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

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Ok, find someone with a mill...&#@/ the machine shops chargeing so much for a simple procedure. I got some dome pistons myself that need to be put to use.
 
Jessearent said:
Ok, find someone with a mill...&#@/ the machine shops chargeing so much for a simple procedure. I got some dome pistons myself that need to be put to use.
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fill yer boots dude, you seem not to care what other sensible or cost effective options you're given so go for it. once you've buggered them and they're un saleable don't say you weren't warned. :thumbsup:
 
Okay dude , the challenge is on. I gonna get it done inexpensive . Starting with my own .080" thick piece of flat aluminum ..making my head shim for free...stay tuned.
 
Jessearent said:
Okay dude , the challenge is on. I gonna get it done inexpensive . Starting with my own .080" thick piece of flat aluminum ..making my head shim for free...stay tuned.
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how are you gonna make .080" longer pushrods, weld a bit on the end and round it off on the bench grinder? :poke: :lol:

edit.. missed a zero, lol.
 
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And I thought I was pressing my luck by turning a 2-groove alternator pulley to a single groove using a drill press, angle grinder, and some odds and ends from my bolt bin. Goodluck and I hope you have a sawstop brand table saw.

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mygasser said:
as above sell the 340 pistons, buy the right 360 pistons. too expensive you say? don't forget shimming the head off the block will need to buy longer custom pushrods and the intake will need shimming too. doesn't make the difference between selling your pistons and buying 360 ones seem so bad now does it. no shims to buy, for heads or intake and no custom pushrods to buy. and you can still be happy you didn't give money to a machine shop :rolleyes:
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mygasser said:
how are you gonna make .80" longer pushrods, weld a bit on the end and round it off on the bench grinder? :poke: :lol:
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My understanding is 3.31" 340 stroke subtracted from 3.58" 360 stroke equals .27" added to the overall increase in thickness. Moparpush rod is 7.5" / SBC is 7.794- 7.8". So .30" is close to .27" I will use adjustable rockers to get it spot on. Not sure where you got the .80" figure. Gonna use the 0.080" head shim combined with standard 0.038" -.040" head gasket equals .120" to startwith and then I will check my dome and see were I stand. And go from there...pushrod length really needs measured when it's close to being assembled but you get the general idea...I hope, there's a lot of heklers and unbelievers out there.
 
junkyardhero said:
none of this makes even a remote amount of sense; which is why it is so utterly fascinating!
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Hello junkyardhero, I like your name and I am guessing you don't like spending money where you don't need too. What do think of spending $200-$300 on Cosmetic head gaskets or head shims when you can make your own with flat piece of aluminum stock & use a head gasket as template, and for the good seal let's spray on a liberal dose of Permatex copper seal and let it sit overnight.?
 
AJ/FormS said:
Where are the rings gonna end up relative to the deck?
and will they survive there?
Recheck your math;
A friend of mine did this with used factory pistons, (don't know which ones) without spacers. It's been a strong street-runner nearly as long as mine has (since 1999)H
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Yes, Top ring land is very important. I will be be shooting for bout 1/8th" - 1/4" from top.
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mopar head said:
Post Pics, Where we all can learn a thing or two:popcorn:
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Will do, and by the way, a good way to measure the thickness of the piston crown/top would be to use a C clamp. Mark the spot on the threads where it stops, remove the piston and run it back to the where you marked the threads...take your measurements.
 
Jessearent said:
Will do, and by the way, a good way to measure the thickness of the piston crown/top would be to use a C clamp. Mark the spot on the threads where it stops, remove the piston and run it back to the where you marked the threads...take your measurements.
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That will work unless you got a giant micrometer...would be better.
 
I think if you used UTG's cinder block method you could have the crowns shaved by the end of summer.
 
You could install the pistons and set the deck on the street and chain drag it for say maybe 25-50 miles.
I'd get out and check every few miles though.
 
Jessearent said:
Hello junkyardhero, I like your name and I am guessing you don't like spending money where you don't need too. What do think of spending $200-$300 on Cosmetic head gaskets or head shims when you can make your own with flat piece of aluminum stock & use a head gasket as template, and for the good seal let's spray on a liberal dose of Permatex copper seal and let it sit overnight.?
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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.
 
Jessearent said:
My understanding is 3.31" 340 stroke subtracted from 3.58" 360 stroke equals .27" added to the overall increase in thickness. Moparpush rod is 7.5" / SBC is 7.794- 7.8". So .30" is close to .27" I will use adjustable rockers to get it spot on. Not sure where you got the .80" figure. Gonna use the 0.080" head shim combined with standard 0.038" -.040" head gasket equals .120" to startwith and then I will check my dome and see were I stand. And go from there...pushrod length really needs measured when it's close to being assembled but you get the general idea...I hope, there's a lot of heklers and unbelievers out there.
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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.
 
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.
 
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.
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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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