Use a table ban saw to hack off the 340 piston crown .

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Rat Bastid said:
Pretty hard to call someone a machinist who can’t take some dome off with a lathe. I’ve done it many times. I can also do it with a mill.
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Have you used the cinder block or chain drag method?
Have you milled a 340 piston for a 360.
 
mygasser said:
i missed a zero, lol. the point about pushrods was it's another expense. as already suggested if you sold the 340 pistons and bought some 360 pistons you wouldn't need to buy pushrods so there's your difference between the sale of the 340 pistons and the purchase of the 'right' 360 ones. plus no faffing about with spacers and the potential for leaks they can create. you said you wanted to use what you have to save money but you won't once you buy pushrods. also i think i mentioned this what about intake fitment? the same as when milling heads the intake needs machining to fit, you'll also need to 'make' more spacers now the heads are higher up. seems a vast amount of work when you'll be miles ahead just selling what you have and buying the right parts with that sale money and the money you save on pushrods (and no work making spacers, 4 of).
if you're doing it 'because you can' then why ask here?
neil.
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Chevy pushrods are plentiful and under $2 apeice if you buy them at summit. But I will get them free ...no cost to me there. Thanks for your understanding . Junkyard
 
James Clews said:
Using a lathe to turn down a piston crown is a bad idea. tell me how do I know? In the seventies when I was a lad I used a guy that had a lathe and was a machinist to turn down a set of 340 pistons for a 360 but he broke one piston and the rest were all over the place.I eventually got those pistons to work with a new piston and further machined by my engine specialist that I still know to this day. He used a special adapter piece to hold the bottom of the piston solid and milled them. I later sent him some pistons for my 340 that were 13to one forged pistons. they were obviously too high of comp for street use so I took him one 10.5 to one 340 pistons and told him to cut the other ones down to about 11 to 1 . He laughed and said he would give it a go. At the time I was a green horned twenty year old but now as a older gent in my late sixties I have learnt a lot about my younger years mistakes. That 340 ran great and did low thirteens back then on not so good tyres.
junkyardhero said:
i value my time so why would i play around with some cockamamie bullshit like that? i'd rather pay the money and have the car back on the road and enjoying it than trying to squeeze and nickle and get six pennies.

this is also discounting the possibility of damaging the engine, or screwing up the job-- thus doing the work twice, and probably having to buy the components you screwed up in the process.

but, obviously, your brain isn't wired that way. which, again, why this is just so damn intriguing. carry on with the chicanery.
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Obviously your well off in the cash department
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So , I need some donations for this challenge. Instead of the 360 block I need a 340 block. I will use the Scat forged crank with a 3.58" throw with the 318 sized mains. Anybody want to supply the block?
 
Jessearent said:
Chevy pushrods are plentiful and under $2 apeice if you buy them at summit. But I will get them free ...no cost to me there. Thanks for your understanding . Junkyard
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Time is plentiful, cash is not. Anyway , I am happy everyone is so well off and can spend like it's no problem. I advise don't get in such a hurry you stop enjoying the spirit of the creation...in whatever You lay your hands to accomplish.
 
Jessearent said:
So , I need some donations for this challenge. Instead of the 360 block I need a 340 block. I will use the Scat forged crank with a 3.58" throw with the 318 sized mains. Anybody want to supply the block?
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a ask for a project "donation" would be some gaksets somebody wasn't gonna use and you pick up the shipping. not, like, a fuggin' 340 block my dude.
 
No joke , the 340 block , will again, accommodate the no cost of machining if the block has .030" or under bore already. What's the block like 4spdragstop? Bore wise.
 
Just leave the rings off entirely. The pistons will go in easier and have less drag on the cylinder walls. This is free horsepower.
 
Rat Bastid, how do you hold the piston skirts in a three jaw chuck without damaging them or even worse braking the skirts by tightening the chuck. and if you do not tighten it the piston will move around damaging it. Now it appears you have a lot more intelligence so tell me how you do it?
 
This thread is all 'BACK TO FRONT'!

Its the 360 pistons that are too tall for the 340 block as I've 'BEEN THERE DONE THAT' myself.
The 340 guy bought cheap used forged 360 pistons for a 340 build.
Had to turn about 30 thou off them to get the compression right...

UTG would have used them as is a run some race gas lol...

340 domes.jpg
 
James Clews said:
Rat Bastid, how do you hold the piston skirts in a three jaw chuck without damaging them or even worse braking the skirts by tightening the chuck. and if you do not tighten it the piston will move around damaging it. Now it appears you have a lot more intelligence so tell me how you do it?
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Long soft jaws. Pretty simple.
 
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