since my heads off.....

[swankmetal]

... . what (else) should i do? i'm going to have the valves done. thinking about putting 60lb springs on (future e-brake). saw some marine pistons for sale. are they worth the trouble? it would be a good excuse to touch up the bottom end. she does have somewhere around 400,000 on her and i swear i can hear a knock. could just be the lower temps though (windows up). would i have to upgrade anything else for those pistons? are they the same compression?

 

["Mad Max"]

well, I'm going to be in the same situation soon, and I decided that since I'm going to have the engine out of the truck and the basic short block open, I'm going to go ahead and install ned bearings. Cummins ROcky Mountain is going to give the bottom end a once-over, mainly because it costs not a lot and it's that far down. The engine will be on a stand so it's the perfect time to do it. Will your engine be out of the truck? If so, now's the time.

- Sam

 

[swankmetal]

nope, blocks in the truck. i was thinking about pulling it, but don't really have the space. i'm guessing it would be a HUGE pain to do in the truck, eh?

 

[1stgen4evr]

head off

If you are working on the truck in your signature, you may be able to get the pan off and do whatever you like on the bottom end. I can tell you for absolutely sure that you can not do that on a twd 250. I am buttoning back up from an out of the frame rebuild on the 89. Heck of a chore. But I had no choice. Number six cylinder was galded severely.



One thing I would mention as to checking wear on your cylinders. You can still have visible crosshatch in the major part of the cylinder but have significant wear at the last eighth of an inch at the top of the ring travel. We were building an engine last month and going second over on the pistons. Some of the cylinders would not clear at the very top of the ring travel. I should mention that this engine had closer to twice the hours of service as yours. If the marine pistons have the rings in the exact same location, you would be ok but seems to me you are chancing trouble. If you have no oil consumption, good oil pressure, and the cylinders look good, do the work you plan on the head and clamp it back on. When you get to about 600k, pull the engine out and build a screamer.



James

 

[JLEONARD]

When your head if off...

that is a good time to wash your hat. :-laf :-laf

Sorry... I figured you needed a break.

Jay

 

[dpuckett]

Ditto everything that 1stGen said- I know a guy who tore down his 1990 model at about 350K- it had been worked pretty hard for an old nonIC truck- and it all was still within new spec. 5K oil changes with Rotella and a $4 Donaldson filter. These engines just dont hardly get worked enough in a pickup application to do any wear. They were designed in the early 80s as a 250 or 300 HP stationary power unit.



As for your knock, I'd suspect a fuel system issue before bottom end- check your injectors, and maybe get a refresh on your pump while it's all apart. Get a stage 3 port... ... I'd definitely go for the HD exhaust springs- maybe both intake and exhaust for future high RPM running- they dont cost that much, I believe.



Daniel

 

[swankmetal]

thanks for the tips. i'll take a closer look at the top of the cylinder. while it's apart i'm definitely going to have the squiters checked. what kind of freshening up could the pump need? the guy i bought it from said that he put a new pump on not that long ago. would it be a matter of pulling and taking to a fuel shop?

 

[swankmetal]

here's a pic of the top of the cylinder wall. is this what you were talking about? if so, is it bad enough to fix now?

 

[swankmetal]

also, what do you think about the carbon on this piston? looks like it could be problematic to me.

 

[1stgen4evr]

cylinder wear

If the cylinder is typical of all the others, it is fine. Doesn't the cross hatch go right to the top of travel? The carbon is about like every one I have ever pulled the head off unless it was maybe the one I droped a screw in when I was building it.



Looks fine to me.



James

 

[swankmetal]

cool!!!!! thanks for taking a look.



dave