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  #16 (permalink)  
Old 06-03-2013, 09:23 PM
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The don;t look like forged pistons to me. Look like a stock replacement ,,,maybe Badger or.... (Not really important)
fine for moderate boost 8-9psi or less with low compression and modest timing. as long as detonation is avoided.
The piston is not highly stressed unless detonation is present, on a street blower motor.
Measure the dish volume by measuring the depth and diameter of the center dish. Add 4cc to 5cc for the 4 valve reliefs to that ..

a "rebuilder piston"
Probabily .045" below deck @ TDC. not a problem.

You can measure the true volume of the piston (dish with the valve reliefs) by setting the crank so that the piston is a convient way down the bore ...say .100" using a dial indicator. then get some common Vaseline and wipe it around the piston bore edge to seal the piston rings. to be water tight. The vaseline seals the piston in the bore. Don;t be shy ...Now Get a old CD ROM disk to cover the top of the bore. Use common Vaseline to seal the CD disc to the block deck. Fill the cylinder with water and find the filled volume of the cylinder with the piston .100" down the bore from TDC.
Note this CC volume. use a shop vac to vac out the water in the bore. The vaseline won';t harm anything.
oil wipe the now dry bore. Now measure the piston to deck clearance @ TDC (.045" ish probabily.)
Tell me these two figures. I will calc the cr for you , with a 72cc head and common .041" gasket.

You can buy a 100ML graduated cylinder (glass or plastic) from many local pharmacies. Go the the counter and ask.
100ML='s 100cc

The piston is likely -15cc (estimate)
The engine compression ratio is probabily between 7.98:1 and 8.27:1 depending on the measured piston deck clearance @ TDC....060" bore 4.166x.041" gasket 72cc chamber head.

Are you freshing up this engine or just want to see what is in it? The .060" cast dish pistons are fine for moderate street supercharger use. Do not sweat this.
Piston ring end gaps should be generous (large) don't be shy on the ring end gaps. Bigger is better.
.026" to .032" is good. Use normal rebuilder rings ( Hastings are fine) and hand file fit the end gaps.
You do not need fancy parts. Just parts that are not already wounded,, and correct assembly.. The blower makes the power.
The piston sees a bit more heat load when under boost. The large generous piston ring end gap keeps the piston from ring butting (broken ring lands).

Again the piston are not stressed unless detonation is present. That is avoided by correct engine tune up. (timing/jetting boost retard////low compression ratio) These pistons will make all kinds of supercharged power.

The cam is fine. Do not mix up the lifters. replace if any hint of wear.
But I prefer using a solid lifter cam in this type of motor. Up to you.

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Last edited by F-BIRD'88; 06-03-2013 at 09:52 PM.
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  #17 (permalink)  
Old 06-03-2013, 10:20 PM
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These XE Comp cams need good valve springs.. What heads are on this motor?
How do you plan on using this motor in a car?
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  #18 (permalink)  
Old 06-04-2013, 02:28 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
The don;t look like forged pistons to me. Look like a stock replacement ,,,maybe Badger or.... (Not really important)
fine for moderate boost 8-9psi or less with low compression and modest timing. as long as detonation is avoided.
The piston is not highly stressed unless detonation is present, on a street blower motor.
Measure the dish volume by measuring the depth and diameter of the center dish. Add 4cc to 5cc for the 4 valve reliefs to that ..

a "rebuilder piston"
Probabily .045" below deck @ TDC. not a problem.

You can measure the true volume of the piston (dish with the valve reliefs) by setting the crank so that the piston is a convient way down the bore ...say .100" using a dial indicator. then get some common Vaseline and wipe it around the piston bore edge to seal the piston rings. to be water tight. The vaseline seals the piston in the bore. Don;t be shy ...Now Get a old CD ROM disk to cover the top of the bore. Use common Vaseline to seal the CD disc to the block deck. Fill the cylinder with water and find the filled volume of the cylinder with the piston .100" down the bore from TDC.
Note this CC volume. use a shop vac to vac out the water in the bore. The vaseline won';t harm anything.
oil wipe the now dry bore. Now measure the piston to deck clearance @ TDC (.045" ish probabily.)
Tell me these two figures. I will calc the cr for you , with a 72cc head and common .041" gasket.

You can buy a 100ML graduated cylinder (glass or plastic) from many local pharmacies. Go the the counter and ask.
100ML='s 100cc

The piston is likely -15cc (estimate)
The engine compression ratio is probabily between 7.98:1 and 8.27:1 depending on the measured piston deck clearance @ TDC....060" bore 4.166x.041" gasket 72cc chamber head.

Are you freshing up this engine or just want to see what is in it? The .060" cast dish pistons are fine for moderate street supercharger use. Do not sweat this.
Piston ring end gaps should be generous (large) don't be shy on the ring end gaps. Bigger is better.
.026" to .032" is good. Use normal rebuilder rings ( Hastings are fine) and hand file fit the end gaps.
You do not need fancy parts. Just parts that are not already wounded,, and correct assembly.. The blower makes the power.
The piston sees a bit more heat load when under boost. The large generous piston ring end gap keeps the piston from ring butting (broken ring lands).

Again the piston are not stressed unless detonation is present. That is avoided by correct engine tune up. (timing/jetting boost retard////low compression ratio) These pistons will make all kinds of supercharged power.

The cam is fine. Do not mix up the lifters. replace if any hint of wear.
But I prefer using a solid lifter cam in this type of motor. Up to you.
I came up with .049 down in the hole and a cc of 46. What can you see from these pix of the bottom end. It shows some of the piston and some of the crank. I can't find anything on either one to ID them. (not a photog either)
Forged or not?
I got it from a widow and want to know what I have before doing anything with it. It still has cross hatching in the cylinders. I keep the lifters in order in a lifter holder from summit.
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Old 06-04-2013, 02:29 PM
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Originally Posted by F-BIRD'88 View Post
These XE Comp cams need good valve springs.. What heads are on this motor?
How do you plan on using this motor in a car?
Either AFR 210's or RHS 200's with comp cam springs. Street and strip will be it's use.
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Old 06-04-2013, 10:20 PM
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and a cc of 46


Where was the piston. in the bore for this. ??? .100" from the top of the bore or was it at .149" from the top of the bore. (.100"+.049")???

I get a -15cc dish .049" piston deck clearance @ TDC 4.06" bore 4.166x.041" gasket 72cc head
engine cr ='s 7.93:1
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Old 06-05-2013, 06:11 AM
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Originally Posted by F-BIRD'88 View Post
and a cc of 46


Where was the piston. in the bore for this. ??? .100" from the top of the bore or was it at .149" from the top of the bore. (.100"+.049")???

I get a -15cc dish .049" piston deck clearance @ TDC 4.06" bore 4.166x.041" gasket 72cc head
engine cr ='s 7.93:1
It was .100" down from TDC, messured at the center of the piston. Sorry, didn't think of that. Set it at TDC, zeroed dial Indcater on block, slid over to piston center, .049, zeroed Dial Ind, turned piston .100" down hole.

Last edited by Fang16; 06-05-2013 at 06:28 AM.
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Old 06-05-2013, 08:33 AM
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measure the deck clearance again. You did it wrong. Measure with the piston @ TDC but measure from the highest part of the piston. not in the center of the dish.

Now what is the piston to deck clearance @ TDC.?


this is the same piston. measure the deck height @ TDC from the highest part of the piston. ( the outer ring part, not the dish)

Then: what is the diameter and depth of the dish of the piston, only..


I know what the valve relief volume is already. just need the correct deck height clearance and the dish dimensions.

so the piston was .149" down the hole instead of .100" down from TDC....right.

46cc @.149" makes sense .but is not the spec I am looking for..... .100" piston lowered down from TDC should be 36.2cc poured measured water volume.

measure TDC from the high point on the piston. then lower the piston in the bore by .100" Then fill that with water using the4 CD rom and vaseline grease. Should be real close to 36.2cc ( no water leaks )

Last edited by F-BIRD'88; 06-05-2013 at 08:51 AM.
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Old 06-05-2013, 08:54 AM
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Ir reguardless the compression ratio is plenty low (w/72cc heads) enough for supercharging and a good bit of boost on pump gas.

7psi ish... You can do very well with 7psi boost without fear of hurting those cast pistons.
Low cr and boost retard and correct jetting are the keys.
It will make way more power than you can use on the street.
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Old 06-06-2013, 10:09 AM
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Quote:
Originally Posted by F-BIRD'88 View Post
measure the deck clearance again. You did it wrong. Measure with the piston @ TDC but measure from the highest part of the piston. not in the center of the dish.

Now what is the piston to deck clearance @ TDC.?


this is the same piston. measure the deck height @ TDC from the highest part of the piston. ( the outer ring part, not the dish)

Then: what is the diameter and depth of the dish of the piston, only..


I know what the valve relief volume is already. just need the correct deck height clearance and the dish dimensions.

so the piston was .149" down the hole instead of .100" down from TDC....right.

46cc @.149" makes sense .but is not the spec I am looking for..... .100" piston lowered down from TDC should be 36.2cc poured measured water volume.

measure TDC from the high point on the piston. then lower the piston in the bore by .100" Then fill that with water using the4 CD rom and vaseline grease. Should be real close to 36.2cc ( no water leaks )
Redone it the right way, lol, and it was 36.1 cc. Happy with the numbers now. Thanks for all your help!
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