Whats up guy's? I've got some questions that have been touched on but no one has really answered. I've got an 86 bronco which doesn't run for crap. I've pulled the plugs and done a compression check. 150 on each cylinder, but the plugs are black. Throttle response was reasonable after replacing the plugs 300 miles ago but idle has always been erratic and power isn't like I remember my 70 short bed with the same engine(300 I6). Most of the emissions equipment is missing and what's there doesn't look good. I would like to remove as much of the crap as posssible. I've heard rumors of an EGR block off plate but I can't seem to find any details. The truck is used for off highway purposes so inspection is not an issue. Efi and a high output ignition are on the agenda but for now I just need to get it servicable before winter. I've invested in a kit and have begun rebuilding the carb. I plan on installing a manual choke as well. I wouldn't mide swapping out the carb for something a little more user friendly.

Thanks in advance!!

 

You probably have the Carter feedback carburetor and the TFI ignition system. The feedback system utilizes a computer to adjust the carburetor and the ignition timing. The computer accepts inputs from various emissions sensors to make its decisions about timing and carburetion. If the signals from the emissions sensors get too far out of tolerance, the computer gives up trying to adjust the timing and carburetor. When that happens, the computer reverts to a "open loop" mode. In the open loop mode, the timing and carburetion defaults to some preset values that are designed to allow you to "limp home". In the open loop mode, power and gas mileage drop off drastically. Given your description of your emissions stuff, it is likely that you are in the infamous open loop mode.

You can replace the TFI ignition system with a Duraspark II system. Unlike the TFI system, the DuraSpark system is not controlled by the computer. The DuraSpark system uses old fashioned centrifugal and vacuum advance mechanisms to adjust the timing. Once the DuraSpark system is in place you can remove the emissions stuff and install a Carter non-feedback carb from the late seventies. You should be able to use this site's search feature to find information on installing the DuraSpark ignition and the Carter YFA carb.

Good Luck, Let us know how it all turns out.

 

Do you recommend the late 70s YFAs? I'm getting mixed signals from different posts. Someone said stay away from them because they are emissions carbs. I'm thinking so what! Thats just extra vacume ports and maybe if I'm lucky leaner jetting. I can get rebuilt YFAs for around $65. Might be worth a try?

 

When it comes to carbs, simple is better. The pre-emissions Carter carbs and the Autolite/Motorcrafts were the best. You can also drop a 2 or 4 barrel on there. Bottom line is find a carb option that you can live with and go with it. Don't waste time/effort fighting a carb that you think sux.

 

With winter around the corner, and your truck running horribly, I would invest in the aftermarket stuff rather than mess with the stock garbage. I have an Offy DP manifold, Carter YF carb and Hedman header that I am using to not only remove the emissions equip but also rid myself of the headache of the 1bbl carb that these motors come stock with.