First of all I apologize if there is already a thread that answers my questions, but I have been looking and looking and can't find a thing that seems to apply.

76 f 150 390 edlebrock carb sitting for 8 years before I bought it

This all started when I replaced my carb, went from a holley 4 barrel to an edlebrock thunder series with electric choke. the holley was bum, running ok with it, but it was leaking fuel from almost every place possible. the switch went fine, drove it for two days with no issues other then a slight backfire occurring when i let off the gas from accelerating. so i tinkered with the timing as I thought it was slightly to fast. I had a friend help me because he has a more experienced ear... got it running great but us dumb asses forgot to tighten distributer hold down bolt. drove 15 miles before i realized something was amiss.
anyway that destroyed the distributer gasket.

I then pulled distributer to replace gasket. Set engine to TDC beforehand and made sure it was on compression stroke.. triple checked this!!!
no signs of wear on distributer gear so i dropped it back in being careful that the rotor landed in the same spot it had been before I pulled it.

started like a champ ran great for 20 minutes, I turned it off and went inside for dinner, when i came back out would hardly start and when I was able to get it running it would either spit out of carb or diesel.

I started all over double checking everything i had done. i am confident i am within reason with the timing, have checked all vacuum lines replaced wires cause the old ones were throwing sparks, i have double checked firing order and made sure i have no crossed wires. tried a new dist* cap but made no difference vacuum advance seems to be functioning properly .... i don't no what else to try, engine is completly stock except for the carb.

I do have a leaky intake gasket but i was driving for 4 months without issues before this whole episode so i don't think this is causing my problems.

I am at a loss as to what else I can try... I was planning on rebuilding the engine in a few months once i have the funds together but It is my daily driver and has been for 4 months so i just need to get it running to get me through till the time comes that can pull the engine.

right now it starts and turns off sounds ok but is significantly underpowered and i get these backfires, if i advance the timing i get diesling and if i slow it down it spits out of the carb (not completly atomized but also not a stream)

I tried to be thorough ..... hope its understandable

Any help would be appreciated

 

Also at idle it seems to have waves of higher and lower rpms, unless i advance the timing to a point where it is obviously to fast, not fast enough for pings but still revving to high,
I am doing a compression check tomorrow and there is a significant exhaust leak on the right bank exhaust flange, the flange pipe is pockmarked with rust and won't allow for a good seal....

 

Could be a worn timing chain. That will cause a wandering idle.

You are timing it by the idle speed? When I tried that on my 289, I had to advance to the best, highest idle, and then back it off a bit to get decent running out of it. Serving suggestion....

To check your timing chain slack, you will have to pull the distributor cap and rotate the engine until the rotor moves. Reverse the rotation and note how far you can turn the crank before the rotor moves. More than 5 degrees points to replacement time. A lot more and you can have the wandering idle, and even have it jump a tooth, which will cause problems like you describe, if it runs at all.

 

Also a leaky intake gasket is something to be fixed not lived with. It can have you chasing all sorts of gremlins.

 

It sounds like the timing chain jumped when you shut the engine off. Typically, they won't start again. At this point, the valves are out of time with the crankshaft. Messing around with the distributor won't change the valve timing. My guess is the intake valve is not closed when the distributor fires the spark plug.

You really need to use a tachometer, timing light and vacuum gauge to optimize your tune. Once you learn how to use real numbers, it is easy to diagnose other problems.

At this point, since you need to get to work, spend the money on a new timing chain and gears. If your local auto parts does not have a loan-a-tool program for the tune up tools, do this:

>Install the timing set for a pre-emissions 390. I don't remember the exact year, but at some point, Ford changed the valve timing, which cost some torque.
>With the distributor cap on, mark the housing at the number one spark terminal.
>With the new timing set installed, timing cover, pointer, and damper installed, rotate the crankshaft twice and stop at 10 degrees BEFORE Top Center.
>Drop in the distributor and rotate the housing to line the rotor with the mark you made.
>Tighten the clamp and DON'T FART WITH THE IGNITION TIMING!

After you get it started, have your buddy adjust the carb by smell. If he is that good, he knows the smell...

 

You can do most all your tuning with a cheap vacuum gauge - timing included.

 

Thanks all for the response!


spent a few hours out there today
we got it running pretty good, used a timing light but I was spot on.... there is some play in the rotor we noticed though, much more then his well running 390. tried his rotor out but it was the same thing, he suggested it was time for a new distributer ( the slot that receives rotor is worn out somehow) but as of now it sounds and performs pretty good a little underpowered... but no spits, backfires, or diesels, and the waves of power have lessened significantly.
we rewired the terminals for the coil pack and that helped the waves greatly... i guess the corrosion wasn't allowing for consistent spark.

I Hear you 69CJ I'm breaking down and am going to do the gasket and whatever else i can without delving to deep, before i continue to drive it. I'm putting a parts list together, and so far i have

intake gaskets
distributer and coil ( might as well do them together right?) also if this is only a daily driver is it worth going for MSD or should i save the bucks and go with a stock replacement?
summit racing header back exhaust kit 2.5"
headman headers

the exhaust is necessary, full of holes.
all in all i think i can keep it under a grand

the engine was also EGR that was removed and blocked off by previous owner with a holley carb spacer, I am wondering wether I can get an aftermarket intake and therefore remove EGR completely?? does anyone have and experience with this?

thanks all for the quick replys

also is a timing set going to be necessary if i don't find slack in chain?

 

If less than 5 degrees slop no but if I was that far into it they are relatively cheap compared to going back into it.

 

Hello all,

Just thought it was time for a update because much has happened since i last posted.

After getting it driving decently (except for a major oil leak) i shopped around some and found a local engine builder who runs three FE powered vehicles of his own. total cost for engine build was 1685$ plus a edelbrock intake ( to cancel EGR Bull) and new distributor which put me at about $2200 for a .30 over mild cam 390 with the dreams of carefree driving ahead....

so I went for it good thing too becuase my builder found a huge list of problems ranging from a rear main seal composed entirely of RTV mismatched wrong length pushrods and the wrong fuel Pump concentric among many others.....

anyway I blew my original budget out of the water..... but now i don't have anymore timing gremlins or oil leaks 1000 miles down with no issues other then a lean condition caused by my now to small edlebrock 650 ( i have re-jetted to get a happy drivable mixture could still use a bigger carb though)

it was a fun challenge made possible by this forum and all those that use it ( i used this site as a reference to many times to count)

thanks to all

Hope the pics post

 

That's great. Which cam did you use?

 

Good deal. I'm running a 770 Holley Street Avenger on my 428cj and it was near spot on out of the box. Been on it two years now and haven't had to touch the adjusters. By the way, electric choke is the way to go.

 

Great job

Love the truck too...

 

I can't remember the cam off the top of my head, engine builder recommended it, similar specs to a comp 270h if i remember correctly.

CJ- I have been thinking about getting a bigger carb, can't budget it yet for another month or two though, Thanks for the suggestion. wanted a eldebrock because everything I've read pointed to them being good out of the box with little seasonal tuning required... have you had to retune significantly for the change of seasons? .... I did go with the electro choke which has helped a lot with the cold weather I've been getting lately.


Just a quick question for y'all... I got a vacuum gauge recently and hooked it up, found something slightly disturbing...

at idle (roughly 800-900 rpm) Im Getting a fluctuation from 6 to 12 hgs that corresponds to the beat of the engine. If i rev engine up and hold it about roughly 2000 rpm I'm reading a steady 20 Hgs of vacuum...

I know everyones gonna say vacuum leaks somewhere, but i have replaced all lines and checked all possible leak points with carb spray and haven't found any leaks... at least with the spray and check method. i mean I've checked from the transmission vacuum switch all the way to the top of engine. new check valve in booster....

I guess I'm wondering what else might cause this. Is it possible a valve is sticking? or something of the sort?

i still get a occasional diesel and it has tried to stall on me twice now at a stop light. which i was blaming on a lean condition after my builder recommended a larger carb. these conditions did get better somewhat with rejeting FYI


Any thoughts would be appreciated
Im borrowing a tach tonight to get more accurate numbers.

Also if this helps my timing is at 12 initial which my builder was happy with, he also thought my timing overall was well curved and that i shouldn't mess with it..

 

ohh and Thank you Krewat!
hope to get enough sun this week to wash it

 

quick update!

SO i got the tach hooked up and have been tuning. I figured out that i was running a slow idle of 600.... got it up to 800 and my vacuum is now fluttering between 10 ad 12 which is a big improvement, still not good enough though!!!

Also if i rev engine up to around 2500 and let off it drops to 1000 rpm instead of coming down to 800.
without changing anything i turned it off. got a diesel( spinning at 1000 wouldn't cause this would it ?). turned it back on and Im back at 800 rpm.

I know a cam is supposed to walk itself down so to speak, but if i rev and let off, the rpms won't drop below 1000.

all that info was from being in park. if i put it in gear it drops about 150 rpm...

Hope this is understandable!!!
I Just don't Know what is normal with a cam