I need to find some lower compression forged pistons...

Psychoholic

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Hey guys,

My other post introducing my project is stuck in limbo for approval I'm assuming because I'm new here and I put a link to a video in it.

Short explanation: I'm building a turbo 472 for my '72 Miller-Meteor hearse (I have 4 videos on VinWiki on Youtube if you're interested). I have a Bulldog intake, 1000 cfm Holley throttle body, Work S485 turbo (dual scroll billet), ON3 wastegates and blow off, 60 lb/hr injectors, gigantic Aeromotive pump, LS coils, MS3Pro, ginormous intercooler, and various odds and ends. I currently have an MTS10 cam in the car and will be ordering a set of either CHP or CadCo rockers and roller lifters.

For the general range that I want I figure I need to make 8.3# of boost which means that ye olde stock rods and pistons are a no-go. Rods don't seem to be much of an issue to find but pistons are proving to be a real bear to locate. So far all I can find in a forged variant are 10:1 compression (with 76cc heads). I want to be able to run pump gas since this is a driver and I love this car dearly so I don't want to have to plan my trips around finding E85 or carrying another 50 gallons of race gas with me just to go on a cruise. Using the power of the internet I figure that with my corrected altitude running those pistons at 8 psi of boost would give me an effective compression ratio of 15.1:1 which is obscene.

I've read an unreasonable number of posts on this forum (looking back I apparently joined in early 2018 but this is my second post) and this a proper wealth of knowledge! Hopefully someone can help guide me. I'd prefer not to buy a set of the bigger chamber late model heads since eventually I'll end up with a set of the nice aluminum ones and I'd have the same compression problem then. I don't mind buying custom pistons as long as they aren't 3x the cost of the normal ones but I don't even know who/where to ask.

Thanks in advance!

Chris (Psychoholic)
 

PSYKO_Inc

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Since you are changing rods anyway, perhaps check out pistons for other applications and find out what combinations of bore, stroke, compression height, and rod length would work. You'd most likely need some custom machine work to make it all fit together though. For example, a Chevy 454 is a 4.250 stock bore, and your 472 is 4.300 stock. So a set of .060 over 454 pistons would work if you bore your block .010 over. Compression height is 1.627 for the 454, and stock compression height for the 472 is 2.020. 472 rods are 6.75, so you'd need a rod that is approximately 0.393 longer (7.143) with the stock stroke. Since the caddy crank uses huge 2.50 journals, you can play with the stroke by offset grinding the crank to drop to a more common rod journal size (like the BBC 2.20 journal.) If you can get your combination of stroke, rod length, and pin height to within 0.050 or so of the block height, you can make up the rest by decking the block. Maybe a set of BBC 7.100 rods and stock 4.060 stroke, then mill the deck by .043, or offset grind by the full 0.300, and run 6.8 rods and the same .043 deck cut. Another option is to get a 500 crank and offset grind for up to 4.600 stroke with BBC size journals. There's an endless amount of combinations to try, especially if you can grab clean used pistons or rods cheap from a race team or something.
 

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Watch the Richard Holdener video on boosting a 500 when he’s finished and see what the stock stuff will take?
 

Psychoholic

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Watch the Richard Holdener video on boosting a 500 when he’s finished and see what the stock stuff will take?
I'm literally waiting to order parts until after that video is done :)

I should probably just call Courtney and pick his brain.
 

5one9

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What info you'll get from Courtney, and what info you'll get from Richard are two different things. Richard isn't selling anything. Once he's done though, you'll know what you need from Courtney.

Myself, I'm stuck between whether to use the '73 piston/head combo on mine, or the '75 stuff. At 8.5:1-ish, cam, intake, headers, Holley, ignition, etc, I expect about 400hp/550tq. At that point it's going to be about how much boost he uses to liquify that stocker that he's taking back to his shop. I'm hoping for mine to survive 10-12psi.
 

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Hey guys,

My other post introducing my project is stuck in limbo for approval I'm assuming because I'm new here and I put a link to a video in it.

Short explanation: I'm building a turbo 472 for my '72 Miller-Meteor hearse (I have 4 videos on VinWiki on Youtube if you're interested). I have a Bulldog intake, 1000 cfm Holley throttle body, Work S485 turbo (dual scroll billet), ON3 wastegates and blow off, 60 lb/hr injectors, gigantic Aeromotive pump, LS coils, MS3Pro, ginormous intercooler, and various odds and ends. I currently have an MTS10 cam in the car and will be ordering a set of either CHP or CadCo rockers and roller lifters.

For the general range that I want I figure I need to make 8.3# of boost which means that ye olde stock rods and pistons are a no-go. Rods don't seem to be much of an issue to find but pistons are proving to be a real bear to locate. So far all I can find in a forged variant are 10:1 compression (with 76cc heads). I want to be able to run pump gas since this is a driver and I love this car dearly so I don't want to have to plan my trips around finding E85 or carrying another 50 gallons of race gas with me just to go on a cruise. Using the power of the internet I figure that with my corrected altitude running those pistons at 8 psi of boost would give me an effective compression ratio of 15.1:1 which is obscene.

I've read an unreasonable number of posts on this forum (looking back I apparently joined in early 2018 but this is my second post) and this a proper wealth of knowledge! Hopefully someone can help guide me. I'd prefer not to buy a set of the bigger chamber late model heads since eventually I'll end up with a set of the nice aluminum ones and I'd have the same compression problem then. I don't mind buying custom pistons as long as they aren't 3x the cost of the normal ones but I don't even know who/where to ask.

Thanks in advance!

Chris (Psychoholic)
Are you already bored out? If so what size?
 

PJ McCoy

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What info you'll get from Courtney, and what info you'll get from Richard are two different things. Richard isn't selling anything. Once he's done though, you'll know what you need from Courtney.

Myself, I'm stuck between whether to use the '73 piston/head combo on mine, or the '75 stuff. At 8.5:1-ish, cam, intake, headers, Holley, ignition, etc, I expect about 400hp/550tq. At that point it's going to be about how much boost he uses to liquify that stocker that he's taking back to his shop. I'm hoping for mine to survive 10-12psi.
Yeah, I think the stock rods will handle some boost as long as the bearings are top shelf! Didn't Courtney run reconditioned rods and make 500 hp on them with arp? If the engine will handle 6 psi of boost I am going to do it. Cause I have a block under the bench. Lol.
 

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I'm waiting for the blower info.
 

Psychoholic

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Both of my blocks (the one in the car is the original with 66k miles on it but it did get a full machine shop treatment at 45k miles but the bores were literally perfect so stock dimensions. The second block is out of a '68 ambulance with about 50k miles on it but it needs at least new cam bearings) are in stock dimensions. The goal is about 600-650 to the wheels on a 'conservative' tune so I need the motor to be making about 800 to get there. That is at the upper range of the duty cycle on the 60 lb/ft injectors but I'll be pretty close I think. Certainly going to run out of head flow pretty quick so we'll have to massage the bejesus out of those until I can save up the coin to get the nice aluminum ones.

I misquoted the turbo - it's a Work S475 which is a 75mm compressor with a 96/88mm turbine, 1.32 A/R twin scroll (T6).

Starting to think I might start off with sending the spare block to the machine shop with @PSYKO_Inc 's idea of using 454 pistons just for availability. I need to check pricing on the offset grind of the crank to use the chevy rods. If what I've read is accurate that should put me at about 507" plus the slight overbore. Probably do a main girdle as well.
 

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Are you going to bore it? Or are you looking for STD bore pistons?
 

PJ McCoy

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Both of my blocks (the one in the car is the original with 66k miles on it but it did get a full machine shop treatment at 45k miles but the bores were literally perfect so stock dimensions. The second block is out of a '68 ambulance with about 50k miles on it but it needs at least new cam bearings) are in stock dimensions. The goal is about 600-650 to the wheels on a 'conservative' tune so I need the motor to be making about 800 to get there. That is at the upper range of the duty cycle on the 60 lb/ft injectors but I'll be pretty close I think. Certainly going to run out of head flow pretty quick so we'll have to massage the bejesus out of those until I can save up the coin to get the nice aluminum ones.

I misquoted the turbo - it's a Work S475 which is a 75mm compressor with a 96/88mm turbine, 1.32 A/R twin scroll (T6).

Starting to think I might start off with sending the spare block to the machine shop with @PSYKO_Inc 's idea of using 454 pistons just for availability. I need to check pricing on the offset grind of the crank to use the chevy rods. If what I've read is accurate that should put me at about 507" plus the slight overbore. Probably do a main girdle as well.
More like 540 if you bore 60 over
 

Psychoholic

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Are you going to bore it? Or are you looking for STD bore pistons?
The motor in my car now has so little mileage on it that I suspect it really doesn't need much machine work since it was refreshed last so I was hoping to be able to get out of this build without having to visit the machine shop at all but if I can't get the pistons I want in a Cadillac variant then doing some big block chevy stuff seems like my only real option.
 

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You can definitely get them. Call CadCo. If you put forged pistons in a standard bore that has a couple of thousandths of wear you better be ready for the cold start up rattle, and possibly some normal driving rattle. If you are unsure of what I am talking about, then contact some piston manufacturers about it, don't look for the answer on forums, they'll run you ragged with opinion. I've already given you one too many opinions.

BTW, I'd watch Holdener finish up his engine, not CadCo's engine, and watch him punish it at his shop, not CadCo's shop. The CadCo engine will be interesting to set a standard for a nicely rebuilt stocker, we know it has rockers and forged pistons. I bet it has rod bolts, bigger valves, maybe rods, rebalanced, etc, but we'll really never know. I bet Holdener's stock piston/rod/gapped ring combo does better than we think...……………….unless CadCo talks him into fixing 'inhererent Caddy problems' while he has it apart. Hopefully he just gets the oiling system good, gaps the rings, and sends it to the boostamometer. This is what I'm doing right now with one of my spare 500 engines.

BTW #2, there is a set of TRW forged 0.060" over 472 pistons for $299 with free shipping. That's at least $400 cheaper than you'll find anything else. You'd have to be careful with cam selection though.
 

Psychoholic

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To be totally honest @5one9 at this point I'm just doing some bench racing. It's going to be months before we are even close to putting the gi-normous turbo on the car and it's just us putting the fuel injection system on. When I put the motor in the car we broke the dipstick so I had to put some Ford jobber in there to just fill the hole. I need to pull the motor to put a new one in and in the classic 'while you're in there' syndrome way of doing things I figure I might as well do pistons/rods while the motor is out so I can get ready for the 'big stupid' project of breathing heavily on it.

This morning was like Christmas with RichardH's videos! My friends and I are actively in a group chat discussing what we're seeing since the last pull (the 416/552 one with the low compression is essentially the combo I have right now but with the 76cc heads and the same compression). I am chomping at the bit to see what he does with all his normal combination of great stuff. I'm positively addicted to this dude's videos. I'll watch him dyno stuff I never even remotely would care about.

Where are you seeing those pistons?
 

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Bench racing here too. I'm waiting on him to finish up before making the big decisions of intake manifold and rocker arms. About everything else I already have or it's cheap enough to buy at any time. This latest video tells me a lot about the current setup in my Malibu. I should be around the 550hp/650tq figure that I have always assumed.

I am also entertaining the thought of putting the 'budget' engine in the Malibu, and putting the Malibu engine/transmission over into the '57 F100 since everything is forged/studded/o-ringed and much more ready for boost. That is a big decision to me, although it does seem kind of obvious.
 

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When I put the motor in the car we broke the dipstick so I had to put some Ford jobber in there to just fill the hole. I need to pull the motor to put a new one in
I'm pretty convinced that it's not possible to remove one of these dipstick tubes without breaking it. I needed to switch mine from rear sump to front sump, and I broke mine in the process. I went with a piece of 3/8 brake tubing for the replacement tube. It's a tight enough press fit that I'm not worried about it coming out or shifting, although if I were to do it again I would have probably put it on the drill press and sanded down the OD with some sandpaper so it wouldn't be quite as tight of a press fit in the block. The line I got from Napa had some kind of plastic coating that I burned off with a torch and hit with a wire brush in order to get the OD close enough to work. I also beveled the edge with a grinder to keep it from snagging on the hole. At the top of the tube, I used a flare tool to put a very slight flare in the end so the dipstick would seat in it. Once I'm sure the tube will clear the crank, I will add 5 quarts of oil, prime the pump to make sure the filter is full, then trim the tube until the stick registers full. Still need to remove the sticker residue, and I'm probably going to hit it with some matching paint since I'm not really digging the OD green look. 20200910_211720.jpg
 

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Oil pan has to be off. The dipstick tube (either front or rear type) is installed and then bent into the correct curve below the oil pan rail. The bend must be undone as the tube is tapped out of the block from the bottom. Absolutely ignorant engineering, but that's what you're up against.

Ball bearing also drives out from the bottom if you are changing from front to rear or rear to front. New ball bearing drives in flush-ish and very easily. Front and rear hole dipstick setups are different too. Hilarious!
 

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Bench racing here too. I'm waiting on him to finish up before making the big decisions of intake manifold and rocker arms. About everything else I already have or it's cheap enough to buy at any time. This latest video tells me a lot about the current setup in my Malibu. I should be around the 550hp/650tq figure that I have always assumed.

I am also entertaining the thought of putting the 'budget' engine in the Malibu, and putting the Malibu engine/transmission over into the '57 F100 since everything is forged/studded/o-ringed and much more ready for boost. That is a big decision to me, although it does seem kind of obvious.
SWAP IT!!!! MAN!!! WHY ARE YOU WAITING???
 

PJ McCoy

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Oil pan has to be off. The dipstick tube (either front or rear type) is installed and then bent into the correct curve below the oil pan rail. The bend must be undone as the tube is tapped out of the block from the bottom. Absolutely ignorant engineering, but that's what you're up against.

Ball bearing also drives out from the bottom if you are changing from front to rear or rear to front. New ball bearing drives in flush-ish and very easily. Front and rear hole dipstick setups are different too. Hilarious!
Careful bending that tube. I had mine hit the crank and didn't know it. I checked with the dip stick in the dip tube. Nothing touched the crank. After start up, for the first time tik tik tik. Out comes the motor and off came that pan. I didn't count for the new 368 pan I used, I checked it with a custome basterized by me, oil pan. All was good. Bro D, me tioned a caddy 368 pan would fit if dimpled in the front. Actually found one and out it on. Not good. Hope this helps.
 
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