I have build a new cylinder head for my super six. New valves (1.725" I /1.42" E) has been made from Ford 300 stuff. New bronze guides, new retainers, new Comp Cam springs etc. Few hundred kilometers before making any hi-rpm performance tests.

At the first w.o.t. test run on the highway (have no well working speedo, no rpm meter) a rattling noise came in. Slowing down. Noise went off. Couple trials to raise the speed and the noise come again. Last time with knocking sound.

I shut down the engine, then called my wife to tow the car home. At the garage I opened the cover and saw one pushrod totally lost the cup at the top end, another just going to crack. These rods were Mopar Performance material. They are not solid steel, but seem to be welded together from a bearing ball, a tube and a small cup. Both damaged rods cracking from the weld. I got them in a hydraulic to solid lifters replacement kit Together with rockers I had some troubles, too. All were packed to MP logo bags.

I like to replace all of them now. Any recommendations, where to (mail-)order good stock length pushrods?

for (at least) temporary replacements try a junkyard, i got some for free out of a 72 gold duster...

I think JKKo is from Finland which makes junkyard cars of his nature rare...

If you have to have a new set made to your specs, you can contact Smith Brothers: http://www.pushrods.net/

I got a nice set the length I needed and they're 3/8" thick not 5/16" so plenty stiff (no 'bends' during operation).


good luck,

-D.Idiot

Is this engine using mechanical or hydraulic lifters?
Please check for spring retainer to valve guide interference, also check for spring coil bind. My bet is that there is interference causing the pushrods to break.
http://www.slantsix.org/articles/hrm-sl ... 03-pg3.jpg

I have a large bucket full of used SL6 pushrods if you need a few good sets.
(I can ship overseas but it takes a while for stuff to get there)
DD

This engine is built with solid lifters and MP 244 deg .436" cam. The springs are stock replacement ones from Comp Cam (970-12) and the coil bind is coming @ 0.51" or something. I have checked this tolerance visually and with tools, because I had to replace the springs for that reason during the head test rotations.

Both broken pushrods are from exhaust valves, the center ones. I have been thinking of the mechanism what could cause this. I had some 100+ kmh speed when the noise came in first time, the rattling one. I tried to lift the pedal as soon as possible but because I was passing a bus and there was another car behind me I could not take the speed down immediately. I have 3.55 gears. so there was about 3000 rpm, not so much for a new valve train? The rattling noise went off slowly when driving at lower rpm, but not immediately when the rpm decreased. The noise never came when making short accelerations, but when the rpm was "off idle" for longer time.

A rattling noise means something is loose. Could it be possible the exhaust guide tolerances went near zero due the exhaust valve heating, the valves jammed a little open and then the pushrods get some hits to upper end cup edge and so on....

I broke my slant at 2004. This was the common oilpump gear failure. Pump get damage at highway at very high speed. There was too much hassle and I put my Dart to a barn. And I bought a VW!!!!

The Engine has been sitting on a stand since 2005 and today I get it finally assembled. There was melt bearings which I replaced. Even the crank was covered with bearing metal but just a polishing and it come fine. Just a honing for the cylinders and new rings. New oil pump. Block milling to 10:1 compression. Short pushrods. And a new cam. I had a NOS Mopar Performance 268 degree cam which I installed to the engine. The engine has also Dutra Duals, which I assume to be the only set in Finland. I have 2bbl super six manifold and the cylinder head has big valves with bronze guides and there is also some porting near the valve area.

What would be the useful RPM range for this combo?

I am thinking to use a BBD from 318 engine (I have it). Or I can use a Big Block 2bbl which is much larger. Recommendations?

I like to get 15sec time slip with "super six"