Should I replace Rod bolts

[cmcfaul]

I am rebuilding my 73 E 2.4 but not splitting the case. It has been suggested that I replace the rod bolts.

Is replacing the rod bolts recommended?

Can it be done without splitting the case?

Thanks,

Chris
73 911 E

[Flat6pac]

Why, theyre still holding arent they?
Bruce

[cmcfaul]

That was my thinking as well. Unless I hear otherwise I am going to leave them alone. The enging was not over reved. I broke a piston ring I believe because of detination resulting from high compression and a distributor that is advancing way too quickly.

Chris

[dhrcr911s]

I had the bolts in hand after a small over-rev.. put the engine back together without doing the bolts... Now i have a new case..... Nuf said, i'd do them.. you never know

[Steve@Rennsport]

If the engine was detonating hard enough to break rings, you need to replace the rod bearings and that means new bolts.

Have them resized, as well.

[Cupcar]

Originally Posted by dhrcr911s

I had the bolts in hand after a small over-rev.. put the engine back together without doing the bolts... Now i have a new case..... Nuf said, i'd do them.. you never know

Hmm..."bolts in hand", does that mean you re-used the rod bolts?

[cmcfaul]

Does replacing the rod bearings / bolts require the splitting of the case?

[Steve@Rennsport]

Originally Posted by cmcfaul

Does replacing the rod bearings / bolts require the splitting of the case?

Nossir, but does require removing the pistons and cylinders.

[cmcfaul]

NP there, already have the pistons laying limply from the case. Took two of the pistions off already. One for replacement the other to be used as an example. There is no free play in any of the pistons, rods, etc. Everything moves as smooth as silk. Pins were nice and tight and came out with a few gentel taps. replace them anyway?

Chris

[boyt911sc]

Originally Posted by Steve@Rennsport

If the engine was detonating hard enough to break rings, you need to replace the rod bearings and that means new bolts.

Have them resized, as well.

Steve,

I have a follow-up question regarding this subject. I'm starting to start my engine rebuild ('78 SC). I'm replacing the rod bolts and crank shaft bearings, do I need to have the case line bored and crankshaft resized? Could you elaborate your statement 'Have them resized, as well'. Thanks.

Tony

[YTNUKLR]

What he means is resize the big end of the rods (make them circular and the correct bore). Also install and ream new brass bushings to the correct sizes.

If your case and crank are standard size and within specifications you do not need to resize them.

[johndaroza]

question? big end of the rods (make them circular) Rods are not cirular in Porsches, untel loded, right? I,m asking because that is what I have learned in School for engine building

[Flieger]

I know when resizing old rods they need to be torqued to spec so I guess it follows logically that they come from the factory shaped such that they are circular only under load from the fasteners.

[Eagledriver]

While some modern engines may have big ends that are not round until high RPM, our aircooled engines don't have that. The big ends are perfectly round when the caps are torqued inplace. The rods are resized by shaving the mating surfaces and then machining the bore back to spec.

-Andy

[Flieger]

I think he meant loaded as in the bolts torqued, not rpm related.

[Ken911]

rod bolts are an easy thing and stock ones are also known to be weak