bad timing issues, video

[Casperfast]

I have been trying to get this car running right but am out of ideas.  previously it had a flat cam when I go it.  that has all been replaced. cam, lifters,  pushrods,  springs,  retainers,  stem seals,  intake manifold,  headers,  coil,  plugs,  plug wires.  I have tried timming with a light,  with a vacuum gauge.   where I set it I seem to make  change a little,  but not enough to run correctly.  backfires through intake and exhaust.  any help is greatly appreciated.  here is a link to a video I made yesterday after it was warmed up.  https://youtu.be/P7x9xVGXFAg

 

[Don C]

Did you check valve/lifter clearance? A new cam may require non-stock pushrod lengths

Cap and rotor?

Firing order? A custom cam may not have the stock firing order

Condition of carburetor and adjusted?

 

[will e]

Firing order or crossfire.

It runs 'too good' to be 180 degrees off but I would verify that as well.

 

[Casperfast]

the cam should be using the stock pushrod length. the car was recently rebuilt. the engine ran much better prior to the cam swap even with 2 flat lobes and a nasty tick. the timming set is new as well. this is an image of the cam specs. and I did not have these issues during the cam break in process.

 

[Casperfast]

as soon as I'm confident my neighbors are awake I will go double and triple check firing order and just for giggles throw on a new cap and rotor. my shop is kinda like a speaker box into the neighborhood behind my property, had a few upset people in the past haha. the car is a Carter competition 770cfm. I believe these are adjusted the same as an edelbrock??

 

[Don C]

Yes, Carter and Edelbrocks are similar.

You said it ran OK during cam break-in. Did you do anything after that, change anything, add anything?

I would pull the valve covers and check the rocker arm movements while cranking it. It's possible the new cam has wiped lobes, wouldn't be the first one that happened to.

 

[Casperfast]

I have actually just finished putting the valve covers back on after checking for this. they are all nice and snug. no slop or wiped lobes. I'm not sure what could have changed after break in. only thing new since the. is a radiator and heater core

 

[Don C]

How long did it sit, while you had the work done on it? Possibly bad gas or water in the tank from condensation.

Ethanol in the gas? It can cause issues with seals and gaskets, plug up passages and jets in the carburetor.

 

[72HCODE]

the carb backfire indicates the motor is going lean when you rev the motor.

the tailpipe backfire is unburnt gas getting into the mufflers and igniting meaning you are rich.

i would make sure as others have said to check all the ignition parts.

i would also want to know what is your spark plug gaping, and what do the spark plugs look like.

I would want to know your ignition setup(stock/aftermarket) what type of wires are you using.

I would also want to know if you have good compression on all cylinders to rule it out like a valve is not closing all the way or staying open.

there seems to be a few problems over lapping here. I would want to rule out the ignition first.

then i would want to look at the carburetor. I would think about swapping in either another new carb or a carb you borrowed that you know works. That would diagnose if the issue is in the carb or not.

my feeling is something is not set right with the valves something is not closing and that is sending raw mixed gas down the exhaust and backfiring down the line.

the REV backfire through the carb would also indicate your accelerator pump is not setup right, needs more fuel, or you need to cut ignition timing. Did you mess with the Mechanical advance springs? Turn off the Vacuum advance right now for testing, plug it and do everything just on mechanical for now. What is your initial timing set at now? also Carb cfm?

i would not try any vacuum tuning it will always leave you too lean. now with all the work you did i would also think about plugging off all vacuum accessories for testing and tuning to rule out an external vacuum leak. and also start looking for a vaccum leak on the motor, like a base port on the carb was not capped off. what vacuum are you getting at idle when it runs ok, and what is your Idle rpms

 

[Casperfast]

new gas in tank, I did all the work, was never left non started more than a week or two at a time all winter. only vacuum accessory connected is booster. which is also brand new, and the distributor advance diaphragm. as for the accelerator pump, that is one thing I suspected that might cause it to have the hard starting issue. I checked compression and got 155-163 across.

 

[Casperfast]

just checked firing order, correct. disconnected and capped all vac ports including distributor and rechecked timming, somehow it was at 25*adv. I set at 8* also found my choke was hanging up and causing secondaries not to function, adjusted choke cover to full open. car still has hesitation and exhaust backfire. I'm unfortunately thinking I might have a hanging valve. and thats rather odd because I didn't notice any valve issues when I replaced the stem seals and springs. almost out of ideas. also I would think a hanging valve would have shown on the commission test. it is running much smoother after the dining adjustments. but with the dist vac line connected it does not run well at all. I also reset the screws on the front of the carb. both were almost at 2.5 turns out, I set them to 1.5. didn't seem to make much difference.

 

[Casperfast]

the plugs look better than I thought they would considering how its running.



upload image album

 

[Don C]

Do all of the plugs look like that?

Was the engine warm when you ran the compression test?

If the idle mixture screws don't make any difference either some passages are plugged up or the idle screw is turned in too far and the throttle plates are into the transfer slots.

Edit:

What is the condition of your harmonic balancer? Has the ring slipped so the timing is unknown?

 

[waterlife]

bent valves

 

[Casperfast]

the balancer is new. the engine is running much better, but I know it's not as it should

 

[clevelandcoupe]

+1 on the bent valves,especially with it popping through the carb. Is there a possibility of too much lift with the new cam ?

 

[mfd]

Your engine sounded like mine after I had changer the plugs.  I used my Haynes manual to put the wires back on.  That manual had 5 and 6 backwards for my 351c. luckily I have reproduction ford manuals for my 71 m code, and it showed the proper orientation. After I corrected the problem no backfire thru the exhaust, and I was able to finish the tune up.

 

[will e]

if he had bent valves wouldn't his compression numbers be lower? (I am not an expert so I am just thinking it through in my own head)

 

[TommyK]

Assuming the car does not idle at an abnormally high rpm, then whether or not the vacuum advance is connected or disconnected should not make a difference (or not much of a difference) in how the engine idles unless it was hooked to a manifold (full) vacuum source or you forgot to plug the vacuum line in which case there was a vacuum leak.

If the initial timing changes when the vacuum advance is disconnected and plugged you need to figure out why.

You said you changed the balancer. Did you check TDC on the balancer with the #1 piston at TDC on the compression stroke? If not your timing may not be what you think it is.

You said you changed the cam. Is there any chance the cam timing could be off meaning the cam was not installed "straight up"?

Do you have an adjustable valve train? If so how was the lifter pre-load set?

Finally, with a new cam there is always the possibility that the lobes and/or lifters were damaged during break in.