots of french to their engines before me. Thanks Quote Link to comment Share on other sites More sharing options...
Leon Posted March 19, 2012 Share Posted March 19, 2012 I have done some searching and have a few good ideas but wanted to get some more direct suggestions. I have a 75 280 and just swapped in a 76 engine I rebuilt. Both engines have been running great. The 75 distributor stayed with the car but the intake manifold and afm stayed with the engines. The only item I changed on the 76 engine was swapping a 17lb flywheel with a 11lb flywheel. The Engine will not crank over with the key. It acts like the batter is almost dead. If I use a screwdriver to connect the pos and starter relay tab it will crank over ok. I do need to charge up the battery but it still does the same with a jumper vehicle running. You're probably not getting enough voltage to the starter solenoid from your wiring. Measure voltage at the spade on the solenoid with a multimeter and have someone turn the key. I don't remember the exact excitation voltage needed at the solenoid, but over 10V should get it going. The solutions are to either clean all connections for the starter circuit or install a "starter relay" (search this). After about 10 min of attempts to start it will finally catch and barely idle. The more it idled the better it got. Prob purging the air out of the lines. It still has a really rough idle and will pop and back fire a bit at low rpms playing with the throttle. The idle is really rough actually real lopey like it has a big cam. It doesn't appear to be running rich from a bad sensor though. I know the lighter flywheel doesn't have that much intertia but would it cause it to idle that rough? The flywheel has nothing to do with idle quality. Torque = Inertia X angular acceleration If the engine isn't changing speeds (accelerating), e.g. at idle, then it doesn't care how much the flywheel weighs. I have checked timing and did a quick check for air leaks(will do a more thorough one shortly). I have done a quick check of connectors and they all appear to be fine. It runs fine at higher rpm and drives around fine but just has the idle issue. Also it seams the idle screw has no where near the sensitivity it did before the swap. I cannot get anything over 750 rpm with the idle screw and turning it down will get it to about 400rpm. I briefly played with the temp sensors to make sure I got the right ones on but will double check. I actually swapped the connectors and to no gain. After letting it sit over night it still doesn't want to start up again. Barely catches on one cylinder then will run for a few second then die. Looks like the cold start/high idle circuit is not putting any effort in to help either. So here is what I have done Put a great running 76fi engine in a great running 75fi car Took 17lb flywheel off 76 engine and installed 11lb/ centerforce clutch. Took 75 3 wire dist that was in car and was installed on the new 76 engine. Removed and reinstalled intake/headers for easier removale/install of engine(yes used a new gasket too) Painted engine bay What its doing Barely starting and then dieing, takes a bunch of attempts then seems to finally start Really rough idle, like a real big race cam(sounds cool though) Idle control screw has very limited influence Slight hesitation and little pops/backfiring just off idle. What I have investigated I have checked to make sure I have reattatched all connectors I have checked and retime it. Only seems happy above 13ish degrees. Did a quick prelim check for air leaks. Still need to do the carb cleaner spray test What I still need to do Do a better check for air leaks Check all the grounds after painting engine compartment. Double check cam timing(never was touched but doesn't hurt to check) So I appreciate any suggestions from those who have scratched their heads and spoke lots of french to their engines before me. Thanks Everything else points to a vacuum leak. Do the spray test before anything else. Quote Link to comment Share on other sites More sharing options...
Justinp551 Posted March 19, 2012 Author Share Posted March 19, 2012 Thanks for the tips Leon. I got a good charge on the battery and it was cranking normally. I had put a block off plate over the egr valve and little did I know it was warped so... Good size air leak on the back side of the manifold. Readjusted the valves, regapped the plugs and it purrs now. Thanks again Quote Link to comment Share on other sites More sharing options...
Leon Posted March 19, 2012 Share Posted March 19, 2012 Thanks for the tips Leon. I got a good charge on the battery and it was cranking normally. I had put a block off plate over the egr valve and little did I know it was warped so... Good size air leak on the back side of the manifold. Readjusted the valves, regapped the plugs and it purrs now. Thanks again No problem, glad to hear that. Nice job! Quote Link to comment Share on other sites More sharing options...
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