Benefits of "locked" timing ?? plus 5-7 plug wire separation ?

Mike Gaines · Jan 6, 2019

I run my timing at 37degrees total. It is "all in" on my MSD distributor at 2400 RPM.
I have my trans brake chip at 3600 RPM and before I installed my trans brake I launched off my foot brake at 3000 rpm.
So...what is the benefit of locking your timing (whether 35, 36 or 37 degrees, etc) if you launch the car at above that rpm so the timing is already at its MAX when you launch.
My motor starts easily because it it NOT at 37 degrees at startup...
Also, I do have my 5-7 plug wires separated ( #7 runs down the top of the intake manifold, around the back of the block and then to #7). I don't know if separating them is a real benefit or solves a real problem but I did it anyway because, why not ?
Your thoughts ??

vintage chromoly · Jan 6, 2019

On a race car, locked timing is fine aside from starting the engine. That can be mitigated by using a “start retard” function or device.
Can’t hurt to separate 5 and 7 as well.

hangn0ut · Jan 6, 2019

My timing is locked out. I push the start button, tap the throttle and flip ignition on in the time it took to read it. Starts right up. And i like the throttle response off idle i get. I feel i get a more stable idle also with no advance moving in and out. Keep 5- 7 separated on the loom by 3 just because.

Johnpat · Jan 6, 2019

I make sure 5&7are crossed before they get to the plugs to prevent cross firing,has worked for me.

khryslerkid · Jan 7, 2019

Johnpat said:
I make sure 5&7are crossed before they get to the plugs to prevent cross firing,has worked for me.

Now I've seen two threads on this "5-7" wire interference guestion. Seems like I read somewhere about crossing wires by a wire manufacturer once but didn't get the reason. Why "5-7" and not other cylinders also? (Old dog wanting to learn)

Johnpat · Jan 7, 2019

5&7fire in succession,voltage can be sent
to both plugs at same time if plug wires
run parallel to each other for any distance
By crossing them that keeps it from happening.

Johnpat · Jan 7, 2019

Also while working for Sun Equipment Co. I saw this happen on the ocilliscope which proved it could take
place at higher RPM

khryslerkid · Jan 7, 2019

Johnpat said:
Also while working for Sun Equipment Co. I saw this happen on the ocilliscope which proved it could take
place at higher RPM

Does it matter where they cross, closer to the plugs or dizzy?

Mike Gaines · Jan 7, 2019

khryslerkid said:
Does it matter where they cross, closer to the plugs or dizzy?

I run my #7 wire up past the carb, around the back of the block to the #7 plug.
Up near the Distributor where the wires are going thru the looms I have the #7 wire separated from the #5 wire by putting the #3 wire in between them.

dvw · Jan 7, 2019

All wires emit a magnetic field. When the magnetic field flows around a conductor (wire) voltage will be created (induced) in that conductor. Think of the magnetic lines of force like looking at the surface of a pond when you through a rock in it. They radiate outward. Voltage occurs when those lines of force (ripples in the water) pass thru the conductor. If the magnetic force lines are crossed they cancel. Thus twisting the wires helps eliminate voltage inductance.
Doug

Johnpat · Jan 7, 2019

I cross mine half way to plug if possible,as long as it
is not right before plug,that won't work

Johnpat · Jan 8, 2019

khryslerkid said:
Does it matter where they cross, closer to the plugs or dizzy?

I run my cross in the middle between distr.
&Plug . Don't do it right. before plug,voltage has
time to be induced by then

dvw · Jan 8, 2019

To be honest they should be crossed anywhere they're close. Or keep the separated. That being said my race motor is 15-1 compression, runs to 7200rpm. Same wires, cap, rotor for 7 years. Plug wires are bundled together in zip ties. Never skipped a beat. Good quality wires should have built in shielding.
Doug

Benefits of "locked" timing ?? plus 5-7 plug wire separation ?

Mike Gaines

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vintage chromoly

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