decreasing timing using arc 6619 flywheel

What will happen if I decrease timing from 36 degree to 32 degree trying to get the motor to run cooler, will this make it loses hp using a arc6619 flywheel?
 
Assuming this is an AKRA/NKA style engine I would try opening up the coil gap to .065 first, or go up on the main jet one size. These type engine make the best HP with 34-36 or so timing. With the 6619 you can use the coil gap to help the timing retard more on the top end, and this would help cool it down some without sacrificing bottom or mid range power.
 
Have you tried a colder plug? Have you tried, if the rules allow it, a higher octane fuel?

The CHT (cylinder head temperature) is not a very reliable indicator of how your engine is running.

Exactly what will happen if you reduce the timing cannot precisely be predicted, although there is a lot of experience out there that says a little more is better.

One jet size might make it better, although that is better than a 5% increase in your fuel delivery, I'm not sure that running richer is going to help the power. Might decrease it. It could be that you're lean and that's what's causing the heat. A bigger jet could help the power. Briggs & Stratton sells a jet kit with metric size holes. These holes tend to be about halfway between decimal size holes. Gives you a little more control over the mixture.
 
Assuming this is an AKRA/NKA style engine I would try opening up the coil gap to .065 first, or go up on the main jet one size. These type engine make the best HP with 34-36 or so timing. With the 6619 you can use the coil gap to help the timing retard more on the top end, and this would help cool it down some without sacrificing bottom or mid range power.

Open up the coil gap, worked perfect for us last year, as most days it was 80+ degrees out. If it cools it to much, you can always tape it up.
 
Have already changed the jet two sizes bigger and the coil is at .075 already the kart is not thight running at 440 degree head temperature that is why i want to change the timing to run cooler temperature
 
Have already changed the jet two sizes bigger and the coil is at .075 already the kart is not thight running at 440 degree head temperature that is why i want to change the timing to run cooler temperature

"two sizes bigger", from what to what? Did going two sizes bigger lower the temp any? 10% more fuel should've done something! Did it?

"thight" what is that?
 
Have already changed the jet two sizes bigger and the coil is at .075 already the kart is not thight running at 440 degree head temperature that is why i want to change the timing to run cooler temperature

440 is on the upper end of heat range but not excessively hot. Try checking to see if the valves are sealed. A leaking intake valve can cause the engine to lean out and run hotter, even with bigger jets.
 
Hey Al,. Briggs and Stratton does not sell a jet kit for the clone. Wrong info to the poster again. Please do what I and others on here have requested and buy an engine and play with it so you will be able to give positive info to those asking.
 
Hey Al,. Briggs and Stratton does not sell a jet kit for the clone. Wrong info to the poster again. Please do what I and others on here have requested and buy an engine and play with it so you will be able to give positive info to those asking.

I'm just positive I saw one mentioned, or advertised, somewhere. It listed all the sizes, there were maybe four or five different jets. Maybe they were for the LO engine. I could be wrong, if so I apologize.

I fail to see how having an engine could help me remember that. LOL
 
Assuming this is an AKRA/NKA style engine I would try opening up the coil gap to .065 first, or go up on the main jet one size. These type engine make the best HP with 34-36 or so timing. With the 6619 you can use the coil gap to help the timing retard more on the top end, and this would help cool it down some without sacrificing bottom or mid range power.

Would a PVL flywheel react the same way?
 
If you have went 2 sizes bigger on the main jet and have not lost any power, or noticed slower lap times on the track, personally i would keep going up on the main jet until you see the temps you want, or until the lap times or engine power falls off noticeably. But in my opinion, i would just go up one more jet size to see if that gets temp down, if not i would leave the engine as it is, 440* is on the high side but i have seen some running much higher temps honestly.

Another thing to consider, make sure your crank bearings in the block are spinning freely, that your rod clearance on the crank is not too tight or rod trying to seize up on the crank, check that your piston to cyl clearance is not too tight and creating drag, and that your ring gaps are not too tight. Friction in the bottom end or rotating assembly can build heat quicker than you may realize, and is a big cause of engines running hotter than normal most of the time. I have worked on engines that ran excessively hot and found the rod trying to seize up on the crank, either from not enough clearance to begin with or oil not lubricating properly....i have also found crank bearings with metal flakes in them from people not changing oil frequently enough or not cleaning the crankcase out properly after an engine blew/seized up from no oil and they reused the block, those metal flakes in the bearing cage will create friction that you normally wouldnt see otherwise. Just some things to look for is all. If this is a professionally built engine, most of the stuff i mentioned should not even be a concern, but you just never know these days so it never hurts to double check!
 
Would a PVL flywheel react the same way?

Are you referring to one of our PVL ignition flywheels or the PVL that Dyno sells? Cause any PVL ignition flywheel will not be affected by larger or smaller coil gaps. We typically set the gaps around .040-.045 on those. From my testing with the Dyno PVL flywheel it does not react the same as the 6619 in regards to coil gap. Usually .050 or so is as much as you can run on it... your results may vary.
 
What is the max air gap can you have with the arc flywheel and still work good for your ignition system?

On engines using red or green plates I have run 38-39 degrees and jacked the coil as high as it would go as stated above and found power. Not only does it help retard timing in the upper RPMs, but it will also reduce magnet drag on the flywheel.
 
Are you referring to one of our PVL ignition flywheels or the PVL that Dyno sells? Cause any PVL ignition flywheel will not be affected by larger or smaller coil gaps. We typically set the gaps around .040-.045 on those. From my testing with the Dyno PVL flywheel it does not react the same as the 6619 in regards to coil gap. Usually .050 or so is as much as you can run on it... your results may vary.

X2

My testing agrees with Jody.
 
On engines using red or green plates I have run 38-39 degrees and jacked the coil as high as it would go as stated above and found power. Not only does it help retard timing in the upper RPMs, but it will also reduce magnet drag on the flywheel.
How far is all the way out on the coil?
 
Depends on the engine and coil. I am only really familiar with Box Stock's engines, they are around .100" all the way out. Which IMO is too much.
 
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