Hey...just the other day I got a generic ebay 4-1 header, and that provided me with the low end kick in the ass I have been looking for, but it seems my power starts to drop with high RPMs. After about 5300, my power just kind of drops off, so I was wondering what the best GENERIC settings would be for my adjustable cam gears. I don't know about other manufacturers, but each mark = 2* on mine so about what should I start to try with my current setup (listed in my sig...mostly stock besides that list). Any help would be great, thanks.

Most posts i've seen say +2/-2. I found this post that you actually started last year, first one on the search under this i think, saying +2/-2 ( http://forums.2gnt.com/dcboard.php?az=show_topic&forum=5&topic_id=106057&mode=full )

Other than that, the stock ECU starts to kill power after 5300-5500 rpm's if i remember correctly. only way to fix that is MS, or a standalone ECU type system.

Come on steve... You can also compensate a little with an safc, but they arent really worth it unless you can get a good deal on one. I have mine set to lean out towards the top end. By doing so, it counteracts the ecu when it starts to pull timing.

Either +2/-2 or +2/-1. Either one of those settings is what people recommend. Also, don't forget that if you have head work and they shaved the head, that both cam gears will be negative a couple degrees since the tensioner is on the back side of the motor.

Ok I went ahead and tried +2 Intake/-1 Exhaust first, and the results for each gear were as follows:
1st/2nd - backfire around 5800 rpms
3rd/4th - backfire around 5400 rpms

So I hopped on the chat and red96rs was helping me with some ideas, so I followed his advice and tried 2 other settings before I got stumped. He suggested taking exhaust back to 0 and it that doesn't help take it to -2. Well here are results:

Exhaust 0* (Intake still +2*)
Real lumpy idle
1st/2nd - no backfire (went up to 6500)
3rd/4th - backfire around 5700 rpms

Exhaust -2* (Intake still same)
1st/2nd - backfire around 4300 rpms
3rd/4th - backfire around 4100 rpms

Now the question is...what is making my car backfire? Is it the way I was timing it or is something else causing it? So I went ahead and put it back to 0/0 and will mess with it when it gets a little warmer outside.

As a side note, when I installed my muffler back last summer, we used a flex section and a clamp to hold it until I can get my hands on a welder. Also, when I installed my header the other night, my cat bolts were so rusted no chemicals would work, so I ended up cutting my old downpipe off with a sawz-all about 2" from the flanges at the cat and wacked the flange off my new exhaust pipe. I then took a 2.25" ID/OD coupler and a couple exhaust clamps to it to hold it in place until I can get a welder. Would this possibly be part of my problem? I got those clamps on there pretty tight, so there no way the pipe will move.

are you ABSOLUTLY sure your cam gears are actually Zero? have you indexed them with your cams to make sure?
some cam gear markings can be off as little as 1* to as much as 4*!!

How exactly do you index them to check and see if they are actually 0 or not?

You just need to check and make sure that when the cam gears are set to 0* that they are truly aligned with 0* on the cam. It shouldn't take a machine shop real long to check it. Or you could try and go +4/+4 or -4/-4 and see if things get better.

Does seem a little wierd that those adjustments are making it backfire. They aren't that drastic. If the backfire is only on the decel I would look at exhaust. If its not just decel, probably not exhaust.

In my research, 4 degrees seems to be "the number". But in my research, and application on the dyno, I ended up taking 4* off the intake. That gave me the most power. In all cases you are just extending overlap.

BUT all set-ups are different, so take that for what its worth.

IT happens on the accel, so I'm wondering if it's my exhaust timing causing it to backfire or what. It doesn't happen when they are set to 0. I'm gonna let it sit for a bit, and when it's warmer out so I can rule out the fact it's chilly outside. When I go to tune them again should I try -4* on intake and what should I try on exhaust?



EDIT: I did some more reading on VX100's post back in the day and through his theory of timing. Sounds like 4 is a good setting, but what confuses me is advancing and retarding timing. To my understanding, could be wrong though, when you set your timing to "+" something you are retarding it, because you are causing it to hit timing later than it should and "-" something being an advancement causing it to hit before. Could someone clear this up for me please? I'm kinda lost...:shrug

I have a stock backfire.

Timing isn't jumped, advanced or retarded.

Pig rich bastard has no cat and likes to shoot fireballs. :)