cudablack2004

hey whats up guys i have a 93 caprice with the 350 tbi motor but converted it to carb and added a 488/488 cam, comp magnum rockers with roller tips, intake manifold, distributor, double roller chain, prw water pump, msd coil and 6AL-2 box, lifters, and push rods...when i go on a little cruise and i accelerate i get a chatter/ping from the top end when i give more acceleration it gets louder and car loses power....yes im using same tbi plugs and gap...stock exhaust manifolds, y pipe converted out to two flowmaster mufflers, and 93 octane....any info is needed and appreciated! i need this fixed!

maxxman04

double check the timing, and maybe have advance curve of distributor checked/changed. sounds like it has too much advance at speed. try changing either the vacuum advance unit if your distributor has one, and also change out the small advance springs to stiffer ones. the springs are under the rotor in distributor, and yes, i do mean small.

cudablack2004

yes my distributor has the vacuum advance on the side and all parts has less then 50 miles they are brand new...so ur suggesting check timing? adjust vacuum speed? what about the spark knock issues i been hearing about? should it be a certain gap since the car isnt ran off the ECM anymore?

maxxman04

typically spark knock is caused by too much timing/too much advance. with stiffer springs under the rotor, your timing won't fully advance till higher rpm's which should eliminate the spark knock. also, plugs should be gapped around .035, though you can open up the gap a bit without hurting anything. i've run .040, but that was with a high end ignition system. also, are you using good, quality plug wires? stock ones typically can't handle the power of aftermarket ignition boxes. a good set of performance wires will help. i personally run taylor wires exclusively, but msd, accel, jacobs, as well as others are good.

cudablack2004

im using moroso wires and car is ran off a msd 6AL-2 box acdelco plugs and planning on using NGK and going a few notches down in heat range!

maxxman04

lowering heat range might help, but i'd start with one step lower at a time. it don't take much. sounds like most of ignition is pretty good, just need to dial in your timing and the advance curve. get the advance to come in slower so you can get higher rpms without the ping. you may have to bump up the initial timing a bit. you'll have to check it after changing springs and/or the vacuum unit. also, is your vacuum advance on distributor adjustable or is it fixed?

cudablack2004

here is a pick!

maxxman04

cuda, try this before anything. unplug the vacuum line from distributor and plug that line off. check your initial timing. if it's above 8 degrees btdc, then take some timing out. let me know what the timing is before you turn distributor.

cudablack2004

thats the thing i have no timing light anymore so when i do need one i either call friends up or bug my father for it....that doesnt help at all cuz it can tell me alot!

maxxman04

yes it can. you absolutely have to get your hands on one somehow. without it, you're only guessing. if at all possible, find one that can read the advance, that will tell alot too.