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Thanks for the explanation. Never knew mains caps could be bolted in like that. Seems excessive for such little power. But I guess now you have no excuse for 20lbs of boost and 1500hp? We can't have little Nismo GTR V6s making 1200+hp now can we
When you say you can buy 10 thousandths under size bearings from Ford, is this a Duratec part no. you're referring to?
Since it spun a bearing, hopefully you won't need to line bore the mains oversize.
IIRC there is an updated small end rod bearing that has a better oil relief in it, introduced in the 470hp cars.
The rod bearings are from the 3.0L Duratec, and are standard aluminum bearings. They are Ford parts. I'll probably replace them with Clevite, but honestly they are the same.
The main bearings are from a 3.5L Duratech and are the same type.
Dropped the crank off today to be magnafluxed, straightened, and then ground. Not in a hurry, which is a good thing as it's race season and they are busy.
I'm probably going to have the block line bored and honed, but one step at a time. Right now I've filled the head domes with oil to see if I have a bent valve. Doesn't look like it, but they will all come up to have new valve seals and guides.
I've always felt that stock is king on the street and so I will probably rebuild it using Ford OEM/replacement parts. I will replace all twelve rods/pistons/rings, the valve lashes and roller rockers.
You should consider replacing (not machining) the liners. There is some talk on PistonHeads about there being some kind of manufacturing defect with the British made liners that caused them to wear out prematurely. Later German made V12s apparently didn't exhibit the problem. See this link: https://www.pistonheads.com/gassing/...f=70&t=1802422
Still worth measuring ovality and see how out of round its become. Whats the mileage and VIN?
Good to know and thanks for the link. In looking at the motor, the wear is consistent with not changing the oil, and then running it 6 quarts low, and not because of bad materials. I cleaned the bores and did a couple of spot checks (top, mid, bottom) of stroke on cylinders that spun bearings and the rear pistons and they are within .001-.002".
Car has 24K miles, original tires, original air filters (even though the AM records show it being serviced). The Oil Filter may have been changed, but I see no evidence of that fact. I have seen rows of modern BMW engines with similar abuse of the top end based on oil being run past viability due to extended warranties. Pretty amazing given how cheap oil is.
If I was using a dealer to change my oil, I'd buy a oil pump and suck it out through the dipstick in between changes and replace it. You can get most of it out through the dipstick.
After some considerable time... The crankshaft is on it's way home. Had the following work performed by Marine Crankshafts. Dave is legendary in the rebuild community and is felt to do great work in a dependable manner.
Here's the text from the invoice:
Aston Martin V12
Inspect & magnaflux
Repair #3 rod journal (weld)
Grind rods to.. 1.9574" - 1.9576"
(Clevite rod bearings # CB1772P)
Grind mains to.. 2.6470" - 2.6472"
(Clevite separate main bearings # MB-3841A)
Ion-Plasma nitride, straighten & micro-polish all journals
All for a bargain price of $900...
I'm having the cams and heads taken care of at webcamshafts. Melissa did the regrind on a Ferrari V-8 for me, and it seemed logical and worthwhile to just crate them up and ship them out to SoCal...
Still collecting parts, and cleaning/repairing little things around the car (amazing # of bolts are rusted in place. I'm getting pretty good at removing and rethreading/replacing inserts.
I took the crank and the block to Precision Engine in Hyattsville to have the short block built up. New pistons, new conn rods, new undersize bearings.
He has an instagram account, so you can see some pictures of what the block looks like:
I dropped off the new oversize pistons and connecting rods at Precision Engine Machine in Hyattsville, MD. Michael had the block honed and trued, and spinning in the washing machine. Armed with new ARP bolts, new plain bearings, pistons, and connecting rods, and the newly refurbished crank, all he needs to do is balance the crank/rods/pistons and build up the short block.
Then I have to wait for Norland Cylinder Head Repair to modify the heads to accept plain bearings (from Dura-Bond) and I can finish building the motor!
Then I have to wait for Norland Cylinder Head Repair to modify the heads to accept plain bearings (from Dura-Bond) and I can finish building the motor!
Could you elaborate on this modification? I'm assuming, you're referring to camshaft bearings? What is special about the original bearings?
Are the new pistons a standard ford part or did you get them custom made?
Could you elaborate on this modification? I'm assuming, you're referring to camshaft bearings? What is special about the original bearings?
Are the new pistons a standard ford part or did you get them custom made?
The camshafts in the Ford Duratec style engines (which the V12 derives much from) don't run in bearings, as is common in other motors. Rather, the Aluminum heads are high in Silica, and thus harder than normal Aluminum. Because Cams run at 1/2 engine speed and don't have a lot of load, you can get away with this type of design. However, when the rod bearings let go they filled the oil passages with metal, which scoured the camshaft journals. The solution the Mustang guys use is these: https://www.dura-bondbearing.com/engine/ bearings. A boring bar cuts an oversize hole and then bearing halves are inserted which the camshaft runs in. This allows a standard tri-metal plain bearing to be used.
The connecting rods are standard Ford Conn Rods (#AL8Z-6200-A), and the pistons are Enginetec Brand, .01" oversize for the Ford Duratec V-6 3.0L. This is not a highly stressed motor, so they are just stock parts. The Conn Rods have the upgraded Ford small end plain bearings, but other than that are identical to those in the AM.
While I wait for the Cylinder Heads to come back from Norland, I have been tracking what is happening at Precision Engine. As Mike has posted these to Instagram, I thought I would just share the links as he builds up the short block. Some nice videos of the crank being balanced, and other photos of the internals.
04-01-2019, 09:54 PM
