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Old 10-05-2012, 11:32 AM
oldbogie oldbogie is offline
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Originally Posted by Icejeep View Post
Well guy's I have decided what i'm going to do..
I'we got my hands over a set of GM rods that have been worked, Arp bolts, beam polished and weight matched, so they should be up for the task. As far as piston's goes i'm decided to buy flat top pistons from speed pro.
I can get a set of ported 461 Double hump heads that are in good condition. would that be acceptable choice for this mild engine, and work well with my other components ?

So what we are talking about here is 350 sbc w. 10.25:1 compression ratio.
Ported #461 double hump heads, Edelbrock Performer or Edelbrock Victor intake manifold, haven't decided yet. Holley HP 850 carburetor
Camshaft is street roller from comp cams #12-769 - 12-769-8 - Xtreme Energy
1.3/4" headers with dual 3" exhaust.

Best regards.
This is a fairly mild engine in terms of power output, but I'm guessing that going into ajeep for rock crawling it's going to spend a lot of time in the high rev, high power out put range with probably a lot of shock loading from frequent excersions up and down the throttle.

If those assumptions are good, I certainly wouldn't use hypereutectic pistons and rebuilt stock rods. This kind of usage drives on a better rod and a forged piston, however it doesn't need to be a 2618 alloy take me racing piston; the high silicon types of VMS 75 or 4032 alloy offer high strength, though not as much as 2618, but with better in-bore dimensional stability. Given your climate I think that the high silicon alloy will be better as it can be run with a tighter skirt clearance when cold, where the 2618 has to be warmed up to get the proper clearance and if shock loaded before that happens they risk cracking a skirt especially with piston that have no pin offset as these allow the piston to snap over hard as the thrust loading changes direction. The high silcon alloy's tighter fit and especially if combined with an offset pin keeps you out of this area of potential damage to the piston and provides a more stable ring alignment which is better for oil control and power output. I'd run a gapless second ring set on this like the Total Seal or Childs and Albert.

For a rod that perfoms way up scale from what it costs the SCAT 6 inch (also in 5.7), floating pin part number SCR6A7 is one tough customer. It has several features I really like in a high RPM engine in that it uses cap screws to retain the cap, 7/16ths ARP in this case and it has a centered strap section on the cap to beef it up so it doesn't distort from the jerk loads at high RPM when the piston is pulled down on the intake stroke. In addition, toward reinforcing this problem the cap locates into the shank with dowel pins which help react the resulting pinch loads from the jerk down, also, the interface boss is extended outboard of the fastener which enlarges the pinch load reaction platform to also help keep the cap from both side loading the capscrews and from bending the cap to where it pinches the rod bearing inward at the cap to shank interface. This is the sequence that is the start of the most common rod failure. As the piston is jerked down the bore at high RPM, the cap wants to stretch in the center. This causes the interface at the shank to bend open on the bearing side and close outboard of the bolt. This wants to bend the bolt and push the bearing edge into the rod journal. When this happens, the oil wedge is wiped out, the bearing overheats grabbing the journal then it spins in the rod's big end bore. When all this finally seizes the rod gets ripped apart just above the big end. The design of this SCAT rod provides as much resistance to this initiating event as you can put into a rod. you've got to look upscale to Crower and Lunati rods to find a comprable design. For some close up pictures of this thing follow the link White Performance Detail Description This is a lot of rod for the money.

Bogie
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