Factory cam specs and propane questions.

[icanfixall]

Please explain more than you did about squaring the block deck and custom head gaskets.The pistons can be milled off to fit the block. The distance from the centerline of the crank to the top of the block is 11.137 to 11.141. Now if your pistons raise up more than the 31 thousands max you can get low compression pistons from Mahle like I did. They machine the wrist pin 10 thousands higher up in the piston plus you can machine off about 15 thousands off the top of the piston. They are between 570 and 580 thousands thick. Don't try to mill 20 thousands off though. The engineers I talked with at Mahle told me that could damage the top compression ring because its that much closer to the flame front. On my other motor I ran with the pistons coming out of the bores between 47 and 54 thousands without the valves and oistons playing tag. I do not recommend this at all. It was something I tried and got away with, thats all. No real reason for it other than thats how it went together. Sure, thats a weak excuse but thats how some things are learned here. The crankcase deck flatness is 0.003 overall and the finish is 63 to 125 in the micro finish. Thats not much either. The crankcase main bearing bore diameter is factory at between 3.3152 to 3.3162. Just in case you wanted to machine a try bar so you can chack the centerline distance.

 

[82F100SWB]

The lift discrepancy is from the stock cam's specs being listed with lobe lift, and the aftermarket one being listed with valve lift, including rocker arm ratio.
Now does anyone know the stock rocker ratio?

 

[tonkadoctor]

The block and crank are super strong there really is not much to worry about there. The IDI's were over built for stock power levels. Hence there reliability. My dad recently turbocharged his 7.3IDI with well over 350,000miles and is running 15 psi on stock everything. They are very strong motors. I put allot of time into coordinating with my machinist about my goals and what it would take. There are allot of things that can help these motors take more power just in machining. Balancing, deburing, line bore check, squaring/decking the block (do not do unless you can get a custom head gasket) are all a few things that can help make more power. The low RPM makes stuff like seen in performance race engine's not necessary.QUOTE]

Ah OK. Make sure you post video of the dyno run when you get it done.

 

[ttman4]

Gary & all, I'm watching all this.
I'll probably never do any of this "closer spec" stuff, but I think I/we all learn really good stuff here.
Makes things more understandable overall.
beside that, I'm a slow learner......
so you guys keep posting!!

 

[Joejohn]

I was trying to keep my compression high but still maintain clearance and have the motor producing even power. I did not mill my pistons, I used thicker head gaskets instead. I could have went with lower compression but the goal was to make the motor more like a true diesel were it almost could start without glow plugs. My machinist and I went back and fourth on this allot and I cant recall what all got set-up at what but your numbers look correct. It was over 1.5 years ago. It really did not take to much for us to square the block it was pretty close in stock form, but this varies from block to block.

 

[icanfixall]

Yes... Squaring the block AFTER the crank bores are align honed or milled. Whatever it takes down their. My second motor has the lo-comp pistons and I milled 14 thousands off those. They are all between 24 and 26 thousands up out of the cylinders. Factory specs state that 31 thousands is max but I know my other motor was 47 to 54 thousands up. If you make up a set of heads by porting them you need to cleanup the head precup chambers. This is not the precups. You really need to leave them alone. But the cast iron chambers in the heads are usually really ruff. I had a custom ball end mill made up and its 1.168. That drops the comp ratio about 1/2. I cut the chambers 60 thousands deeper in the heads. Years ago Ford had to make these motors run cleaner so the pulled the injectors up out of the heads 60 thousands. Its really hard to measure down into the injector bores plus any mistakes in there and you wipe out some threads. Then the injectors don't grip well and they will blow out like a Weatherby Nitro Express Rife. For those that have never heard of such a rifle it was the weapon of choice for the great white hunters in Africa for taking down big game and elephants. Nuff said there. Anyway these are just some of the things I experaminted with to make my motors run smoother because all the power pluses were all the same... I checked this by CCing the heads with the precups installed. The effective compression ratio was 21 to 1.... But with the pistons raising up out of the bores as much as they did I never did check what the end result on the C-r was. Didn't get a compression check till I burned the motor dawn. By that time the heads were cracked and the rings were bailing wire.

 

[Joejohn]

I want to say mine was up at like .052. I do remember checking that because I had a pain in the ass of a time choosing the correct dial indicator I wanted because I didn't have one and so I had to purchase one. I think it will work out. I just want as much power as it can produce and still have a reasonably long life.

 

[aaklingler]

joejohn, Where did you get your head gaskets?

 

[Joejohn]

T&P automotive from San Antonio Tx. I will double check but I believe H&H gaskets made them for me and they are about .020 thicker than normal if I recall. Both places are small.

 

[kent01]

I was trying to keep my compression high but still maintain clearance and have the motor producing even power. I did not mill my pistons, I used thicker head gaskets instead. I could have went with lower compression but the goal was to make the motor more like a true diesel were it almost could start without glow plugs. My machinist and I went back and fourth on this allot and I cant recall what all got set-up at what but your numbers look correct. It was over 1.5 years ago. It really did not take to much for us to square the block it was pretty close in stock form, but this varies from block to block.

I have dropped the compression on Idi engines by milling the pistons .
Milled .062 off. Got static compression down to the 17.1 range,
There are no starting issues, it allows for a lot more boost, more fuel and inj.timing. factory rods are only good for 250 horsepower to the ground in these engines. Any more than that is asking for failure. 7.3 power stroke rods can be used by narrowing the big end to IDI rod specs, head studs are a must for any performance upgrades. There are performance cams available as well. Performance tuned pumps and injectors are out there too. Realistic power levels above 250 to the ground are near the limits of this engines parimeters.
Kent.

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[79jasper]

I have dropped the compression on Idi engines by milling the pistons .
Milled .062 off. Got static compression down to the 17.1 range,
There are no starting issues, it allows for a lot more boost, more fuel and inj.timing. factory rods are only good for 250 horsepower to the ground in these engines. Any more than that is asking for failure. 7.3 power stroke rods can be used by narrowing the big end to IDI rod specs, head studs are a must for any performance upgrades. There are performance cams available as well. Performance tuned pumps and injectors are out there too. Realistic power levels above 250 to the ground are near the limits of this engines parimeters.
Kent.

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Not questioning what you're saying.
But, who are you? Lol

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[pelky350]

I feel like 250 isn't the limit, I bet I'm just about there now and I just have the basics. 90cc pump, stage1's, intake, exhaust, factory turbo with wheel upgraded and intercooler.

 

[snicklas]

Didn’t Justin get 400 before the rods went?

 

[no mufflers]

must have dug deep to get an 11 year old thread.

 

[Thewespaul]

Kent, respectably that information is wrong and very outdated.