Timing Question

[Taylorman]

I was reading an article in Hot Rod magazine about the new GMPP crate 572" engine. They were trying to make it run on pump gas with 12:1 comp. They backed the timing off from 32-27. I noticed in other articles the author making reference to changing timing. My question is are they referring to the initial timing or total timing with a centrifugal advance. I have an MSD dist which advances. Im just wondering if some set there initial timing this high and have no advance?

[RandyH]

Some of us on here lock our timing on the MSD distributors at the total advance. For the life of me I dont know why this works. When I first got my boat it was locked at 35 and it started like a champ. First rotation or two it would fire right off. Then I started playing with a new Carb, etc. , rebuilt the motor and put some intitial in and it wont start worth a darn. I think its a carb issue so this year I will get that nailed.
But for what its worth running with the timing locked worked for my jet boat. Some people run with ingnition switches. Get the motor turning over and then let it fire. I have heard that works as well.
Good luck,
RandyH

[HammerDown]

What your looking for is (Total Advance)...true some racers lock out their advance that gives them their total all the time.
As far as the 572 doing down from 32 to 27, I'm wondering how much Power they lost from the drop. You only want the highest advance # that gives the most power without detonation.
EX. Don't go 35-38 degrees total (all in by 3000 rpm) if you stoped making power at 30-32.

[Taylorman]

I think they lost about 15hp due to the reduced timing.
So whats the advantage of running locked out timing as opposed to mechanical advance?

[Foggerjet]

I'm curious about that too. I've read about this on these boards, but still don't fully understand it. We run drag cars, most of them with timing computers to prevent wheelspin with 10.5" slicks. I've never run or tried to run with the advance locked out. The only thing I can figure is that a Jetboat is loaded at max RPM. Kinda like a car with a real loose converter? Some expert will hopefully help us out on this one. Do us slow guys have any benefit to this on a typical 400-500 HP daycruiser?
Thanks
fog

[CrdStang]

I think the idea behind locking the timing in is being at "total advance" at as low of an RPM as possible. You make a bit more power at lower RPM that way.
The down side is that most engines will be hard or impossible to start with the timing locked in. Race-oriented ignition systems often have a "start retard" function, or you can put really light springs in your distributor so the advance comes on even at idle.

[Taylorman]

I decided to try locked out timing on mine after thinking about it for a while. Last night i pulled my distributor and locked the timing. So today i cranked it up and advanced the timing to 30 btdc. It ran fine. Throttle response if very crisp. Thats one thing i noticed. I turned it off to crank it back up and it cranked fine. Im going to take it out this week to see how it does on the water. Seems ok on the trailer. I'll post the results later.
Kevin

[Dana Marine Products]

CRD Stang is right on the money. I always set up MSD distributors with the lightest springs and bushing to advance to total timing as quickly possible. That way you can have easy starts with the advantage of good low end power. Locking the timing out at 32 or 35 degrees on a high compression motor will make it hard to start when the engine is hot. Cars are different than boats. You don't have 40 feet of wire transferring power to the starter. With the lightest spring and bushing combo on an MSD distributer you get full advance around 2K RPM, so it doesn't really need to be completely locked out.

[Havasu Hangin']

My timing is locked at 32 degrees. I was having some trouble turining it over after it was run hard, so I just installed MSD start/retard modules (they back off the timing while cranking only).

[Taylorman]

I cranked it again this morning before i left for work and it fired right up. Its set at 30 btdc. I had the two light springs on it once before and i had problems with it returning to the initial timing. The springs were not strong enough to pull the weights back in. This would cause it to idle fast and never return to the initial timing setting.