heywier427

I was/am a rotary noob. But Im learning lots, with the help of trial and error

I am also a carb/msd noob, so I was running uphill for the past few months.

I broke an apex seal and couldn't really see why after the engine was broken down. It was a large bridge port 12a na, and it happened at high rpm's.

Well, I dropped in another stock 12a, and it was just running "funny" in the upper rpm's.

My trailing timing also almost never lit up. So I adjusted the pot to the middle, as thats where it was on almost all the cars/internet pic I looked at.

Turns out my noobishness was running the trailing and timing pickup wires, unshielded, next to each other, right along side the coil wires, in the same loom with all the other wiring.

Well that was causing the trailing to pick up the signal from the leading and firing the trailing at the same time as the leading. That equaled detonation at the upper rpm's and the eventual breaking of the apex seal.

The engine (both engines), had an idle misfire, but it was completely random, and was accompanied by a ticking sound. One single tick, which sounded like spark jump to me. But every time it sounded, the engine misfired/stumbled. I also had a shut down back fire with both engines.

The fix was to shield the cables and ground them.

No more misfires. No more ticks. No more back fires. And hopefully, no more detonation

Did alot of reading on the MSD shielded pick up wires, and would have needed to buy 3 lengths of cables at 40.00 bucks each, and have to cut/modify their ends.

My solution was at home depot. Shielded alarm/audio wire:

Southwire 500 ft. 18-2 Shielded Security Cable-57573144 - The Home Depot

It comes sold per ft. at the store. Its the same wire that comes from an MSD type signal wire.

I used a drill to spiral the now shielded trailing and leading wires together, and tucked it back into my loom.

Grounded both ends of the jacketed wire (it comes with a ground wire inside the sheath).

If you are having trouble with your trailing never showing when you hook up your timing light. This could be your solution. It was mine Yay.

RXBeetle

You should only ground one end to prevent ground loops. Also be cautious of heat with the HD wire, PVC insulation isn't rated for much temp, typically 105C. Most of the high temp stuff is really expensive though.
Not trying to put down you're work, just some good practices to keep in mind.

heywier427

No, good to know thanks.

It is all protected by a double wire loom. One solid (inside) and one braided for awesome sweet looks

And the area by the header is is silver insulated heat loom (approx. 6-7" away).

The header (RB) is also double header wrapped.

And if 105c is really what you meant, that equates to 221f, so pretty decent.

I will disconnect one of the grounds at each end.

See, learning is fun!!!

Thanks again!

heywier427

And going from full bp to stock is depressing...