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30 over block pure stock rules tanked block checked for cracks speed-pro 6 inch dome hypers, rod clearance .002 mains .0015 ran motor on run in stand set timing at 34 degrees @ 3000 run for about 2 hours and it had 95lbs oil pressure cold came down to 75 cold 160 degrees water temp.put in in the car ran it about 5 laps and it broke up real bad.brought it in checked timing timing was then 49 degrees so we locked dist and went back out motor developed a knock so shut it off ,removed motor ,wix oil filter felt like about 5 lbs heavy pulled pan checked rod bearings they all had a scratch in them .pulled mains and down to copper.i put a magnet in the pan and the left over oil was magnetic? the new piston skirts look like they were sanded with 80 grit and most all the coating is gone .003-.004 clearance on piston skirts when put together. not sure what happened.it feels like a fine sand in the oil pan piston coating? i found no other part of the engine worn other than scratches in crank . could the bearings have been washed with too much oil pressure or timing hammered out mains?
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Not enough bearing clearance for a race motor. Those clearances are fine for a tight street motor. Your piston skirt wear is probably due to the lack of engine temp. JMO. -
you didnt have enough clearance on the rod and main bearings you needed at least .003 on the rods and .003 to .0035 on the mains the piston skirt wear is from the bearings in the oil on the cylinder walls and piston skirts, you probably ruined the cam and lifters as well, for sure the cam bearings are messed upLast edited by 362CID; 05-18-2011, 09:30 PM.Comment
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engine problems
the cam and lifters look good i will retank and change the cam bearings ,i will also check the line bore.no spun bearings just deep gouges in the mains.would i have better off using a stock pump so as not to have so much oil pressure?M-55HV pumpComment
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Did you disassemble oil pump? Sounds like the pressure relief plunger could be sticking.Comment
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Not enough bearing clearance. Rods should be .0025, mains .003. Lucky you didn't spin some bearings with cleanances that tight. Surprised you didn't blow the filter off with 95 lbs of pressure. Curious what you used to prime the engine with before you started it?JD's Performance
13034 Hwy 99
Wapello, IA 52653
319-931-0677Comment
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engine prime
i used a distributor oil pump drive.Comment
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Setting your timing at 3000 RPM is alright if your max RPM is 3000 out on the track, If you max RPM out on the track is 7000 roll the throttle up that far and make sure its where it has to be at that RPm and don't use a dial back light!!
Sound like a very dirty build, Not plugging the oil filter bypass will allow unfiltered oil to get to the bearings more so where your running a HV pump and maybe heavy oil.
If your block has the press in plug up near the top if the head on the left side and it was not removed that could be a problem as there is no way to clean that oil galley with out plulling that plug out.
I have seen engines come in the shop with that tight of bearing clearances and not seen and bearing issues.
Also was the block aligned honed?? plate honed?? what did they use for a hone to hone the cylinders with and what stones?? Was the block even decked??
Hyper pistons should not be used in any performance engine as we have seen guys try that with not very good results!!!
Also make sure the plug is under the rear main cap!!Last edited by CNC BLOCKS; 05-21-2011, 01:47 PM.Comment
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engine
the oil filter by pass is not plugged im guessing it should be.
you say not to use a dialback light why is that? the block was a 100 block that at some time was line bored and decked.Comment
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I hate to ask this but did you wash the block after you got it from the machine shop and before you put it together? They do not do this most times and I have seen a BUNCH of machining debris come out of a block when I started on them with soap and water.Comment
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I dont think i would run the lifters after all that metal went through the engine. You can disassemble and clean them though. Maybe easier to buy new if you have the extra money.Comment
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Racing engines should be finished with an align hone!!!the oil filter by pass is not plugged im guessing it should be.
you say not to use a dialback light why is that? the block was a 100 block that at some time was line bored and decked.
Here are some links to look over on dial back lights
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Ive compared my dial back with my flaming river light and it is accurate as well as its been tested many times on the chassis dyno and proven accurate.
I run msd ignition box msd in my opinion wants you to buy their light. bla bla bla.
I dont find it hard to find power for my dial back light. As I have a rubber valve stem in the dash with a hot wire soldered to the end inside from the starter button on the dash. I keep a plastic cap on it a little loose and just clip on.. no sweat. I thought everyone had one of these by their push button on the dash?
jjComment
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Not every dial back light is the same!! I seen burnt pistons over the years with dial back lights as there are some that don't work very well.
We use and our customers use the flaming river timing lights but there are alot of guys that don't know haw to mark there balancer.Comment
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I run 30 dollar balancers with a 22 dollar balancer cover that is degreed. Summitt and lots of other places sell them, no marking needed!Originally posted by CNC BLOCKS View Post
The burnt up motors Ive heard of were USERS who didnt know how to use the dial back. They set the dial to full advance 36 and still go to that mark on the balancer instead of ZERO. A friend of mine did this last year to a new crate!
Ive had 3-4 different lights in the last 10 years all dial back and all were accurate even with my MSD. It seems like a myth to me. I always compare to my flaming river cheapie light.Comment
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