Animal PVL Timing

[Ldubois823]

I have read the post about pvl timing and so forth on how to, etc. etc.. I'm being told that if I run 34-36* ignition timing the rod bearings will not stay within the Arc Rod. How much truth is there to this? Is this only on High Compression motors with welded heads? The motor is a 100% WKA Limited Modified Animal as per rules. Compression of engine, unknown...

Thanks in Advance.'

[Jimbo]

I think you have a very generous amount of timing at 36*

[CarlsonMotorsports]

Way more timing than you need with a pvl. With the OS ignition, maybe you'd be alright.

If it's got the adjustable center hub flywheel, have Jimbo play with the timing while he's dyno-ing your engine.
Then you'll know you've got it right, without detonation.
Run it on a dyno with the knock sensor going off very long and you'll see first hand how 36* timing works for ya.


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Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
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29 years of service to the karting industry
Linden, IN
765-339-4407
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[Ldubois823]

Thanks! I guess ill back it down a little before the weekend. Don't want to blow it up

I'd love to had the puppy off to you at PRI but we racing this Saturday Indoors @ Russellville, KY. I will be in touch Jimbo.

I think you have a very generous amount of timing at 36*

[Ldubois823]

So what happens? Melt piston? Rip the top ring off it? or knock the bearings out of the rod?

If it's got the adjustable center hub flywheel......you'll see first hand how 36* timing works for ya.

[flattop1]

30* is stock.
from the previous posts 36* is too much.
I broke a rod bearing roller pin in my boat by cranking in more than recommended ignition timing.
4 pistons and an overbore.

[CarlsonMotorsports]

Depending on how much you've cut from the top of the piston and how close the top ring land is...generally the ring land is not the problem. Wrist pin and boss of the piston are much more susceptible to damage with pre-ignition / knock.
Definitely flat spot the bearings and hard on rod bolts.

[Jimbo]

If you create random excessive pressure spikes in the combustion chamber one of the first things to go is the head gasket.
I have found that people often just put an offset key in the motor to advance the timing. Often times they never actually what timing they end up with.
I had one person that kept melting down pistons. He swore he had 33* degrees of timing but he actually had 40*
The best way to actually check the timing is with a piston stop and a large degree wheel.

[Ldubois823]

Okay. Question Jimbo, On small Arena track will on beable to tell the difference from 32-33d from the stock key installed?

If you create random excessive pressure spikes in the combustion chamber one of the first things to go is the head gasket.
I have found that people often just put an offset key in the motor to advance the timing. Often times they never actually what timing they end up with.
I had one person that kept melting down pistons. He swore he had 33* degrees of timing but he actually had 40*
The best way to actually check the timing is with a piston stop and a large degree wheel.

[Jimbo]

I doubt it.

[Ldubois823]

I doubt it.

With all that said, Welded Animal Head vs Non-Weld Head Chamber ignition timing? Sounds like a large head combustion chamber is more forgiving than a welded shrouded valve head as per your post due to lack of compression.

Has your failures on the motors been with welded up heads?

Also, What head gasket you recommend for a Open Motor, Aluminum Copper or Multi-Layer Cosmetic Gasket?

[Jimbo]

There are self induced issues with head gaskets when people tape the air inlet on the blower housing shut. As a result there isn't any air blowing across the head from the flywheel fan.
The problem can be amplified by people milling the head gasket surface excessively thus weakening the head.
Improper ignition timing can also contribute to excessive head temperature and warp the head.
Using gasoline as fuel also raises the engine temp.
Using very sticky tires and locking the kart down to the track is another.
Very heavy kart's also contribute to this issue.
In the perfect storm of all of these things the #1 head bolt can prematurely loose clamping force. The aluminum under that bolt gets so hot that it compresses and that head bolt gets loose. You blow the head gasket between the top 2 head bolts.
What head gasket you use depends on how big the bore is. If it's stock bore or under 2.750" i like the Briggs fire ring gasket.
If it's bigger than that i have my own custom made fire ring gaskets.
It's a good idea to slightly loosen and re-torque the #1 head bolt periodically. That's the one under the exhaust header flange.
Usually that will prevent any problems with a head gasket no matter what kind you use.

[87silvert]

I know I am late to the party but I feel I have something to add about timing. It is a common misconception by newer guys that more advance makes more power. Proper timing makes for a happy engine and also the most power. One thing to remember is the higher the cylinder pressure the faster the flame travels. A very efficient engine will want less timing than a stock engine. That efficiency can be compression or VE. I tune timing with exhaust temp and output. You will see egt lowest when timing is right. Too slow and you lose a lot of power and unburned fuel out the exhaust brings temp up. Too fast and you get detonation and temps go up. You also lose power and your motor.
The point is more is not always better. In fact, if you put your engine on the dyno and it wants a couple degrees less timing you most likely have a good one.