Hello once again all. I greatly apologize for the beginner questions..I appreciate all the feedback and I do try to take all the advice. I have a 69 f250 with the 390. My question is I heard early fe 390 engines were retarded with the cam timing for emissions purposes. I heard that to improve performance greatly that I should change the timing gears work a 70s era timing gear/chain..
Is this correct? Anyone done it? I recently changed my timing set but with stock stuff. Just ole cheap kit from napa I believe. But now I'm second guessing myself on the information I heard about it being retarded on the cam

 

You'll have to dive into some of the archive forum posts, here and elsewhere. Ford did retard valve timing at some point in the 1970s. I don't know what they were doing in '69, keep in mind though Ford has been known to change parts without changing part #s, and this is true especially of things that affect emissions. So the question becomes what parts are you using, NOS? Or aftermarket, what is the part # and application. They can be sneaky about it. They have the cripple-factor baked right in.

What all this means in practice? When selecting a timing set it's difficult to know what yer gonna get.

Now, add to all this the fact without actually degreeing in the cam when installing any timing set it's a guess and by golly where the valve timing will actually end up. There's no way to know for sure, without at least checking the valve overlap in relation to TDC. This can be done without a degree wheel.

I wouldn't say improve performance "greatly", but it's noticeable for sure. It depends. Rule of thumb says 4° valve timing one way or another to feel it in the seat of your pants. Let's say the chain is stretched and worn. That can be 4° easy, or more. Ford had also retarded valve timing from the factory say, by 4°. That's 8° off from "straight up" say.

Then you dial in the new set using an adjustable keyway with 4° advance from "straight up". A 12° total change from the old set will be noticeable, better low end grunt, better cold starts, better compression, etc. A bit of camshaft advance at installation will also tend to compensate for the inevitable chain stretch that occurs. It can be beneficial to add even more advance if living at altitude, or rock crawling. One nice thing about stock, factory stuff. Don't have to worry too much about stuff banging into each other. Keep in mind as valve timing changes, the pistons start chasing the valves and will eventually catch up, if you go too far.

A good way to infer valve timing on a stock engine is using a vacuum gauge. With the engine idling at factory RPM and adjusted to factory ignition timing specs it should pull 19" to 21" at sea level. Slow or late valve timing will have a low manifold vacuum. It takes some experience to interpret vacuum test results, allowing for corrected #s due to altitude, but the gauge never lies.

 

I honestly dont know the part number anymore..I just went to napa and said I have a 68 f250 390. I threw away the box too. I was just curious. I remember I was having issues getting the crank to get to tdc and the dist to point at cylinder 1. I ended up 2 degrees advance on the crank....last I remember. Maybe I got it to the 0 eventually but i can't recall. I did this months ago. So either my crank is 2 degrees advance or it's at 0. I tried to set up the dist with a vacuum gauge but my advance isnt working in the dist and I have a few vacuum leaks I need to address. Also my carb started leaking. Once I replace the carb and dist. I'll redo the timing of course. I'll even add a fuel/air ratio gauge to help with fine tuning

 

Without degreeing in a cam, there is no way to know for sure where it's at. You can install it with the dots lined up aka "straight up", retarded, advanced, whatever but that doesn't mean it really is.

The reason for that is because of manufacturing tolerances, whether in the cam itself or the accuracy of the keyway placement cut into the crankshaft, camshaft, crankshaft gear, and camshaft gear. Usually tolerances will tend to cancel each other out, though not always. Sometimes, they will "stack up". Keep in mind too valve timing or camshaft "phasing" has nothing to do with distributor ignition timing or where the the rotor is pointing.

You can pull the valve covers and observe carefully where the TDC "0" mark on the balancer falls in relation to the pointer when the #1 cylinder valves are exactly at overlap. Not as precise as using a degree wheel, but you'll be able to tell right away whether the camshaft is actually advanced, straight up, or retarded, regardless of whether the dots are lined up or anything else.

 

I'll check her out when I get back to her

 

Not sure about this statement. You can rotate the distributor, so how can it be a problem? You set the crank at TDC compression, you stick the distributor in and then set the timing while it runs.
I don't think a change in the timing chain(either straight up or retard) will make any kind of real power difference you will see or feel. It surely makes no difference in setting the initial timing. Moving the camshaft timing with the chain only moves the power band up or down ever so slightly.

 

Assuming that the camshaft is truly installed "straight up", that's (mostly) true, but without degreeing the cam there's no way to tell where it's at. All things being equal, it's said to take about a 4° difference in one direction to feel it with the butt-dyno.

If the camshaft somehow ends up appreciably out of phase despite "lining up the dots" it can make a big difference. That's the whole point of degreeing a camshaft in the first place, engine builders don't want to leave something like that to chance, and this should also be true considering the labor involved when replacing a timing set.

Then, to add to that, there's the emission considerations. Somewhere along the way the timing sets, regardless of what the part # is, depending on who made it, and when, the camshaft phasing was modified. So "lining up the dots" may well end up with late valve timing, on top of any potential tolerance stack.

 

Agree, but the backyard guy that is just replacing a timing set, as long as you matched up the dots it will run just fine no matter what timing set is used. That type of individual will not make a piston stop, buy an indicator and go through the hoops to confirm camshaft timing. You go on the assumption that the timing set is make correctly.

 

I think everyone is on the same page at this point, but just in case gtman, you do see how cam timing and ignition timing are not the same thing, or even relatable?
You can't read cam timing with the ignition timing numbers on the damper and with the pointer, and cam timing does not change ignition timing. Well, it does in a sense, as almost everything within an engine is related at one point or another, and has an effect on one thing or another, but my point is that they are two entirely different things and are used in two entirely different ways. Whenever your ignition timing changes due to excessive wear on other components, you simply re-adjust the timing to where it's supposed to be.

Sounds like you need to re-set your ignition timing with an actual timing light so you know what you're dealing with. For now the cam timing is a done deal and you're not going to change it unless you feel it's wrong and want to go through all the crap of removing all that stuff again just to change the rpm at which the torque peaks.
I didn't think so...

So do a tune-up, and set your ignition timing to get the best state or tune, and run with it.

Paul

 

Maybe, maybe not. "Matched up the dots" doesn't mean a thing. We can hope it will run OK, but hope is not a strategy.

 

Yes I understand and I will remove the valve cover and check. It will be a few months before I get back to her. I was saying I heard by changing the timing se . The truck does run. I need to do other things in order to get a accurate reading with timing light. Example a new carb. Mines shot. And vacuum leaks. But I appreciate the info and I'll definitely check the overlap just to see where the cam is. And yes I would redo the job again...I pulled the oil pan off 3 times because I kept dropping the shaft for oil pump. I dont want perfection but if I could get a few hp outta her ima try lol

 

A few HP can be had by changing from the stock exhaust manifolds to headers, just an idea.

 

For what its worth, When doing a repair, I take pictures of the boxes, to include their part numbers, The new parts themselves, the old parts laying there with the new parts, the receipt etc and have them in a file with that particular repair as the file....those minutes taking those photos are at very least interesting when I come across them a couple of years later just by mistake in doing a search for something else but they have been important when trying to figure out a mistake that was made or if there is some other concern I am trying to get to the bottom of....be sure to ALSO CAPTION the pictures....today's cameras are a valuable tool to help diagnose etc. Its great proof of what was done to the vehicle also when selling it....the guy buying it wont be able to shoot holes in your claims of what was or was not done....