I am learning about the recent 302 powered 79 F150 I bought last month. I have been haveing a jerky condition at partial throttle when the truck is warmed up and off the choke. The U-joints were worn and exagerated the problem. I now have new U-joints and it has smoothed out to some degree but has exposed the engine to be running a little rough at deceleration and partial throttle under load. It also pings easily when under load, but only after the truck is warm. I haven't had a chance to check the timing or plugs, but I will tomorrow. I'm thinking that I have a lean condition maybe caused by a vaccumm leak, or perhaps a carburator that has debris in jets. I haven't ever messed with carburators much so they are allittle intimidating to me. I had been told a few times by mechanics that the motorcraft 2V is crap to try and rebuild. As far as vaccum leaks, I don't see any obvious ones. I see evidence of leaked brake fluid on power brake booster (the master cylinder is full). I don't really know how to evaluate the EGR valve or the power brake booster for posible leaks. Any ideas for trouble shooting this? I never have much trouble starting the truck, it never floods. Always a short turn of the key and it's running. No pumping the gas or extended cranking. When I set the choke in the morning, it's one foot to the floor. It does run kinda rough at first and I coxe it with some gas untill it smooths out after a minute or so.

BBT


BBT

 

It sounds like your on the right track with checking the timing and plugs. Before removing the plug wires, check to se that they are in proper firing order. I had a 79 F100 in school that I changed plugs in shop class. Another guy in class installed the wires on one side of the motor while I did the other. He got two of the wires crossed. The truck ran, but showed the same symptems you have explained. Check the wires first, then timing, give er a tune up and see what happens. Let us know if this solves your problem.

Nathan

 

unless your in Cali, ditch the EGR, 2V motorcraft carb, and the stock intake, slap a 4 bbl 600-650 cfm and check all vaccum lines , have your self a real stump-puller :O)

SEANSTER 77 F150 XLT RANGER 2WD 400 C6
Edelbrock cam, intake
CARTER AFB 625 cfm

 

Aahhh.....
Cali isn't the only place w/ emmissions. The good news is here in WA, if the sniffer is happy then the inspection is good. I have an Edelbrock manifold for the 302 (Performer 289 Dual plane) but without raiding my 390, I don't have a carb. Money is an issue at this point, and I don't want to start removing emmissions stuff off the 79 because it is going to have to be tested a few more years. I still haven't decided whether this motor will get swapped into my engineless 76 or whether I will just leave the 79 alone while I have my 390 (in my 69) rebuilt. Before I get very involved in spending money on this 302, I want to troubleshoot all the noises and problems. I don't want to start polishing another turd. Well, off to play with the truck on a sunny spring Saturday.

BBT

 

Sounds like timing but check you vaccum line going to your transmission modulator. Sometimes it can come off or crack and you will never hear it because it's under the truck !

 

Stump puller? with the 302 and 2.75 gears it's more of a weed puller. Nix on the transmission modulator, it's a manual. I'm going today to a buddies house who has my timing light. I also am diving into my first carb rebuild on a 2bbl Holley I took off my 390 when I first got it. Got the kit, got the book, got a buddy to baby me through it, it's been soaking in cleaner. Here goes.....

BBT

 

I have an Edelbrock 4V on my 360 powered truck now but the Motocraft carb. is fine. The rebuild kits often!! do not have the correct power valve in them and you get the parts guy to look up the right one. My truck had a lean surge to it that was corrected with the right powervalve. You cn see that the springs have different ratings for different applications... For what it's worth...
TomC