I recently purchased a 1977 F150 with a 302. When I bought it I thought the timing was way off. The guy said that he had a new timing chain put in (by a neighbor) and that it didn't run right since then. I bought it thinking that the distributor needed to be reset at TDC (It was off). After I reset the distributor to TDC and started it however, it backfired out of the carburator. It didn't stop until I advanced the distributor. The truck continued to idle really rough. It dies whenever it is in gear and I stop. It gets no power and can barely climb a small hill. I got to thinking about the timing chain. I just checked it out and it looks solid. No real slop or slack. I measured only a 1/4 inch in deformation. The Haynes manual said if it wasn't in spec to get a new one, but doesn't provide the specs. Does that sound like it is loose or worn? Also the gears marks were lined up according to the manual, but I am concerned that the guy may not have taken the original gears off while the marks were in line. Can that even be done and if so, how do I know it is in time? When the marks line up does that mean it is in TDC and if so, is the number one piston at compression? I also looked into setting the timing before I got into the timing chain mess and the manual keeps telling me to check under the hood for a list, but I can't find any plate, list, or sticker with this information. Anyone know the timing on this? Any other suggestions as to what could be causing these problems or what I probably should do would be helpful.

 

it doesn't matter if the timing marks on the gears are lined up when you take it out or not only if they are lined up when you put them back together, and since you said they line up you are ok there, as far as whether the marks together is #1 fire stroke or not, I have seen them both ways, my old 302 had them at 180deg off ( the cam and crank gears both had to have the marks straight up to be at the #1 fire) but if you are getting it to run then you are ok there also because if the dist was 180 off it wouldn't run at all. the amount of deflection you are talking about sounds fine. I would start by checking you time with the vac hose unhooked, and plugged and start a 8deg BTC that should get it running decent, it jus tsounds to me like your timing is very retarded probably off by one tooth which is easy to do.

 

The index marks on the cam gear and crank gear should be across from each other at TDC. The crank rotates twice for each revolution of the cam and distributor. The crank will also have the keyway at 12 o'clock when harmonic balancer is installed; the timing index pointer should be pointing to TDC on the balancer unless the outer ring of the balancer has slipped on the inner (get replacement balancer). Insert distributor so it points to number 1 cylinder wire while at TDC. There is no magic tooth for the distributor; just get as close as you can and rotate the distributor body to bring the cap #1 to the rotor position. If you have to make major adjustment; then there is something else wrong; balancer defective; dist cap with wires in wrong positions; etc. Follow a manual to set up and use a timing light to make final adjustment.

 

actually there is a "magic tooth" you can be off by one either way usually but if you are off then the dist may not rotate around far enough to get it timed, this isn't a problem with mechanical advance dist so much but it definatly can be with a vac advance or TFI ignition

 

The truck is a 1977; not fuel injected or anything else. If the timing chain is installed properly and you place the distributor in approximately the right position and pointing to number one then you should be able to time it by rotating the body. Naturally things like radiator hose; water outlet and other accessories would prevent you from doing a 360 adjust on the vehicle. But if you have this kind of problem it is not because of one tooth. If it can't be rotated far enough, moving the wires around in succession will offer another adjustment. But why. The distributor on these vehicles is just a switch and a distribution of power. If you are one tooth either way and you have adjustment, I just can't see a person having to pull their distributor to move it one tooth to the ultimate correct position. If you put the distributor in like so many pictures in manuals you should have enough room to rotate the distributor without the vacuum advance can hitting anything. I can do 30 degrees or more in either direction with no interference on my 302 (1979). So does this magic tooth have a recognizable index mark or is it just happen to be the one that let's it work? You can't really see which tooth is engaging the cam can you.

 

No there isn't a index mark but the proper position is when it is setting at aboout the middle of possible movement when it is in the correct position for proper timing, and on some fuel injected vehicles (although the origanal posters vehicle will not meet this criteria) if you just move the wires you have moved the firing signal and the bank fired injectors or sefi fired will be firing the wrong injector at the wrong time, and then it will not run correctly, but yes you can move the wires around, but on some vehicles then some wires will be stretched to hard the best thing to do is to do it right rather than cobble it together, so set the engine at the #1 fire position, then figure out where the #1 plug wire is supposed to be at on the dist (the manual should show a diagram for the firing order and the plug wire positions on the dist.) then with the dist in approx the center of it's possible travel set the dist into the whole with the rotor pointed at the proper position (remember it will rotate slightly as it engages the cam watch it when yo pull it out, and yo will see how much, and which direction) making sure it drops all the way in and engages the oil pump shaft (once it has engaged the cam you can bump the engine or turn by hand slightly to get the oil pump shaft to engage), then start the engie, and set the timing properly; or yo can cobble it by switching wires, and turning the dist and keep messing with it until you get it close enough to run well enough to get by.

 

Thanks. You have eleviated some of my concerns. After checking the timing chain, I came to the realization that the timing chain was actually installed and properly so. When I initially reset the distributor I thought I was at top dead center and the distributor at the number one firing pin. It started to backfire and I advanced the distributor one notch which stopped the backfire. That makes me think that I was off "one tooth" or more, say the difference between setting it at 1:00 and 2:00. While I originally thought it was the timing, the truck would start and even idle, it just doesn't do anything under load. This makes me think (now) that it may have something to do with a vacuum leak or improperly placed vacuum hose. (I just found out yesterday from the guy I bought it from that he replaced the carburator gasket, meaning he had the carburator off the vehicle.) Now I have to put it all back together and deal with the real problem. At least I am sure the timing chain is no longer an issue. My new question is how should I go about diagnosing a vacuum problem? Do you agree this may be an issue? If not, any suggestions other than setting the timing?

 

for checking vacum leaks get a can of carb cleaner, and with the engine running spray around your gaskets, and vac hoses if the engine rpms increase at some point you found your vac leak, but don't spray so much it starts to puddle as I could catch fire if the engine gets hot enough, usually as you spray it at the gasket areas it will evaporate fairly quickly, then continue on until you either do or don't find a leak.

 

Thanks. I'll try that.