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-   -   Rods and Pistons (http://www.clubcobra.com/forums/fe-talk/113745-rods-pistons.html)

redmt 12-28-2011 11:17 AM
Rods and Pistons
 
I'm lining up my ducks for a motor build for my Cobra. Target is 400 to 450hp + or - using a 428 stock block, and crank. Probably in the 9 to 1 range with E'brock heads. Hyd roller set up and Blue Thunder intake w/ stock 428 factory carb. B2 has recommended the Probe pistons so I'll more than likely go with Brents recommendation unless something else pops up in the barely used dept. I have several sets of C8 rods but after 40 years of abuse and unknown heritage, I just don't trust them. Any suggestions?

ZOERA-SC7XX 12-28-2011 11:39 AM
Rods should be okay unless you plan on racing. Just have them resized for trueness and (NDT, aka Zyglo or X-ray) inspected by the engine builder or an aircraft source and install good rod cap bolts. Dish top pistons will give you between 9.0:1 and 10.0:1 comp ratio, depending in the cc size of your heads. These components should perform well for years within the 400-500 HP range, as long as you red-line the thing at 5500.

blykins 12-28-2011 03:08 PM
By the time you pay to have the rods magnafluxed, then resized, fitted with good quality rod bolts, etc., you're only $100-200 away from a set of Scat rods.

That would personally be my advice, then you wouldn't have to worry about anything in the rotating assembly.

ZOERA-SC7XX 12-28-2011 03:29 PM
I'd rather have a good set of Ford rods. To each his own.

redmt 12-28-2011 03:34 PM
Quote:
Originally Posted by ZOERA-SC7XX (Post 1167689)
I'd rather have a good set of Ford rods. To each his own.
I'm with you on that one, but I've been running the same rods for about 30 years in this motor. They are already beam polished and balanced, and I can Zyglo myself. Something about them though, I don't trust them 100% I'll stretch measure them when I get them out and go from there.

blykins 12-28-2011 03:37 PM
I can understand that, and you're absolutely correct....to each his own.

However, as an engine builder, I would rather not have to worry about a 40 year old rod failing. Even when magnafluxed, it's hard to account for the years of fatigue stress that the rods go through.

Would they work? They would probably work just fine. But if a bullet proof bottom end (for 500hp) is just within $200-300, that's a small amount over the cost of an entire engine build.

Jerry Clayton 12-28-2011 04:01 PM
the stress on those rods from the press fit of the bolts and the tension from being torqued up is much more than the stress of a running engine!

Barry_R 12-28-2011 04:09 PM
How many 427 blocks with windows from broken "perfectly good" old Ford rods would you like me to show you? The factory rods were great in 1966, decent in '76, OK in '86, and we are now 25 YEARS after that.

There is no nondestructive test available that can tell you when fatigue will fail the part. Wrong place to save a dollar.

If you're going stock stroke the Probes are your best bet - compression with the dished ones still ends up in the middle 9s with a 76cc edelbrock. If you go stroker you can get a Mahle for around 9:1 with the 72cc heads.


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