kjl1

I see these often in street vettes but never was sure if they really do much at lower RPMs. I know some timing lights will not work with them.

fauxrs

It all depends. For high compression,nitrous and blown engines it is very helpfull, in a normal engine - about all you will see is improved starting, idle, and sometimes throttle response. If you do see a benefit, it is most likely that its actually covering up for something else thats wrong.

By themselves, little to no performance improvement.

Gordonm

:iagree: A well tuned stock ignition on a stock motor will see no improvement. If big cams and nitrous or blowers are used a CD box will help improve it. I put one in and it starts much better and idles better. It also has a rev limiter which I have come up on many times so it might have saved a few parts along the way. A well built HEI unit is tough to beat though.

Fevre

No performance gains? :confused: You guys must have forgot to install your stickers. :D

I just installed a Crane unit in my 89 Formula and I swear it now starts harder, with a MSD 6A in my vette along with ProBillet dist it starts immediately.

mrvette

ON a DPFI computer car you will never see any differance....

BUT on an older car with a rich carb at idle, yes, they help smooth out the engine and burn the fuel....

that's about it.....

OH, don't forget at about 3000 rpm's the extra 'sparks' disappear, so there is NO advantage at higher rpm's/power

GENE

tshort

But the rev limiter is great insurance. :yesnod:

no_radio

They work just fine with timing lights, BTW, I use my dial-back Craftsman all the time with my MSD 6AL. It does start much easier, idles smoother, great off-idle performance. In my case my distributor was somewhat worn so I replaced it with a Pro Billet MSD unit so high RPM performance is MUCH better as well. From what I understand most HEI units are about done around 4500 RPM. I have an Accel module, cap, rotor, and coil on my 454 Suburban and it pulls well to 5000 or so where the tranny shifts.
Jeff

Gordonm

OH, don't forget at about 3000 rpm's the extra 'sparks' disappear, so there is NO advantage at higher rpm's/power


The extra spark disappers but the much hotter spark stays there. A points dist and stock coil cannot generate the spark that a CD box can at any rpm. If you are pumping in extra fuel or air (nitrous, blower or turbo) it can "blow" out the stock spark. With a CD ignition the spark is much more powerful. Mine never misses a beat to 7000+ rpm and I trigger my Crane HI6 box with a set of heavy duty points.

trw

- about all you will see is improved starting, idle, and sometimes throttle response.

Gee, that's me.
:D

Terry

fauxrs

there are no extra sparks! - the only thing that is different is the duration of the spark which is something along the line of 20degrees of crankshaft rotation. Multispark is something of a misnomer.