Big block motor people,,I need help!!!!!!

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Jims71duster

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First off,, I posted here cause I know more people come to this topic so if its in the wrong place please move it.. Here goes,, A mildly built 383, kb 10.5-1 pistons, comp cam with matching springs and hyd. lifters. 850 holly,rpm edlbrock intake,msd ignition.
I started it for the first time and it cranked for about 15-20 seconds before it fired up. I checked the timing right away and it was at 11 btdc so I lifted it to around 2000 rpm for about 10 minutes ( at about 2 minutes I realized I never had a crank case vent so I took off one filler cap and there was a bit of presure in there).It seemed to be warming up a bit too much so I idled it down for 2 min. and shut it off. I repeated this one more time a hour latter. It seemed to run great. the third time I started it, it was back firing a little then the back firing got real bad. I took off the valve cover and found one push rod off and a different lifter was collapsed as well as a different lifter was destroyed. the cam wore it off until it had a hole in the bottom of the lifter. I already know the cam has to be junk and the motor has to come out and be ripped apart. WHAT THE #%^&& would cause this, every part was new and I was anal about perfect torques and cleanliness was perfect. I'm sure you can all realize how upset I am so If anyone could point me in the right direction in my search it would sure help me. side note here is that a machine shop did the short block and I did the rest.
 
Did you have cam break in lube applied? Did you prime the oil system before start up? What type of oil did you run during the break in process?
 
Ten minutes is no where near long enough to break-in a flat-tappet cam IMHO. WAY too soon to idle it down. Once it cooled, shoulda fired it up and ran it at 2500-3000 for another 10 minutes. Also, I have mentioned on here before about alot of the modern oil blends having reduced sulpher content not being safe for flat-tappet cam break-in.
 
perhaps too much spring pressure as well.

i allways have broken mine in the same way. 2000rpm for 5 or so, shut it off cool down, do it again, maybe 10 min. shut it down, cool off a few times and good to go.

some advice. that motor needs to come apart and gone through now, dont just take a short cut and change the cam. that cam is all over the inside of that engine and you will be putting bearings at least into it if you run it.

royal purple makes a non synthetic break in oil
comp makes a break in lube pt# 159
i have used (gulp) GM EOS (engine oil supplement) with good results.

shell rotella still has a bunch of zinc in it thats a option too
 
Todays oil can destroy a flat tappet cam during break in. You need a quality non synthetic oil with a good zinc package.

What you experienced is sadly becoming more and more common for home builders.

Follow the cam manufacturers break in procedure.
 
I agree with the masses here. I use the Comp Cams break in lube. I like to fast idle to 2000-2500 with a blip of the throttle to keep the lifters rotating for 10-20 min. A new engine will generate alot of heat, I keep a water hose close by to mist the radiator if need be to cool the radiator and complete the breakin cycle. Make sure you coat the lobes and lifters with some sticky cam lube. Most wiped out lobes are at start up and before a good oil film is established on the liters and lobes. Make sure you don't have to much valve spring seat or open preasure. Man I know this sucks, I know this has happened to many others. Be patient, walk away from it for a week if you have to.
 
all good information here. The oil situation is a HUGE factor, you cant just walk into your local parts store & grab the first non-synthetic 30 wieght you see for break-in anymore. Alot of the oils formulated for use in heavy commercial vehicles will work too. This issue is another by-product of the opinions your local greenies taking priority over the opinions of engineers...
 
yup,,,I ripped er down,, the cylinder walls look ok,,,but the cam and half the lifters are a mess, one won't even come out the top and will need to go in to remove it. I'm gunna try a little to at least get the machine shop to get me a replacement at cost, but im pretty sure its all my fault. It will be ready to come out after work tomorrow and should be a bare block by 10pm and maybe round 2 will be better for me. There is a local guy here that I just found out will come and do the start up for a reasonable price,, might do that
 
was just on the comp site and it says that the cam the machine shop installed needs to have adjustable valve train and requires machining on the heads. The people that machined and built the short block were also the ones that did my heads. Wonder if they put the wrong cam in it and its binding up cuz, they knew the heads were not adjustable. The cam is a 21-222-4 part number,(comp) and is a xe 262h grind with .462 lift.
 
Dont have the specs handy, but with .462 lift, theres no way that the non-adjustable rockers are the problem. By the way, dont force that mushroomed lifter out through the lifter bore, or you will REALLY have a mess on your hands.
 
I just looked up the specs on this cam, and its REALLY mild. Honestly, I'm more than a little puzzled here. The springs are pretty wimpy too. I have to back to your break-in procedure, and the oil. For what its worth, I have run the factory non-adjustable rockers(with shims under the shafts) in my old 440 with a [email protected] .525 lift hyd. which is light years bigger than the cam you are running, no problems.
 
george said:
Dont have the specs handy, but with .462 lift, theres no way that the non-adjustable rockers are the problem. By the way, dont force that mushroomed lifter out through the lifter bore, or you will REALLY have a mess on your hands.
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there was about 4 lifters that where snug but i could still pull them out by hand and I dont see any scratchs on the bore, the last one will have to come out once the engine is on the stand. Once the machine shop opens for the day I'll call them and have them check thier numbers to make sure everything is good to try again,,,thx for the help
 
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