400 Piston questions
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From: Smiths Grove, KY
400 Piston questions
So I removed all of my pistons in my 400 bored .40 over and set them in order on the shop floor. My son moved them and now I have no idea which ones went to which cylinder. There was no irregular wear to any of the cylinders or pistons. I know this is a crucial part of rebuilding a motor...keeping them in order, should I take my chances with the old pistons or buy new ones? I will be taking the block to a machine shop either way but any advice from experience would be greatly appreciated
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What is it going to the machine shop for?
.040 over (not .40) may be the limit for that block, so you need to check that.
IMO swapping holes is going to result in a poor result.
But back to machine shop. What machine work is planned?
.040 over (not .40) may be the limit for that block, so you need to check that.
IMO swapping holes is going to result in a poor result.
But back to machine shop. What machine work is planned?
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New User
Joined: Mar 2018
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From: Smiths Grove, KY
Im just taking it to a machine shop to have it polished and checked for any problems. Ive had a 79 f100 300 speed on the column for 20 years. This past summer I bought a 77 f150 400 bored .40 over 6 inch lift, power steering,power brakes automatic, a step up from my f100 custom 2wd. The 77 400 has been sitting for 6 years because the transmisson went out, engine was locked due to the header being off after pulling the trans. Im doing a frame swap and rebuilding the motor. So you say new pistons?
Hotshot
Joined: Feb 2004
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From: The Shenandoah Valley
All 8 are 0.040 over? (no way 0.40 over)
How long (miles) were they in their assigned holes?
If all mixed up, I guess you took them off the rods?
Rods & caps are numbered, paired at least, right?
If all 8 were bored 0.040 over, if no unusual wear, you're gonna re-ring it anyway, right?
If mine, I just test fit a piston in each hole to make sure all will fit "a hole", hone the bores lightly for a cross hatch to help new rings seat, put them in.
How long (miles) were they in their assigned holes?
If all mixed up, I guess you took them off the rods?
Rods & caps are numbered, paired at least, right?
If all 8 were bored 0.040 over, if no unusual wear, you're gonna re-ring it anyway, right?
If mine, I just test fit a piston in each hole to make sure all will fit "a hole", hone the bores lightly for a cross hatch to help new rings seat, put them in.
Laughing Gas
Joined: Sep 2013
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From: North Idaho
How is it the pistons aren't attached to the rods anymore? The rods are numbered. If they really are mixed up, then I'd simply put new rings on and reuse the pistons. The pistons shouldn't be touching the cylinder walls anyway - only the rings and a thin film of oil.
More Turbo
Joined: Mar 2019
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Here's an example of the rods being cast with the cylinder numbers (2 and 3 in pic) in them. This is on a 460, but would be similar. There are numbers on the main caps (3 and 4 in pic) and on the rod caps. They're also marked on the rods/caps right where they meet each other where they bolt together, but it's hard to see in the pic.
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New User
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From: Smiths Grove, KY
I cant find any numbers on the rods. Ill clean them up to see if I can find any, everything else is numbered well except the pistons (my fault). A few cylinders would not move which would not let me rotate the crank over enough to pull it out. I do plan on putting new rings in as well. And yes .040 over which I do not plan on changing. Im not sure how many miles it was driven due to buying it off a guys wife she got the truck in the divorce
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From: Regina, Saskatchewan
All 8 are 0.040 over? (no way 0.40 over)
How long (miles) were they in their assigned holes?
If all mixed up, I guess you took them off the rods?
Rods & caps are numbered, paired at least, right?
If all 8 were bored 0.040 over, if no unusual wear, you're gonna re-ring it anyway, right?
If mine, I just test fit a piston in each hole to make sure all will fit "a hole", hone the bores lightly for a cross hatch to help new rings seat, put them in.
How long (miles) were they in their assigned holes?
If all mixed up, I guess you took them off the rods?
Rods & caps are numbered, paired at least, right?
If all 8 were bored 0.040 over, if no unusual wear, you're gonna re-ring it anyway, right?
If mine, I just test fit a piston in each hole to make sure all will fit "a hole", hone the bores lightly for a cross hatch to help new rings seat, put them in.
FTE Emeritus
Joined: Jan 2006
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From: springfield Missouri area
Haven't been into a 400 for many a moon, But most pistons have a notch or groove on the top of the piston, It designates toward the front of the engine. Rods should be numbered, But the engine being rebuilt once they may have not went back in original holes.
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OP stated 0.40 over, that’s nearly 1/2 inch. Tbear was just pointing out he really meant 0.040 over.
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Joined: Apr 2004
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He would be .040, or "40 thousandths".
The machine shop can probably find the right holes via measurement of each piston and bore and matching them up. A hone job and new rings and keep your fingers crossed. The shop should also tell you what your piston clearance is as well, so you can stay or go with this set up.
As to the rods, if you don't know what position the rod came from the safe way would be to have the shop again try to match them up or just resize them all.
You have some chance of an oil burner, a spun rod, a stuck motor, or galled mains, or a smooth running reliable motor with many miles left. A few extra steps here will increase you chances of a good outcome.
Serving suggestion.
Logistics Pro
Joined: May 2010
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From: Regina, Saskatchewan
.50 over would be 1/2 inch!
He would be .040, or "40 thousandths".
The machine shop can probably find the right holes via measurement of each piston and bore and matching them up. A hone job and new rings and keep your fingers crossed. The shop should also tell you what your piston clearance is as well, so you can stay or go with this set up.
As to the rods, if you don't know what position the rod came from the safe way would be to have the shop again try to match them up or just resize them all.
You have some chance of an oil burner, a spun rod, a stuck motor, or galled mains, or a smooth running reliable motor with many miles left. A few extra steps here will increase you chances of a good outcome.
Serving suggestion.
He would be .040, or "40 thousandths".
The machine shop can probably find the right holes via measurement of each piston and bore and matching them up. A hone job and new rings and keep your fingers crossed. The shop should also tell you what your piston clearance is as well, so you can stay or go with this set up.
As to the rods, if you don't know what position the rod came from the safe way would be to have the shop again try to match them up or just resize them all.
You have some chance of an oil burner, a spun rod, a stuck motor, or galled mains, or a smooth running reliable motor with many miles left. A few extra steps here will increase you chances of a good outcome.
Serving suggestion.
And yes, I missed a zero. Thanks for catching it.EDIT: I corrected my post for those who would lose sleep tonight.
Super Moderator
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Lots to lose sleep over here, this is the least of it!
Thanks
