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Some of you may have seen this on another forum I frequent, however I figure some here may want to see too. Although some do this regularly, others may want to see the pain, I mean fun
I am starting assembly on my 489 FE, should be a pretty rugged build, but very street friendly, basically a detuned motor, goal is a bit under 600 hp at 5600.
I used Diamond pistons sized at 4.272. We planned on a .005 clearance, so that is a bore size of 4.277. However, my new machinist is able to hold a tolerance to the 10 thousandth in bore size!!!!!, so we custom fit each piston to each bore for a true .0050 fit.
Actual piston sizes ranged from 4.2720 to 4.2726, really insignificant, but he offered to get that fussy, so we did
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I got the block back Friday and started my assembly today
First off today was to file fit all the rings, chase all the bolt holes, then wash everything pretty, double check bearing clearances and get the crank in. I got there and said enough for today
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Here are a few pics. First is a picture of my little cheap, but very effective piston ring grinder, came from Summit for 39 bones, I am happy with it. You first fit your ring to the bore, measure, then keep cutting until you get there. It cuts VERY fast, you just square the ring on the table, then when all done, clean the edge a bit with a small fine file
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The way you measure, is you first put the ring in the bore, then use a piston to make sure its square in the bore. Here is a pic of that (the ring is in the cylinder, then I push down with the piston
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Pull the piston out, and measure the gap with a feeler gauge, if its tight, go back to the grinder, if its right, clean up the edges with a hand file, if its loose (slow the F%$^ down next time LOL)
![]()
There are a lot of changes to how pistons and rings work nowadays. Common practice is .004-.005 of ring gap per inch of bore for the top ring and 30% more for the second.
Reason for this is two fold, one you dont want ring gaps to close to zero when hot, BUT the reason for the second ring gap to be wider is to prevent trapped pressure beneath the top ring AND allow some clearing pressure past the 2nd ring to pressurize the holes behind the oil ring pack.
I promise it doesnt cause blowby, it actually makes top ring sealing better due to the fact the pressure beneath it doesnt cause it to float in the land. Matter of fact, through most circles, zero gap rings of any kind are seriously frowned upon because the lack of pressurization and flow between ring packs
I have a 4.277 bore x .0045 = .0192 ring gap, however, I like a little more ring gap rather than less, so I rounded up to .020. For the second ring, I took my .0192 number, and multiplied it by 1.3 and came up with .025, thats what I used.
When done, a real nice bath LOL the engine was already hot tanked, but I have a pile of brushes for any orfice LOL SO I washed first with cheap WD40. I like to use WD-40 first because it'll break up any oil-based gooch that may be around. You can see in the next two pics I did some scrubbing. I then went to hot water and soap, then back to WD_40 so it wouldnt rust. You'd be amazed at how much still comes off on a rag after the last cleaning
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I did get the crank in and ready for pistons, checked thrust bearing clearance as well as a quick Plastigauge check for the already checked bearings, but unfortunately it got a little messy in the garage, I got a little tired and grumpy, and I didnt take pics of that. However, if you guys care to see, I'll take some more tomorrow with the rest of the short block assembly.
4 day weekend planned for nothing but 489 FE building LOL
<font size=-1>[ This Message was edited by: My427stang on 2/18/06 9:56am ]</font>
<font size=-1>[ This Message was edited by: My427stang on 2/19/06 7:13am ]</font>
I am starting assembly on my 489 FE, should be a pretty rugged build, but very street friendly, basically a detuned motor, goal is a bit under 600 hp at 5600.
I used Diamond pistons sized at 4.272. We planned on a .005 clearance, so that is a bore size of 4.277. However, my new machinist is able to hold a tolerance to the 10 thousandth in bore size!!!!!, so we custom fit each piston to each bore for a true .0050 fit.
Actual piston sizes ranged from 4.2720 to 4.2726, really insignificant, but he offered to get that fussy, so we did
First off today was to file fit all the rings, chase all the bolt holes, then wash everything pretty, double check bearing clearances and get the crank in. I got there and said enough for today
Here are a few pics. First is a picture of my little cheap, but very effective piston ring grinder, came from Summit for 39 bones, I am happy with it. You first fit your ring to the bore, measure, then keep cutting until you get there. It cuts VERY fast, you just square the ring on the table, then when all done, clean the edge a bit with a small fine file
The way you measure, is you first put the ring in the bore, then use a piston to make sure its square in the bore. Here is a pic of that (the ring is in the cylinder, then I push down with the piston
Pull the piston out, and measure the gap with a feeler gauge, if its tight, go back to the grinder, if its right, clean up the edges with a hand file, if its loose (slow the F%$^ down next time LOL)
There are a lot of changes to how pistons and rings work nowadays. Common practice is .004-.005 of ring gap per inch of bore for the top ring and 30% more for the second.
Reason for this is two fold, one you dont want ring gaps to close to zero when hot, BUT the reason for the second ring gap to be wider is to prevent trapped pressure beneath the top ring AND allow some clearing pressure past the 2nd ring to pressurize the holes behind the oil ring pack.
I promise it doesnt cause blowby, it actually makes top ring sealing better due to the fact the pressure beneath it doesnt cause it to float in the land. Matter of fact, through most circles, zero gap rings of any kind are seriously frowned upon because the lack of pressurization and flow between ring packs
I have a 4.277 bore x .0045 = .0192 ring gap, however, I like a little more ring gap rather than less, so I rounded up to .020. For the second ring, I took my .0192 number, and multiplied it by 1.3 and came up with .025, thats what I used.
When done, a real nice bath LOL the engine was already hot tanked, but I have a pile of brushes for any orfice LOL SO I washed first with cheap WD40. I like to use WD-40 first because it'll break up any oil-based gooch that may be around. You can see in the next two pics I did some scrubbing. I then went to hot water and soap, then back to WD_40 so it wouldnt rust. You'd be amazed at how much still comes off on a rag after the last cleaning
I did get the crank in and ready for pistons, checked thrust bearing clearance as well as a quick Plastigauge check for the already checked bearings, but unfortunately it got a little messy in the garage, I got a little tired and grumpy, and I didnt take pics of that. However, if you guys care to see, I'll take some more tomorrow with the rest of the short block assembly.
4 day weekend planned for nothing but 489 FE building LOL
<font size=-1>[ This Message was edited by: My427stang on 2/18/06 9:56am ]</font>
<font size=-1>[ This Message was edited by: My427stang on 2/19/06 7:13am ]</font>
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