Hello, i did a bit of searching around but i cant seem to find the unofficial method of adjusting the distributor on my 400 (in a 79 F250 custom 4x4). everyone says "loosen up the base a little, start the truck, then slowly turn the distributor base and listen for rev changes" although it looks like, on mine, the base of the distributor is held on in the same fashion that the cap is, that is to say, just 2 clips, that you can flick off with your thumb. this is all well and good, except, they can only clip on in a certain designated spot, so i dont believe i can adjust mine in that fashion. is there something im not seeing? this truck is driving me insane, lol.

thanks in advance for any help, and sorry for not paragraphing!

 

You need to look down further. The cap is held to the dist in that fashion but the dist is clamped to the block by a single bolt and metal lever. Timing should always be adjusted using a timing light if your not familiar with what you are doing.

 

aye, i know, but im in a bit of a "really effin broke" situation. i aloso know that working on these trucks is not the job for a broke man, but i dont have much choice. anyway, i plan to mark where its at right now, so, worst comes to worst i can always put it back to where its already at, but (if you look back to my old old posts on here) my truck is hiccupping on rev, and i gotta do something about it, everyone i talk to tells me try that first, just spin it a little bit, and listen to the revs. thanks for the info!

 

ps, a little off topic, but why are there like 100 ads for the silverado on this ford truck enthusiast site? lol.

 

Totally understand the broke part so no disrespect intended. If you cannot find the clamp down that holds the dist post a pic and maybe we can give you a hand. Is your vaccum advance hooked up?

 

bahh, my digi-cam is missing its usb cable. i think ima run down and buy one of them right now. there IS 1 vacuum line that isnt hooked up, i believe it goes to the breather. the breather was off when i got the truck. i do believe youre right about the location of the clamp down, but i'd like to post some pics all the same, as i want to be sure vacuum routing is correct.

 

vacuum advance will be a small 1/4" line going from the carb to the distributor. Does it backfire from idle when you rev it or from mid rpms and rev it higher? and does it backfire when you let off the gas?

 

it pretty much only backfires (through the carb, always) when i go from idle, to mid-gas. it doesnt happen while idling, and when i slam the gas, the revs up nice and high, and doesnt usually backfire, except sometimes when i keep it at wot for like, 5 plus seconds. it doesnt backfire when i let off the gas, though sometimes it will make a bit of an unsettling clank sound when i let off the gas from high rev. also im not entirely sure if it even has vacuum advance. running to the store real quick to get a usb cable though. need it anyway. p.s. i recently rebuilt the carb, if thats of any consequence.

Edit: It was doing the same thing before carb rebuild.

 

vacuum advance is a small silver half conical looking round thing for lack of a better term. It is found at the top of the distributor and is right by the base of the cap. It has a small round nipple sticking out of the middle of it. If you have this the dist has vacuum advance, it very well should. If you can go WOT from idle and it doesn't pop out the carb I am not convinced that it is a timing issue (ignition timing anyway). I'm curious if your accelerator pump is delivering the correct amount of fuel when you push the gas. Is your choke set and working properly?

 

alright, well it appears you are correct as to the vacuum advance. and it appears to be plugged in correctly. (i put it back where it was before i rebuilt the carb based off pictures i took before i dis-assembled it) as for the accelerator pump, i put the linkage on the "c" position, which, according to the manual that came with the carb kit, is the correct spot for this engine on a truck during the winter. it recommends "b" for the summer. the choke, i did mess that up. i hooked one of the linkages up to the wrong of the 2 spots it could go, so it stays open, however, it was functioning properly before i rebuilt the carb, and it was still doing exactly the same thing. i havent bothered to fix it yet, cause the truck being lame is so discouraging. if you think it will make a difference i can fix it easy enough, but it appears to be unrelated. and none of the stores i went to had the cable i needed, so no pics

 

Have you tried adjust the timing yet then? If you are popping out the carb I believe you need to retard the timing a big which will lower the rpm's. When changing timing moderation is key, a little movement does a whole lot so don't move too much. I am seriously questioning this being the case but it is easy enough to check and should do no harm. I have one suggestion to make. Start the engine first before loosening the clamp on the distributor that way you are there to loosen it and the force of starting the engine doesn't turn the distributor.