Main journal service limit?

[garrett73]

Does anyone know what the service limit is for the crank mains? Mine are already .020 over and I don't think a simple polishing will get them to like new shape. Does going .030 over have any significant negative effect ? I will be producing about 70 H.P. over stock (approx 260 HP) when it's all back together and really don't want to pull the motor again anytime soon.

[LMJD]

Mine are already .020 over and I don't think a simple polishing will get them to like new shape.

I assume you mean you already have an .020 undersize ground crank. If the journals won't polish up, yes, a .030 under crank is fairly common.

[garrett73]

Thanx for the input, I think I have an over conservitive mechanic / friend that wants to spend my cash on all new parts.

[LMJD]

If you have any doubts, why don't you check with a prominent local automotive machine shop? They're the ones that do the turning and have all the data at hand. After dealing with machine shops for over 3 decades I've found machinists can be compared to guys that want to fly an airplane. Neither learns JUST A LITTLE BIT about it, then goes and does it. I've always found them to be above average at their trade, very helpful and VERY smart at what they do.

On the other hand, the fastest way to seal one's fate in a bad way with a machinist, (but fun-watch'in from a distance) is for some yahoo off the street or mechanic with a puffed up ego, to take something in the shop and tell the machinist how to do his job.

[icanfixall]

I dought you can buy a "new" crank anymore. At least I have never sen one for dale.... Yet. How did you get 20 under on this? My experiance has been usually a 10 10 under is the standard for these cranks. They are plenty strong and they are forged steel of a proprity material just for our motors.

[cdnsarguy]

7.3 Engine spec sheet does indicate....... 10, 20 or 30 is allowed......I checked.

[94_turbo]

as ican said--how in h did that crank get that far?????? those cranks are H A R D ----and ring like a bell???? dirty oil from what????

[garrett73]

I bought this truck in 2000 it had the rebuilt motor in it. This is the first time I've had it apart myself, I figured since I was going to do some upgrades and produce more power it would be a good idea to know what the internals looked like. Glad I did, when I got it apart it was .010" under on the con rod journals and .020" under on the mains with some signifigant scoreing on thw #1 main and the first 2 con rod journals. I don't think the previous owner was as diligent with the oil changes as myself. He told me the rebuild was a waranty issue caused by bad coolant. It had the Ford rebuild sticker with serial number and has always run good. I'm getting rid of the dual mass flywheel, adding an ATS Turboo and exhaust upgrade as well as a Hypermax cold air intake. It should chug along pretty sweet after that.