Chevy powdered metal rods

[Truckedup]

14102187. The date code comes out to Nov '86, one of the earliest versions. They are a heavy casting with center bolt valve covers and 72 degree bolt angle on the center 2 intake side.

They are the TBI truck heads? The ones some call "junk" ?

[rfoll]

These came from a marine engine.

[midnightbluS10]

They're still 187 swirl port TBI heads. Found on 87-up 305 TBI trucks.

[rfoll]

I mentioned the heavy casting because many of the 305 heads were not and prone to cracking. I started the engine on the test stand a couple days ago. My current test stand carb is a Street Demon 1904, the 750 carb. It started instantly and ran like a top. No leaks!

[pdq67]

I would not use the spdp manifold for anything.
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You put an SP-2P on a low compression 350 smog engine along with say an old stock -929 cam OR smaller along with a set of small long tube headers and pipes and I think it will work for you.

I have an SBC 4-barrel SP-2P as well as a BBC 4-barrel one in my garage as well as a good pair of old -206 BBC true closed chambered heads to play with.

pdq67.

[Krooser]

Smacking a powered metal rod on its side in a vise with a big hammer is introduceing a force into the rod that it will never see unless the Crank and or a cylinder wall gives out first!

It is only indicative of rod material, "Toughness"! And right, it is not a true engine part test!

But it sure illustrates if a rod will bend or break, imho. And I know PM rods have come a long way but I will install forged rods.

pdq67

The PM rods ARE forged...but they forge them of PM instead of a chunk of cast steel.

[cardo0]

Well I think they are more like squeezed or squished than hammer forged. And they are fairly accurate in weight and dimensions. Problem is there's no balance pads to grind off material to re-balance them. And some types with the broken caps can't be reconditioned on the big end from what I have read though some can be. Replace the stock rod bolts and you need to recon the big end.

And I was looking over the LS 6.098" rods for Gen I sbc use as the journal sizes and pin sizes and rod width are the same as sbc rods but no one that I can find sells pistons for a Gen I motor using LS 6.098" rods.

[pdq67]

Not onna the General's better idea's as I see PM Rods.

pdq67

[pamotorman]

I believe the new ZL-1 755HP corvette uses PM rods

[midnightbluS10]

Well I think they are more like squeezed or squished than hammer forged. And they are fairly accurate in weight and dimensions. Problem is there's no balance pads to grind off material to re-balance them. And some types with the broken caps can't be reconditioned on the big end from what I have read though some can be. Replace the stock rod bolts and you need to recon the big end.

And I was looking over the LS 6.098" rods for Gen I sbc use as the journal sizes and pin sizes and rod width are the same as sbc rods but no one that I can find sells pistons for a Gen I motor using LS 6.098" rods.

Forging requires heat and compressive forces. Whether from constant pressure or hammering, compression is compression. Like the difference between a blade/blacksmith using a hand hammer and a hydraulic press. You wouldn't make a thing out of a bladesmith using a hydraulic press to form and shape the billet. Why would that change just because the size of the machine is larger? Still the same process.

[midnightbluS10]

Not onna the General's better idea's as I see PM Rods.

pdq67

Not sure why you think that. They're made almost the same as a regular forging. They just start with a powdered metal, like Japanese swordsmith do when they make swords from powdered steel.

It's been proven over and over that they outperform the pink rods they were made to replace.



https://www.dragzine.com/news/howards-r ... etal-rods/


What makes you say it's not one of their better ideas? They don't have a rash of failures. There weren't recalls on them. They don't have odd properties or require extra maintenance. What makes them so bad to you? Why do you think they're something "less" than pink rods? Some personal experience where they failed miserably and caused a catastrophic failure with little to no identifiable cause? Help us out here.

[rfoll]

The reason I asked in my first post was to determine what parts would be in an engine I was considering. Turned out the guy didn't really know what year he had, same old mid 70"s junk. I have a set of rods and pistons from a low mile Vortec 350 I am going to use in my current build. When I dropped rod and piston assemblies on the scale, the differences high to low are less than 2 grams. This build is going to clear a bunch of junk from the shelves. I had a low mile block that only need a hone. I am using a pair of 305 boat motor screw port heads with 1.84 valves and 58 cc chambers. Static CR comes out to 9.27:1. The cam is the 204/214 rv grind I have had for over 10 years. As this is a low rpm application, (2.73 gears), I am going to use the SP-2P manifold I have no other use for. The out of pocket cost is the set of 1.5 mm piston rings. It should make all the power I need, hopefully it will get decent economy.

The screw port heads use no more than 25 deg. total timing but still need the same initial as "normal" for the cam timing, so you need to have a short mechanical advance curve. With the 204/214, 12 initial, start 1000 RPM, total 25 at 2500~~3000 or so. The screw heads are really-really-really "fast burn" heads and will not tolerate more than 25.

The SP-2P intake will work OK but if you play with the carb jetting will you will find the jet size may fall outside the "normal" range for the carb you are using. The unusual carb jetting may be why some people had bad experiences with them. I recall tuning a stock 350 with one on it that required a jet and metering rod combination in the QJet that would have been ridiculously rich on the stock intake. Another one with a 600 Holley, small cam and headers, went the other way, unusually small jet size. Go figure. Ain't we lucky jets are threaded.

I have the car on the road, and I thought I would share a quick update. I installed a ready to run MSD distributor with a black,(largest), bushing and a light silver and blue spring set. with 8 degrees initial. It pinged so bad I was almost afraid to drive it home. I replaced the light silver with the heavy silver, and it was drivable, but would still ping badly under certain loads. I didn't even fool with the next step and put in the second heavy spring. Everything is happy now and the engine runs like a top. It pulls really hard from a dead idle to wherever the intake and 2 1/2" single exhaust system run out of capacity. I need to get my AFR meter on it to check the fuel curve. The QJ I'm using was really rich on my truck, but this combination is night and day different. I will need to adjust my odometer calibration before I can make a mileage run. The transmission isn't original to the car, and the speedo is way off.

[autogear]

In reference to an earlier comment:

PM for gears that are in direct mesh, under load, and pass contaminant laden oil through them...is a bad idea.
PM for con-rods in any engine resembling a factory street car, with safety margins built into the system...is a good idea.
PM rods in the hands of a loon with an Acme cartoon mallet? well...its still funny

Just like hypereutectics are "bad" pistons and you should never use them....if you insist on going north of 5500rpm or don't have a handle on your tune. I imagine there are millions of hypereutectic pistons in use across the world, with no problems at all.

Using a material outside of its intended purpose and seeing a failure, does not necessarily mean its junk.

[peejay]

Well I think they are more like squeezed or squished than hammer forged. And they are fairly accurate in weight and dimensions. Problem is there's no balance pads to grind off material to re-balance them. And some types with the broken caps can't be reconditioned on the big end from what I have read though some can be. Replace the stock rod bolts and you need to recon the big end.

PM rods typically use capscrews, not bolts and nuts. There is no need for a pressfit bolt to locate the rod and cap when the fracture does a better job of locating than a "traumatic" pressed in bolt ever would.

If the rods are manufactured to a close spec (the entire advantage of PM in the first place), why would you need to rebalance?

Likewise, if for some reason you need to resize them, oversize OD bearings exist. Of course, people have anurysms over the next thing they encounter with modern engines: No bearing tangs. It's not like bearing tangs do anything useful other than making assembly slightly easier, anyway...

[pdq67]

The reason I asked in my first post was to determine what parts would be in an engine I was considering. Turned out the guy didn't really know what year he had, same old mid 70"s junk. I have a set of rods and pistons from a low mile Vortec 350 I am going to use in my current build. When I dropped rod and piston assemblies on the scale, the differences high to low are less than 2 grams. This build is going to clear a bunch of junk from the shelves. I had a low mile block that only need a hone. I am using a pair of 305 boat motor screw port heads with 1.84 valves and 58 cc chambers. Static CR comes out to 9.27:1. The cam is the 204/214 rv grind I have had for over 10 years. As this is a low rpm application, (2.73 gears), I am going to use the SP-2P manifold I have no other use for. The out of pocket cost is the set of 1.5 mm piston rings. It should make all the power I need, hopefully it will get decent economy.

Heck, if his decks haven't been decked, the Letters at the end of the VIN stamped on the little deck pad that is just above the pass. side top water pump bolt will decode the engine.

Post them up and somebody can decode your engine!!

If I remember right, NastyZ28 has a long list and if it's code isn't there, my two engine books each have very long lists!!

pdq67