Breaking Belts

I've broke 3 belts in 7 passes. 2 on the burnout and one after peddling due to tire shake(was a tree malfunction so I was on converter way too long on that pass). 4 of those 7 passes were perfect though so I wasn't breaking them all in a row.
Checked tooth engagement and it looks great. Also checked ignition connectors and plug wires. Looking for ideas in what else to look at?

Blown Alcohol 470" BBC
Littlefield 14-71,HH,K-8 rotors,Davenport mods
35% overdrive
8000rpm max
65 tooth bottom,48 tooth top
1600/8mm RCD belt
Stout belt idler with outside support
MSD Pro Mag 20, Serviced by Bob Wyman
MSD Power grid
Leaving on Grids two step @ 4500 rpm
No fuel bypass on two step
125" altered
2 speed converter drive

 

Hi Mac,
Good info, but you didn't tell us anything about your ignition timing and what your plugs look like? I'll bet your problem is a combination of your timing and a lean condition using the two step.
Joe

 

33 degrees
Plugs barely showing heat
I take 5 degrees out of the timing at the starting line all in by .8 of a second

 

belts

just something to think about not saying its your problem..... we broke a belt every 2-4 runs (6-7 times and new belts not old dry ones) ....during normal matenice forund a bad broken crank , new crank put 10-12 on and have not broke belt since

 

Mac,
Do you have a data logger? If so, you should look at your spark curve; that Mag 20 might not be able to do the job. You stated that you have good belt alignment and support; misfires are next common cause for breaking belts. Also you should look at your fuel flow data, if you are fortunate to have a flow meter.
Sorry I can't be more helpful, Joe

 

I've heard of guys breaking them because pieces of blower stripping material were breaking off and getting "caught" in the intake valve as they were trying to close, thus hanging them open and igniting the intake manifold air/fuel.

I think we broke some in the past because we used a relay to kill our mag and I think the relay was momentarily killing the engine.

 

No data logger. I would think the 20amp mag would have enough juice? A buddy of mine ran a similar combo with a old Super mag 4. Les Davenport does my fuel system so I'm going to pull the pump and have him confirm flow. I'm also going to put new plug wires on then send the mag and Powergrid in for service.

 

That's what I was thinking but shouldn't I blow a burst panel? The engine is coming out for winter service so I will go over everything.

 

Mac,

I had a 2 year old grid and had ign problems.
Sent the grid back to MSD and it came back with a note saying " no problem found, updated to latest specs" still had the ignition problem.
Bought a new grid and problem solved.

Just a FYI.

Jim

 

That's what I'm wondering. I'm going to send my mag and grid to Electromotion for a check up

 

You can bench test parts all day long and it still may not reveal a problematic part, it can be hard to duplicate real world conditions on a bench. I'm not saying your plan is a bad idea but just saying that there have been a lot of parts that "tested good" but still were the problem. So if they do come back as good don't automatically take them off the suspect list.

Joad Donnelly

 

I have 1.3.2 from 2012 and each time I try to upgrade it shows me nothing and says I have the current version. What am I missing and what do I need to do to upgrade? Where can I find the current file?

Tom

 

Yeah, done all you have said, several times and it's not working. I'm a computer guy by profession so I should be able to figure this out you would think, LOL. Appreciate the help Mike. I'll call MSD as there may be a bit stuck in my unit.

As an update, just got off the phone with MSD. Turns out if the serial number of you unit is between 1722 and 2460 it needs to be sent back to them as it won't auto update. They have to "unlock" it to make that feature work.

 

As another update to the Power Grid upgrade issue. It turns out my Grid's S/N was in the 2700's so it fell out of the range for sending it back. After several exchanges with a very helpful tech person at MSD and their engineers, they gave me a View and Review software update package that allowed me to update the Grid. I also run the ARC module and there are no new updates to that from 2012.

The real bonus with this software package is it has a conversion utility in it. When you open up old files, it makes them compatible with the newer firmware update! You don't need to recreate the file again. You just need to remember to save the new converted file and you are good to go.

Here is the upgraded software.

Tom