I finally found the time to finish installing the carb and intake on my truck, 1985 F350 460 4x4 MT. I installed a non emission Edelbrock Performer (2166)and an Edelbrock 1411 carb. I aslo took off the air injection, EGR valve and associated plumbing. This is a non computer controlled engine. The previous owner told me he had installed a new performance cam and timing set in the truck last year. It ran just okay when I purchased it. The carb was leaking internally and it was down on power, terrible fuel mileage, the timing was off or it had a vacuum leak as it back fired through the carb when shifted and was difficult to start.

I decide to strip the emissions stuff and replace the carb and intake.

When I first tried to start it, it back fired through the carb, and would not start so I figured I had replaced the distributor incorrectly. I lined up the mark on the balancer to TDC and verified the rotor position, it was about 1 cylinder position off of the #1 tower on the dizzy cap. At this point I made the assumption that the dizzy was installed correctly but the timing was way off. I turned the dizzy to align the #1 tower with the motor at TDC. At this point the truck started, it struggled to start, acting as if it was flooded but started and stayed running after a idle speed and air/fuel screw tweak. I stopped and started it a couple more times, checking a fixing a couple of leaks and trying to set the timing.

While setting the timing, I noticed I was not able to get any more than about 8 deg initial advance before the vacuum advance housing hit the air injection pump bracket. I tweaked the mixture and idle screws a little more and shut the truck down to tighten the dizzy hold down and pick up my tools for a test drive. After sitting for about 30 minutes it would not re-start. Tried about an hour later, same thing, not even trying. I did verify that I have spark and fuel.

I do realize that my dizzy is most likely set up for emissions stuff and egr. I know I will have to re-curve the advance for the best performance. I would not think the emissions curve would be so much as to make the truck difficult to start? The dizzy appear to be a newer re manufactured replacement, no idea if it is for an emission or non emission engine. I plan on replacing or re curving it in the very near future.

Any thoughts as to what is going on and where to go from here? I'm wondering if the cam timing is not correct (from the PO replacing the cam) or maybe I have "tweaked" the carb and/or timing too much? The truck seemed to run okay after my initial adjustments, I did not get to drive it though.

 

Did you have the vacuum advance hooked up when you set the timing? If so, the initial timing is waaaaay to late. In any event, you are one tooth off on the dizzy, which is causing the vacuum canister to hit. You will have to pull the dizzy and install it one tooth advanced. And I'm thinking the late timing is causing the starting problem.

 

Gary, thanks for the response. I set the timing with the vacuum advance disconnected, carb port capped. I will pull the distributor and try it again. Dumb questions, how much is one tooth? I need some sort of a reference for how much I should rotate when I reinstall. Second dumb question, which way should the rotor be moved when I reinstall?

 

If you pull the dizzy up slowly you can feel when when the gears clear. Then set it back down gently and rotate it clockwise until it meshes at the next space and that should be it. The crank rotates clockwise so the dizzy rotates counter. To advance it you have to rotate it clockwise.

 

Spark plug wires installed incorrectly?

 

Thanks Gary. I will mess with it when I get home from work this afternoon.

 

I think so. It ran decent once I was able to get it started. But I will check them when I reinstall the dizzy.

 

I don't care what the PO told you, your description in the first post reads like textbook worn timing chain.
Backfiring through the carb will blow the powervalve in a 4180 and it will constantly leak fuel in the primaries.
So, that makes complete sense...

Maybe he used the wrong distributor gear and that is causing the sloppy ignition timing?

Maybe he installed an adjustable timing chain on the wrong keyway?
(though this wouldn't explain the backfire when you lift off the throttle to shift)

Either way, take the distributor cap off and put a breaker bar on the crank bolt.
Rotate the crank one direction until you see the rotor moving.
Now rotate the crank back the other direction and see how far you have to turn it before the rotor follows.
6 degrees (that would be one minute on a clock) is way too much slop.
You can imagine your ignition timing being that far off and changing every time you let off the gas.

A worn chain will affect both cam and ignition timing.
A worn out cam or distributor gear (from using incompatible metals) will only affect ignition.

 

The PO timing chain/cam install has been in the back of my mind through all of this. I have found a lot of half a$$ things the PO did, neglected maintenance items, it makes me doubt everything he told me and the quality of his work. On a happy note, I got a screaming deal on this truck and it is in very nice condition

I will go through the timing and distributor trouble shooting that you guys have suggested and see where I end up. If nothing works, I will dig into the timing chain and see what if find there.

 

I imagine if you are messing around with the distributor you could pull it and visually inspect the gear (and the one on the cam, through the hole)
Steel gear on an iron cam blank, a bronze or iron distributor gear with a steel cam will eat itself up too.

Another way I have found to see a worn timing chain is to put the timing light on and bring the revs up to 3k or so.
Then let the throttle snap shut and watch the timing marks.
Advance should retreat smoothly.
If the marks are all jumping around, you know the distributor has a sloppy connection to the crankshaft.

Use a stick or something to push the throttle linkage.
You don't want to be draped over the fan of a revving engine like that.