clearance questions
Feb 1, 2008, 06:22 PM
#1
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clearance questions
okay first off i have been searching for an hour..lol
I have built many motors but i am wanting to see what yall suggested for clearnces... i have a 2.0 with standard bore weisco pistons and acl race bearings... i will be running high hp as a dd.... weisco suggest 0.0025 piston to cylinder wall clearnce but what would yall suggest?? .006? also what clearances should i run for the rod and main bearings?? lastly what should the ring end gaps be? all help appreciated!
I have built many motors but i am wanting to see what yall suggested for clearnces... i have a 2.0 with standard bore weisco pistons and acl race bearings... i will be running high hp as a dd.... weisco suggest 0.0025 piston to cylinder wall clearnce but what would yall suggest?? .006? also what clearances should i run for the rod and main bearings?? lastly what should the ring end gaps be? all help appreciated!
Feb 1, 2008, 09:12 PM
#3
as far as ptw clearance. do what the piston maker suggest, as they should know their expansion rates / amounts for their piston design.
0.0025 for wesico's are fine, even for big hp enines...pistons now days are not like the old venolia or arias pistons that required .006 / ,008" clearnance....unless you want your car to sound like a diesel from all the piston slap...not to mention, extra piston slap will agrivate your knock snesor output.
bearing clearances should be ~0.0010" for every 1.0" in diameter. i forget the basic rule of thumb for the ring end gaps, but too tight where they butt is far more damaging to the engine vs. being 0.002" to large.
0.0025 for wesico's are fine, even for big hp enines...pistons now days are not like the old venolia or arias pistons that required .006 / ,008" clearnance....unless you want your car to sound like a diesel from all the piston slap...not to mention, extra piston slap will agrivate your knock snesor output.
bearing clearances should be ~0.0010" for every 1.0" in diameter. i forget the basic rule of thumb for the ring end gaps, but too tight where they butt is far more damaging to the engine vs. being 0.002" to large.
Feb 2, 2008, 12:00 AM
#5
as far as ptw clearance. do what the piston maker suggest, as they should know their expansion rates / amounts for their piston design.
0.0025 for wesico's are fine, even for big hp enines...pistons now days are not like the old venolia or arias pistons that required .006 / ,008" clearnance....unless you want your car to sound like a diesel from all the piston slap...not to mention, extra piston slap will agrivate your knock snesor output.
bearing clearances should be ~0.0010" for every 1.0" in diameter. i forget the basic rule of thumb for the ring end gaps, but too tight where they butt is far more damaging to the engine vs. being 0.002" to large.
0.0025 for wesico's are fine, even for big hp enines...pistons now days are not like the old venolia or arias pistons that required .006 / ,008" clearnance....unless you want your car to sound like a diesel from all the piston slap...not to mention, extra piston slap will agrivate your knock snesor output.
bearing clearances should be ~0.0010" for every 1.0" in diameter. i forget the basic rule of thumb for the ring end gaps, but too tight where they butt is far more damaging to the engine vs. being 0.002" to large.
If you plan on running the ptw clearance a bit on the tight side, I recommend adding a good skirt coating (that doesn't normally wear off). This way you have the benefit of a quiet startup and a safety barrier in the event the piston expands more than expected.
This same clearance theory applies to ring end gaps (how much heat for how long). Don't skimp on ring end gaps...butting can cause a serious failure.
Feb 2, 2008, 08:37 AM
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awesome.. well i just heard from the machine shop and as the block sits there is about .0030" ptw clearnace without the block being honed..so my question is would it be safe/okay to run .0040" max ptw clearnce?? as far as ring end gaps what are high hp people running?
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Feb 3, 2008, 07:14 PM
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well the thing about weiscos clearance is its only .0025" thats not alot of room for expansion.. this car will be a dd and also see the trake alot..i have read many people running .0040" on diff types of pistons.. so i feel .0035-.0040 is a little safer and yet not that big to casue skirt to wall scraping.... sooo how does everybody feel about the .0040" clearnce??
