Copperhead and Vintage Con rods

[mcbob]

Are the conrods for the Copperhead / Vintage engine the same as the P/N S175016 for the US820 .............. The Copperhead US 820 dropped a rod yesterday at the races i still have to do the strip down and cry check but it managed to do the rod failure at idle straight after start up so hopefully it won't be to messy inside and it wasn't reving high.

Stand by for a i want it now list
I already have a spare rod P/N S175016 on it's way and new needle rollers plus a set of the Dave Bonbright special bolts for the cap here.

Right here's what i need a new piston ( chunk out of side )
Conrod and needles


The bottom of the lower window on the lower curve has a couple of needle marks but i'll proberly be able to lightly file them out smooth and the lower transfer cover has a crack in it from the rod letting go.

Mc Bob.

[Mark Brubaker]

Well that's the crap McBob!! What would have caused that at an idle? ( besides rotten luck)

Mark

[mcbob]

Well i don't know for sure but we won the fastest timed cut at the Australian nationals last Nov all we did was retune the saw to the fresh fuel and turned her off it was when we were at the block and restarted the saw for a local race the saw started great and was let idle and given a lite blip and "BINGO"

All i need now is a Piston as i have a rod and rollers coming

"Wanted a Copperhead / Vintage US 820 Piston Assy "

Mac Bent Bob.

Note ... i have emailed Dave Bonbright as regards the Piston and i hope he checks his email as he's a hard man to contact if you fellas are talking with Dave you could mention my plight.

[Rob Voska]

Do you think the rod broke? Rod cap broke? Bolt broke? What kind of bolt? Splined?
Allen brand socket head cap screw? Under torqued? Over torqued?

[mcbob]

Do you think the rod broke? Rod cap broke? Bolt broke? What kind of bolt? Splined?
Allen brand socket head cap screw? Under torqued? Over torqued?

G'day Rob,

This engine had done less than 10 minutes work before i changed it into the Mac chassis from the Root frame i used to have it in .... so i had to do a crank change from the straight shaft to a tapered 10 degree shaft which i got from Rick the tapered shaft was new and with this little amount of work or time on the engine i reused the conrod bolts ( maybe that was my mistake not using new bolts ) and torqued them to 90 lbs.

I'm a little disappointed in the cylinder and the chrome finish for when i stripped the engine to remove the piston and crank i seen a lot of the chrome still shiny new and unmarked but the rest of the cylinder settling in as regards bedding the cylinder to the rings ... maybe these chrome bores take a while to bed into with the rings.

The lower face on the crank looks stressed the section i'm taking about is the face at the bottom when the crank is at it lowest point in the cylinder with no full contact with the needle rollers so the edges of the journal show no wear and are still dull compared to the rest of the journal.

The damage to the cylinder itself is minor and i have filed it clean, I'm glad it didn't spit the dummy at much higher RPM as i'm sure i wouldn't have an engine to rebuild.

So if any of you fellas have a spare new piston i don't need rings as i have them as i bought a couple of spare sets off Rick some time back ..... then please let me know.

This time when i screw the engine back together i'll leave the head gasket out and use a special sealant and to be sure i'll use the new Dave Bonbright conrod bolts.

Mc Bent Bender Bob.

[ted johnson]

Hi, McBob. Sad about the new engine. Did it have the Dave B./ARP 320KSI socket head rod screws when it broke? You can safely torque these to 115 In/Lbs per Big Dave. These things ain't cheap, but.... I'm putting them in the 101, and they're in both my Dave B. 610's. Glad you got a set. WIHA has a very nice tee handle preset torque wrench that's set to just over 112 In/Lbs. It is perfect for the ARP bolts, and is also fine for the Bender's head bolts. I've changed the head bolts out on both 610's for studs with nuts and flat washers. I feel better about a steel nut on a steel stud over a steel screw in an aluminum block. The best of luck with the rebuild! Ted

[Rick Chapman]

Mc Bob...
Sorry to hear about your delema... I'd have to say the rod bolts broke since they are the weak point of that assembly. If you used a used rod, are you sure the bearing end is round??
I always used the 101AA spline head rod bolts and torqued the rod bolts to 115 inch lbs and use Red Lock-tite. The the only time I had a rod failure, and it was actually the rod bolts broke, was when I used the Allen Head bolts. But I replaced any rod bolts 1/2 way through the season, just for precaution. Keep me posted on how things are going down under...
Email me at Rixkart@aol.com... I may be able to offer some other tips..
Rick

[mcbob]

Your right Rick i'd say it those origional useless bolts letting go tore the head off one and yanked the other straight out taking the thread along with it.
The rod and bolts were the one's that came fitted standard you think that US Power would be wise enough to fit the better rod bolts to start with considering what one pays for a new motor





Mc Bob

[Rick Chapman]

I know what you mean. This is just one reason the engine never caught on here in the states. When the engine came out, it came with a weak rod. To many destroyed engines. Then there was the poor quality control on the port location. Couldn't always pass tech. Then there was the clutch. NORAM was not a good racing clutch. Don't skimp on the rod bolts, I guess I should have told you this before.. I still like to 101AA rod bolts. I have never rounded the head off a spline head.
Rick

[ted johnson]

McBob and Rick - The 320 KSI ARP fasteners are FAR stronger than the McCulloch spline head bolts. These were developed by the best known racing fastener company in the world. Talk to Dave Bonbright. I had Dave shorten a set especially for my 101, to replace the brand new spline heads in my new rod. Standard socket heads are generally 180 KSI, and I believe the spline heads are 210-240 KSI tensile. The ARP alloy and fabrication methods are much better. TJ