ttoptom1

Done with my 68 coupe and got new toy-69 Camaro with transplanted 454 circa 1974-75. Been having a backfire or miss at 4500 rpm up. This happens when secondaries kick in while full throttle. I've rebuilt Holley 750 and ordered new cap, rotor and module yesterday. While looking at dist saw no weights or springs for advance. Instead looks like two small buttons in holes that holds weights. Not being familiar with HEI don't know if I need weights and maybe problem. I think newer engines use computer to advance timing but this isn't computer controlled. Do I need to get weights,etc? Could this be problem and if so why were they removed? Thanks, Tom

resdoggie

The two buttons are pads and should be there. But you do need springs and weights. Suggest you buy a dist'r advance kit and play with that. Does the dist have a vac can?

ttoptom1

Yes, it has the canister. After posting, I googled HEI and found that as you said I need weights and buttons are there for weights to ride on. I think I read the Accel weight kits says where to start with springs then use dial back light to get correct spring combo with timing in by 3000rpm. Am I thinking this correctly? I guess this could cause upper rpm's to not have right amount of timing causing backfire/miss issue. Thanks again, Tom

resdoggie

You're thinking correctly. Are you positive the secondary air valve is opening? If not, could be a lean condition you're experiencing.

ttoptom1

Went to local engine bldr and told him a few extras I keep finding and besides no weights the whole advance assembly is rusted causing nothing to move! Ordered new Pertronix unit tonight and hope to try it Sat with 2 day shipping. Thanks for all the input. Not many followers on Camaro forum like this. Wait for days sometimes for reply! Thanks for quick response. Thanks again, TTOPTOM1

molsen

You will like that Petronix unit. Just put one in and was impressed by the overall response by just switching HEI dist.