The Stovebolt Site Forums The Shop Area Engine Shop New engine run dilemma

Finally got around to starting the '57 rebuilt 235 (from a bel air in a "53 truck). I know from reading the forums the proper way to do it is to run it for 20 min or so even if it doesn't run great to break it in, then do adjustments. My question is below. I'm not the mechanic, my cousin is, and he kept wanting to start it for a minute, shut it dow and adjust and do that over. He did this 3 times as the carb needed adjusting, the timing was a bit off, and i know the valves need some adjustment. When i said I'd really like to just keep it going for 20 min (which i believe it would do) to make sure oil gets everywhere, he took great offense that i questioned him instead of just saying how great it was it would run (which i did do, but apparently not enough). I'm not a mechanic and he thinks this is the way to do it, that is, he says getting it running better before letting it run for so long is the way to go. When i told him what i read, he said to let "those" people work on it then. We are friends, and this didn't cause a huge fallout, but before i go back, i just want to know how horrible it would be to just let him do it his way. Oh, and we did use assembly lube and primed it really good. It also has all stock parts (cam and such), if that helps. Thanks for any advice

Considering it is a stock cam with stock spring pressures and you primed it and hopefully ran an oil with zinc or a zinc additive you will be just fine. I am the same way, would rather time the engine and adjust the carb in lieu of a poor running engine at 2000rpm for cam break-in. Your cousin is on the mark IMHO. BTW, there is nothing in the repair manual about cam break in and you can bet they didnt do it at the factory either.

Steve

Yes, i used the lucas zinc additive for engine rebuilds

BTW, there is nothing in the repair manual about cam break in and you can bet they didnt do it at the factory either.

But, the oils were different and the factory had a way of running-in engines before they hit the frame rails, back in the day!

Being a stock rebuild with very little valve spring pressure, shutting it down to tune probably is ok, BUT you really should run them as is for the 20 minutes as long as it's not hurting itself or overheating. In my mind, a little out of tune is OK, and you can always do simple, on the fly tuning to the carb and timing without shutting them off. New camshafts need oil on the lobes, and the only way it gets there is from being thrown off the crank and rods, and each time it is shut down, the oil drips off and you have to start again.

There are a thousand different ways of starting a new engine, if it still runs when you are finally ready to go for a drive, then your way worked, if for some reason it all goes bad, your way didn't work..........

Joe

Joe, I here what you are saying but if they ran them in , it was for rings not camshaft. The cores were good and hard in those days and like I say the spring pressures are nothing. Running an engine in with bad timing especially retarded can cause excessive heat and in my opinion much worse than the other. He has a full pressure 235 so the oil is getting there. Again, if it were a big deal, it would be in the service manual on the cam R&R.

If I had my preference, I prefer to break in my cams the traditional 20 minute non stop run in. However, there have been times when the motor would over heat if i did. Sometimes if I had access to a fan I would set up a fan. But there were more then enough times when I had to stop and start, stop and start the motor in order to do the break in without over heating the motor. I have quite a few 235, 261 motors under my belt and no break in failures So I think you will be just fine.

If the break-in run can't be completed without stopping and tinkering, somebody didn't do his homework right to begin with. A little valve rattle isn't going to create any permanent damage, so I add .002" to the "hot" valve lash setting and leave things that way until the initial run is done. Ditto on ignition timing- - - -tweak it by ear for the best sounding exhaust note and press on. Running at no load, it's virtually impossible to get any detonation damage, even if the timing is advanced a little too far. Use a squirrel cage blower on the radiator, or just run a garden hose over the outside of the radiator if a little extra cooling is needed.
Jerry