HELP PLEASE...306 backfiring

[1982matthew]

I have posted this in the tech part and didn't get any response.

My friend put a 306 into a 1993 mustang and it only has about 5 miles on it because it seems to be backfiring through intake manifold. He put the motor in like 4 years ago an switched the valve springs. he needs cash an wants to sell it to me, so before I jump into this and might be spending more money in parts than the car is worth, does anyone have an idea what this might be. It is running an starts right up an it seems as though all the power is there, someone said it might be a bent valve but wouldn't that affect the performance of it? It seems as though the 4 valve is staying open when it shouldn't.

Anybody who has any idea at all please let me know, I can get this car at a good price since it isn't running correctly and want to buy it if I can fix it cheap enough

Also, does anyone know anybody in the Easton/ Allentown are of Pa that specializes in mustangs or in fact Ford motors that could help me?

 

[BlownFiveLiter]

Probably a stupid question, but what's the base timing set at? Should be 10° BTDC with the spout plug removed. You can go as high as 14-18° but you may run into detonation issues the higher you set it.

 

[1982matthew]

At this point no question is a stupid question, I'm sure he checked the timing but I will make sure to ask him tonight.. thanks

 

[BlownFiveLiter]

Also make sure it doesn't have any vacuum leaks or codes while you're at it. Intake gaskets love to move when you're putting the lower on, if you didn't use studs in each corner to guide it down.

 

[DrMaxit]

Also make sure it doesn't have any vacuum leaks or codes while you're at it. Intake gaskets love to move when you're putting the lower on, if you didn't use studs in each corner to guide it down.

Nailed it I think, saying the timing is right, which you, too, have already addressed, I guess I'm just a bit late! hah!

Let us know what you find, but hell, if you fix it for him, he might not want to sell it to you, id buy an engine that was backfiring if all the junk in there was new just to tear it down and re-do it, also how was the cam timed? Did he make any adjustments to it? ect so on.

--Chuck

 

[1982matthew]

what do you mean by "cam timed" and i am gonna check the timing. i am not fixing it for him i am gonna buy it if I can fix it easy/cheap. I was just looking into it before I make any quick decisions and spend all kinds of monies.

 

[57fairlane]

what do you mean by "cam timed" and i am gonna check the timing. i am not fixing it for him i am gonna buy it if I can fix it easy/cheap. I was just looking into it before I make any quick decisions and spend all kinds of monies.

Setting the valve timing events relative to the crank with the timing chain