I'd like to bump the starter on my Yblock that has never run. It is a rebuilt engine, but has never started. Thinking about bumping the starter just to turn the engine as it needs that every now and then. I do not have the electrical system in yet - no solinoid installed/no wiring, etc. I'd be jumping directly to the starter. Any worries about this? Will it turn the crank?

 

First let's define our terms. A "rebuilt engine" - means different things to different people - that has never been run will have properly have assembly lube on the (new) camshaft lobes, about a $200 item. Y blocks have solid lifters, these run $200 to $350 a set for good ones. The important, critical thing if this is the case, is to break in the camshaft and lifters so as to not wipe out a cam lobe. Get one chance to do this.

Normally this is done by immediately upon startup bringing the engine up to 2000 to 2500 RPM or so and maintaining this for about a half hour. The camshaft manufacturers are very specific about this operation. No idling, no dinking around with the carburetor mixture settings or adjusting the timing, or extended cranking sessions just trying to get the damn thing to start. Everything should be pre-set so the engine will start right away and cam/lifter break in goes smooth. Spinning the engine over "every now and then" with the starter may contribute to wiping out a cam lobe.

 

Why not just use a socket and breaker bar on the crank bolt? (spark plugs out, maybe put a few drops of oil in each cylinder)

 

I have been turning the crank with a breaker bar. Last time was when adjusting the lifters. Just thought it would be fun to bump the starter and was wondering if anyone would warn against it - any pitfalls?

It is mounted in the frame, but has never been started to seat the values, etc. That is coming soon once the gas tank and fuel lines are in and some electrical.

 

This was something I was not aware of, and I have built a lot of engines. Back "in the day", it was usually just coating the cam with some preparation such as Lubriplate, spinning up the oil pump to prime it good, then lighting off the engine. Running the RPMs up to 2500 wasn't something you normally did.

Then again, that was several decades ago when there were sufficient levels of zinc and other wear additives in oil.

Just "tried" to read an article on Hot Rods website concerning cam break-in on older V-8 engines with flat tappets. "Tried", because I couldn't get through all the article. Hot Rod, along with many other websites clog their pages with so much dynamic content/ads/crap, that it almost freezes up my browser.

In the article, they speak of how they wasted the cam on a build they performed on a SBC within the first few minutes of operation. Had to rebuild it again. A lot of what went wrong had to do with a lack of proper additives in the break-in oil. The article went on to discuss the relative merits of different oils and additives, along with charts listing test results showing actual zinc, molybdenum, and calcium content in differing brands.

If you can get through their webpage without your browser crashing, there was some very good information there, along with suggestions on the best oils for a break-in.

That said, I wonder just how much we need to worry about cam break-in in these vintage engines of ours. My feeling, is not so much.

The reason is that we, for the most part, don't do a performance build on our old flatheads and Y-blocks. One glaring difference between the small-block Chevy they built, and our engines, is in tappet spring pressure. In their engine, the valve springs measured 130 lbs. Whoa! Guess they were worried about valve "float". Even the authors admitted that was too much pressure, and went on to relate that they consulted some professional builders who suggested pressures of 80-100 pounds was sufficient, even for a performance build.

Compare the spring pressures recommended by their professionals, 80-100 pounds, with a stock 1948-52 239 flathead, which is about 42 lbs. Less than half of what the SBC was supposed to run. I would suspect that a Y-block wouldn't have significantly higher spring pressures than a flathead.

Point is, my feeling is that while we should be concerned about using the proper break-in lubricants, and not wiping off the cam lube by "occasionally" cranking the engine as Tedster suggested, the start up isn't as critical.

 

Valve spring seat pressure (closed) actually has more to do with preventing the valve from bouncing excessively when closing. But higher seat pressures go hand in hand with higher lift spring pressures, that are helping to prevent valve float. My only point was if it were me, I wouldn't let a newly rebuilt engine idle nor spin it with the starter or anything other then break it in per the camshaft manufacturers directions.

"As a point of interest, the most critical time in the life of a flat tappet (solid lifter) camshaft is the first 20 minutes of “break-in” during which the bottoms of the tappets “mate-in” with the cam lobes."

"Set your valve lash or lifter preload. Try to minimize the number of times that you rotate the engine, as this can displace the moly paste from the lobes and lifters."

http://www.cranecams.com/uploads/breakin/548e.pdf

 

Periodic running with no load is the worst thing for new rings in fresh bores. Some of that is unavoidable in reality, but the less of it the better.

 

Yep. Cylinder bores glaze over, rings never seat.