I say go for it. You seem hell bent, so why even ask for opinions? Use a bastard file to get the crank journals undersized, too.
Use a table ban saw to hack off the 340 piston crown .
- Thread starter Jessearent
- Start date
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The rat bastard will remove more metal quicker. He could finish it up with the regular bastard file.
mopar head
Well-Known Member
Chuck em up in a wood lathe, use a sharp tool.
If ya really want to get the job over with, clamp em up in a electric miter box, with a triple chip blade, rrrrrrrowe done,
If ya really want to get the job over with, clamp em up in a electric miter box, with a triple chip blade, rrrrrrrowe done,
mopowers
Well-Known Member
You guys are brutal. 
Haha, that’s right up there with my coat hanger coil spring compressor…….
What you need is a set of custom rods or destroke the crank.
Phreakish
Well-Known Member
The way American shops keep ditching good quality machines and buying the next cheapest thing on the market, that ain't far off the mark.
Take it to Uncle Tony! He'll do it for Free and have it All Done in One Night!
mygasser
Well-Known Member
re the rods just shorten them with the 'ban' saw and stick weld them back together, sorted
and the crank? now we're back to the bastard files again
jos51700
Green Bearing thread connoisseur
I've always wondered if you took the doors off a jeep and then drove down the road hanging out the door opening with pencil in hand, how long of a line could you draw with said pencil before the graphite ran out.
A similar method could be used to remove the excess material from the 340 pistons without the risks of cutting round material in a band saw. That's generally a bad idea.
A similar method could be used to remove the excess material from the 340 pistons without the risks of cutting round material in a band saw. That's generally a bad idea.
"Measure carefully=band saw"?? Who knew...
jos51700
Green Bearing thread connoisseur
I know, right? That's back when commercials were actually cool, entertaining and actually made sense.
Another thing to consider when removing a lot of metal from the crown: the top ring is exposed to more heat, & could soften it such that it loses tension. It will also need a larger gap, being exposed to more heat.
DrCharles
Well-Known Member
OP is keeping awfully quiet 
Probably enjoying the results of a successful trolling.
I will have to visit the smallblock forum more often, we rarely get entertaining threads like this in the bigblock forum...
Probably enjoying the results of a successful trolling.I will have to visit the smallblock forum more often, we rarely get entertaining threads like this in the bigblock forum...
Dave999
Well-Known Member
kind of action necessary if you have an obsolete engine with no or little support...
or the nearest spares are 13,000 miles away.
but a lathe or milling machine is what you need.....not any kind of saw
i run magnum pistons in a Australian hemi 6 maninly becasue i couldn't stomach the cost of custom pistons for what was a pretty standard build (carbs, headers, cam and CR changed) $200 for 8 magnum speed pros from the mexican equivelent of summit (i.e 2 for experiments) or $200+ per piston as a custom job from Jaycee.. nice pistons but champaign taste didn't fit my beer budget
Put head on reach down bore and scribe the bore shape into the head
put piston on rod and rod and crank in motor see how far piston sticks up out of the bore
scribe round it at deck height
30 thou in my case
check head/chamber shape inside your scribe line. does the head need work with a flycutter to accomodate your piston ??
decide on angle to cut piston based on the angle you could cut the head chamber perimeter
45* might be good for a quench ring
all looked too hard to me...maybe next time, so didn't bother and just took the edge off the piston, flat
open chamber head on mine and bore and edge of chamber matched pretty good but the piston would have hit head without surgery
So i cut 30 off the edge of the piston crown in a band of about 1/8 inch all round
i put head on motor with no gasket and torqued it up
then checked clearances with platiguage strands glued to the new edge at 12 and 6 o'clock
i.e more clearance than zero but still bloody close at the very outer edge
all good.. i will be running a gasket with an appropriate bore.
i then checked distance from my new edge of piston down to the top ring
found it no worse than a many others
then used this as a model for the 6 i would eventually use
gave me static cr of 12.5:1 with nail head valves as apposed to dished and a standard monotorque gasket. 30+ thou
carbs x3 cam and gearing chosen to suit
been running it like that for 10 years
some luck involved i'm sure, but when i did the build i was perfectly happy in my ignornace of many things... i would not run so fast and loose, these days and would be a little more careful, piston rock with hypers is small due to tight clerance. but i was working with the crapest core in the world, that had been converted to run chevy pistons with a massive deck cut and an odd overbore on a New house new familiy constrained budget i own 50% of all of these engines in the whole of the UK and apart from my spare the rest are in cars I had to use what i had.
as it turns out the special versions i.e race versions of the motor i had, used a similar set up from the factory...
so i lucked into doing something similar to what the factory did
short answer as said by many above
if you can get the correct pistons get them
if you want to modify pistons a lathe is a better bet
this kinda things is dpendent on chamber shape
can you get it all to work effectivly when saddled with a perfect new set of too tall or indeed the wrong pistons?
...... yes i did, and so did chrysler Australia.
easier to do with open chamber head
would not be possible with a near flat heart shaped chamber
never had a wedge head so don't know about them
don't use a saw
Dave
or the nearest spares are 13,000 miles away.
but a lathe or milling machine is what you need.....not any kind of saw
i run magnum pistons in a Australian hemi 6 maninly becasue i couldn't stomach the cost of custom pistons for what was a pretty standard build (carbs, headers, cam and CR changed) $200 for 8 magnum speed pros from the mexican equivelent of summit
(i.e 2 for experiments) or $200+ per piston as a custom job from Jaycee.. nice pistons but champaign taste didn't fit my beer budgetPut head on reach down bore and scribe the bore shape into the head
put piston on rod and rod and crank in motor see how far piston sticks up out of the bore
scribe round it at deck height
30 thou in my case
check head/chamber shape inside your scribe line. does the head need work with a flycutter to accomodate your piston ??
decide on angle to cut piston based on the angle you could cut the head chamber perimeter
45* might be good for a quench ring
all looked too hard to me...maybe next time, so didn't bother and just took the edge off the piston, flat
open chamber head on mine and bore and edge of chamber matched pretty good but the piston would have hit head without surgery
So i cut 30 off the edge of the piston crown in a band of about 1/8 inch all round
i put head on motor with no gasket and torqued it up
then checked clearances with platiguage strands glued to the new edge at 12 and 6 o'clock
i.e more clearance than zero but still bloody close at the very outer edge
all good.. i will be running a gasket with an appropriate bore.
i then checked distance from my new edge of piston down to the top ring
found it no worse than a many others
then used this as a model for the 6 i would eventually use
gave me static cr of 12.5:1 with nail head valves as apposed to dished and a standard monotorque gasket. 30+ thou
carbs x3 cam and gearing chosen to suit
been running it like that for 10 years
some luck involved i'm sure, but when i did the build i was perfectly happy in my ignornace of many things... i would not run so fast and loose, these days and would be a little more careful, piston rock with hypers is small due to tight clerance. but i was working with the crapest core in the world, that had been converted to run chevy pistons with a massive deck cut and an odd overbore on a New house new familiy constrained budget i own 50% of all of these engines in the whole of the UK and apart from my spare the rest are in cars I had to use what i had.
as it turns out the special versions i.e race versions of the motor i had, used a similar set up from the factory...
so i lucked into doing something similar to what the factory did
short answer as said by many above
if you can get the correct pistons get them
if you want to modify pistons a lathe is a better bet
this kinda things is dpendent on chamber shape
can you get it all to work effectivly when saddled with a perfect new set of too tall or indeed the wrong pistons?
...... yes i did, and so did chrysler Australia.
easier to do with open chamber head
would not be possible with a near flat heart shaped chamber
never had a wedge head so don't know about them
don't use a saw
Dave
Last edited:
Jessearent
Well-Known Member
I will post photos when I get around tuit....laughter is healthing medicine. And stand far away when I crank it and rev it.
EdsWelding
Well-Known Member
I want to see pics please !
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