I have a set of .060 over 292 bore pistons at the machinists along with other parts.  They are Badger pistons.  The machinist said one of the pistons was 5 grams heavier than the others, and that there wasnt good choices for removing that much material.  He mentioned that some of the decrease may have to come from the rod small end.  Does this sound right? 

We have an appointment tomorrow to get a rough idea of where TDC is in relation to the deck, using an extra rod while waiting for the set of rods to come back from their reconditioning.

Mike

(started to post this under Moonshadow's 312 piston post, but figured a new subject should be started.)

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Mike:

There has to be extra material somewhere to make it heavier.  If there is really nowhere to lighten the piston that much, how about grinding some material from the bore of the wrist pin.  Steel is heavier than aluminum, so less volume of material would have to come out of there.  Be sure that pin stays in that piston when you assemble it.

John

John - "The Hoosier Hurricane"

5 grams of aluminum is going to be equal to a piece about 1/8 inch thick by 1 inch square - seems like a lot of volume to be removing from a piston. But you don't know if its in the skirt or pin bosses or the top deck at this point.

Aluminum weighs .0979 pounds per cubic inch and steel is about.283 pounds per cubic inch - close to three times as much. What is the configuration of the pin?

 
 Steve Metzger       Tucson, Arizona

John, good idea about the inside of the wrist pin.

Steve, I dont know what you mean "configuration of the wrist pin".  It sounded like a lot of material even before you did the calculation.  Seems like with some comparative measurements a person could find out what dimension accounted for the extra weight.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Mike,

          By configuration he means tapered ID or not. As far as the piston goes, the inside of a cast piston, is made with a "Collapsable Core". This is basically part of the cast iron mold used to make the part. No two of these are exactly the same, they're finished by hand. the mold maker uses a rotary file to clean them up after machining. Also wear and different cavities will affect the dimensions. They try to keep everything consistent, but wear happens. You might be able to see it inside the piston, might not. If you do a displacement test you'll find differences. 5 Grams is really not a lot. Grind it off the id of the skirt or the side of a pin boss.

                                                            Frank 

Frank/Rebop

Bristol, In ( by Elkhart) 

Along that line guys hows this for price?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=012&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=220079970823&rd=1,1

Anyone ever deal with Speed O Motive? Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Mike.  5 grams really shouldn't be a major issue in which to take out of the piston.  If taking the material out of the deck portion of the piston, then just be sure to have at least 0.200" thickness in that area when removing material.  The area between the piston deck and under the wrist pin (looking at the piston upside down) is usually fair game if running out of options but as has already been mentioned, the sides of the wrist pin bosses can be also trimmed.  The type of tooling being used to remove the weight has a lot to do with where and how much can be removed so this also becomes a consideration.  The Sealed Power and older TRW sets come in at this much variance and more within the sets so there shouldn't be that much issue in working out 5 grams in just one piston.  I'd shy away from working on the small end of the rod to compensate for a heavy piston as that will make that connecting rod specific to being matched with that particular piston.

As far as using a rod from another set to find TDC, you'll need to check the length of that rod against the lengths of those that have been reconditioned to insure you're not dealing with significant length difference.  This could potentially throw off your deck measurements.  Connecting rod big end reconditioning will typically shorten the rod length and the actual amount shortened will vary depending upon the condition of the rod, if the rod has been previously reconditioned, if all the rods are from the same set or not, factory variances, and the person(s) actually doing the reconditioning.  I'll also suggest checking the lengths of all the reconditioned rods to insure they are also the same length also.

Hope this helps.

Lorena, Texas (South of Waco)

Chuck, Mike

      Never heard of this guy, they might be great, might not.  Make sure you match up the piston deck heights with the correct rod lengths. I don't know what crank (stroke) you're running either, but that matters. Ted or John Mummert have access to redone rods, you know you can trust them. Mummert can get Eagles done for not a whole lot more than that. I run 4.6 Eagles in mine, so far so good. I'll guarantee you those are stronger than the EBU's. I'd be tempted to let one of those guys do the heavy lifting here.

Steve, the .0979 is a generic number for aluminum, depends on the alloy. castings often weigh slightly less, (lower specifics) because of porosity. not supposed to be any porosity in a cast piston, but.......

                                                             Frank 

                                                                    

Frank/Rebop

Bristol, In ( by Elkhart) 

Thankyou all very much for the information!  It is all printed off and ready to go with parts to the machinist's.  I've been waiting 3 months to get a piston to deck measurement.  When he offered to do the trial mockup I said "sure".  We both knew the measurement wouldnt be exact but wanted a fair idea.  The rods are C2AEs and the crank is 292.  He was supposed to contact the rod refinisher and have him try to ream/bore/hone the bushings in such a way as to gain as much length as possible and still have equal lengths.  Actually that may be why he wanted this assembly activity today, because they may have let him know of significant additional costs in the rod prep.  I was figuring that even if they could only stretch them .005 longer, that would help.

The way the numbers work out now, assuming a piston to deck clearance ends up at .040, .023 would be taken from deck, a total of .026 off of heads, and head intake flanges milled .056.  With a .023 steel head gasket that comes up to 9.16 CR.  Heads are 113s.

Mike

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

And here are the piston/deck numbers,  TaDa .  Values are all below deck:

#1 cylinder  .030 #4 cylinder .031 #5 cylinder .026 # 8 cylinder .025

Better than they might have been.  Now to wait for the return of the reconditioned rods and do it over (block is C2AE).

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.