Preferred Alpha Plus Engine break in procedures.
By Jimmy Wright
The first step after removing the engine from its box and packaging, is to set up the carb in the manner that will be used for your vehicle. (i.e. the fuel nipple direction and carb angle if not 90 degrees from the crank centerline) be careful when tightening the main needle housing as it is brass and can strip or break if over tightened. Also the carb pinch bolt does not need to be super tight. I tighten it as I would a screw into plastic and then give it another 1/8th turn. While you are at the carb make sure that the high speed needle (HSN) adjustment is one turn out from flush and that the low speed needle (LSN) is turned in 2 full turns from flush (or there about being that this is just a starting point)
The next step is to install your flywheel and clutch that you will use. After this is accomplished rotate the piston to near top dead center and remove the back plate. Take a clean vessel of fresh fuel and wash the assembly lube out of the engine. Two quick douses is all it will take. (This is done to aid in the start up process as the assembly lube does not burn well and can make initial start up difficult) Reinstall the back plate and tighten the screws. At this point it is a good practice to check the head bolts as well to make sure they are tight.
Now install your pipe and air filter along with a throttle return spring or device such as the GMK “Carb O’s”. (I highly suggest this as ROAR and many club tracks mandate them and it’s just a good practice to use them) Install the engine into your vehicle and don’t forget to set the gear mesh properly also installing your fuel line and pressure line. (About 6-8 inches is recommended in most all pipe applications)
With no glow plug in the engine or fuel in the tank, I put my car on a well charged, good starter box and take a heat gun (or good hair drier) and heat the block and heat sink to a minimum of 150 and up to 180 degrees F. My method is to get the engine to 180 and rotate the engine on the starter box for 2-3 five second bursts. Now fill your tank and prime the fuel line. (I personally use a syringe to push air into the tank using the pressure line before attaching to the pipe) Install the proper glow plug of your choice. (A hot plug will allow for easier start up and tuning) Make sure the engine is still at or above 150 degrees, checking it as you would at the glow plug. If not reheat the block and heat sink to at least 150 as instructed before.
Now that your engine is at a good temp to start and you are primed, go ahead and fire it up. You will probably need to screw in the idle screw just about half of a turn in (or 6 hours) to allow the engine to run at a med-high idle on its own. Once started and idling take the temp at the head again you should see a steady rise in temp. Make sure it stays idling steady with no throttle input at 180-200 degrees. If the ambient temp is cold I suggest wrapping the cooling head (heat sink) with a towel, aluminum foil or what we use; a sweat band for the wrist.
If the temps do not rise or stay up between 180-200 turn the LSN in (clockwise) a couple hours at a time (leaning the bottom) making sure to recheck your temps between each adjustment. By doing this your idle may increase. If so just reset the idle by turning the idle adjustment screw counter clockwise until the desired idle is reached. (a mid-high idle is suggested) Run the engine this way for almost the complete tank making sure that you don’t run the tank dry (as you will have a run away and possibly damage your engine) Once you shut the engine off (Pinching the air filter boot is the best method of shutting down as is stopping it by the flywheel. Plugging the pipe stinger is never recommended as it puts undo back pressure into the case and against the seals and orings.) Remember to rotate the crankshaft around to BDC (Bottom Dead Center) and allow the engine to cool at least under 100*F.
Fill the tank for the second run and heat the engine block and head to above 150 and fire back up. This tank will just be idled through until its almost dry again making sure that you don’t run the tank dry and remember to rotate the crankshaft around to BDC (Bottom Dead Center) and allow the engine to cool at least under 100*F before the next run.
For the next run, fill the tank and heat the engine back up above 150 and fire it up. Get the temp back up to where it has been running and then lean the LSN a little at a time until the engines idle rises higher then drop the idle back down to a med-high idle (you may need to do this a couple times until the engine temp comes up around 210-220. Make sure you recheck the temp often as to not let the engine climb temp too high. We’re looking for a steady idle temp like before.
Now here is where things get a little less boring. Don’t yet shut your engine off toward the end of tank three. Instead fill the tank back up while still running and pull about 1/4 throttle just for a second but not too quickly as you may kill it. (If so just fire right back up) throttle it open again to somewhat clean the engine and pipe out. Let idle for about 10 seconds and repeat pulling slow at about ¼ to ½ throttle each time for 2-3 times. Let idle again. What you are looking for here is the beginning of where you start sneaking up on the tune. You will need to tune the low end back to reach 170-180 degrees only using the throttle to clean out the engine. Once you are back down to this point shut the engine down as you have before and let sit to under 100 degrees F. Also at this point if you have a towel or foil on the head, remove it.
Tank number four is where you start things off as you have before with heating the block and head, filling the tank and firing your engine up. You will now use your radio (if you haven’t already) to warm the engine up as if you were getting ready to run on the track. Pulling the throttle open in short bursts warming the engine back up to 180 degrees and then putting a bench tune on it. Once it sounds just about right, keep running it until the tank is almost dry by using the throttle as before. At the end of the tank shut it down and always remember to rotate the crank to BDC.
You will notice by paying close attention to your engine during the break in process that the temps and idle will generally stay right around where you set the engine to begin with. That is until you hear it start to break in. You will see the temp change, the idle become erratic (dropping and raising to and from your preset idle) and if you have a keen ear, you’ll notice that the engine’s pinch will stop “singing”. (There is a distinct sound that an engine with pinch makes. It’s hard to describe but when you hear it you’ll know)At this point you are almost there. I suggest at least 4 tanks of the above mentioned procedure even if the “singing” stopped, the temps dropped and / or the idle started to fluctuate.
So…. It’s been four tanks or more of baby sitting your engine and now you want to drive. Well, go ahead! Just keep in mind that you need to sneak up on the tune and it’s not recommended that you tune it to kill and go race your new engine right away. Give it at least 2 tanks of running in your vehicle before putting a race tune on your engine. During your first driving run make sure you have everything double checked especially your receiver batteries. Now that you’re ready, pre warm the engine, fire it up and give it a few minutes to build its own heat. Take a temp reading you should be upward of 160-180 to set out on the track. Run a few laps to build more heat being easy on the throttle. Bring it back in for a temp check. You should be just over 200 degrees. I suggest running your Alpha Plus for these two tanks upward of 220-230. The Alpha Plus engines have a very efficient cooling head on them and thus you may have to lean the needles a bit. The LSN will be pretty far in from flush at optimum tune. The HSN needs to stay right around flush but conditions do vary, but anything beyond 2 turns in from flush that we have seen is too lean. With a very accurate temp gun we have run the “S”, “Z” and “F” motors anywhere in between 240 to 280 degrees with great results. Don’t be afraid of temps as long as the engine is running correctly without running-on or lean bogging.
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