The Day We Timed, Tuned, and Tortured our Friends
The engine is a really important (and most expensive!) part of our T-Bucket so we asked a few friends to help us break-in our new 383 Chevy Stroker Blue Print Crate engine. As we’ve found with a lot of the guys that work around here, they were very happy to help!
Greg had already primed the engine with the help of #cuteasabucket, basically making sure ‘break-in oil,’ which is higher in zinc, had gotten into all parts of the engine to avoid a dry start. Priming is so critical for an engine – that many engine manufacturers will void a warranty if the process isn’t performed!See his tech video here! For the break in, tuning and timing – the crew worked in tandem together.
We had already found top dead center and had our spark plugs in the correct order on the distributor, so after the T-Bucket started up, the guys looked at the oil pressure gauge. To protect our hydraulic flat tappet camshaft, Greg initially revved the engine between 2,000 and 2,500 RPM – all by ear, since we didn’t have a tachometer. The cam shaft lobes needed oil from the crankshaft. This lubrication is minimal until the engine RPM increases. Greg kept the load on the engine varied- he’d let it rev up a little for a few minutes, then rev it much higher, continually changing the RPM’s.
Tuning a carb sounds super complicated but it’s all about finding the correct air and fuel mixture at idle. Our air filter had already been removed, so our BFF Josh looked at the exposed Edelbrock Thunder Series carburetor. He narrowed in on two adjustment screws at the front of the carb, which adjust the air and fuel mixture. When turned clockwise, the screws reduce the amount of fuel mixing with the air coming through the carburetor at idle. He first turned them clockwise to lean out the engine until it began to run rough (too lean) and then he backed out the screws slightly (and equally) in order to get a crisp sound. This prevents the carburetor from loading the engine up with excess fuel while idling. There were moments after shutting off the engine that it sounded like it wanted to keep running. Josh called this “dieseling.” The lower octane gas we used initially was detonating without a spark in our high compression engine. Lesson learned – we filled the gas tank with a higher octane fuel after that.
An engine’s timing refers to the firing of the spark plugs at specific moments in the ignition cycle. If an engine doesn’t sound quite right, backfires or runs too rich/too lean, you need to adjust the timing. The four “strokes” in the 4-cycle engine are the process of intake, compression, power, and exhaust. The timing of the ignition refers to the point between the compression and the power strokes at which the spark plug fires. After the spark plug fires, the combustion (fuel meets fire) forces the piston down into the cylinder which results in your horsepower. We used a timing gun, which is a strobe light and illuminates the timing marks on the flywheel. Joe turned the distributor housing one direction or the other, depending on whether or not he was advancing the timing or retarding it. He did this until the timing mark was where he wanted it. He also listened to the engine – when it sounded happy, he tightened the distributor back down. Joe and Josh worked in sync with one another and adjusted the carb and distributor more or less together.
Normally, you wouldn’t change your break-in oil until after 300 miles, but we just weren’t quite sure when this little lady was going to get to 100 miles, so it was best to do it now. Plus, we didn’t know what kind of metal shavings would now be flowing through our engine after the break-in process. We replaced the break-in oil with another oil high in zinc content – Hot Rod Oil from Lucas. It provides maximum protection for our flat tappet camshaft.
I’m used to hand tightening oil filters when I change the oil in my 2007 Chevy. So when I hopped in to drive the T-Bucket around to another shop space I was immediately signaled to shut off the engine. Oil had spewed out of the tightened oil filter and followed my path through the garage. Fun Fact: the higher end race filters need to be tightened with a wrench to compress the thick gasket on top. My hint should have been the fairly thick gasket and the 1” nut built into the bottom of the filter, which fits a wrench quite nicely. Bonus: I had an audience of Goodguys employees to witness my blunder. Neat. Added bonus: I got to spend an hour cleaning up the mess I had made. Double neat. Having a bunch of gear-heads crack a smile and tell me it happens to everyone at some point didn’t make me feel much better.
I’m off to clean some more. Until next time,