340 Piston identification. Silvolite?

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nick455440

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pretty sure based in searching threads they are Silvolite, the only markings is the 60 over and a B296 on the inside. I came across an insane mostly Mopar parts hoard, one of the 340’s I picked up had been machined, crank turned (to not sure what) and 1.88 j heads rebuilt but I don’t think they were planned, it came with these pistons, does anyone know what these are and what compression ratio they are. Would they be good in a j head motor? What’s the ideal compression ratio trying to build a pretty hot but streetable 340

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Silvolite pistons are still made and sell under the Keith Black name as well as others. They are cast aluminum and are basically a economy/replacement line.
 
Those are probably just off the shelf replacement pistons. Look to be 72+ 340 low comp pistons. They are good for a decent street driver. Certainly hotter than your average 318 but you wont be blowing the doors off. Yes, 1.88 is what was originally paired up with these pistons.
 
nick455440 said:
pretty sure based in searching threads they are Silvolite, the only markings is the 60 over and a B296 on the inside. I came across an insane mostly Mopar parts hoard, one of the 340’s I picked up had been machined, crank turned (to not sure what) and 1.88 j heads rebuilt but I don’t think they were planned, it came with these pistons, does anyone know what these are and what compression ratio they are. Would they be good in a j head motor? What’s the ideal compression ratio trying to build a pretty hot but streetable 340

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Look for a 'SL' inside the skirt or near the pin. Its an old silvolite imo, I just sold a set like that.
th part number B makes ya think badger, but then the SL
Either way.. the pins should be thrown into the freezer before installing...or the pistons heated. Those ol Cast pistons accounted for their expansion... and so at room temp the pin wont slide right in, you can chill the pin or heat the piston to ease the installation.
 
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Those B296 pistons are Badger replacement pistons, I used a set in a motor I built for a friend about a year ago. I picked them up at a swap meet about a year or so ago & put them on the shelf for later use.
 
Demonracer said:
Those B296 pistons are Badger replacement pistons, I used a set in a motor I built for a friend about a year ago. I picked them up at a swap meet about a year or so ago & put them on the shelf for later use.
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Look at the SL mark. What's that designate?
Where did badger pistons start?
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The only current Silvolite 340 piston is number 1267, which has a CH of 1.824”.

Just measure from the top of the piston to the top of the pin bore, and then add .492”.
That will give you the CH...... and then you’ll know which piston you have...... high CR or low CR.
 
Strange markings and oh..the badger #is p296 and P294, still weird with the SL

Here's some info

These are part numbers from www.nhra.com
http://www.nhra.com/tech_specs/pistons/
Stock pistons that are accepted by NHRA in Stock Eliminator.
68-71 CHRYSLER 275-290HP 340 10.5:1
L2316F TRW
2332P SEALED POWER
P1610 CHILDS & ALBERT
275-340 VENOLIA
B284 BADGER
JE 136627
55328 ROSS

72-73 CHRYSLER 240HP 340 8.5:1
L3062F TRW
2369P SEALED POWER
P296 BADGER
L2385F TRW
240-340 VENOLIA
148623 JE
99588 ROSS
CP Pistons M5-CP
 
Thanks for all the geat info, I measured (with a Harbour Freight micrometer) they came out to 1.230 and with adding the .492 came out to 1.722, so from above if they are 8.5-1 would it be a big difference to run a better piston, also what’s the ideal for a hot street car 10.5?
 
nick455440 said:
Thanks for all the geat info, I measured (with a Harbour Freight micrometer) they came out to 1.230 and with adding the .492 came out to 1.722, so from above if they are 8.5-1 would it be a big difference to run a better piston, also what’s the ideal for a hot street car 10.5?
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Ideal is a good dynamic/effective compression aka cranking psi.
 
nick455440 said:
Thanks for all the geat info, I measured (with a Harbour Freight micrometer) they came out to 1.230 and with adding the .492 came out to 1.722, so from above if they are 8.5-1 would it be a big difference to run a better piston, also what’s the ideal for a hot street car 10.5?
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Oh yeah! A BIIIG difference. 'Hot street' is a bit variable of a term but you are getting into the right ballpark. What heads are you going to use?
 
NHRA has done this since the 1970's - 296 Badger! post#4 1.72" made by someone and boxed by some more. heavy replacement cast slug. try for something taller and lighter
 
badger has been gone 20 years
no real use for those slugs unless hooked to a more stroke crank- maybe even a 360
do the math
else for Mexican gas?
 
Wyrmrider said:
badger has been gone 20 years
no real use for those slugs unless hooked to a more stroke crank- maybe even a 360
do the math
else for Mexican gas?
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I just sold a set where in a 71 duster I had.
Ran it with a Crower hyd cam w/EDM lifters I'm going to put that up for sale now since I quit running hydraulic cams.
 
Thanks for the info, will probably spring for new pistons,
For at least a while the heads will be 1.88 J heads since they were already rebuilt with the machined 340, planned on doing some port work to make best of them, I have a set of unrebuilt x and j heads with two other less bor, performer rpm,
 
Hit “post”prematurely, performer rpm intake and was looking at some of the lunati cam and lifter kits,
 
nick455440 said:
Hit “post”prematurely, performer rpm intake and was looking at some of the lunati cam and lifter kits,
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Put 11/32 stem valves in those J heads, like a +.100 1.94 /1.60 for a chevy. You can get a set for under 100.00 bucks
Cuz if you're going to do guides anyways may as well put a lighter valve in there.
 
L2136F Speed Pros are high compression flat top pistons and are stock weights, so no re-balance is needed. There are some lighter options that can save a good amount of weight from the rotating assembly but you will need to do an engine re-balance with those.
 
Marco and nm9 the L2136F pistons are they stock weight for a forged or cast crank or does it matter, I am going to go with these so I don’t have to rebalance, I have a cast crank that would have stock come with the 8.5/1 pistons, would switching to these 10.5/1 pistons is that same weight? or if I run these 68-71 replacement pistons on a 72 cast crank would I need to rebalance? Thanks
 
You know.... I don't know. If you held a gun to my head, I would guess that the piston weights are the same early to late but I never found the data on the later piston weights.

If you get to dismount one of these low compression pistons and weigh it, the early higher compression ones weighed around 719 grams.
 
1968-1973 340pistons are 720 grams. the L2316f is the forged replacement that we used in the 1970s and now - no rebalance needed. I bought a good slightly used set 10 years ago for $100.
 
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