BTW,i see your running what look to be Bosch platinum plugs in your BBC and they look diry enough to possibly missfire under load.
I have not personally tried the pltinums in my bbc but i have read many times here in t/chevelle over the past few yr's where members have stated the platinums dont run as well/clean in our older non computer controlled perf motors with carbs,why who knows . Maybe it's that the platinums are designed for the precise /cleaner mixture control EFI gives along with the hi powered elec ign's and better oil control on todays motors thats the difference. It's not the higher comp ratios as sometimes thought to be the diffetrence because the new vette has platinums with high comp & rpm and hondas with the v-tech motors thats have high 10:1 comp that red line at like 7k-7500 rpm use platinums too with no issues so its not that.
Since i had seen this stated mult times over the past few yrs here in t/chevelle i would think it has merrit but either way go for a good quality std type non platinum plug this time arround of same approx heat range like autolite/ngk/maybe even in AC Delco and see if that does any better.
Bad plug wire/s that dont have to be that old but could be damaged by header heat which happens fairly often (esp the boots or where the wires are closest to headers) could also cause or at least add to this problem so keep that in mind too.
Also,while your at it dont forget to check the the cap/rotor for wear/cracks and coil to ensure the rest of your ign system is ok and up to the task so you dont overlook something that sends you chasing your tail trying to get it corrected.
Scott
I have not personally tried the pltinums in my bbc but i have read many times here in t/chevelle over the past few yr's where members have stated the platinums dont run as well/clean in our older non computer controlled perf motors with carbs,why who knows . Maybe it's that the platinums are designed for the precise /cleaner mixture control EFI gives along with the hi powered elec ign's and better oil control on todays motors thats the difference. It's not the higher comp ratios as sometimes thought to be the diffetrence because the new vette has platinums with high comp & rpm and hondas with the v-tech motors thats have high 10:1 comp that red line at like 7k-7500 rpm use platinums too with no issues so its not that.
Since i had seen this stated mult times over the past few yrs here in t/chevelle i would think it has merrit but either way go for a good quality std type non platinum plug this time arround of same approx heat range like autolite/ngk/maybe even in AC Delco and see if that does any better.
Bad plug wire/s that dont have to be that old but could be damaged by header heat which happens fairly often (esp the boots or where the wires are closest to headers) could also cause or at least add to this problem so keep that in mind too.
Also,while your at it dont forget to check the the cap/rotor for wear/cracks and coil to ensure the rest of your ign system is ok and up to the task so you dont overlook something that sends you chasing your tail trying to get it corrected.
Scott
