cam question, need help

[4bangerhotrod]

ok been havin trouble with the car not running right. 2.3 ford wont run unless the timing is around 70*, check the post esslinger power pulley question for all the info about it. i was checking things out and noticed that when the intake valve opens on the intake stroke it stays open past bdc and dont close completly till the piston is coming up on the compression stroke. and same for the ex valve it opens as the piston is coming up on the ex stroke and is still open at tdc and dont close completly till the piston is going down on the intake stroke. the cam is set up 3 deg adv, i thought about trying the cam at straight up with the stock cam gear but it seems that would make it even worse. im not sure about all this, that might be right but it dont look like thats right seems like the valve should be shut when the piston starts the other direction on a diff stroke.
thanks,
4bangerhotrod

[Milford Motorsports]

Pull the head off your Briggs lawn mower motor,you will see the exact same thing.The valve timing has been designed to maxamize the fill and evacuation of the cylinder.Some heavy physics to try and explane here,mass air flow,density of charge,air reversion.Simply put that is the way the cam is supposed to work.

[Dan32]

its called over lap its leting the exhaust help pull ur intake charge along with piston!! how are u coming up with 70 degrees of timming? wheres ur pointer at? and did u mark gear ur self at top dead center!! sounds like ur mis reading ur timeing! my car want even run with that timing urs shouldnt either!!

[Dan32]

Well ????????????????:d

[4bangerhotrod]

with #1 at tdc, the pointer is at tdc on the pulley. im reading the timing right cause i dont thing 2 other people that know's how to set these up would be doing it all wrong to, checked the pulley with a adjustable timing light and the marks are all coming out right. set the light on 0 and set the dist at 32* then set the light at 32* and its at 0* and im geting 70* cause thats where the the timing light hits the pointer when it's running right.

[Headhunter]

When the pointer is right at TDC the piston is also? how did you check that because 20 or so degrees of rotation may be a little hard to get right with the byeye measurement system.

Is it possible you twisted the nose of the crankshaft? Maybe sheared the key off? Or even damaged the keyway on the pulley. Either it is mechanical or a possible electronic problem. But if the cam was that far off you would be hitting valves.

As for the timing I doubt that you would even be able to get the motor to turn over at 70+ degrees of advance. and with that much advance there is a good chance that even race fuel could go into detonation. I really think there is something in the pulley marking that is throwing it off.

I just read this again and again you say. "set the light on 0 and set the dist at 32* then set the light at 32* and its at 0* " That is correct your at 32 degrees The 32 you dial into the timing light is so the light flashes on the TDC ,mark of the pulley if you had the light at 0 timed to 36 then set light to 36 it would read 0.

[PitManArm]

I can tell you that the motor will run with 70* of ignition timing if you can get it started. I set mine there once by accident. Luckily it wasn't running great and when I checked my timing light I saw it was switched to 2 Stroke. The light read 36* in 2 Stroke mode, but 72* when I switched back to 4 Stroke. Glad I didn't race it like that.

I would be checking very carefully for a vacuum leak some where. If the engine picks up RPM when you hold your hand over the carb, you know something is making it run lean.

Also make sure your octane isn't too high, that's right I said too high. High octane fuel burns slower and likes to start sooner.

Is the timing the same on cyl #4? Maybe the crank is bent in the middle:confused:

[84Dave]

4banger....... in your initial statement you said, & I paraphrase, 'the exhaust valve begins to open when the piston is rising upward on the exhaust stroke' ? The exhaust valve should begin opening when the piston is 30-50 degrees BBDC on the power stroke. If your statement is correct, and mine is incorrect, you have a major problem with cam position in your engine. -Dave-