Ted (7/22/2018)
Florida_Phil (7/22/2018)
....Can you please tell me the correct way to break in a new engine? The engine will be in the car.For me the key to a successful engine engine/camshaft break-in is for the engine to start up immediately without any unnecessary turning over prior to it firing up. Pre-filling the carburetor with fuel and having the initial ignition timing at 15-20° BTDC are two important factors for this to happen. Pre-checking all wiring and insuring a solid voltage supply to the coil/distributor helps here also. I do a lot of customer assisted engine break-ins on the dyno and the two biggest mistakes performed by the do it yourselfers are the distributor being installed at 180° off and the distributor itself timed for TDC rather than some realistic BTDC value. As soon as the engine fires up, it’s desirable to bring the rpms up to 2000-2500 rpms just to insure an adequate amount of oil to be thrown up around the cam and lifters. Twenty minutes is the accepted time frame for this and is typically long enough to bring any potential engine problems to the forefront. It’s important that the cam lobes and lifters ‘burnish’ themselves during that break in process and this is more easily accomplished with the engine running at the higher rpms rather than at idle. If there are any noises coming from the engine during this period, shut it down and do some follow up.
DANIELTINDER (7/22/2018)
Ted, I am a bit surprised that you recommend so much initial timing advance for first start-up? In my experience, more than 15 degrees (estimated since my dampner doesn’t havean aftermarket tape) makes the engine very hard to start (thus a common methodfor setting maximum advance without a light). Never owned a Model T, but didn’t antique cars usually have a collumn-mounted lever for retarding the spark (to ease starting)? Or maybe, the requirement of running the engine at higher rpm during break-in somehow dictates more total advance, and it would obviously not be practical to stop and reset the timing after first start (?). Please elaborate.
This deserves its own post rather than be buried in a thread about solid lifters.
If it was an easy answer, it would be short. But alas it’s not an easy answer.
There’s a lot of leeway with advanced initial timing when the compression ratio is low and the engine is cold. Fresh rebuilds always start easier with the timing more advanced than usual and there’s none of that fighting the distributor when trying to start the engine as a result of arbitrarily dropping in the distributor with the rotor pointing at #1 in the cap. Stabbing the distributor with the rotor pointing at #1 with the damper at compression TDC is just a shot in the dark (pot luck) if the freshly built engine will start cleanly or not. With a points distributor it’s relatively easy to get the initial timing within a couple of degrees of target by simply putting the damper at the desired timing mark and then rotating the distributor clockwise until the points just barely crack open. With an electronic distributor I’m aligning the pickup coil and reluctor while the damper is set at the desired starting timing mark. I do prefer the damper being at the ~20° mark for first time start ups as I find the engine being not only easier to start but also with the engine running cooler during that initial break in period. Once the engine is fired up and run for a short period of time, then the total timing can be checked with a timing light without having to drop the rpms during the camshaft break in period. If the distributor is curved correctly, then the initial timing typically falls in close to where it needs to be. If not, then the distributor is recurved accordingly.
There will be no first time starting issues on stock compression Y’s with the initial timing as high as 20° BTDC. I find that many of them with any kind of aftermarket camshaft likes 12-14° initial timing for normal running. Don’t confuse initial timing with total timing. Initial timing set at 30° or more could cause starting problems when the engine is hot. My roadster Y engine runs over 13.0:1 static compression ratio and cranks up fine at 26° BTDC; as soon as the engine goes from the start to run mode, the ignition timing electronically switches to 36° total timing which in this case is also the initial timing. That engine has a crank trigger ignition so an advance curve is not utilized but I do have the electronics configured so that the total timing retards 10° while in the start mode; hence the 26° for cranking purposes. I do have race engines on the dyno where the advance curves are locked out and some of these start okay while other must have the ignition turned on only after starting to crank the engine. Engine temperature and fuel mixture are both players on how these engines start.
Other comments or suggestions always welcome.