Topic: engine switch

[mightymowe]

You dont need an adjustable timing light. Take an old spark plug,knock out the porcelain,thread it with a tap and screw a bolt in it.Then you put it in an engine and turn the engine until the piston touches it,note where on the degree wheel your pointer is,then you turn the engine the other way until your piston touches the stop again,half way between is TDC.At this point turn the degree wheel so 0* lines up with your pointer,you can check it because your pointer will show the same degrees either side of 0 when you turn your engine against the stop.Now hook up your timing light with a car battery to power it and put the pickup on the plug wire just like a car and start the engine,your pointer will show how many degrees before TDC your ignition is firing.
For future referance you can make a mark on the flywheel and the block to show where TDC is,as long as your flywheel does'nt move it will give you a referance point.
You can also make a mark anywhere on the flywheel and start the engine.point the timing light at the mark and make a mark on the block that lines up with the mark on the flywheel,this will be the point where your coil fires.when you shut the engine off and line up the two marks you can see the point where the coil fires.
One more thing the piston stop will probably only work on an OHV engine,I dont think the spark plug hole lines up with the piston on a flat head.

[Ron Atchison/A.C.E. Race Engines]

I can't remember where i saw the thread on this timing issue but, i believe that with the briggs coil ignition timing really retarts itself quite a bit as rpm changes/increases, can anyone elaborate on this? ..and do you think theres power left on the table if this is true? I know that trying to start with high timing can tear things up but, generally taking timing out at high rpm's drops power. With the automotive stuff i either program a low rpm start-up timing table with efi or use a msd starter saver wich, retards timing untill a certian rpm is achieved to reduce the kick-back on start-up on engines with high c.r. and or cams that create a lot of low speed/rpm cylinder pressure. Anyway, what 'cha think? As far as cranks breaking, i think that the detonation is doing the damage..maybe too much timing for the fuel octane but, not just because of too much timing. If the breakage due to higher timing were the case, it's basically the additional hp made throught the extra timing that's crossed the threshhold of the cranks capabilities... again, just my opinion

[mightymowe]

I hope I am saying this right.I read somewhere that the amount of timing that you need is a measure of the efficiency of your combustion chamber.An example would be if you had an engine on a dyno and you found that it made its peak HP with 30* advance,then you changed something in the shape of your combustion chamber,or even the way your spark plug pointed,and found that when you dynoed it again,it made it's peak HP with 29* of advance,then you were probably succesful at making your combustion chamber more efficient.I think they called it negative work,the engine has to fight against the pressure that is building because of excessive timing advance just to get over TDC.
An OHV engine has a much more efficient combustion chamber than a flathead VIB,so it needs less timing advance.
  To answer your question,da.racing,if you check and set your timing at about 3000 or 4000 rpm most of the retarding action of the magneto ignition happens at a lower rpm,then you are good to run in the 3000 to 7000 rpm or so range.You could also start cranking the engine before you put your tether on so that the engine does'nt start sparking until it is spinning good.

[Ron Atchison/A.C.E. Race Engines]

yes i understand that but, do people set the timing statically or do they use a light? i'm from the karting side and, most refer to the timing in a numeric value as to how much distance the piston is from tdc and using the side of the coil in reference to the magnet for set-up..insted of using offset keys to get it a bit more accurate..as you know briggs didn't machine 2 items the same! also, i tried 2 different timing lights and neither worked when engine was running, they did when i pulled it over w/o a plug? what type of light do you guys use? thanks!

[fordman21]

You've got it backwards, taking timing out at high rpm helps make or keep the hp and not drop it like you said in your post. The way the briggs coil works is nearly perfect.

[Ron Atchison/A.C.E. Race Engines]

You've got it backwards, taking timing out at high rpm helps make or keep the hp and not drop it like you said in your post. The way the briggs coil works is nearly perfect.

..not with most of my dyno results unless, i have a really high starting point to make better torque. this is what i've experenced  many times!

[fordman21]

On engines with a timing curv ideally you would want the most timing at the engines peak volumetric effiency. It might not be that high of rpm or it could be pretty high up there in the rpm range depending on the engine and other variables. You want to pull timing out at the engines peak torque.
When it comes to hard core racing, the idea is when the load comes off the vehicle they take timing out to free up the crankshaft to get the engine up in rpm, very much unlike a street car that will never see that kind of rpm or that light of a load.
On our engines with no timing curv, you are probably going to run too much timing down low to hit the clutch and to rev quick but at a fairly low rpm the timing will start to retard gradually, its not that much, keep in mind that we have to use that timing (in my case) as high as 10,000rpm.
To set the timing I use a snap on digital timing advance light.

[Ron Atchison/A.C.E. Race Engines]

On engines with a timing curv ideally you would want the most timing at the engines peak volumetric effiency. It might not be that high of rpm or it could be pretty high up there in the rpm range depending on the engine and other variables. You want to pull timing out at the engines peak torque.
When it comes to hard core racing, the idea is when the load comes off the vehicle they take timing out to free up the crankshaft to get the engine up in rpm, very much unlike a street car that will never see that kind of rpm or that light of a load.
On our engines with no timing curv, you are probably going to run too much timing down low to hit the clutch and to rev quick but at a fairly low rpm the timing will start to retard gradually, its not that much, keep in mind that we have to use that timing (in my case) as high as 10,000rpm.
To set the timing I use a snap on digital timing advance light.

yeah, i time around 35 degrees to start with (after 1000rpm)  then around 500rpm before peak torque i'll go with a safe numer like 32 and fuel for around a .52-.54 bsfc at peak torque and, i throw more timing in and reduce the fuel to around .45 to get the power up high... a lot of my race engines go 8500rpm+ ..i'm using a digital programmable timing.

[fordman21]

What system are you using?

[Ron Atchison/A.C.E. Race Engines]

What system are you using?

PN 4217