This subject has probably been done to death but is something I feel uneasy with I am rebuilding my 351W and was going to fit new cam and lifters but feel uneasy about firing for the fist time and revving straight up to 2500 RPM for half hour of un- interrupted running on new shells /pistons /rings /bores to harden the cam The carb I have has not been set up for this engine , its been rebuilt but could need jetting , what if it leaks or the choke does not work properly and I have to shut down Then there is the ignition side of things IE setting the timing , from what I have read if you piss about during the first half hour of running chances are you will toast the cam, or am I over thinking this ? The other option I have is the cam from the engine is good (don't know the make or specs ) So if I fit new lifters I can break the engine in gently /set everything up and at a later stage change the cam and lifters if I am not happy with performance once I have ironed out any other problems that are likely to occur with the engine/trans conversion Don't intend to add any performance parts as the rest of the engine is stock apart from changing the intake from 2 v to 4v and a 600 cfm carb
You are kinda over thinking it BUT understandable when you have lots of time and money into the rebuild. I always use non detergent break in oil, lots of Zink additive, get timing close, turn in the fast idle screw a turn or 2 and cross fingers! Use just water in rad. incase of leaks, have fan ready to keep new motor cool if need be. On the unknown carb it's a crap shoot BUT remember rich is better than lean on break in. I only like to have one person with me at time of break in, not a group. Have him or her keep an eye on the potential leaks, oil & temp gauges while you do the adjusting. 2k, 20 min. is good enough for break in..............................................
If you can pre-oil it first, this is the way to go and wards off many evils. The last one I did, new carb out of the box, a Holley. It was easy to set the float level, the rest was plug-and-play. One of the biggest things is to get the distributor dropped in right. I always have had a helper or 2 that knew what they were doing, guys who can think on the run. Go with what the cam manufacturer recommends. Mine recommended an additive, so I got that. I used a high ZDDP 10w-30 oil, you want something that flows immediately, if not sooner. You need to have all your ducks in a row to keep it running through the cam break in period. Put it off to the next day if you are short on time.
My engine shop buddy's always use a known carb to start new motors, that is they have a QF 750 that they start and break in every new gas 4V motor on. That way there not dealing with carb issues while breaking in a cam. So if you have a good carb or can barrow one to get the 351 up and running then swap your rebuilt carb on after the first break in.
Lucas sells an great break in oil and look for low pressure valve springs to break in the cam. From what I remember Chrysler put the good valve springs in the trunk for the max wedge cars.
See link below for a completely different take on break-in oil, zinc additives, etc. Claims zinc in oil is kind of a red herring. Hm. Test results on a couple hundred different Warning, it's pretty long. https://540ratblog.wordpress.com/ @Blues4U might be interesting to hear your take.
You have a few misconceptions. If you have a problem shut it down, it won't hurt anything. What hurts it is letting it idle. I've started a lot of engines that didn't run a half hour the first time they were fired and I've never ruined a cam. You will do more damage running a lean, or hot, leaking or timing way out of wack engine than you will by shutting it off and fixing the issue. You can set timing with it at 2000RPM to get close enough for the break in time. Same for the carb. If it's close it's good enough for break in. If it's crazy rich or lean, shut it down and fix it. As for using the old cam with new lifters you still have the same issue. Break in isn't to make the cam hard, it's to create an interface between the cam lobes and lifter bases. Nothing more. Has nothing to do with making anything harder. Pre oil, fill the radiator, get your fire extinguisher, set your distributor, fire it up and set your idle at 2000-2500. Let it run as long as you safely can. If you have to shut it down for an issue, do it. No worries. Once you get 20 minutes high idle run time, you're golden. As for oils, I use whatever is cheap with some ZDDP added. It won't be there long and no oils left on the market are truly bad. I tend to use Castrol 10-40 for break in with the ZDDP additive and when putting the engine together I use Isky Rev Lube on the cam lobes and lifter bases. After the break in run I dump the oil, put in my good oil (I prefer Brad Penn) and go on about my life. When we raced it wasn't uncommon to change engines every few weeks while experimenting with different cams. Never hurt one with this system. SPark
Thanks for all the replies, this my 1st ,American V8 build so being cautious plus reading horror stories on the net doesn't help , Never come across the issues I have raised before as mainly worked on English / European / Jap cars / bikes Thanks again
It should be noted that when these cars were finished at the factory the guys who drive the cars from the assembly line to the parking lot are payed by 'cars per hour", so they run em hard for a few minutes getting to the lot & they're shut down until cranked up to load on a transport to go to the Dealer....
I was pretty young, don't remember much, but took a tour of Detroit once. Two things I remember is watching a humongous block of red hot steel on a conveyor being rolled into sheet, and, LOTS of squeeling tires as the new cars were driven off the line, they didn't waste any time that's for sure.
Nearly everything you guys have suggested happened to me. Just got my 390 back from the builder and installed a month ago. We used my stk dist at start up that came out of the 352 because we new it worked. New Holley as I spent some cash on the build and didn't want any issues. I had him come over on start up. Ran 2000 for 20 mins total. We also started with no thermostat just to make sure we were flowing out the gate. He suggest 400 miles with the breakin oil then it should be good. We had a few leaks as you guys noted and we shut it down for a quick sec to tighten some clamps but got 175 miles on the motor and going strong.
I also suggest leaving the thermostat out until the cam is broken in. A few times during break in I’ve watched coolant temp get up to 215 before the new thermostat opened. This will be one less thing to worry about. Sent from my iPhone using The H.A.M.B. mobile app
I like the known-carburetor idea, it should help someone I'm sure. I also go conservative on the valve lash, instead of a 1/2 turn, I'll go a 1/4. Then adjust them after the oil change. Which gives another chance to see if anything funky is in the oil under the valve covers. I follow what is on the cam card, just about every cam I see now has the lube with it. Years back a smart counter-man at the parts store would give out a tube of lube with every cam sold.
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