axoid Posted August 2, 2003 Report Share Posted August 2, 2003 I'm out of ideas. My SBC starts to miss once it top 4800 rpms. The fuel is fine, I've confirmed that on the Brian's dyno. I have check and replaced everything in the ignition system: coil, HEI module, plugs, plug wires, distributor. I've played around with the initial timing and the timing in the computer. The miss has gotten better, but it's still there. Does anyone have any useful suggestions? Thanks. Quote Link to comment Share on other sites More sharing options...
Dave1647545494 Posted August 2, 2003 Report Share Posted August 2, 2003 what kind of module? the stocker will get you yo about where your miss is now, an aftermarket one may go 5500. I solved the problem by using an msd box to replace the module. hth Quote Link to comment Share on other sites More sharing options...
axoid Posted August 2, 2003 Author Report Share Posted August 2, 2003 I've had the stock one and two different Accel modules in since the problem started. The newest of the Accel modules is current in the destributor. Quote Link to comment Share on other sites More sharing options...
slow4now Posted August 2, 2003 Report Share Posted August 2, 2003 Have you checked your spark plug gap or tried gapping the plugs tigheter? Quote Link to comment Share on other sites More sharing options...
axoid Posted August 2, 2003 Author Report Share Posted August 2, 2003 The spec is .035. The orginal plugs were at .040 when I pulled them out. The new plugs were gaped just under .035 when I installed them a week ago. Quote Link to comment Share on other sites More sharing options...
Boost-n-Juice Posted August 3, 2003 Report Share Posted August 3, 2003 I'd check the valve springs. Quote Link to comment Share on other sites More sharing options...
axoid Posted August 3, 2003 Author Report Share Posted August 3, 2003 I'll check them, but they were installed new this spring. They're 100 lbs springs and rated for .550 lift. I only running than .459 lift. Quote Link to comment Share on other sites More sharing options...
Boost-n-Juice Posted August 3, 2003 Report Share Posted August 3, 2003 Do you have any head work done? Maybe a valve isn't sealing. What kind of rockers to you have? May be out of adjustment. Even though your springs are new, 1 may be bad, you never know. Quote Link to comment Share on other sites More sharing options...
axoid Posted August 3, 2003 Author Report Share Posted August 3, 2003 The S/R Torquer 305 heads are also new. They came with the valve and springs pre-assambled on the heads. There have been no modifications made to the heads. The lifters, rods and rockers are stock GM. Quote Link to comment Share on other sites More sharing options...
Boost-n-Juice Posted August 3, 2003 Report Share Posted August 3, 2003 Might have a bad lifter or push rod. Chevy rockers are adjustable right? Quote Link to comment Share on other sites More sharing options...
axoid Posted August 3, 2003 Author Report Share Posted August 3, 2003 Originally posted by BC: Chevy rockers are adjustable right? If you mean adjustable buy being able to set the gap or pre-load on the spring, get yes they're ajustable. Quote Link to comment Share on other sites More sharing options...
Boost-n-Juice Posted August 3, 2003 Report Share Posted August 3, 2003 Ok, you might have one too tight causing a valve to hang open at high RPM. What method did you use to adjust them? Is it popping? If so, does it come from the exhaust or intake? Quote Link to comment Share on other sites More sharing options...
axoid Posted August 3, 2003 Author Report Share Posted August 3, 2003 The spec is for 0 valve lash. I tightened each rocker nut as I twisted the pushrod. Once the rod stopped twisting I added a quarter turn and moved to the next rocker. There is definitely popping when I let off a 5500 and there has been some popping below that in the past, but not consistently. I don’t know if it has any thing to do with it, but I had some intake backfires when I was first tuning for the new heads, cam, intake, but that went away when I added timing to the ignition map in the ECU. Quote Link to comment Share on other sites More sharing options...
Dave1647545494 Posted August 3, 2003 Report Share Posted August 3, 2003 you may want to reset your valve lash the old school way. engine running back the rocker nut off slowly till the vlave starts to tick slowly tighten till it just stops then tighten one full turn a quarter of a turn at a time (or the car will stall) works every time. Quote Link to comment Share on other sites More sharing options...
SamZman Posted August 3, 2003 Report Share Posted August 3, 2003 Maybe try the pick-up coil? I know I had a miss in my GTA that kept getting worse and worse.. Of course it was throwing bogus codes when it went out. I know this is quite a few years ago but it was only 13 bucks. Problem is you have to take out the distributor... Quote Link to comment Share on other sites More sharing options...
SupraGlue Posted August 4, 2003 Report Share Posted August 4, 2003 While we're throwing out guesses, you could also check your grouding points and ground straps/leads. Clean up the contacts if they're dirty, and replace them with new thicker gauge wire if they look like they might be corroded. Quote Link to comment Share on other sites More sharing options...
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