vamprobozombie Posted September 30, 2023 Share Posted September 30, 2023 My father is performing the 2.8 to 3.4 swap and looking to add a FiTech EFI Go 3003 Throttle Body Injection. He has a modified intake manifold that takes a standard Chevy 4 barrel. Fires up good but finding 2000 rpm idle. Gets a little bit better 1200 rpm when disconnect vacuum advance on original distributor. Was wondering what is the ideal vacuum reference on that with original emission equipment eliminated. Looks like a standard Chevy HEI but wondering what adjustments need to be made to run it like this or should just pick up a new one. Vacuum measuring 17 inch from the Fitech going to validate that with a gauge. Verified fuel pressure is correct and having it recalibrate the idle air controller controller did not do anything. After I verify is hooked up right and and all readings make sense will be off to the Fitech Forum. 1986 Jeep Commanche Link to comment Share on other sites More sharing options...
zomeizter Posted October 1, 2023 Share Posted October 1, 2023 Vacuum advance needs ported vacuum when acceleration occurs, the carburetor has this port to properly advance timing when the accelerator is depressed. If your vacuum routing diagram is still visible, you can find the correct port where the advance gets hooked up. But if you're going EFI, then that system will be controlling the ignition advance otherwise. My MJ is equipped with the 2.8L and the original 2SE Varajet carb with all those emission hoses and plumbing still there, I recently refreshed the carb with a rebuild kit and man does it run well, but it took some effort getting all the linkages properly adjusted, patience is a must here... Link to comment Share on other sites More sharing options...
vamprobozombie Posted October 1, 2023 Author Share Posted October 1, 2023 Ok think I found it in the Fitech drawing and forwarded it to my father. This is just a simple throttle body injection system where it basically acts like a carb but more efficient atomization of the fuel. No fancy timing controls or anything but am stuck with the old distributor carried over from the 2.8 to the 3.4 unless there is some obvious reason to move on from that should be good assuming we hook it up right. Link to comment Share on other sites More sharing options...
Greenjeans Posted October 3, 2023 Share Posted October 3, 2023 For what it’s worth, 2.8 distributor requires 10 inches of vacuum to pull the vacuum advance canister arm all the way in. IMG_0215.mov Link to comment Share on other sites More sharing options...
zomeizter Posted October 4, 2023 Share Posted October 4, 2023 7 hours ago, Greenjeans said: For what it’s worth, 2.8 distributor requires 10 inches of vacuum to pull the vacuum advance canister arm all the way in. IMG_0215.mov Nicely done jeans! Just today I pulled my MightyVac out of hibernation to check some old choke pull-offs and the vacuum advance on my K5, damned thing wasn't working at all. Took it all apart, cleaned out all the crust and replaced and lubed all o-rings, damned thing sucks good again! Link to comment Share on other sites More sharing options...
Greenjeans Posted October 4, 2023 Share Posted October 4, 2023 I dug out my old vacuum pump when I got into this project (30 year old tool probably) and it was nasty so unfortunately I had to make a trip down to Harbor You Know Where.. one of several trips down there I’m afraid.. Link to comment Share on other sites More sharing options...
zomeizter Posted October 5, 2023 Share Posted October 5, 2023 Yeah man, I always take stuff apart that can be taken apart and try to repair it before tossing in the recycle pile. Once in awhile, a little time and tinkering can save you some dough... Link to comment Share on other sites More sharing options...
Robert U Posted October 7, 2023 Share Posted October 7, 2023 Anyone within 200 miles of Roanoke Va. that could/would contemplate rebuilding and enhancing the 2.8 in my 89' Comanche? Link to comment Share on other sites More sharing options...
zomeizter Posted October 9, 2023 Share Posted October 9, 2023 On 10/6/2023 at 8:00 PM, Robert U said: Anyone within 200 miles of Roanoke Va. that could/would contemplate rebuilding and enhancing the 2.8 in my 89' Comanche? 2.8 in a 89? Link to comment Share on other sites More sharing options...
Robert U Posted October 9, 2023 Share Posted October 9, 2023 5 hours ago, zomeizter said: 2.8 in a 89? Sorry..1986 Link to comment Share on other sites More sharing options...
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