1972 340

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duster 2

dustertwo
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So i have found out one of the low compression problems with the 72 is relocation of wrist pins on pistons...dont know if this true..
I know intake valves are small...Can I use piston set up as per the older year 340s...Just want to wake engine up...planning on installing aluminum heads, intake manifold , headers , cam...Know I have to do a lot of research on this combination...looking for a few different options
Thanks
 
It is not a "relocation of the wrist pin". It is a change in the distance from the wrist pin centerline to the crown of the piston that changed. Also known as 'compression distance'.
 
My brother used stock 1969 340 pistons in his 1973 block with x heads and a purple shaft cam and it works great. Bobby
 
why not go with an aftermarket piston?

i know that 8.5:1 compression isn't *ideal* but if the bottom end doesn't need a go thru and you were just looking to wake it up a little, a cam swap and thinner headgaskets would be a reasonable course of action without spending a boat load of cash.
 
how low do the low cmpression pistons sit below the deck? maybe you can just put closed chamber alumn heads on it and get the compression right where you want it.
 
It is not a "relocation of the wrist pin". It is a change in the distance from the wrist pin centerline to the crown of the piston that changed. Also known as 'compression distance'.
ok thanks for the feedback
 
why not go with an aftermarket piston?

i know that 8.5:1 compression isn't *ideal* but if the bottom end doesn't need a go thru and you were just looking to wake it up a little, a cam swap and thinner headgaskets would be a reasonable course of action without spending a boat load of cash.
 
why not go with an aftermarket piston?

i know that 8.5:1 compression isn't *ideal* but if the bottom end doesn't need a go thru and you were just looking to wake it up a little, a cam swap and thinner headgaskets would be a reasonable course of action without spending a boat load of cash.
 
why not go with an aftermarket piston?

i know that 8.5:1 compression isn't *ideal* but if the bottom end doesn't need a go thru and you were just looking to wake it up a little, a cam swap and thinner headgaskets would be a reasonable course of action without spending a boat load of cash.
ok thanks for the feedback
 
So i have found out one of the low compression problems with the 72 is relocation of wrist pins on pistons...dont know if this true..
I know intake valves are small...Can I use piston set up as per the older year 340s...Just want to wake engine up...planning on installing aluminum heads, intake manifold , headers , cam...Know I have to do a lot of research on this combination...looking for a few different options
Thanks

Depending on your budget, this is a pretty sweet combo TRICK FLOW HEADS , add this manifold Edelbrock Performer RPM , and THIS CAM all this should work with your stock converter, and be a blast to drive on the street.

if you hit up @pittsburghracer or @GTX JOHN sometimes they have 10% off coupons from Summit Racing.



There are some chinesium heads that are available, I forget the name but a lot of folks dig them.

Get some Dougs Headers from Autozone when they have a 20% coupon I think they are 453's.
 
If you are serious about installing Alloy heads, it behooves you to study it out.
Smarter men than me have said that with a straight swap to alloy heads with no other changes, your engine is likely to lose power. They say that this is because the alloy heads suck heat out of the combustion chambers, and heat is power.
Most sources will say that the engine needs a compression ratio boost of at least a half a point, to compensate.
IMO,
it's more like a full point for a street machine.

I'm not telling you what to do, BUT
For alloy heads, I have boosted my cylinder pressure up to 195 psi, on my alloy-headed 360, and the engine ran gangbusters, and even ran on 87E10 at WOT at full ignition timing. At my elevation of 900ft, and with my cam, this required a static compression ratio of 11.3:1
My engine is definitely not lazy, and will pull any gear I ask it to. I installed a 4-speed behind it.

I suppose, this 11.3, would be considered the equivalent of 10.3 Scr, if the engine had iron heads. But you cannot compare them directly that way, because at 10.3 the pressure is likely to be close to or greater than 170psi which with open chamber iron heads would very likely self-destruct in detonation.

The point is this; If you truly are gonna use closed chamber alloy heads, and you are installing new pistons anyway, it behooves you to set the Quench up right and crank the pressure up; to take the most advantage of the swap. Else you will spend a lotta money on a mediocre build.

As a newbie, I highly recommend you just get a crate engine from a builder right here on FABO. I think they all know what they are doing, and they'll give you the right engine the first time.
If you make it a 360, you'll get the benefit of extra bottom end torque, allowing you to run a more hiway friendly rear gear, and/or less stall; and then you can sell your 340, or save it for later.
If you make it a Magnum, you'll get the benefit of the roller lifters.
These are my opinions.
Happy Hotrodding
 
So i have found out one of the low compression problems with the 72 is relocation of wrist pins on pistons...dont know if this true..
I know intake valves are small...Can I use piston set up as per the older year 340s...Just want to wake engine up...planning on installing aluminum heads, intake manifold , headers , cam...Know I have to do a lot of research on this combination...looking for a few different options
Thanks

So what is the combination now? "72" 340's ran pretty sweet as I remember.
 
If you are serious about installing Alloy heads, it behooves you to study it out.
Smarter men than me have said that with a straight swap to alloy heads with no other changes, your engine is likely to lose power. They say that this is because the alloy heads suck heat out of the combustion chambers, and heat is power.
Most sources will say that the engine needs a compression ratio boost of at least a half a point, to compensate.
IMO,
it's more like a full point for a street machine.

I'm not telling you what to do, BUT
For alloy heads, I have boosted my cylinder pressure up to 195 psi, on my alloy-headed 360, and the engine ran gangbusters, and even ran on 87E10 at WOT at full ignition timing. At my elevation of 900ft, and with my cam, this required a static compression ratio of 11.3:1
My engine is definitely not lazy, and will pull any gear I ask it to. I installed a 4-speed behind it.

I suppose, this 11.3, would be considered the equivalent of 10.3 Scr, if the engine had iron heads. But you cannot compare them directly that way, because at 10.3 the pressure is likely to be close to or greater than 170psi which with open chamber iron heads would very likely self-destruct in detonation.

The point is this; If you truly are gonna use closed chamber alloy heads, and you are installing new pistons anyway, it behooves you to set the Quench up right and crank the pressure up; to take the most advantage of the swap. Else you will spend a lotta money on a mediocre build.

As a newbie, I highly recommend you just get a crate engine from a builder right here on FABO. I think they all know what they are doing, and they'll give you the right engine the first time.
If you make it a 360, you'll get the benefit of extra bottom end torque, allowing you to run a more hiway friendly rear gear, and/or less stall; and then you can sell your 340, or save it for later.
If you make it a Magnum, you'll get the benefit of the roller lifters.
These are my opinions.
Happy Hotrodding
If you are serious about installing Alloy heads, it behooves you to study it out.
Smarter men than me have said that with a straight swap to alloy heads with no other changes, your engine is likely to lose power. They say that this is because the alloy heads suck heat out of the combustion chambers, and heat is power.
Most sources will say that the engine needs a compression ratio boost of at least a half a point, to compensate.
IMO,
it's more like a full point for a street machine.

I'm not telling you what to do, BUT
For alloy heads, I have boosted my cylinder pressure up to 195 psi, on my alloy-headed 360, and the engine ran gangbusters, and even ran on 87E10 at WOT at full ignition timing. At my elevation of 900ft, and with my cam, this required a static compression ratio of 11.3:1
My engine is definitely not lazy, and will pull any gear I ask it to. I installed a 4-speed behind it.

I suppose, this 11.3, would be considered the equivalent of 10.3 Scr, if the engine had iron heads. But you cannot compare them directly that way, because at 10.3 the pressure is likely to be close to or greater than 170psi which with open chamber iron heads would very likely self-destruct in detonation.

The point is this; If you truly are gonna use closed chamber alloy heads, and you are installing new pistons anyway, it behooves you to set the Quench up right and crank the pressure up; to take the most advantage of the swap. Else you will spend a lotta money on a mediocre build.

As a newbie, I highly recommend you just get a crate engine from a builder right here on FABO. I think they all know what they are doing, and they'll give you the right engine the first time.
If you make it a 360, you'll get the benefit of extra bottom end torque, allowing you to run a more hiway friendly rear gear, and/or less stall; and then you can sell your 340, or save it for later.
If you make it a Magnum, you'll get the benefit of the roller lifters.
These are my opinions.
Happy Hotrodding
great info...
thanks
 
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