motorman524

So I've been replacing some old parts that prove to be inadequate as we continue to smooth out some rough patches trying to make everything right on the car. So far I've had to replace the shift cable because it kept slipping off the shifter and it was very hard to shift, the throttle cable because it wasn't opening all the way at wide open throttle and the coil because it was sleepy to say the least. Two or so days after I replaced the coil, the car starts to misfire when you try accelerating quickly, it doesn't have to be anywhere near wide open. when I bring it back in to check it out I see that my upper intake is cracked near the front where the shorter bolt is bolted into the lower intake. eventually it cracked all the way through and is now completely separate from the intake. I just ordered another upper but I was wondering why this happened? did I over torque it? is this my misfire while accelerating? My dad said it sounded like an ignition misfire. My last question is what is a hydrocarbon misfire?

mjr46

check to see if there is a vaccum leak there, as for why it cracked, over torque?? is the lower surface true???

motorman524

yeah it completely broke off and there was a vaccum leak. I have a 1 inch spacer between my upper and lower, gaskets are new, intakes are clean. are those "high performance" spark plugs worth anything? maybe I need to upgrade something else in my ignition system?

STROKED_LX

If the last thing you installed was coil before the misfire started, i would go back to your old coil and see if its ok, but first get that upper intake sorted out.

motorman524

Ok I found the problem, The spark plug wire boot was cut causing the spark to arc to the header. Is there any type of spark plug wire or boot that you can buy to work with headers?

lxman1

Are yours shortie or equal length? My MAC's are shorties and the 45* boots on the Accel fit fine. AutoZone brand fit fine as well.

motorman524

They are unequal length headers. The plug boot on #4 is the one that was cut. I think it happened when we were bolting the headers to the head. You have to put the plug wires on first then the heads or you can't get them on. Anyway, #4 was pushed up against the header really hard so we had to take the header back off. I used a punch to dent an area on the header so we could bolt it on. I noticed that the boot is starting to melt now too. Has anyone else had this problem and what can I do to fix it?

motorman524

Has anyone ever had this problem? (read last post)

zebo87

ive heard of people doing that also. making a little room for that wire.

lxman1

Put a 90 degree end on that wire instead of the 45*.

I had one that melted back on #4 once and I wrapped the boot in rubber wire splicing tape and had no more issues with it.
Also, if you are running a colder spark plug, it will be longer and cause clearance issues. This was my problem when I ran N.O.S. on mine. The stock plugs don't cause it to hit.