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Offline pitdog72

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piston identification?
« on: October 12, 2015, 09:49:58 pm »
Anyone familiar with these piston in my scj? I believe they are .030 over. Is it safe to assume they are not stock?

Offline redscj

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Re: piston identification?
« Reply #1 on: October 12, 2015, 11:44:12 pm »
     I believe that is a Sealed Power part number (2287P).
Grant
69 Mach 1 Dearborn SCJ 4.30 4spd 6/17/69 Candy Apple Red
69 Sportsroof Metuchen SCJ 4.30 C6 5/28/69 Acapulco Blue

Offline 161854

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Re: piston identification?
« Reply #2 on: October 13, 2015, 10:31:07 am »
    Yes it is Grant. Speed Pro  +.030 replacement forged piston. The old go to piston. Weighs a ton and uses 5/64hts rings. There are much better offerings out there now in .025 as well as .035 over. No need to go to .060 over.
      Randy
« Last Edit: October 14, 2015, 10:38:05 am by 161854 »
68 1/2 CJ FB San Jose white/blue "C" stripe Foulger Ford
 66 GT350 Hertz SFM 6S 477 white/ blue side stripes 1  of 18
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Offline redscj

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Re: piston identification?
« Reply #3 on: October 13, 2015, 11:15:26 am »
    Yes it is Grant. Speed Pro  +.030 replacement forged piston. The old go to piston. Weighs a ton and uses 5/64hts rings. There are much better offerings out there now in .025 ans well as .035 over. No need to go to .060 over.
      Randy
     I just did a quick Google of the part number. Did Sealed Power buy out Speed Pro or did they change names? Are they any heavier than the TRW version? I think 2304 is the number.
     Going off subject, I picked up a couple of used Probe pistons awhile back. Not that I intend to use them but rather as mock up's to measure my blocks deck height. What is your opinion on the sleeve wall thickness a guy should use? I know a guy that is going down that road on his restoration. ;) BTW, just the price of the sleeves adds up fast when you're looking at 8 of them.
Grant
69 Mach 1 Dearborn SCJ 4.30 4spd 6/17/69 Candy Apple Red
69 Sportsroof Metuchen SCJ 4.30 C6 5/28/69 Acapulco Blue

Offline 69mustangSCJ

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Re: piston identification?
« Reply #4 on: October 13, 2015, 11:35:26 am »
Best to use the exact piston you plan to use for the rebuild to check deck height.   Seems every piston manufacture varies slightly on their compression height and what one piston might show you will be different from the next.  Seems they can't make pistons "exact" anymore and they vary a tad from their advertised compression height ::)  Even stock compression height aftermarket pistons come up a bit tall it seems lately.

I recently ran into this doing a Windsor for a customer.  Not only was the deck off (lower on one end than the other) but when doing the math the new pistons were going to stick out of the deck about .010 before we even took anything off the block.
 However when we mocked it up the piston only stuck out .006" because the stroke was short on the crank.  Another common issue, factory cranks sometimes aren't exactly at their advertised stroke and come up short.  This was a saving grace however because even after decking the block in the end we don't have to take as much off the tops of the pistons as the math would indicate.

Offline redscj

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Re: piston identification?
« Reply #5 on: October 13, 2015, 11:59:31 am »
     Not an issue, been a machinist for 42 years. I can accurately measure the pin to piston top down to .0001" then plug that into a formula with the measured rod center to center to the same tolerance. Then order pistons to the height that I need or even cut then at home.
     My job involves rebuilding aircraft parts. The parts rarely match the original blue prints. So a lot of reverse measuring is required to decide what feature moved in which direction. A lot of times you end up at a "best fit", not blue print perfect. Considering how far off all of the USA aircraft manufacturer's make parts (at least what I've work on). I can't even imagine the odds of getting a perfect block.
     Your example of the Windsor is a perfect example.  The stroke is a common variance to my best knowledge. IIRC way back, NHRA allowed stock & probably super stock cranks to be up to .015" off. Probably any class that ran on weight per cubic inches. You want to guess which way the racers wanted their cranks ground? My guess is there is a lot of plus .013" cranks around.
Grant
69 Mach 1 Dearborn SCJ 4.30 4spd 6/17/69 Candy Apple Red
69 Sportsroof Metuchen SCJ 4.30 C6 5/28/69 Acapulco Blue

Offline 161854

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Re: piston identification?
« Reply #6 on: October 14, 2015, 10:37:33 am »
Best to use the exact piston you plan to use for the rebuild to check deck height.   Seems every piston manufacture varies slightly on their compression height and what one piston might show you will be different from the next.  Seems they can't make pistons "exact" anymore and they vary a tad from their advertised compression height ::)  Even stock compression height aftermarket pistons come up a bit tall it seems lately.

I recently ran into this doing a Windsor for a customer.  Not only was the deck off (lower on one end than the other) but when doing the math the new pistons were going to stick out of the deck about .010 before we even took anything off the block.
 However when we mocked it up the piston only stuck out .006" because the stroke was short on the crank.  Another common issue, factory cranks sometimes aren't exactly at their advertised stroke and come up short.  This was a saving grace however because even after decking the block in the end we don't have to take as much off the tops of the pistons as the math would indicate.

      Piston companies are FULLY capable of making pistons correctly. They are TOTALLY dependent on the customer's input about the parts he's using. Block height is the first of three CRITICAL dimensions needed for determining what piston to use. "STOCK" in not acceptable. The nominal block height for FE engines is 10.170. The same goes for rods 6.490 is the "accepted" center to center dimension. The 428 stroke is accepted as 3.980. These dimensions would require a 1.690 compression height to be flush with the top of the block. "Aftermarket" piston manufacturers have to content with blocks that "may " have been decked and other variables , so pistons are most oftem made short to compensate. The compression height commonly used on "off the shelf" pistons where TRUE dimensions are not known is 1.670 or .020 short of the "possible"1.690 ideal number. ANY variance in the three critical dimensions will lead to the piston not being "where it should be". I can't speak for every company but "most" aftermarket pistons are extremely accurate dimensionally due to CNC manufacturing used currently. Custom pistons are not that expensive and can be made to the customers exact needs/dimensions. Guess how i know.
       Randy
68 1/2 CJ FB San Jose white/blue "C" stripe Foulger Ford
 66 GT350 Hertz SFM 6S 477 white/ blue side stripes 1  of 18
3 magazine covers- Car Craft July '77,  Modified Mustangs Feb '11 , and June '14 Mustang Monthly
'78 F350 Oleynik racecar hauler

Offline 161854

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Re: piston identification?
« Reply #7 on: October 14, 2015, 10:49:29 am »
    Yes it is Grant. Speed Pro  +.030 replacement forged piston. The old go to piston. Weighs a ton and uses 5/64hts rings. There are much better offerings out there now in .025 ans well as .035 over. No need to go to .060 over.
      Randy
     I just did a quick Google of the part number. Did Sealed Power buy out Speed Pro or did they change names? Are they any heavier than the TRW version? I think 2304 is the number.
     Going off subject, I picked up a couple of used Probe pistons awhile back. Not that I intend to use them but rather as mock up's to measure my blocks deck height. What is your opinion on the sleeve wall thickness a guy should use? I know a guy that is going down that road on his restoration. ;) BTW, just the price of the sleeves adds up fast when you're looking at 8 of them.

        The cost of 8 sleeves far out weighs the cost of a custom piston. They can be made to ANY size that a ring is available for as I mentioned in reply #2. Plus block integrity is not compromised by the removal of SO much parent material. The TRW and Sealed Power/Speed Pro pistons were forged and machined by the same company and weigh virtually the same ( heavy). "Modern" forged pistons are closer to the original cast piston weight. Sleeving should only be done for repairs , not "restoring to standard". .125 wall would be the minimum sleeve thickness I would use.
    Randy
68 1/2 CJ FB San Jose white/blue "C" stripe Foulger Ford
 66 GT350 Hertz SFM 6S 477 white/ blue side stripes 1  of 18
3 magazine covers- Car Craft July '77,  Modified Mustangs Feb '11 , and June '14 Mustang Monthly
'78 F350 Oleynik racecar hauler

Offline pitdog72

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Re: piston identification?
« Reply #8 on: October 16, 2015, 12:05:45 am »
So basically my block was bored .030 over already to use these piston? Any idea of compression ratio with stock heads? What is the weight of these slugs?
« Last Edit: October 16, 2015, 12:12:48 am by pitdog72 »

Offline 69mustangSCJ

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Re: piston identification?
« Reply #9 on: October 16, 2015, 08:49:32 am »
Best to use the exact piston you plan to use for the rebuild to check deck height.   Seems every piston manufacture varies slightly on their compression height and what one piston might show you will be different from the next.  Seems they can't make pistons "exact" anymore and they vary a tad from their advertised compression height ::)  Even stock compression height aftermarket pistons come up a bit tall it seems lately.

I recently ran into this doing a Windsor for a customer.  Not only was the deck off (lower on one end than the other) but when doing the math the new pistons were going to stick out of the deck about .010 before we even took anything off the block.
 However when we mocked it up the piston only stuck out .006" because the stroke was short on the crank.  Another common issue, factory cranks sometimes aren't exactly at their advertised stroke and come up short.  This was a saving grace however because even after decking the block in the end we don't have to take as much off the tops of the pistons as the math would indicate.

      Piston companies are FULLY capable of making pistons correctly. They are TOTALLY dependent on the customer's input about the parts he's using. Block height is the first of three CRITICAL dimensions needed for determining what piston to use. "STOCK" in not acceptable. The nominal block height for FE engines is 10.170. The same goes for rods 6.490 is the "accepted" center to center dimension. The 428 stroke is accepted as 3.980. These dimensions would require a 1.690 compression height to be flush with the top of the block. "Aftermarket" piston manufacturers have to content with blocks that "may " have been decked and other variables , so pistons are most oftem made short to compensate. The compression height commonly used on "off the shelf" pistons where TRUE dimensions are not known is 1.670 or .020 short of the "possible"1.690 ideal number. ANY variance in the three critical dimensions will lead to the piston not being "where it should be". I can't speak for every company but "most" aftermarket pistons are extremely accurate dimensionally due to CNC manufacturing used currently. Custom pistons are not that expensive and can be made to the customers exact needs/dimensions. Guess how i know.
       Randy

Fully capable...yes.   As of late I've been seeing quite a few off the shelf pistons with compression height too tall.  apparently this is not all that uncommon because I just had the machine shop tell me he's seeing a lot of this happen.  My most recent case are a set of KB pistons I just used in a Windsor build.  Compression height was + .010 from stock so that was a little bit of concern since we had not taken material off anything yet (block deck).  Another concern was that the block was already short of it's advertised deck height (another common issue) and it had never been rebuilt before.
   However  2 things were in our favor.  One, we didn't have to take too much off the block to square it up (.006 straightened it out) and two, the stroke of the stock crank was short (rod center to center was spot on)  Again the machine shop told me they find it very common that factory cranks often times are slightly shorter on stroke than what is advertised. 
  Because of that he wasn't too worried about the piston compression height being higher than what ford advertised for this engine, there is plenty of meat on the tops of the pistons to shave.   Sure enough, he was right.
    Taking a little off the tops of the pistons works fine (in this case .011") so we could place the pistons .005" in the hole to give some wiggle room for another rebuild yet keep quench tight.      Either way is fine.  Every engine I am always trueing up the deck and most times shaving the pistons to set the piston near the deck height and keep the quench tight.   But my own personal preference is to have a taller compression height and shave the piston so it leaves the block alone as much as possible, saving it for more rebuilds down the road.
   The SCJ build is getting a custom piston ordered after the block is squared up (decked if needed), and the crank will be checked for proper stroke, so the piston will be correct in the beginning and save an extra step of machine work.

My whole point of the first comment though was that since we are seeing varying compression heights with off the shelf pistons, and because factory cranks seem to come up short from factory advertised numbers, plus the fact that some deck heights are also shorter than advertised (and they have never been cut),,,,we can't simply plug in a math formula and expect it to be correct.  I prefer to mock them up first.  This Windsor was a classic example of that.
    Actually glad the pistons weren't at stock compression height (or worse even shorter) or we would have had to shave quite a bit off the deck to get the quench we wanted, and I never like taking more off the deck than needed.
« Last Edit: October 16, 2015, 09:27:02 am by 69mustangSCJ »

Offline 161854

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Re: piston identification?
« Reply #10 on: October 16, 2015, 10:28:56 am »
   The Windsor was supplied in two different deck heights. '69-70ish were 9.480 and subsequent blocks were/are 9.503. Most manufacturers make them to be "zero" at 9.480. If you have an early 9.480 block that has been trued , the piston is going to stick out. If that happens you can cut the piston or use a thicker head gasket. The thicker head gasket is often preferred as it helps intake manifold fitment. 460 blocks have the same situation varying frm 10.300 to 10.322 depending on the year of the block.
    The mathematical formula works IF the true dimensions are known and not assumed. I use it many times everyday with excellent results.
68 1/2 CJ FB San Jose white/blue "C" stripe Foulger Ford
 66 GT350 Hertz SFM 6S 477 white/ blue side stripes 1  of 18
3 magazine covers- Car Craft July '77,  Modified Mustangs Feb '11 , and June '14 Mustang Monthly
'78 F350 Oleynik racecar hauler

Offline redscj

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Re: piston identification?
« Reply #11 on: October 16, 2015, 11:24:58 am »
     Just a side note, one of the 2 used Probe pistons that I bought has a perfect outline of the intake valve in the valve relief. The mark is only a few thousands of an inch deep. I should contact the seller for the story. Might be nice to know if it was a valve hanging open, crooked deck or too much lift. Always do a forensic study of used parts! Look carefully guys.
Grant
69 Mach 1 Dearborn SCJ 4.30 4spd 6/17/69 Candy Apple Red
69 Sportsroof Metuchen SCJ 4.30 C6 5/28/69 Acapulco Blue

Offline 69mustangSCJ

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Re: piston identification?
« Reply #12 on: October 16, 2015, 11:49:15 am »
   The Windsor was supplied in two different deck heights. '69-70ish were 9.480 and subsequent blocks were/are 9.503. Most manufacturers make them to be "zero" at 9.480. If you have an early 9.480 block that has been trued , the piston is going to stick out. If that happens you can cut the piston or use a thicker head gasket. The thicker head gasket is often preferred as it helps intake manifold fitment. 460 blocks have the same situation varying frm 10.300 to 10.322 depending on the year of the block.
    The mathematical formula works IF the true dimensions are known and not assumed. I use it many times everyday with excellent results.

And that is the key point I was trying to make.  Sorry if I didn't come across well enough.  We simply can't use what is advertised from the manufacture because the tolerances vary greatly.
   This particular Windsor is the original 69 Mach 1 engine that has never been rebuilt, or even out of the car until now.  The deck was .002 short on one end and .004" on the other from it's supposed factory 9.480" height.  So not only was it short, but it was crooked.  Right away being short before it's even decked really throws off the numbers.  I've seen this fairly often with OEM blocks, not just ford but others as well.  Not a big deal since I always plan on decking during the rebuild process anyway.

Offline redscj

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Re: piston identification?
« Reply #13 on: October 16, 2015, 12:23:30 pm »
Quote
The deck was .002 short on one end and .004" on the other from it's supposed factory 9.480" height.
     I would suggest that Ford would consider that block in tolerance. .006" on a 9.480" dimension. I bet their allowed variance was bigger, But maybe going up. Meaning 9.480/9.486.
Grant
69 Mach 1 Dearborn SCJ 4.30 4spd 6/17/69 Candy Apple Red
69 Sportsroof Metuchen SCJ 4.30 C6 5/28/69 Acapulco Blue

Offline 69mustangSCJ

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Re: piston identification?
« Reply #14 on: October 16, 2015, 03:04:54 pm »
I agree redscj, I think you are exactly right.  They likely had a realm of tolerance with this mass production stuff they were pumping out thousands of, and close was good enough in most cases.   The racing shop sees more of these than I do and he told me it's fairly common to see one like this, especially on these windsors according to him.