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Piston detonation evidence - 1998 Northstar

7K views 46 replies 9 participants last post by  Submariner409 
#1 ·
Okay so I picked up another motor and transmission back in in July for my son for a $142.00 and they pulled it. I thought that was good deal, since now he has a spare tranny.
Any been slowly dissembling it since then. It is now all gutted and was cleaning the pistons with extremely hard and heavy carbon buildup on them, when I discovered number 1 piston on right bank looks like it has pits in it.
Which I am guessing is from detonation.


My question should the piston be replaced?








Thanks in advance for any input,
Dave
 
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#29 · (Edited)
Not necessary to buff the tops, but again, before the heads go on it looks trick and would make a nice file picture..............

Just for grins and kicks, here are some of the possibilities for a Northstar - BUT many are NOT workable in the FWD configuration - the modifier - CHRFAB - does some gorgeous engines for sand rails and kit cars.................. this article merely explains some of the Northstar technical points.

http://www.hotrod.com/pitstop/hrdp_1006_northstar_cadillac_engine_buildup_question/viewall.html

SC2150 asked how many engines I have built. I have no idea - a lot - been doing engines of various types, makes, models since my first MG OHV 1250cc overhaul in 1954. Worked part-time as an engine mechanic at 3 foreign car shops in DC during high school. Did a flathead V-12 Lincoln Zephyr in the late 50's, along with a bunch of B-Block flatheads. Even throughout my Navy career I still built engines as a hobby - and Navy bases seem to have great automobile hobby shops where sailors can work and store stuff while at sea. In '83 I started on the Ford 302 series in the Mustang "GT" Fox body cars. Among other engines, my marine business builds Olds 455 engines from slow-speed workhorse to tweaky screamer (although - you twist a 455 over 5500 for a while, it comes apart). Anyway, I enjoy the challenges and the friendships - as SC2150 knows, as an engine builder you become acquainted with every gearhead and machinist in a wide radius of your work. Right now, I'm in the middle of doing a '65 Pontiac 389 for a guy in the Kent Island Cruisers - he's restoring a '65 LeMans sedan as a sleeper. I will probably never touch a later Cadillac engine than 2003 - no desire to start over, and arthritis is slowly eroding my ability to do fine assembly work. One thing I can take pride in is that over the years none - not one - of my engine rebuilds has been a "come back".

EDIT at 1255: 1968, Naples, Italy. Apartment parking lot. My '65 Chevelle Malibu SS 327/350 developed a bad head gasket - coolant leaking into #2 cylinder. Did a decarbonising and top overhaul in the open with essentially NO proper tools or parts. The top of the piston looked exactly like dkoz' "mouse bites" analogy. Rolled it to TDC, packed the edge of the crown with grease and rotary wire brushed the edges of the hundred or so pits smooth. Cranked the piston down an inch and cleaned the bore. I blew that engine at the strip in Willimantic, CT in 1972.
 
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#30 ·
I was using 1200.
The only other grit I could find in my hoarding mess was 150 LOL, I think I have a file smoother than that.
Wish I had lower grits, that would save me a lot of work and finger swapping.

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Sub you just made me drool on my keyboard with link. :lick:
 
#31 ·
What I dont get submariner is I would never think I had more knowledge than you on anything related to the operation or maintanance of a submarine, or even what it is like to live for an extended period on one, but this area I put my experiance and qualifications up with any builders in the country, and have been doing this for over 38 years and do keep up on all new technology as we are one of the most respected perfomance shops in the SE US, and I do this daily with all these different engines, yet you always attack and are beligerent in the few areas where you are not the expert (even though you are 99% of the time right on and a huge asset to this forum). Why cant you accept there are some areas where us that do this day in and day out for a living may have a bit more expertise in these areas? I dont make a dime sharing information that has taken a lifetime to gather....and it takes time to contribute to those looking for guidance that is correct.

I want no quarrel with you yet you throw in the jabs and insults far to often....what is the purpose of this? Just a bug up your but that somehow encourages this? How does this benefit the mebers looking for correct advice? Never do I come into a thread you have given accurate advice in and challenge you, but you seem to make it a priority to do this in my case.

This is not a contest.....this is simply sharing information and for some reason you have the wrong impression that I am not who I am it appears. What is it you want to stop this?
 
#32 ·
I want world peace.
This is starting to look like the quarrel between Tim Carroll and Jake over at Northstar Performance. I appreciate all info, good or bad. If I go with bad then I have no one to blame but myself, because Google is MY friend.

All that I need is suggestions, there is no need for headbutting.

Maybe there should be another category added on somewhere for members to rant at each other, but then again other members would throw their 2 cents in when they had no business being involved, and then it gets real ugly. I guess that wouldn't work either. Forget that idea.

Anyway I went out and got more sand paper, 320, 400, 600, 800, 1000, and I already have 1200 and 2000.
Lets see what happens.

Thank you ALL :cheers:
 
#35 ·
No tend to agree with Sub - no big deal if you had left it - no harm done by lightly sanding. Interesting that the crown did not show the factory machining marks. I used an air die grinder and a steel wire brush attachment to remove carbon on my piston crowns (and combustion chambers/valves). I guess maybe the wire brush could have been a little dull, but it did not seem to cut into aluminum at all and very fine concentric or spiral machining marks were clearly left remaining visible on the top of the pistons - I don't see that in your pictures.
 
#47 · (Edited)
Good for you. Thanks - we all need prayers. I'll light a candle at Mass on Sunday for you, too. (You [apparently] desperately need it). You are perfectly welcome to pity me, but don't ever feel "sorry" for me.

When you get around to trying to build or repair an engine (any engine), call SC2150, me, Tim Carroll, Jake Wiebe, Joe Blau, Mike Lawson - a host of others - it's all in here somewhere.

To put this all in context, click on Tom's Caddy's username in his recent post. Now go back in time and read his recent posts in CF. I stuck a barb in him for posting huge file size pictures of his car and suggested ways to reduce the memory storage space - hardly something to feel 'sorry' for.

Fast Forward to daveyhouse' polished crankshaft thread............
 
#45 ·
He is usually dead on with most advice so he is a huge asset to the forum so I dont interfere in his threads. Just want peace and all good advice to the members as many of us cant be on very often. Thx for the support Tom's.

davey, you will be fine like that...good job and good luck with the rebuild. Lots of good info here.

:thumbsup:
 
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