Hi, I am getting ready to drop my 350 back in my buick after a extensive rebuild. What I want to know is how I should break this in. It has been a long time since I have broken a motor in and just dont want to forget something. I have over 5k invested and would hate to ruin something because of lack of knowledge or forgetting something. The thing I am worried about the most is the cam as I always hear people mention the cam being flattened out with improper breakin procedures. Any information or help would be great. Do some people have their engines broken in on a dyno just to be safe or is this really expensive and not neccessary? Thanks Jason
Im currently breaking mine in as well and would like some insight on this. I know that the original manual for my 71 says to drive it at steady speeds and not to over accelerate. Also it mentions to keep it at resonable speeds on the highway 65 mph. Ivan
Jason, Breaking in an engine right is very important. You want a clean, fast, start that avoids cranking the engine excessively. You'll want to use a straight weight 30 oil with a pint of GM EOS. Make sure all the other fluid levels are taken care of. I would install an oil pressure gauge and a temperature gauge. It helps to have a few friends there, each person can watch something different. There is an enormous amount of friction and heat generated when you start a new engine. A big fan that you can aim at the radiator is a good idea, the car won't be moving, and the fan can supply the needed air to keep the engine as cool as possible. To break in the cam, you need to keep engine RPM at about 2000 for 20 minutes. Do not let the engine idle during this time. You can shut it down if something doesn't look right, just dont let it idle. After that, you need to drive the car, and break in the rings. What I've read in the past involves accelerating briskly in high gear to about 50 MPH, and then coasting down to about 30, then accelerating again, and coasting down. When you accelerate, it loads the rings against the cylinder walls, and coasting brings oil up around the rings to lubricate them. At least that is what I remember reading. I'm sure their are other things that will be suggested. There is alot of experience on this BB. I've heard of breaking in an engine on a dyno. Don't know how expensive that would be, but if it is reasonable, and you have the extra money, I would do that.
I've heard that when breaking in the cam you should also vary the RPM a bit, keeping it above 2000 all the time. This will supposidly vary the oil splash pattern, so it will cover everything. The reason you want to keep it above 2k is to keep the lifters spining in their bore. If they don't spin during break in, that's where you will flatten the cam, or so that's what I hear....
breakin the cam is the most delicate piece of hardware & needs to be run , upon initial startup , for 20 minutes @ 2000 rpms . be sure to prime the oil pump prior before startup . guys, correct me if i am wrong , but that is the info i am familar with . a new motor is a terrible thing to ruin !
Thanks for everyones input so far. I cant wait to get this motor going but its a little scary when you have a lot of money at stake. I will def. have some friends over to help the process along and keep that thing running over 2k at initial start. Thanks again Jason
I like to get a garden hose with a spray nozzle and aim a light stream at the radiator during break-in. A lot of us have enough trouble with overheating idling normall, 2000 RPM when the car is still will really create some heat. Water will take a lot of heat away from the radiator (much more efficent heat transfer than air), and as long as you don't blast it with too much water it won't spray all over the place (most of it will evaporate). The tough thing about break-in is that you should have your timing exactly right and your carb exactly right as quickly as possible so you don't burn a valve or backfire as the engine heats up. (I know of a guy that decided he wanted a set of 3X2 carbs on his 440 chrysler, they had never been run before and when he went to break in his motor he had to spend so much time trying to get the carbs right that he ruined his cam. Next time around he did the smart thing and borrowed a 4-barrel car from a friend for break-in, and then switched to the 3X2s after the cam was broken in.) -Bob Cunningham bobc@gnttype.org
Right on that one! When I broke mine in my carb had the needle valve stuck open by a little sliver of fuel hose... it was dripping gas down the carb. My headers actually glowed a nice cherry red since the gas was still burning in the exhuast. It still ran enough to break in. also MAKE SURE the distributer is in right! if it's a tooth off, it won't start up right, and enough cranking will wipe the prelube off of the cam. Mine wasn't right... but I corrected it soon enough, and the cam broke in good. Do you guys really have troule keeping you cars running cool? My needle stays right at 180 all the time. It starts to climb up to about 200 when the radiator is half empty, I know because I had a small leak. I had overheating problems a while ago, but a new radiator solved it all. I also had AC, so that comes with a better fan to.
