Upgrade rod bolts?

[fred cook]

Looks like I will have to go back into my freshly built 3.3SS engine to replace the oil pump and pump to block seals due to one or more of them being incorrectly manufactured. When I built the engine, I used a new set of standard 3.0 L (10mm) rod bolts. While I'm in there, should I spend the $$$ to replace the new stock rod bolts with a set of ARP bolts? Keep in mind that this will be an engine that will be limited to 7,000 rpms as I am using the CIS system. I know that the ARP bolts are superior to the stock ones, but will the engine speeds expected stress the stock bolts excessively?
What say ye?

Thks,

[HawgRyder]

Fred...all a matter of insurance.
How much is a complete rebuild worth?
Compare that to the peace of mind you will have with a set of known very good hardware inside.
Your choice...like the old commercial said..."you can pay me now...or pay me later".
Bob

[Das Schnell Ei]

If you are already inside the case I would swap them out....cheap peace of mind

[ajwans]

It's not just that ARP bolts are stronger, your stock bolts are torque to yield which means that they can only be used once as they are now permanently deformed.

andy

[fred cook]

Originally Posted by ajwans

It's not just that ARP bolts are stronger, your stock bolts are torque to yield which means that they can only be used once as they are now permanently deformed.

andy

I will not need to remove the rods from the crankshaft, therefore I could just leave them as they are. On the other hand, a set of ARP bolts for $230 or so is a very small percentage of the total engine build costs!

[304065]

Yes, do it.

[PFM]

Fred,

7000 RPM sounds ok on the stock bolts until a missed gear change hits second not fourth.

Yes a small fraction of the total.

[MBruns]

You will need to resize the big end housing bore when you change bolts with a different tq. value, figure on avg. 40.00 per rod plus bolts
Mike Bruns

[ChrisBennet]

Originally Posted by MBruns

You will need to resize the big end housing bore when you change bolts with a different tq. value, figure on avg. 40.00 per rod plus bolts
Mike Bruns

What Mike means is that you will need to deliver the rods with the new ARP rod bolts to your machine shop and have the big end resized. You can't just pop the old stock ones out and put in new ones. The ARP rod bolts use a different "squeeze" and will distort the big end differently. The machinist machines the rods in their assembled state i.e. all torqued up.

Personally, wouldn't worry about the stock 3.0L rod bolts. It has probably happened but I've never heard of a stock 3.0L rod bolt failing. Compare the price/availability of used 3.0L and 3.2L cranks sometime . Hint, a good used 3.2L crank is a lot rarer...

Unless you are a gifted driver, it's pretty easy to miss a shift with a 915 transmission.
If you are concerned about damage from a missed shift (I would be), double check your piston to valve clearance and use a stiffer valve spring. The stiffer spring will cost a tiny bit of horsepower but it can make the difference between saying "oops!" on an overrev and cutting your track day short with bent valves.

[fred cook]

Thanks, all. Lots of wisdom shared here! I appreciate everyone's input.

[nocarrier]

Just curious but what brand of main bearings are you using?

I'd save some money and get the genuine ones.

[fred cook]

Originally Posted by nocarrier

Just curious but what brand of main bearings are you using?

I'd save some money and get the genuine ones.

The main and rod bearings are from PP and are the Glyco brand. I compared the thickness of the old (but in very good condition) bearings to the new Glycos to make certain that they (the Glycos) were not going to be problematic. It turned out that the Glyco bearings were very slightly thicker than the old bearings which is how it should be. All journals on the crank measured well within the standard range and oil pressure was good in the original engine. At this point, I am fairly certain that the problem is being caused by one or more of the oil pump or case seals.

[nocarrier]

While you are in there, I'd remove all of the main bearings and carefully inspect them for any manufacturing flaws. If you have the means to measure them I'd do that as well.

When you get the genuine ones, you can see where each one is measured for thickness.

Here is a picture of a glyco bearing with a manufacturing defect in the back if the shell.

Ive also seen where the bearings have what looks like a "paint drip" for lack of a better term on the back of the bearing shells.

[Ken911]

as far as resizing the rod ends when you swap bolts. Measure first. they might be fine. mine were ok i plastigauged all of them and they were perfect. if they end up too tight then get them resized.