Timing scatter

Markus · Post by **Markus** » Sat Dec 05, 2015 9:25 pm

I've just had my TR7 V8 on the rolling road for a check and tune and we can't get rid of what looks like scatter on the timing marks.
The engine idles and runs but is down on power so we tried to set the timing more "scientifically" than my eyeball effort previously but when we point the timing light at the balancer we're seeing multiple timing points.
I'm using a Mallory magnetic distributor, Mallory 6AL controller and Mallory coil and leads, all new. Engine is a 4.6 running Eddy carb.
I wonder if the modern digital timing light is too sensitive and if we should go back to an older "analogue" type?
Is there too much energy in the leads?
Should I run a ballast resistor?
Should I take a very large blow torch and burn the mongrel?
As always your assistance and collective wisdom would be most appreciated.
Please.

sidecar · Post by **sidecar** » Sat Dec 05, 2015 9:33 pm

You say Mallory 6AL....Do you mean MSD 6AL?

If so the 'M' in MSD stands for Multi, as in multiple sparks per firing point, 5 in fact spread over 20 degrees of crank rotation. (S=Spark, D=Discharge)

I run a programmable MSD unit with a locked out dizzy and my strobe just about picks up the multiple sparks on tickover but as soon as the revs get above 1000 RPM my strobe only 'see's' the first spark and not the 4 others that follow it.

I believe above 3k RPM the MSD unit returns back to a single spark unit as there simply isn't enough time to get muliple sparks within the firing stroke.

If there is such a thing as a 'Mallory 6AL' then please ignore my post!

When you say your engine is down on power how much power is it making and how much were you hoping for? The standard heads don't flow well enough to make any decent power, they need porting and larger valves fitting along with a decent cam before you start getting any real BHP.

Markus · Post by **Markus** » Sat Dec 05, 2015 11:31 pm

Definitely a Mallory 6AL which is/was confusing but ....
Good tip about the flash settling over 1,000 rpm so we might give that try.
Engine was dyno'd at 297hp at the flywheel and we're seeing 179 at the wheels which is a lot less that the usual 30% parasitic loss you'd expect.
Thanks for your reply and Merry Christmas!

sidecar · Post by **sidecar** » Sat Dec 05, 2015 11:43 pm

Markus wrote:Definitely a Mallory 6AL which is/was confusing but ....
Good tip about the flash settling over 1,000 rpm so we might give that try.
Engine was dyno'd at 297hp at the flywheel and we're seeing 179 at the wheels which is a lot less that the usual 30% parasitic loss you'd expect.
Thanks for your reply and Merry Christmas!

I've never heard of a Mallory 6AL, I can't find anything on the web either.

297BHP at the fly is pretty good in my humble, to get much more would cost a fair bit. It does sound like you are losing a lot through the transmission, was the engine dynoed out of the car when you got 297. If so what exhausts and manifolds were used? Also I have seen a lot of Edelbrock carbs setup with really bad air filter setups, the filter lid being way too close to the top of the carb.

Happy Christmas to you too!

Markus · Post by **Markus** » Sun Dec 06, 2015 12:00 am

I just had a look at their website and it seems that since being bought out by MSD they may have changed the designation to VI-6AL.
The engine was built for me by V8D with all the goodies so I trust their figures.
Once we get the timing set, as I said, more accurately than my dodgy eyeball setup we'll look for those missing ponies.
Thanks for the tip about the air cleaner, mine is pretty close to the carb top due to clearance issues with the bonnet so might be worth a look.
Thanks!

ged · Post by **ged** » Sun Dec 06, 2015 1:31 am

They are out there sidecar. I've been using this since 2005.

Markus · Post by **Markus** » Sun Dec 06, 2015 2:26 am

That's the one.
Do you recommend running a balast resistor?
Not called up in the 6AL wiring diagram so I haven't installed one.
Regards,

sidecar · Post by **sidecar** » Sun Dec 06, 2015 10:33 am

Well you live and learn!

Anyway looking on Summits website I read the following statement...

"These highly efficient ignitions deliver multiple sparks per combustion event"

So it in similar to my MSD unit and therefore I'm not surprised your strobe appears to show timing scatter.

ged · Post by **ged** » Sun Dec 06, 2015 11:31 am

Markus wrote:That's the one.
Do you recommend running a balast resistor?
Not called up in the 6AL wiring diagram so I haven't installed one.
Regards,

Hi Markus,

The white block behind my coil is the ballast resistor fitted as per the instructions supplied with it.

DaveEFI · Post by **DaveEFI** » Sun Dec 06, 2015 11:46 am

The Mallory Unilite dizzy I had recommended a ballast resistor. But space in a dizzy is going to be tight for electronics. If it uses an external box as well, I can't see why it would need a separate ballast resistor?

Markus · Post by **Markus** » Sun Dec 06, 2015 7:30 pm

The ballast resistor is shown in the distributor installation diagram but the text states that if using the controller to wire the system up using the controller diagram which doesn't show the resistor.
We'll see what happens next.
Anyway, thanks for all your help on this one chaps and I'll try to update as we go along.
Merry Christmas!