Mill the pistons?
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Elder User
Joined: Apr 2002
Posts: 950
Likes: 2
From: West Bend
Mill the pistons?
So I got the heads off my donor 6.9 last night and it appears that cylinder 2 must have eaten a glow plug tip at some point and possibly cylinder 4 as it's got one single dent in it. I'm debating leaving it alone or should i mill the pistons down? She's getting Victor Reinz head gaskets and ARP studs along with a turbo.
I think Dave S has milled pistons? What's safe to go on these? Or should I stick it together and not worry about it until a full rebuild??
Thanks! I can grab some pictures later if anyone wants to see 'em.
Edit: I have a CNC machine in my shop so milling it is just a matter of pulling them and milling them.. My issue is drawing the line of where to stop lol.
Chris
I think Dave S has milled pistons? What's safe to go on these? Or should I stick it together and not worry about it until a full rebuild??
Thanks! I can grab some pictures later if anyone wants to see 'em.
Edit: I have a CNC machine in my shop so milling it is just a matter of pulling them and milling them.. My issue is drawing the line of where to stop lol.
Chris
Methanoholic
Joined: Mar 2009
Posts: 6,442
Likes: 8
From: Maine (NorCal Native)
As I understand it, Dave S. milled his tops .045.
Remember turning the tops lowers the compression, thus harder cold starts...
Dave S. states his starts good, he lives in the snow belt!
-Enjoy
fh : )_~
Remember turning the tops lowers the compression, thus harder cold starts...
Dave S. states his starts good, he lives in the snow belt!
-Enjoy
fh : )_~
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Elder User
Joined: Apr 2002
Posts: 950
Likes: 2
From: West Bend
That's what makes milling them so tempting... I figure the small surface dents are the "better do that" reason lol
Ok so maybe I'm looking for an excuse to mill them hah
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
With the cost of fuel, which again is on the rise, and the amount of fuel you need to run to get thet high boost, if I had was going to build my engine again, I probably would not mill the pistons.
I think I would just leave the pistons alone, run head studs and limit the boost to around 20 PSI.
Yes it's fun, but you still pay for that fun every time you pull up to the fuel pumps.
17 MPG, I wish.
Try 12 MPG for a yearly average.
I took 40 thou off mine, dropped the compression ratio to 20.25 to 1.
Little harder to start cold.
Slightly lower torque at very low RPM's.
Plus if you stay under 20 PSI, you don't have all the issues I had with blowing the valley pan, exhaust manifold gaskets and exhaust plumbing joint leaks.
If you do plan on higher boost numbers, you also need to think hard about an intercooler on summer days.
I wish I could get my truck to run like it does at sub zero temps during the summer.
I think I would just leave the pistons alone, run head studs and limit the boost to around 20 PSI.
Yes it's fun, but you still pay for that fun every time you pull up to the fuel pumps.
17 MPG, I wish.
Try 12 MPG for a yearly average.
I took 40 thou off mine, dropped the compression ratio to 20.25 to 1.
Little harder to start cold.
Slightly lower torque at very low RPM's.
Plus if you stay under 20 PSI, you don't have all the issues I had with blowing the valley pan, exhaust manifold gaskets and exhaust plumbing joint leaks.
If you do plan on higher boost numbers, you also need to think hard about an intercooler on summer days.
I wish I could get my truck to run like it does at sub zero temps during the summer.
Thread Starter
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Elder User
Joined: Apr 2002
Posts: 950
Likes: 2
From: West Bend
Thanks for the input Dave!
I think I'll stick to stock right now then and just dress them up to make sure there's no sharp edges. She's my plow truck and nearly everyone I know is giving me crap that it'll never start in winter so for now the better starting the better to prove 'em wrong lol. With the ARP head studs I'll keep her to <20 psi, double coat the intake valley pan with copper spray and call it good.
I wish I could pull 12mpg with my gasser...
I think I'll stick to stock right now then and just dress them up to make sure there's no sharp edges. She's my plow truck and nearly everyone I know is giving me crap that it'll never start in winter so for now the better starting the better to prove 'em wrong lol. With the ARP head studs I'll keep her to <20 psi, double coat the intake valley pan with copper spray and call it good.
I wish I could pull 12mpg with my gasser...
Senior User
Joined: Sep 2009
Posts: 204
Likes: 1
From: in denial.
where do you guys get the arp stud kit ? i emailed them and they stated they had no kit for the 7.3...........if i could find em id buy em too !
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Lead Driver
Joined: Nov 2003
Posts: 6,900
Likes: 3
From: Campbell River, B.C.
I took 20 thou off of mine and seem to be able to get good economy and cold start performance. Part of the reason was for to survive boost pressures a little better, another reason was knowing that the heads had been milled down and feeling better about piston to valve running clearance. Last couple trips towing had gave me 17 MPG @ 62 MPH. Tall gearing helps though since thats at about 1500 RPM. Boring as heck to cruise that slow, but it gained me a solid 2 MPG for the same trip. I also had to drop back the timing a little recently because the engine was eating glow plugs. Seems to be happy right now and idles smoke free right off cold start. I'm also running stanadyne fuel lubricity suppliment if that makes any difference?
Running without the fan well into april seems to be helping the city fuel economy stay 1-2MPG higher than usual. Yesterday was a bit warmer and I can see I will want to have the AC working in a couple weeks so it will probably go back on very soon.
I hate driving it for short trips into town though. Bad MPGs and hard on the engine running it almost completely withing the warmup period. I have another vehicle that I'm working on for a parts runner or other little "go getter" duties so the beast can stick to what it does best - wearing down the local freeway. My truck is also a feather weight compared to some others here at a mere 6000lbs.
Running without the fan well into april seems to be helping the city fuel economy stay 1-2MPG higher than usual. Yesterday was a bit warmer and I can see I will want to have the AC working in a couple weeks so it will probably go back on very soon.
I hate driving it for short trips into town though. Bad MPGs and hard on the engine running it almost completely withing the warmup period. I have another vehicle that I'm working on for a parts runner or other little "go getter" duties so the beast can stick to what it does best - wearing down the local freeway. My truck is also a feather weight compared to some others here at a mere 6000lbs.
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Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
I don't remember what application the guys using ARP head studs on the 7.3 were originally for, but I do remember they has to cut the length down some.
For the 6.9, Summit Racing has them for a bit over 200 dollars.
For the 6.9, Summit Racing has them for a bit over 200 dollars.
Lead Driver
Joined: Nov 2003
Posts: 6,900
Likes: 3
From: Campbell River, B.C.
I put the word out on the other forum and got this info:
AR7.000lb - stud
ARN12-1 - nut
ARW78N - washer
If you were to call up ARP, they should be able to give you a price on those part numbers.
Hope it helps
DPS was selling a stud kit for the 7.3 IDI for over $700 for a while.
AR7.000lb - stud
ARN12-1 - nut
ARW78N - washer
If you were to call up ARP, they should be able to give you a price on those part numbers.
Hope it helps
DPS was selling a stud kit for the 7.3 IDI for over $700 for a while.
Fleet Owner
Joined: Jul 2006
Posts: 20,389
Likes: 850
From: Mi'kma'ki
Quite a few folks have had them break, so those aren't worth what they charge. Go with ARP, a little more than the 6.9 studs, just a little more work to get them to fit right.
Here's how to order them:
The ARP studs that fit our 7.3 motor are part number AR7.00-1LB at $8.45 each without nuts or washers. They are about 1/4 inch too long but they fit fine. Both Typ4 (Russ) and I are running them. They are 200,000 lbs psi where the new Ford head bolts are only 153,000 lbs psi breaking strength.
The only stud that comes close they make is 7 inches long with 1/2x13 threads on the bottom and 1/2x20 threads on top.
Its just as Russ posted. These studs for our motors were not designed for them but they fit. They are 7 inches long and about 1/4 to 3/8 inch too long. What happens being longer than needed is the stud is sticking out thru the nut so far that the threads touch the deep socket and will iterfere with final torque. Maching orr or grinding off the top threads will stop this from happening and you will still have enough hex for installation. Do not remove any of the bottom threads thinking that would lower the overall length of stud in the motor. That just wont happen because the studs fit into the block a specific way. Shortening them in the block will only cause you to loose some of the clamping force. Not a good thing. The top of the thread past the nut is doing nothing for clamping force so loose that and all will be fine. Or be very careful when torqueing.
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Here's how to order them:
The ARP studs that fit our 7.3 motor are part number AR7.00-1LB at $8.45 each without nuts or washers. They are about 1/4 inch too long but they fit fine. Both Typ4 (Russ) and I are running them. They are 200,000 lbs psi where the new Ford head bolts are only 153,000 lbs psi breaking strength.
The only stud that comes close they make is 7 inches long with 1/2x13 threads on the bottom and 1/2x20 threads on top.
Its just as Russ posted. These studs for our motors were not designed for them but they fit. They are 7 inches long and about 1/4 to 3/8 inch too long. What happens being longer than needed is the stud is sticking out thru the nut so far that the threads touch the deep socket and will iterfere with final torque. Maching orr or grinding off the top threads will stop this from happening and you will still have enough hex for installation. Do not remove any of the bottom threads thinking that would lower the overall length of stud in the motor. That just wont happen because the studs fit into the block a specific way. Shortening them in the block will only cause you to loose some of the clamping force. Not a good thing. The top of the thread past the nut is doing nothing for clamping force so loose that and all will be fine. Or be very careful when torqueing.
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Jim Allen
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
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