identification help...cam nuts, oil pump, and...

[tom1394racing]

Lars

Here's the details on my 95X70.4 RSR spec motor:

Another RSR Clone Project - Dyno Day

One thing to look out for. The stock SC heads have a combustion chamber volume of 90 CC. In order to get the 10.5 CR with these Mahle pistons, the heads need to be cut back to 84 CC volume. At the stock size, the CR is a little below 10.0

[tabasco]

Nice stuff !

Correct me if I'm wrong, but I think you would need a 930/02 or 930/12 case to run the small crank. I would guess your engine is a 3.0L.

-Guillaume

[speedo]

When I bought the engine...I hoped for the best...and feared for the worst. So far I have been lucky. There are a lot of good nice parts, and interesting machine work. The cams look great, I only noticed one wear area on the #5 rocker, and minimal on the coresponding area on the cam. The towers look clean
And the heads are going out to be cleaned and checked over. I want to know what springs I have

I turned my attention to the cylinders. I had seen some scoring on the inside of the bottom of the cylinder cuff on #6 when I was looking at the crank and rods through the sump cover. I didn't think much of it, figuring I would pull the cylinders and see what shape the pistons were in. Pulled #1 and noticed some striations on the inside top and bottoms of the cylinder walls...more than normal wear. Hmmm not good. Pulled 2-6 and started not to feel so great...this is the worst of it, generally on the top and bottoms of the walls.



In a couple of the cylinders, the striations have become grooves...not good. I turned my attention to the pistons...now I know why the PO said the engine smoked




I looked at the orientation of the rings, and while they where not correctly 120 degrees apart, the rings themselves did not look damaged.

[speedo]

I couldn't figure out why the tops and bottoms looked "scored" till I remembered that the engine had gone into the shop for broken head studs. The shop did a great job of replacing the ARP studs. There was little consistancy in the heght of the studs. So I laid a straight edge across the tops of the studs and found a variation as much as 3/16s


While the ARP studs use a dedicated nut vs the the barrel nut, and the cylinders were torqued correctly...I'm guessing the cylinder damage was caused by the cylinders "rocking under load" when the factory studs broke. I don't know how many studs broke, but it work make sense that the pistons were not happy and scored the cylinders as they moved. The shop that replaced the broken studs probably just reassembled the P and Cs as they were and paid no attention to the scoring. Thus the engine allowed oil by the rings and smoked. If someone wants to weigh in here...feel free. I guess the cylinders can be re-plated (nicasiled) , but I'm not sure what I can do about the pistons. Pity as the domes looke so nice. I am more used to opening up engines to find the domes have met with things dropped in the intakes or valves burning and dropping. In those cases, the cylinder walls were still nice, but the domes and heads were trashed. Depending on what folks think caused this...I may go ahead and split the case. If this was potentially caused by debris in the oil, it would be crazy not to split the case and evaluate the bearing journals.

Looks like I may be in the market for some 10.5 Mahle RSR 95mm pistons?

Speedo

[lupin..the..3rd]

This looks like a cool project. I hope you'll change the color theme though. PO's choice of red and yellow = Ronald McDonalds. Do you want fries with that?

[KTL]

US Chrome or EBS can bore and replate them no problem. However given the level of scoring, its likely you'll need to overbore them.

Our Pricing | Cylinder re-plate | Big Bore Upgrade | Cylinder Exchange | Big Bore Kit | Cylinder Boring | Usnicom.com

Pistons are trashed. JE is always an option......

Cams can be reground or hardwelded to a more modern spec for your use. What are you looking to get out of the engine? I suspect the MFI setup is going to determine what cam you should go with.

I think you should split the case. Might find some ring/piston material down there.