I am nearing the end of assembling a 383 SBC . Obviously, I want the break in of the engine to be done properly. Except for the block, headers, manifold, carburetor and accessories (the block has been bored over, clearanced, align honed.) it is new stuff. Springs, crank, rings, pistons, cam, rocker arms, heads, valves, etc. In short, every internal component is new.
The dilemma I have is that everything I read about a specific part, has somewhat different break in procedure. It's a hydraulic retro-roller cam, so it's said that no break in is necessary. But the beehive springs I'm using say that I should run the engine at ~2K rpm until the oil temp. is within normal operating range, to seat the piston rings properly, is a different procedure. Now I hear that the modern conventional wisdom is to start it up, and drove it like you stole it for a few miles.
Needless to say, I don't feel like damaging this engine and want it to last. Anyone here have any suggestions about how you break in an engine will all new internal parts?
If you honed the cylinders to the piston diameter with a head plate then the rings should seat almost immediately (within a few minutes). You never want to over rev a new engine.
You rev a flat tappet cam to 4,200 to obtain splash lubrication on the cam's lobes to prevent them from wiping as the tappet and lobe wear in. You vary the RPM from 2,000 to 4,200 to prevent accelerated wear during this process. With a roller cam there is no noticeable wear, but the wheel at the bottom of the tappet needs lubrication to keep rolling. So you break a motor in at 2,000 RPM.
Obviously if you have full oil control in the form of windage trays and wipers then a roller cam needs lubrication from some other source such as a groove cut in the lifter bore to run a keyed roller lifter or a hole in the body of the lifter to feed oil to the bearings in the wheel (I use Isky Red Zone lifters for this reason). If you see the profile of a Bactrian camel on your dyno sheet (two peaks in horsepower) that dip in performance in the middle is due to valve float. You want it to look like a Dromedary camel's hump.
Biggest issue you will have with a hydraulic roller will be valve float at higher RPM as those tappets are much heavier than a hollow solid lifter. As such you need stiffer valve springs (under the 300 pound upper limit of a hydraulic lifter) to control the valve train. It also helps to lighten the mass of the valve train.
Everything in parts selection is a compromise as you can not increase spring tension without reinforcing the push rod's strength to prevent deflection. This adds more weight if you increase the diameter of the push rod (in a SBC don't forget to machine the head or replace the guide plate with bigger hole to clear the bigger push rod). On the street you can not run titanium (or aluminum) as those metals work harden and fail very quickly. I recommend chrome-moly valve spring retainers that can be made thinner (and therefore lighter) than a steel retainer. Same reason I use chrome-moly roller rocker bodies.
I know your motor is together and ready to run but these are things I recommend to those who are putting a motor together for the first time. I also recommend a dyno for start up unless you have a dedicated engine test stand in your shop (basically a stand with radiator and gauges to simulate being in a car) when firing it up. Lot easier to find and fix leaks or other issues and to give it a proper tune up before it goes between your fenders.
Thanks, Dave. Looks like 2k is where I need to break it in. The cylinders were bored with a torque plate installed. Due to your advice, I will definitely be using a pan with a windage tray and will use wipers. I’m using Lunati beehive springs. 318 open pressure, if I remember it correctly. 130 closed. Chrome moly retainers. Hardened 5/16 push rods, AFR adjustable guide plates. The only thing is that I am using different from your recommendations I have Harland Sharp heavy duty roller rockers. You think that will be ok? I don’t have dyno available, so I’m sure I will be in the engine bay wrenching on something.
others more knowledgeable than me may chime in but the main concern during break in on old school push rod engines was cam lobe wipe out. that is taken out of the equation with the roller cam. piston rings will not completely seat on your first initial break in and will take some driving to do that. you want to make sure you use break in lube on your distributor drive gear. start engine, get it up to temp, get timing dialed in and drive it around a little. change oil and filter. go to town. i try not to rev a fresh motor too high for the first few hundred miles....
Only if the cylinders are round. Dingle Berry hones do not make a cylinder round. they put a cross hatch pattern into the cylinder walls to hold oil (a hold out from the age of cast iron pistons in the stovebolt six). You need an actual hone to make a cylinder round. The head plate stresses the block the same way a head does so the cylinders can be honed round.
It will be for a while. You shouldn't have issues with valve float. 318 pounds is very near the upper limit on a hydraulic roller, but Bee Hive springs are variable rate. that is to say the rate changes becoming stiffer the more they are compressed. So you will probably not have issues with the metal fatigue you would have with aluminum body roller rockers and solid lifter springs hitting 500 pounds of open pressure.
Only worry I would have is accelerated wear due to lack of splash lubrication. Watch for cast iron filings in the oil from wear by cutting open the filter and looking for the filings with a clean bar magnet. Even roller cams fail without lubrication.
I had shots on photo bucket showing stock cams failing at 48,000 miles were the steel wheel had eaten a trench into the cam lobe. These were warranty claims at the local Chevy dealership that I learned about from the line mechanics.
It will be for a while. You shouldn't have issues with valve float. 318 pounds is very near the upper limit on a hydraulic roller, but Bee Hive springs are variable rate. that is to say the rate changes becoming stiffer the more they are compressed. So you will probably not have issues with the metal fatigue you would have with aluminum body roller rockers and solid lifter springs hitting 500 pounds of open pressure.
+1 on 2k rpm initial start up with a hydraulic roller. This keeps oil pressure up. I run motor for about 20 min this way using that time to constantly check from up top & under car for leaks and I use a IR temp gun to monitor exhaust temps to confirm they stay fairly equal. set timing.
You can use a high zinc content oil if you want like Valvoline VR1, Joe Gibbs, etc. After 20 min shut off and drain oil & replace filter. There will be assembly lube and sometimes very minimal debris but you certainly should not see "sparkle" in oil.
I then go for a drive where I, in first gear or low, accelerate to 3500 rpm and decelerate letting engine brake the car. Do this 4-5 times then 4500 rpm 4-5 times. This loads the pistons both ways helping the rings set. Then I just drive "normal" (read don't baby the car nor biatch slap it with clutch dumps and high RPM rev) for 500 mi. Also don't maintain a constant sustained rpm if driving on fwy, just vary the rpm up/down some
Change oil & filter at 500 mi and just drive the car as you wish form there
In my younger years, I was taught by a WW1 vet whom had fixed most anything on this earth.
Smitty suggested you can do the 20 to 60 WOT/coasting 10-12 times in high gear, 4th was it as there was no OD then, or, if you want a snappy running engine, drive it like no tomorrow.
Then change oil after break-in.
I did the latter and drove with a heavy foot. After 3K miles, changed oil and did a compression check and had 2-3 PSIG difference in all eight cylinders with clean spark plugs and no smoking. I did the same with my 11.90/115 MPH '68 Camaro, but then she was a 1/4 mile girl and she only seen WOT. Nary a drop of oil used for the next six years of racing.
Chose your poison. Piston rings do seat within the first few seconds.
Lots of new engines are broken in on the Dyno. That is how I did mine. On my Kawasaki KZ I just hammered it from the start up. I have never had an issue with oil consumption and I drag raced it.. I break em in like I will be using them. Just be sure to change the oil after a short time. Breaking them in on a dyno I would change it after a couple of pulls and then hammer it again.
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