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#1
09-27-2016, 11:19 PM
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Broken piston rings again
I disassemble my 350 engine again and found all piston rings smashed and mushroomed out. One of the photos has the Piston Ring broken and carbon underneath the Rings. This was at 9.5 compression using 89 octane engine was running pretty good but obviously not for long. What option do I have
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#2
09-27-2016, 11:48 PM
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What rings are these? Are they gapless rings?
You need to be sure the rings have the correct radial depth[distance from the ring face, to the back side of the ring]. The radial depth should be around .005" less than the depth of the ring groove, minimum. If the rings stick out of the piston when bottomed out in the ring groove, that would explain what you have going on. The pistons swells up, and shoves the rings into the cylinder wall with excessive pressure, which in turn mushrooms the ring. Usually tears up the cylinders also.
__________________
Paul Carter Carter Cryogenics www.cartercryo.com 520-409-7236 Koerner Racing Engines You killed it, We build it! 520-294-5758 64 GTO, under re-construction, 412 CID, also under construction. 87 S-10 Pickup, 321,000 miles 99Monte Carlo, 293,000 miles 86 Bronco, 218,000 miles |
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#3
09-28-2016, 12:07 AM
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Quote:
__________________
Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress. |
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#4
09-28-2016, 01:33 AM
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As said:
Piston/ring geometry--does the ring fit the piston properly End gap--does the ring fit the cylinder properly DETONATION--not enough octane rating Not mentioned yet: Is there a ridge at the top of the bore? Top rings can be pounded to death by NOT boring a worn cylinder. Did you re-use the pistons that had prior broken rings? The ring lands could be damaged or worn |
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#5
09-28-2016, 03:59 AM
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Broken installing them?
A good ring compressor is a good investment. Only takes a small wooden dowell to install a piston. |
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#6
09-28-2016, 06:03 AM
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What do the rod bearings look like, do they still clip in tight into the rid big end?
Please post up a good close up picture of the big end of a few rods, split apart and without the bearings in. 9.5 comp with too small of a cam can make for the same cylinder pressure as a 10.5 motor and hammer the rings like that as can the tune or timing being off. Do you know what the motors cranking compression was before things went south ?
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#7
09-28-2016, 08:01 AM
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No just ordinary ductile steel rings with moly coatings. The only thing that I did was bought them one size bigger because I want to to file fit them. My piston size was.040 can I buy .060 and file the ins to form 8.016 Gap
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#8
09-28-2016, 08:04 AM
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You can not do that as filing a ring that much makes for a oval ring that will never seal right and lead to oil getting into the chamber and detonation !!!!
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#9
09-28-2016, 08:31 AM
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I can't seem to buy file fit rings for a Pontiac 400. I tried looking everywhere unless I get total seal gapless rings. Do you know of any manufacturer who has file fit rings
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#10
09-28-2016, 08:37 AM
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Rod bearing
Here is a pic of the rod bearing comma no damage done no copper showing. Detonation may not have been an issue here or it wasn't that much. I may have screwed up on the piston rings. This is the
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#11
09-28-2016, 09:25 AM
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You can buy Total Seal conventional rings & still file fit the gap your looking for.
__________________
Carburetor building & modification services Servicing the Pontiac community over 20 years |
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#12
09-28-2016, 09:43 AM
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I'm thinking you have either worn ring lands or the incorrect width ring pack, as stated by others. You shouldn't need file fit rings, KISs
What piston/ring are you using, part #'s/manufacturer? |
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#13
09-28-2016, 09:51 AM
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Top Ring Thickness: 5/64 in.
Top Ring Material: Iron Top Ring Facing Material: Moly Second Ring Thickness: 5/64 in. Second Ring Material: Iron Second Ring Facing Material: Cast iron Oil Ring Thickness: 3/16 in. Oil Ring Material: Stainless steel Oil Ring Tension: Standard |
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#14
09-28-2016, 09:55 AM
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Quote:
What pistons are you using, the ring pack must match. 0.040 350", but what piston part #, and ring part # did you use? |
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#15
09-28-2016, 09:59 AM
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I don't know the Piston manufacturer anymore, doesn't really matter I'm not using same block. I'm using a 400 block now we have speedpro TRW forged pistons .040 and I will get the appropriate piston rings weather there going to put me at the correct ring Gap or not
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#16
09-28-2016, 10:21 AM
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L2262F40?
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#17
09-28-2016, 10:47 AM
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Never try to out engineer an engineer...lol
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#18
09-28-2016, 11:02 AM
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Yes those are the ones that I bought
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#19
09-28-2016, 11:23 AM
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Quote:
At 4.165" (4.125+.040=4.165') it will be the same as a .005 file fit ring for your 400(4.120"+.040"= 4.160"). Lots of 5/64"x5/64"x3/16" rings for Chevy 400's |
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#20
09-28-2016, 11:38 AM
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E299K40, if they are tight, file them, but they likely will be a drop in.
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