How to advance timing ? step by step needed

[Orangecrush]

Okay, my truck runs GREAT when warm. However, it doesn't want to start. I mean it's really an art to get this thing running. My first suspicion is that the timing is off, most likely too ********?

First, here are the symptoms: cranks and cranks with hardly a sputter when cold. If you pump the peddel, eventually you'll get it to catch just for a second. Once it does start to catch, you have to continue to crank it (great for the starter /emoticons/[email protected] 2x" width="20" height="20" /> ) and pump the throttle. Once it gets to the point where it MAY run on it's own you have to continue pumping the throttle. The weird thing is that the engine "bounces" at this piont. It is sort of like it's running and then not then running then not, almost like the key is being turned off and on and off and on....... This goes on for maybe 5-7 seconds. Then, it roars like normal. I'm thinking this could be the timing not being advanced due to low ported vacuum but then bouncing back to advance and so on and so on. It also like to backfire when trying to start (fuel not burt).

Now, assuming this may be a problem with the initial timing, I want to be able to adjust.

I know how to rotate the distributor clockwise to advance and counterclock to ******. The problem is that the vacuum mechanism is as far as it can go and is hitting the water inlet neck. I understand that there is a way (if it turns out that retarding the timing makes it worse) to advance the spark more by moving the distributor to another tooth on the cam.

Can someone walk me through, step by step, how to accomplish this??

 

[BLADE262US]

Well I usually use the vaey back middle plug on the cap as number one . First you have to remove the front passenger side spark plug as this is number one . The you have to roll the motor over by hand till that cylinder is on top dead center compression stroke , The bolt in the middle of the harmonic balancer is 15/16 . With the plug out put your thumb over the hole and roll the motor over with a ratchet till you feel the compression in the cylinder then stop . I usually use a screwdriver from this point and put it in the spark plug hole now slowly roll the motor over hanging onto the screwdriver so you can feel the piston coming to the top once it hits top dead center you will feel it start to go down . Back the motor up a bit till you just feel it start to back down again now go just a bit forward again . This is not exact within a degree but it will get you very close to top dead center . Now that you have that done take the ditributor hold down bolt out , Remove the cap and note which plug wire the rotor is pointing too it should be the number one cylinder , Now move the vacuum advance unit half way between the water neck and the other side of the intake . Then take the rotor and move it to which ever one you want number one to be I usually do the one straight back. Now when you go to put the distributor back in you will have to move it one tooth to the right of where you want it to point so if you want it too point straight back you will have to start it in the hole a bit to the right . The distributor gear is helical cut so when it meshes together it will move back to center . Once you have the distributor back in and the rotor is pointing to where you want put the cap back on and rearange your plug wires starting with number one at the post where your rotor is now pointing and then follow you firing order moving to the left around the cap . The you should have plenty of fine adjustment by moving the distributor base . /emoticons/[email protected] 2x" width="20" height="20" />

 

[Orangecrush]

Wow. Thanks for the detailed instructions. I was kind of hoping it would be easier. I figured I could just center the distributor, remove the bolt holding it in place, pick up the distributor and move one direction (to the right / counterclockwise I guess?) by like one tooth then fine adjust as normal. I guess this won't work?

 

[BLADE262US]

Nope have to be at top dead center or you will throw off the relationship between the cam lobe events and the rotor position . /emoticons/[email protected] 2x" width="20" height="20" />

 

[S_bolt19]

A quick question, how many miles does this engine have on it? The reason for this question is that your symptoms are eerily familiar to what I had about 3 years ago. I would do the exact same thing you are doing and then I ended up rebuilding the engine. When I went to take everything apart, I took the timing cover off and I lifted, yes lifted, the timing chain off the gears. The chain was so streched out and the nylon timing gear was worn down to the aluminum gear and that was almost smooth. Needless to say, that is what 420k miles will do to an engine though /emoticons/[email protected] 2x" width="20" height="20" />. But that is only an after thought. If it is the problem, it gives you a great excuse to go to EFI, which is exactly what I did and I love it. I wont ever own another carb'd Bronco in my life. It is so much better off road than anything I have ever driven that has a carb. And it is "hill and off camber" friendly....lol

 

[Orangecrush]

I don't know how many miles are on this motor. The guy who sold it to me said the engine came out of a '74 LTD. That's all he knew. I'm sure it's high mile. You can just tell.

The thing is, I've spent so much money on the components, I hesitate to rebuild for another $4500. I figure that's what the bill will come to. You're right, the chain could be totally stretched thus delaying the cam timing (would that also ****** the spark?....seems like it would?). The other thing that concerns me is maybe this a symptom of lack of compression due to worn rings and/or cylinder walls. That would explain why the thing runs like an ape when warm, but barely starts when cold. hmmm......

Well, on another topic, how much compression would you expect to see on this motor? It's a 351W from '74 (I think that would put it at 8.5:1 compression ratio). How much pressure per square inch would be acceptable on a compression test? I'll check later today.

Thanks!

 

[BLADE262US]

It should have atleast 100 lbs on it any less and youll have to do something with it . Pull all the plugs out , put the compression tester in the cylinder you want to check ,have someone hold the throttle wide open then crank the engine over a couple times you should see the guage come up and level off at the max compression that cylinder is capable of . That is a dry test . Now squirt some oil in there roll motor over a couple tmes then reinstall the gauge and see what your reading is now if its alot higher the rings are worn badly and will have to be changed another thing you can do is like the snap on comression guage adapters will plug into an air hose so you take the valve stem out of it bring the cylinder in question up to top dead center and put the adapter in then hook an air compressor to it . If you have air coming out the carb the intake valve is worn and not seating if you have it coming out the exhaust the exhaust valve is shot be warned that if the motor is really loose when you apply the air to the cylinder that you have at TDC the motor may roll over to bottom dead center as the air will push the piston down , /emoticons/[email protected] 2x" width="20" height="20" />