Got a tuning question for a wizard!!

mustang196718 · #1 (**permalink**) 10-13-2006, 01:11 AM

Okay guys, here's what's going on. I just recently dropped my new completely built 331 stroker into my '67 mustang. I timed it by ear and got it fairly close, close enough to where it was driveable at least. I've been breaking the new motor in, so I've only got about 250 miles or so on the new engine. I let the car sit in my garage for a couple weeks without starting it, and when I went to drive it, it ran like complete crap. The engine would backfire every time I let off the gas. After replacing the distributor cap and rotor, wires, and plugs, I finally attributed the problem to timing. I retarded the timing a few degrees and the backfiring stopped, but the car falls on its face when you gun it now. I have one of the pertronix electronic ignition kits on the car, but other than that, everything else is pretty normal. The part that has me stumped is why would the car run great when I put it away and then all of a sudden run like a pos when I let it sit for a couple of weeks? Any ideas as to what might be going on here? I definitely need some help because tuning is definitely not my area of expertise.
Thanks for the help,
Mike

mustang196718 · #2 (**permalink**) 10-13-2006, 10:40 PM

I also did play with the carb a little bit because it sounded like it was loading up a little bit. It's a Holley 600 4 barrel. I'm also wondering if the vacuum advance on the distributor isn't working properly. I don't remember off the top of my head whether I've got a 13 or a 15 distributor plate, but I'm curious if it might not be working properly anymore, or it's maybe just stuck from sitting for a while. Anyone got any ideas?

mustang196718 · #3 (**permalink**) 10-15-2006, 02:51 AM

okay, it's definitely not a timing issue because the timing is set perfectly now and i'm still getting backfires. I went through and checked and retightened all the valves, which all seem fine. the only other thing that i think it could possibly be would be something wrong with the carb because it's definitely backfiring no matter where you set the timing at. i also checked all the plugs and they were all fine as well.

mustang196718 · #4 (**permalink**) 10-15-2006, 09:00 PM

wow, does no one read this forum anymore? it's been 3 days and it still seems like i'm just talking to myself.............

78KingCobra · #5 (**permalink**) 10-15-2006, 10:59 PM

i read it. i still come here everyday. i just dont know how to help you. i wish i knew.

mustang196718 · #6 (**permalink**) 10-15-2006, 11:24 PM

Quote:

Originally Posted by 78KingCobra

i read it. i still come here everyday. i just dont know how to help you. i wish i knew.

that's alright man, i didn't mean anything by it, i was just starting to wonder where everyone disappeared to. thanks for the reply though, at least now it doesn't LOOK like i'm just talking to myself!

78KingCobra · #7 (**permalink**) 10-16-2006, 10:31 AM

have you tried other forums and google? every once in a while i lurk on this one website called allfordmustangs.com or somethnig liek that.

i never bothered registering, that place is flippin huuuuugeee. but you could try there.

mustang196718 · #8 (**permalink**) 10-22-2006, 02:55 AM

Quote:

Originally Posted by 78KingCobra

have you tried other forums and google? every once in a while i lurk on this one website called allfordmustangs.com or somethnig liek that.

i never bothered registering, that place is flippin huuuuugeee. but you could try there.

alright, thanks, i'll give it a shot.
-Mike

mustang196718 · #9 (**permalink**) 10-26-2006, 08:34 PM

Finally, I've gotten everything staightened out. Car runs like a raped ape again. What happened was that it was initially the carb that was the problem, but from playing with it and trying to fix it, it ended up fouling some of the new plugs that I had put in. So after I replaced the carb, it didn't seem to change anything, but then I replaced the plugs AGAIN, and then walah, everything works great. Turns out that the plugs were still sparking because I tested them outside of the heads. What was happening was that when they were under compression the spark was getting blown out. So now with a hotter set of plugs and a new 650 double pumper carb, I'm golden. Thanks to anyone who read this and attempted to help me.
Sincerely,
Mike

78KingCobra · #10 (**permalink**) 10-26-2006, 11:48 PM

well thats good that you got it all sorted out. i was waiting for you to post some progress up, lol.

is it just me, or does the fron wheels in your signature look kind of small?