going with 72CC chamber to help with that

 

offset grinding DOES NOT require welding. Anyone who has a crankshaft grinder can offset the crank. All you do (as long as the crankyou haveis std on the rods) is leave the outermost portion and offset the grind to take more from internal section. It is more set up but if you cut 0.020 offset you gain 1/2 that in quench so you are 0.010 closer to tdc simulating a piston with 0.010 more compression height but you also attain the same goals at the bottom, meaning your stroke grows by 0.020. This turns your 400 std bore into a 404 as well a figuring 0.030 deck height as stock to the "new" 0.010 deck height would bring compression from 8.3 to 8.6; then if bored 0.030 over that put you to 8.7:1, now we are getting there. Mill the factory heads 0.020 and now we are well over 9:1 maybe close to 9.5:1 that is gods plenty if you really want to be reliable and not too timing sensitive and run regular gas, I would NOT go over 10:1 unless you are like me and high elevation or want to buy 91+ octane. That is just a suggestion to build a good bottom end, stock pistons, stock heads, and some machine work. I would hope you crunch the numbers on a crank grind vs a set of heads/pistons, also remember that the longer stroke will help, also remember that the smaller chamber heads will perform better down low.
Just don't forget that a set of t meyer pistons call for more ring gap. More ring gap is a bigger hole to leak fire through into the crankcase. fir in the crankcase is blowby. blowby causes crankcase pressure. crankcase pressure causes leaks and heat and oil to be broken down. More compression means more squeeze means more blowby. Good luck. My blow by issue might be from me not having really great bores to startwith, but tmeyer sent these wierd head gaskets and seals with my kit that weren't felpro and they all leaked right away. I tore it down... right away, and installed felpro and 4 years later no leaks. I am h=not sold on his stuff yet.

 

Now, if you offset grind a crank 0.030 and bore 0.030 and cut heads, all things that need done on all the engines I build anyway, you are well over 9.5:1 now with stock pistons. So point being if you need to flatten the heads, your crankhas some runout, and it needs bored, this is a build for basically negligible dollars because all of this is needing done before you even order parts anyway, Unless you want to cut corner on your wife's truck. I would never do that.

 

Now, Since I have drove trucks since I was knee high to a toad stool, I will elaborate on the comment of heavy rotating assy vs light. I have driven several trucks (big trucks like twin screws) with 361/391 industrial powerplants. I have also driven those similar trucks with automotive 390 platforms and also small block chevys. If you want to catcha gear with a 361/391 it is easy when you let out of the gas or stab it the rpm are really smooth and controllable and she falls right into gear, with the automotive engines, rpm falls really fast or even flashes up really fast causing you to need to feather the pedal to obtain rpm to get a ratio. Now, as far as heavy vs light to not matter, then why is it when I kick the pto on a feedtruck and the little light automotive crank and pistons bog instantaniously to the basement and die, but the old heavy 361/391 industrial just pull down and lug then slowly come back? Reason is heavy mass in rotation is stored energy. Stored energy provides more mass to offset the action of the work to be done, moving a truck and a load. No different than ford installing heavier pistons in their later 460 efi engines. More weight, more rotating mass, more forward motion to keep the chain gang moving. Is it easier to stop a marble rolling toward you at 50 FPS than a base ball? how about a bowling ball the same rolling toward you at 50fps. weight is mass, mass is energy, energy is the ability to do work, Torque is the ability to do work.

 

Cranks and flywheels and to a certain extent the big end of the rod are rotating mass. Pistons reciprocate. They stop twice each rotation of the crank. Any inertia they carry is lost when they stop.

Truck engines like the 361/391 have smaller valves and low end camshafts, and really low gearing.

Rotating mass helps get you going. The rest of the time it mostly works against you as it's more weight for the engine to accelerate.

 

OK well alrighty then. So the 7 pistons that are still moving don't make any impact on the 1 that stops. So a marble that is stopped is has the same inertia as 7 bowling ***** on the move. On a 1 or 2 cylinder I can see that theory. On an 8 cylinder piston mass is moving and helping shove you up the hill.

 

It is the same reason that heavy piston 460s aren't recommended to rev high because it is TOO MUCH MASS. Or why a 361/391 industrial has to have the entire rotating assy lightened up to be turned fast.

 

Not to mention that doing stationary work via pto the "low gearing" Means nothing. YOU ARE STOPPED. I made this very clear.

 

I will readily admit I don't "KNOW" whether or not a heavy reciprocating assembly has much to do with torque or not. I would be curious if it can be dyno proven - put some 500 gram pistons in an engine - dyno it, put some 1,000 grain pistons in it and dyno again. Then do the same with a heavy flywheel. I'd be inclined to think rotating mass is where the torque comes in, not so much from reciprocating mass. I do know that if the reciprocating assembly heavy, you're putting more stress on rods, rod bolts, and bearings.

I think F-250 Warhorse probably works his 400 gas engine like most folks would a diesel - low RPM work, all over by 3,500.

i think more than torque production - it's WHEN you want it in your RPM range.

 

TDC and BDC come in pairs, so there are not 7 other pistons moving. I get what you are saying, but you need to look up "reciprocating" vs. "rotating".

 

Power (torque) is produced by combustion events. A heavy rotating mass helps smooth the process and maintain rotation at lower speeds. (idle). A heavy rotating mass does not produce torque. It might maintain it, but the power comes from the air/fuel burning.

Nothing moves without combustion or some other outside force. (starter, drivetrain)

 

It all matters. the more mass and weight the more off idle and low rpm you have. That is proven by 100 years of engine building. It carries all over a rotating assembly even into air compressors, the more weight that you get moving, the more weight there is to have to stop to stall the engine. That is all over the engine industry. anyone who has pulled a mountain pass with a truck that is 100,000 pounds or more or anyone who has spent hundreds of hours dragging a plow and ripper around in a tractor drag a plow with a massey tractor then hook that plow to a john deere and feel the power. Then hook it to a case, and youwill be afraidyour plow will come out of the ground in several pieces. It is simply the ability todothe work without the help of low gearing, clutch, or turbo forced induction. Run a caterpillar then run a cummins. The caterpillar will pull down to the basement the cummins, 1800 rpm. I don't really care what anyone thinks, or reads, or does. I know from EXPERIENCE. I have built the engine then done the work with it. I know what works. I have a job to do and I know what works best for that job. Anyone can read a dyno, read a theory, read a calculation. I have an idea lets put your engine to my tests vs my engine, and see who gets more land plowed, more logs hauled, more fuel moved, more hay stacked, more fertilizer applied, more heavy machinery moving and more cattle hauled.
Come on out,.. we have to chain up the pickups now to get into the log deck. It snowed. That is why we all drive f350s. I am not in a position to worry or care, I know what makes power, torque, reliability, longevity, driveability, so good luck.

 

I get what you're saying F-250 Warhorse. You've got to build the engine for the application. This is true of a daily driver car, drag racer, endurance racer, 4x4 Jeep, or F-350 work truck - no one solution fits all.

 

Old post but thought id throw it out there. After several phone calls not returned and several dead end emails, I gave up on the guy that most recommend for these engines. I stumbled across a place in California that will forge pistons for these engines in about configuration youd want! While theyre a touch more expensive than the popular pistons, they were very responsive to calls and emails and we dialed in EXACTLY what i want for this build. If any one is interested, try Clegg Engine out of Orem Utah for pistons and other goodies for these engines, Theyre very knowledgeable, very responsive, and very helpful. They dont offer a specific package for these but can get about anything you want at very competitive prices. takes 3-5 days to make then a few days shipping. Im not trying to bash anyone or drum up business for someone else. just throwing an option out there

 

That’s good info Mitch. I’m in rural Northern Nevada and Orem’s Just a couple hours away. Thank you.