what the heck? look like 18:1 compression pistons.? lol

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340plot said:
pump gas-able? lol
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Not really,I could run mine on 94 sonoco and octane booster with the outer carbs unhooked (sixpack)but you need atleast 110.octane.
By the way do you know where this engine came from.There were at least 10 engines built in my area with them pistons and there is one left.When Tcars they were in were dusters,darts,and a aar cuda.The aar cuda engine was mine and I sold the engine to the guy that had the car.All the cars were from Pa.If that engine came from Pa i can give you all the spec,s on it. Mark
 
Like someone stated eariler...cut the tops off. The bal job will not be that close if it was done back in the day (strobe balancer) cut them to weight and run them.
Those were my go to piston back in the day...cut many a dome down...ring lands were almost indestructible back then.
I saw the same pistons used in 3 different blocks and two of the pistons were collapsed...didn't make any differance..LOL
 
dartcuda1 said:
Not really,I could run mine on 94 sonoco and octane booster with the outer carbs unhooked (sixpack)but you need atleast 110.octane.
By the way do you know where this engine came from.There were at least 10 engines built in my area with them pistons and there is one left.When Tcars they were in were dusters,darts,and a aar cuda.The aar cuda engine was mine and I sold the engine to the guy that had the car.All the cars were from Pa.If that engine came from Pa i can give you all the spec,s on it. Mark
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yea, it was built by ed miller out of va
 
cut the tops off and rebalance (if necessary)
...before cutting, a .030 pistion (TRW)weighs
826 grams (piston and pin)
i'll have to dig out the "cut" ones to weigh..
mine did not require rebalance
note-.006-.007 wall clearance
 
i am going to call my machine guy, and ask him about just cutting them.


so i will not lose any strength in them? how much should i have taken off?
 
Looks like the Manley 12.5 to 1 pistons I have in my 340 I was told they were made by speed pro. No longer made by anyone. I could of used one of those a few weeks ago. My motor sucked the air cleaner stud in on the dyno and dented the piston.
 
340plot said:
i am going to call my machine guy, and ask him about just cutting them.


so i will not lose any strength in them? how much should i have taken off?
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LOL...also have a set of those that have had the dome cut off in a standard bore 340 that was bracket raced since 1995....and the pistons were used then...


so yes...you can remove some of that big ugly dome...
 
Sorta reminds me of the piston out of a Honda RC 166 6 cyl. 297 cc. race bike from back in 1966... good for 22k rpm.

250cc6CylPistonandRod.jpg
 
You better make sure they are not hollow dome pistons before you follow some possible bad advice.
 
i just got the engine out today, and will pull apart tommorow to post info

now, if i get these cut down, do i have to change out the cam??????????????

i just noticed under the hood that there is a mopar performance sticker for the valve adjustment. i am now wondering if it is a mopar perf. cam......?
 
340plot said:
i just got the engine out today, and will pull apart tommorow to post info
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Looking foward.

now, if i get these cut down, do i have to change out the cam??????????????
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No. Cam dictates RPM (Useable)


i just noticed under the hood that there is a mopar performance sticker for the valve adjustment. i am now wondering if it is a mopar perf. cam......?
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The sticker means nothing. It's a way to adjust the rockers as you turn the engine by hand. It insures the lifter is on the base circle.
 
I wouldnt bother with cutting them. Just replace them with soemthing like the KBs that are lighter. Then the crank just get's drilled to rebalance. You'll have to rebalance anyway. I dont think there's enough meat to mill them to flat tops but you'll know when you look at the dome from the bottom. If it was me, I'd just rebuild it and move on.
 
well, i did not want to take them all the way to flat top pistons. i thought maybe if half of the dome was cut off would bring me down to like 11.3333:1 lol , and id be able to run 93 octane
 
ok, here is pics of the pistons out of the bore. i cannot find a brand on the them but there is a part number on the tops that is 3690825, and on the inside of the piston, there is a letter b, then 265-99 under it...............are these stock rods? i think so, but never noticed what looks like a p inside the letter d , on the shaft of the rod
 

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ok, i just googled the part number, and it says they are mopar performance 12:1 compression. and i just got off the phone with the person i picked the car up from, he said his cousin had it set up to run 93 octane. now i am wondering if i should even get them cut now????????????????????????????????????????????
 
I don't think you're willing to admit defeat... It was ntoed earlier... With open chamber heads and no quench or way to control the burn, you cannot run those pistons on any pump fuel I get at my local 7/11. You can get the pressures don with a huge cam at idle or just off it, but the thing will detonate whether or not you can hear it. They are antiques from a by-gone era before people knew about good flame propogation, fast controlled burns, and squish/tumble. The fact that some guys run up to and over 12.5:1 now on pump fuel is becuase the modern engines use all those theories to make it work. Those pistons and your heads simply dont. Tosd them out, or sell them to someone who's going bracket racing if the pistons are still good.
 
Buy the time you pay the power bill for keepin your computer on long enough to talk yourself into usin them pistons, you couldda bought some better ones.
 
Put an E85 carb on and have fun with it - (E85)

Should be real sweet 8)
 
...or you could just build you a billy badass high compression motor that runs on race gas only. It would not be boring.
 
340plot said:
ok, i just googled the part number, and it says they are mopar performance 12:1 compression. and i just got off the phone with the person i picked the car up from, he said his cousin had it set up to run 93 octane. now i am wondering if i should even get them cut now????????????????????????????????????????????
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If you are on a budget and the engine needs nothing else (cylinder walls are good), I would just cut the pistons down to the stock 340 height (i think it is .040" out past the deck? I can verify this if you do it to get the compression down) The difference in balance will be minimal and not worth redoing. In the balance formula you only use 50% of the piston weight, in this case it would change only half of what was removed. so pretty small amount.

Now, if you have the money or want to spent the money, as others have mentioned there are all kinds of "modern" quality pistons available.
 
well, i had them cut, and the bores, crank and everything else is in perfect condition. it really does not need rings/bearings, but i think it would be stupid to re-use them while it is apart.
 
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