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Was this cylinder scoring caused by previous builder not using torque plate?

General engine tech -- Drag Racing to Circle Track

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rebelyell
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Re: Was this cylinder scoring caused by previous builder not using torque plate?

Post by rebelyell » Thu Jul 30, 2020 8:14 am

maybe that pattern was there Before he bored/honed it; and he didn't go far enough/larger piston ?

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Re: Was this cylinder scoring caused by previous builder not using torque plate?

Post by rebelrouser » Thu Jul 30, 2020 8:43 am

Did not say what kind of engine it is, but if it has Siamese bores and no water runs between cylinders, looks to me like it may have had cooling issues, or was run hot. As mentioned with the photos it is hard to tell, but the minor scratches are something I see all the time, but the shiny areas all line up between the bores. And the brown deposits at the bottom of the cylinders also looks like the results from high temps coking the oil.

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Re: Was this cylinder scoring caused by previous builder not using torque plate?

Post by ptuomov » Thu Jul 30, 2020 8:48 am

Can we see the piston?
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Re: Was this cylinder scoring caused by previous builder not using torque plate?

Post by Bwh998 » Thu Jul 30, 2020 9:11 am

Yes I will get pics of the pistons when I get home. Mics are all at work so I don't really have any way of measuring until I bring the block to work.

Its a goodwrench 350 block thats .030 over and .010 under on the crank journals. According to the main bearings it was rebuilt in the lates 90s. Still had the nodular crank and pm rods with some cheap rebuilder pistons hung on it.

Other than light scoring the pistons didn't look bad, will post pics soon.

Top rod bearings do look hammered though, possibly from detonation?

Thanks for the help everyone.

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Re: Was this cylinder scoring caused by previous builder not using torque plate?

Post by Bwh998 » Thu Jul 30, 2020 9:28 am

Double post.
Last edited by Bwh998 on Thu Jul 30, 2020 9:33 am, edited 1 time in total.

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Re: Was this cylinder scoring caused by previous builder not using torque plate?

Post by Bwh998 » Thu Jul 30, 2020 9:29 am

bigmike wrote:
Thu Jul 30, 2020 4:07 am
Could someone have pressed piston pins on and off a couple times and distorted the pistons?

How much over are the bores now? It is interesting to note that coolant flow is not the best in that area between the cylinders. Could the water pump flow be marginal? Was a thermostat used? If so what temperature is it opening? Was this used in a boat with fresh water cooling?
Man i really think you might be onto something there. Its .030 over right now with a cheap rebuilder piston hung from the stock rods. Work done by an unknown source before I bought the engine.


I use a weiand team g water pump and 160 degree tstat and aluminum 3 row rad. Have never pushed water out of the overflow tank.

The engine is out of my 3900 lb road race car (squarebody suburban) that ran for a few years with a small rv cam and 600 cfm carb. The rpm and power was kept quite low.

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