The 340 Forged Piston Is So Heavy....

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kend

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I'm thinking about taking some weight out, any instructions anywhere that will help as far as how much and where to cut? Thanks
 
I assume you're talking about the old TRW/Speed Pro pistons?

True, they are heavy. However, they were once all there was. People used them in droves. What you didn't see in droves were engine failures due to heavy pistons.

I am sure there were some, but nowhere near as many as pistons used. Bottom line is they WORKED and STILL work. Is lighter better? Yeah but it;s probably splittin hairs on all but the hottest of race engines.
 
they can be lightened to stock weight easily in a milling machine. we've done many sets before. saves on having to rebalance the crank unit!! it's worth the effort.
 
373 cubes @ .040, yea, I can live with that one easy. I may try it soon.
 
Typically weight is removed from the underside of the slug next to the piston pin...

I'm repairing the SB 383 that I bought for my dirt late model. I was really concerned about rotating weight until I weighed my 3.79 crank... 67 lbs! I guess saving a few hundred grams on light pistons and rods won't mean too much!
 
changing pins, doesn't remove enough weight. also, light pins with heavy pistons leads to broken pins. they will flex, and cause piston to give and ring seal problems. eventually then break. the head of the piston is very thick. you can mill out .250 easily. will not affect piston strength. leaves plenty of meat in top of piston. then can use a lighter pin to help weight loss. BTW, we've removed .350 from the underside.
 
lighter pins are usually made of tool steel....not your every day pin material...and light pins are not cheap...by the time you pay for lighting of the piston..and lighter pins...you could have bought a brand new set of light weight pistons...
 
KB #980X300K is only 63g (down from ~154 stockers) and its under $5. Too bad its .980 is not a hair bigger for a Mopar at .9842. Thats a pretty light pin.
 
I suppose you could take a drillbit and make it a little bit larger
 
RustyRatRod said:
I assume you're talking about the old TRW/Speed Pro pistons?

True, they are heavy. However, they were once all there was. People used them in droves. What you didn't see in droves were engine failures due to heavy pistons.

I am sure there were some, but nowhere near as many as pistons used. Bottom line is they WORKED and STILL work. Is lighter better? Yeah but it;s probably splittin hairs on all but the hottest of race engines.
Click to expand...

True, I bracket raced a stock 340 and a 440 6-pk motor back in the day and never had 1 failure in 10yrs of racing and I turned that 6pk to 7300, a 6pk rod/piston weighed 2000gms!!!...if I remember correct....if its all out race then yes, go light.
 
Nothing wrong with TRW 73 340 (346) Duster street car running 11.03 You know how heavy those doors are.
This is the second car this motor bin in, it was in a 72 Duster. Still running strong

I also ran TRW in my 440 68 Barracuda street car that ran 11.23 back in 1989.

We now have a lot more piston to choose from.
 
kend said:
I'm thinking about taking some weight out, any instructions anywhere that will help as far as how much and where to cut? Thanks
Click to expand...

I have a set of the trw 340 pistons new in the box. Would I use them on a real under the index killer setup, that would be no, But these can be used still to build an engine that could easily run .30 under the index.
 
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